2,440 results on '"SCHIFF bases"'
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2. Anchoring of Copper(II)-Schiff Base Complex in SBA-15 Matrix as Efficient Oxidation and Biomimetic Catalyst.
- Author
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Mureseanu M, Bleotu I, Spînu CI, and Cioatera N
- Subjects
- Hydrogen Peroxide, Schiff Bases, Silicon Dioxide, Copper, Biomimetics
- Abstract
A new mononuclear Cu(II) complex [Cu(L
2 )(H2 O)2 ], where L is the Schiff base 2-[2-(3-bromopropoxy)benzylideneamino] benzoic acid, was synthesized and covalently anchored onto an amino-functionalized SBA-15 mesoporous silica in order to obtain an efficient heterogeneous catalyst. The elemental, structural, textural and morphological characterization confirmed the coordination of the central Cu(II) ion with two ligands and two H2 O molecules in the synthesized complex and its successful immobilization into the inner pore surface of the NH2 -functionalized support without the loss of the mesoporous structure. The catalytic activity of the free or immobilized Cu(II) complex was tested in the oxidation of cyclohexene with H2 O2 under an air atmosphere and the dismutation reaction of the superoxide radical anions with very good results. In addition, catalyst reuse tests claim its suitability in alkene oxidation processes or as a biomimetic catalyst.- Published
- 2024
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3. Schiff Bases Functionalized with T-Butyl Groups as Adequate Ligands to Extended Assembly of Cu(II) Helicates.
- Author
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Fernández-Fariña S, Velo-Heleno I, Martínez-Calvo M, Maneiro M, Pedrido R, and González-Noya AM
- Subjects
- Ligands, Electron Spin Resonance Spectroscopy, Schiff Bases chemistry, Copper chemistry
- Abstract
The study of the inherent factors that influence the isolation of one type of metallosupramolecular architecture over another is one of the main objectives in the field of Metallosupramolecular Chemistry. In this work, we report two new neutral copper(II) helicates, [Cu
2 (L1 )2 ]·4CH3 CN and [Cu2 (L2 )2 ]·CH3 CN, obtained by means of an electrochemical methodology and derived from two Schiff-based strands functionalized with ortho and para-t-butyl groups on the aromatic surface. These small modifications let us explore the relationship between the ligand design and the structure of the extended metallosupramolecular architecture. The magnetic properties of the Cu(II) helicates were explored by Electron Paramagnetic Resonance (EPR) spectroscopy and Direct Current (DC) magnetic susceptibility measurements.- Published
- 2023
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4. Spectroscopic Characterization and Biological Activity of Hesperetin Schiff Bases and Their Cu(II) Complexes.
- Author
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Sykuła A, Nowak A, Garribba E, Dzeikala A, Rowińska-Żyrek M, Czerwińska J, Maniukiewicz W, and Łodyga-Chruścińska E
- Subjects
- Humans, Schiff Bases pharmacology, Schiff Bases chemistry, Spectroscopy, Fourier Transform Infrared, HeLa Cells, Caco-2 Cells, Oxygen, Ligands, Copper pharmacology, Copper chemistry, Coordination Complexes pharmacology, Coordination Complexes chemistry
- Abstract
The three Schiff base ligands, derivatives of hesperetin, HHSB ( N -[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]isonicotinohydrazide), HIN ( N -[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]benzhydrazide) and HTSC ( N -[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]thiosemicarbazide) and their copper complexes, CuHHSB, CuHIN, and CuHTSC were designed, synthesized and analyzed in terms of their spectral characterization and the genotoxic activity. Their structures were established using several methods: elemental analysis, FT-IR, UV-Vis, EPR, and ESI-MS. Spectral data showed that in the acetate complexes the tested Schiff bases act as neutral tridentate ligand coordinating to the copper ion through two oxygen (or oxygen and sulphur) donor atoms and a nitrogen donor atom. EPR measurements indicate that in solution the complexes keep their structures with the ligands remaining bound to copper(II) in a tridentate fashion with (O
- , N, Oket ) or (O- , N, S) donor set. The genotoxic activity of the compounds was tested against model tumour (HeLa and Caco-2) and normal (LLC-PK1) cell lines. In HeLa cells the genotoxicity for all tested compounds was noticed, for HHSB and CuHHSB was the highest, for HTSC and CuHTSC-the lowest. Generally, Cu complexes displayed lower genotoxicity to HeLa cells than ligands. In the case of Caco-2 cell line HHSB and HTSC induced the strongest breaks to DNA. On the other side, CuHHSB and CuHTSC induced the highest DNA damage against LLC-PK1.- Published
- 2023
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5. Probing Biothiols Using a Red-Emitting Pyridoxal Derivative by Adopting Copper(II) Displacement Approach and Cell Imaging.
- Author
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Bhardwaj V, Patel DA, Majeed SA, Sahul Hameed AS, Aatif MA, Kumar ASK, and Sahoo SK
- Subjects
- Dimethyl Sulfoxide, Fluorescent Dyes chemistry, Glutathione, HEPES, Homocysteine, Protons, Pyridoxal, Schiff Bases, Solvents, Spectrometry, Fluorescence, Copper chemistry, Cysteine
- Abstract
An aggregation-induced emission (AIE) active Schiff base L was obtained by reacting pyridoxal and 2-hydroxy-1-naphthaldehyde with p-phenylenediamine in two simple steps. The colorimetric, UV/VIS and fluorescence studies of L revealed that the yellow emissive L (λ
em =540 nm, λex =450 nm) in pure DMSO turned to a red-emissive L, when the poor solvent fraction (HEPES buffer, 10 mM, pH 7.4) was increased above 50 % in DMSO. The SEM and DLS results indicated the formation of self-aggregates of L that restricted the intramolecular motion and promoted the excited state intramolecular proton transfer (ESIPT) process. The cations sensing ability of the AIEgen L was explored in HEPES buffer (5 % DMSO, 10 mM, pH 7.4), where Cu2+ selectively quenched the fluorescence at 608 nm due to the chelation-enhanced fluorescence quenching (CHEQ) effect with an estimated sensitivity limit of 0.9 μM. Subsequently, the in situ formed AIEgen L-Cu2+ complex was applied for the cascade detection of glutathione (GSH), cysteine (Cys) and homocysteine (Hcy). The decomplexation of Cu2+ from the AIEgen L-Cu2+ by GSH, Cys and Hcy restored the quenched fluorescence emission of AIEgen L at 608 nm. With this Cu2+ displacement approach, the concentration of Cys, Hcy and GSH can be detected down to 2.8 μM, 3.12 μM and 2.0 μM, respectively. The practical utility of AIEgen L and AIEgen L-Cu2+ was examined by monitoring the selective analytes in real environmental and biological samples, and also applied successfully for the cell imaging applications., (© 2022 Wiley-VHCA AG, Zurich, Switzerland.)- Published
- 2022
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6. A highly potential acyclic Schiff base fluorescent turn on sensor for Zn 2+ ions and colorimetric chemosensor for Zn 2+ , Cu 2+ and Co 2+ ions and its applicability in live cell imaging.
- Author
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Jayaraj A, Gayathri MS, Sivaraman G, and P CAS
- Subjects
- Humans, HeLa Cells, Density Functional Theory, Schiff Bases chemistry, Colorimetry methods, Fluorescent Dyes chemistry, Zinc chemistry, Zinc analysis, Copper chemistry, Copper analysis, Cobalt chemistry, Spectrometry, Fluorescence
- Abstract
Herein, we report two acyclic Schiff base receptors CS-1 and CS-2 capable of being selective fluorescent turn on for Zn
2+ ions and colorimetric chemosensor for Zn2+ , Cu2+ , and Co2+ ions by showing a colour change from colourless to yellow in 1:1 ratio of acetonitrile and HEPES buffer (1:1, v/v, pH 7.4) without the interference from other metal ions screened (Cd2+ , Hg2+ , Sn2+ , Ni2+ , Cr3+ , Mn2+ , Pb2+ , Ba2+ , Al3+ , Ca2+ , Mg2+ , K+ and Na+ ). The fluorescence turn on enhancement towards Zn2+ ions is ascribed to PET blocking, suppression of -C=N- isomerisation, and the ESIPT process. The selectivity, competitivity and reversibility of the synthesised probes (CS-1 and CS-2) made them promising chemosensors for the detection of Zn2+ , Cu2+ , and Co2+ ions. The density functional theory (DFT) calculations have theoretically endorsed the colorimetric changes in the examined absorption spectra and binding mode of both CS-1/CS-2 with metals ions. In addition,1 H NMR titrations were also consistent with the recognition mechanism of Zn2+ ions with the CS-1/CS-2. Further, the Jobs plot analysis infers a 1:1 stoichiometric ratio for both evaluating receptors CS-1 and CS-2 with Zn2+ , Cu2+ and Co2+ ions and was supported by DFT, NMR (only for Zn2+ ions), UV-Visible, and fluorescence spectroscopic studies. Moreover, the detection limits of CS-1 and CS-2 for Zn2+ ions were determined to be 7.69 and 5.35 nM, respectively, which is less compared to the detection limit of Cu2+ , Co2+ ions as well as the limit approved by the United State Environmental Protection Agency (US EPA). The probes CS-1 and CS-2 found to show high fluorescence quantum yields at pH = 7 during the titration with Zn2+ as compared with other pHs (5-6 and 8-11). Gratifyingly, fluorescence microscopy imaging in HeLa cells revealed that the pair of receptors can be employed as an excellent fluorescent probe for the detection of Zn2+ ions in living cells, indicating that this facile chemosensor has a huge potential in cellular imaging., (Copyright © 2021 Elsevier B.V. All rights reserved.)- Published
- 2022
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7. DNA cleavage mechanism by metal complexes of Cu(II), Zn(II) and VO(IV) with a schiff-base ligand.
- Author
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Rodríguez MR, Lavecchia MJ, Parajón-Costa BS, González-Baró AC, González-Baró MR, and Cattáneo ER
- Subjects
- Schiff Bases, Copper chemistry, DNA chemistry, Molecular Docking Simulation, Molecular Dynamics Simulation, Vanadates chemistry, Zinc chemistry
- Abstract
Metal ions and metal complexes are important components of nucleic acid biochemistry, participating both in regulation of gene expression and as therapeutic agents. Three new transition metal complexes of copper(II), zinc(II) and oxidovanadium(IV) with a ligand derived from o-vanillin and thiophene were previously synthesized and their antitumor properties were studied in our laboratory. To elucidate some molecular mechanisms tending to explain the cytotoxic effects observed over tumor cells, we investigated the interaction of these complexes with DNA by gel electrophoresis, UV-Vis spectroscopy, docking studies and molecular dynamics simulations. Our spectroscopy and computational results have shown that all of them were able to bind to DNA, Cu(II) complex is located in the minor groove while Zn(II) and oxidovanadium(IV) complexes act as major groove binding molecules. Interestingly, only the Cu(II) complex caused double-strand DNA nicks, consistent with its higher cytotoxic activities previously observed in tumor cell lines. We propose that the DNA-complex interaction destabilize the molecule either disrupting the phosphodiester bonds or impairing DNA replication, giving those complexes strong antitumor potential., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)
- Published
- 2021
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8. A new highly selective colorimetric Schiff base chemosensor for determining the copper content in artisanal cachaças.
- Author
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Onça LO, de Souza JCP, Dos Santos IGN, Santos ES, Soares SM, and Diniz PHGD
- Subjects
- Brazil, Colorimetry, Ions analysis, Copper analysis, Schiff Bases
- Abstract
This work demonstrated the feasibility of applying the Schiff base 5-bromo-2-salicyl-beta-alanine as a colorimetric chemosensor for the spectrophotometric quantification of the copper content in artisanal cachaças. For this, the experimental conditions were optimized to obtain an efficient, sensitive, reversible, and highly selective chemosensor to Cu
2+ ions. The complex stoichiometry was 1:1, with a formation constant of 5.82 × 102 L mol-1 and molar absorptivity of 5.82 × 103 mol L-1 cm-1 . Then, a spectrophotometric analytical method was developed and validated according to the Brazilian legislation. The linearity of the analytical curve was demonstrated by ANOVA, at a confidence level of 95%. The limits of detection and quantification were 0.0659 and 0.200 mg L-1 , respectively. The coefficients of variation for both the intra- and inter-day precisions were lower than 3.83%, and the accuracy presented a mean recovery of 100.55 ± 2.87%. The absence of a matrix effect was confirmed by the standard addition method, and the copper content in three artisanal cachaças from different geographical origins was estimated as lower than 2.93 mg L-1 . This result was in accordance with the Brazilian legislation but reinforces the need to carry out stricter quality control to achieve exportation standards. Therefore, the proposed method can be considered a simple, selective, linear, precise, and accurate tool that involves only a simple complexation reaction through the addition of the chemosensor solution in a buffered medium. As a consequence, the simplicity, practicality, rapidity, and low cost of synthesis of the proposed Schiff base chemosensor are highlighted., (Copyright © 2020 Elsevier B.V. All rights reserved.)- Published
- 2020
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9. The first and low cost copper Schiff base/manganese oxide bio nanocomposite from unwanted plants as a robust industrial catalyst.
- Author
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Naeimi A, Abbasspour S, and Torabizadeh SA
- Subjects
- Alcohols chemistry, Catalysis, Colloids, Hydrogen Peroxide chemistry, Metal Nanoparticles chemistry, Oxidation-Reduction, Schiff Bases, Amaranthus chemistry, Copper chemistry, Green Chemistry Technology, Manganese Compounds chemistry, Nanocomposites chemistry, Oxides chemistry
- Abstract
In this paper, the first bio-nano colloid including manganese oxide nanoparticles and copper nanocomplex in the presence of Amaranthus spinosus as one unwanted plant was prepared (Mn
3 O4 /CuL bio-nanocolloid). As-prepared bio nanocolloid was analysed completely by different techniques such as FT-IR, ICP-AES, SEM, EDX, TEM and elemental analysis to have the size, structure, morphology and elements in this compound. This bio-nanocolloid showed high catalytic activity towards green oxidation reactions of alcohols using hydrogen peroxide under solvent free conditions. The longevity, easy and practical recoverability of the solid catalyst was also confirmed for six times. The natural starting material for a long-term stability catalyst preparation, using ideal oxidant (H2 O2 ), solventless and easy work up show the great potential in scalability for actual industries applications.- Published
- 2020
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10. Modulation of Nuclearity in Cu II -Mn II Complexes of a N 2 O 2 Donor Ligand Depending upon Carboxylate Anions: Structures, Magnetic Properties and Catalytic Oxidase Activities.
- Author
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Ganguly S, Mayans J, and Ghosh A
- Subjects
- Catalysis, Electrochemistry, Ligands, Magnetic Phenomena, Models, Molecular, Molecular Structure, Oxidoreductases chemistry, Structure-Activity Relationship, Carboxylic Acids chemistry, Copper chemistry, Manganese Compounds chemistry, Nitrogen Oxides chemistry, Oxidoreductases metabolism
- Abstract
Three new hetero-metallic copper(II)-manganese(II) complexes, [(CuL)
2 Mn3 (C6 H5 CO2 )6 ] (1), [(CuL)2 Mn(CH3 CO2 )2 ] (2), and {[(CuL)2 Mn(C6 H5 CH2 CO2 )2 ] ⋅ 2CH3 CN} (3), have been synthesized using [CuL] as ''metalloligand'' (where H2 L=N,N'-bis(2-hydroxynaphthyl-methylidene)-1,3-propanediamine). Single-crystal structural analyses show an almost linear penta-nuclear structure for complex 1 where a square planar [CuL] unit is connected to each of the two terminal MnII ions of a linear, centrosymmetric [Mn3 (benzoate)6 ] unit through the double phenoxido bridges. Both complexes 2 and 3 possess a linear tri-nuclear structure where two terminal square-pyramidal [CuL] units are bonded to the central MnII ion through double phenoxido oxygen atoms along with a syn-syn bridging acetate (for 2)/phenyl acetate (for 3). All three complexes exhibit catecholase, and phenoxazinone synthase-like activities under aerial conditions. For catecholase like activity, the turnover numbers (kcat ) are 595, 40, and 205 h-1 whereas, for phenoxazinone synthase like activity, the turnover numbers are 25, 4, and 11 h-1 for complexes 1-3, respectively. The mechanism of both catalytic oxidase activities is proposed on the basis of mass spectral evidences. Variable-temperature (2-300 K) dc molar magnetic susceptibility measurements of 1 reveal antiferromagnetic interactions between the Cu-Mn centres (J1 =-29.3 cm-1 ), and also between the Mn-Mn centres of the [Mn3 (benzoate)6 ] unit (J2 =-0.68 cm-1 ). On increasing the magnetic field at 2 K, its ground spin state changes from S=3/2 to S=5/2 at 4 T, attributable to the low value of J2 which makes the excited spin states close in energy with the ground spin state. Complexes 2 and 3 show antiferromagnetic coupling interactions between the Cu-Mn pairs with J values of -9.51, and -5.32 cm-1 , respectively., (© 2020 Wiley-VCH GmbH.)- Published
- 2020
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11. Dinuclear Copper(II) Complexes with Schiff Bases Derived from 2-Hydroxy-5-Methylisophthalaldehyde and Histamine or 2-(2-Aminoethyl)pyridine and Their Application as Magnetic and Fluorescent Materials in Thin Film Deposition.
- Author
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Barwiolek M, Kaczmarek-Kędziera A, Muziol TM, Jankowska D, Jezierska J, and Bieńko A
- Subjects
- Crystallography, X-Ray, Ligands, Magnetic Phenomena, Models, Molecular, Copper chemistry, Fluorescence, Histamine chemistry, Organometallic Compounds chemistry, Organometallic Compounds metabolism, Pyridines chemistry, Schiff Bases chemistry
- Abstract
Two Cu(II) complexes, 1 and 2 , with tridentate Schiff bases derived from 2-hydroxy-5-methylisophthalaldehyde and histamine HL1 or 2-(2-aminoethyl)pyridine HL2 , respectively, were obtained and characterized by X-ray crystallography, spectroscopic (UV-vis, fluorescence, IR, and EPR), magnetic, and thermal methods. Despite the fact that the chelate formed by the NNO ligand donors (C26-C25H
2 -C24H2 -N23=C23H-C22-C19Ph(O1)-C2(Ph)-C3H=N3-C4H2 -C5H2 -C6 fragment) are identical, as well as the synthesis of Cu(II) complexes (Cu:L = 2:1 molar ratio) was performed in the same manner, the structures of the complexes differ significantly. The complex 1 , {[Cu2 (L1)Cl2 ]2 [CuCl4 ]}·2MeCN·2H2 O, consists of [Cu2 (L1)Cl2 ]+ units in which Cu(II) ions are bridged by the HL1 ligand oxygen and each of these Cu(II) ions is connected with Cu(II) ions of the next dimeric unit via two bridging Cl- ions to form a chain structure. In the dinuclear [Cu2 (L2)Cl3 ]0.5MeCN complex 2 , each Cu(II) is asymmetrically bridged by the ligand oxygen and chloride anions, whereas the remaining chloride anions are apically bound to Cu(II) cations. In contrast to the complex 1 , the square-pyramidal geometry of the both Cu(II) centers is strongly distorted. The magnetic study revealed that antiferromagnetic interactions in the complex 2 are much stronger than in the complex 1 , which was corresponded with magneto-structural examination. Thin layers of the studied Cu(II) complexes were deposited on Si(111) by the spin coating method and studied by scanning electron microscopy (SEM/EDS), atomic force microscopy (AFM), and fluorescence spectroscopy. The Cu(II) complexes and their thin layers exhibited fluorescence between 489-509 nm and 460-464 nm for the compounds and the layers, respectively. Additionally, DFT calculations were performed to explain the structures and electronic spectral properties of the ligands., Competing Interests: The authors declare no conflict of interest.- Published
- 2020
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12. A hydrophilic naphthalimide-based fluorescence chemosensor forCu 2+ ion: Sensing properties, cell imaging and molecular logic behavior.
- Author
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Liang S, Tong Q, Qin X, Liao X, Li Q, and Yan G
- Subjects
- Copper chemistry, HeLa Cells, Humans, Hydrophobic and Hydrophilic Interactions, Logic, Schiff Bases, Spectrometry, Fluorescence, Water Pollutants, Chemical chemistry, Biosensing Techniques methods, Copper analysis, Fluorescence, Molecular Imaging methods, Naphthalimides chemistry, Water Pollutants, Chemical analysis
- Abstract
In this work, a hydrophilic naphthalimide-based fluorescence chemosensor (sensor 1) was synthesized for Cu
2+ recognition, in which 2-(2-aminoethoxy)ethanol was introduced to improve the hydrophily and Schiff base acted as the multidentate ligand for Cu2+ . The effect factors, sensing mechanism and regenerability of sensor 1 for Cu2+ sensing were systematically investigated. It was found that sensor 1 displayed a long emission wavelength of 532 nm upon excited in visible light region (436 nm), and the good water solubility made it utilized in aqueous media. It could selectively react with Cu2+ over other common metal ions to form a 2:1 complex within 1 min and result in significant fluorescence quench. The fluorescence change was linear to 0.5-10.0 μmol L- 1 of Cu2+ with a low detection limit of 3.74 × 10- 8 mol L- 1 . Sensor 1 has been successfully utilized for analyzing Cu2+ in water samples as well as imaging cellular Cu2+ . Moreover, in view of fluorescence "on-off-on" switches of sensor 1 induced by Cu2+ and EDTA, an IMPLICATION logic gate was constructed based on fluorescence mode with Cu2+ and EDTA as inputs., Competing Interests: Declaration of competing interest The authors declared that they have no conflicts of interest to this work. We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2020 Elsevier B.V. All rights reserved.)- Published
- 2020
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13. Copper(II) complexes of coumarin-derived Schiff base ligands: Pro- or antioxidant activity in MCF-7 cells?
- Author
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MacLean L, Karcz D, Jenkins H, McClean S, Devereux M, Howe O, Pereira MD, May NV, Enyedy ÉA, and Creaven BS
- Subjects
- Female, Humans, MCF-7 Cells, Saccharomyces cerevisiae metabolism, Schiff Bases chemistry, Antioxidants chemical synthesis, Antioxidants chemistry, Antioxidants pharmacology, Coordination Complexes chemical synthesis, Coordination Complexes chemistry, Coordination Complexes pharmacology, Copper chemistry, Oxidative Stress drug effects
- Abstract
A series of copper(II) complexes of Schiff base-derived ligands (1-7) were studied for their pro- and antioxidant behaviour in the MCF-7 human breast cancer cell line. The coordination modes of two of the copper(II) complexes were investigated by pH-potentiometry, EPR and UV-Vis spectroscopic methods. The solution studies indicated that monomeric species are present in the Cu(II) - L1 system at neutral pH, whereas dinuclear species were observed in the case of the Cu(II) - L7 system. This difference in speciation was reflected in their relative cytotoxicities with the copper(II) complex of L1, showing significant cytotoxicity against MCF-7 cells whilst the complex of L7 was inactive. In fact, only three of the seven complexes studied in this series were cytotoxic to MCF-7 cells but this cytotoxicity did not correlate with their ability to bind to DNA, cleave DNA or act as a pro-oxidant. In contrast to previous copper(II) complexes studied by our group, the compounds studied here do not appear to lead to intracellular reactive oxygen species generation at any significant level. In a yeast-based assay, all of the copper complexes had the ability to protect Saccharomyces cerevisiae against menadione-induced oxidative stress but not hydrogen peroxide-induced stress, indicating a lack of catalase activity. Given that the adaptive mechanisms induced by hypoxia in cancer cells have selective effects, with a fine-tuned protection against damage and stress of many kinds, particularly against oxidative stress, chemotherapeutic compounds which are not pro-oxidants may offer a therapeutic advantage., (Copyright © 2019 Elsevier Inc. All rights reserved.)
- Published
- 2019
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14. Example of two novel thiocyanato bridged copper (II) complexes derived from substituted thiosemicarbazone ligand: structural elucidation, DNA/albumin binding, biological profile analysis, and molecular docking study.
- Author
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Biswas N, Saha S, Khanra S, Sarkar A, Prasad Mandal D, Bhattacharjee S, Chaudhuri A, Chakraborty S, and Roy Choudhury C
- Subjects
- A549 Cells, Animals, Binding Sites, Cattle, Cell Cycle drug effects, Cell Proliferation drug effects, Coordination Complexes chemistry, Crystallography, X-Ray, DNA chemistry, Hemolysis drug effects, Humans, Ligands, Protein Binding, Protein Conformation, Schiff Bases, Serum Albumin, Bovine chemistry, Serum Albumin, Human chemistry, Spectrometry, Fluorescence methods, Coordination Complexes pharmacology, Copper chemistry, DNA metabolism, Molecular Docking Simulation, Serum Albumin, Bovine metabolism, Serum Albumin, Human metabolism, Thiosemicarbazones chemistry
- Abstract
Two novel copper (II) substituted thiosemicarbazone Schiff base complexes [Cu(L
1 )(µ-SCN)]n (NO3 )2 ( 1 ) and [Cu2 (µ-SCN)(SCN)(L2 )2 ](NO3 ) ( 2 ) have been synthesized by condensing substituted thiosemicarbazides like 4-methyl-3-thiosemicarbazide or 4-ethyl-3-thiosemicarbazide with 2-acetylpyridine. Both the metal complexes 1 and 2 are characterized using different spectroscopic techniques like IR, UV-Vis, ESR spectroscopy followed by elemental analysis, cyclic voltammetric measurement and single crystal X-ray structure analysis. X-ray crystal structure analysis reveal that complex 1 is polymeric while complex 2 is dimeric in nature. The coordination geometry around Cu(II) are square pyramidal in which thiosemicarbazone Schiff base ligand coordinate to the central Cu(II) atom in tridentate fashion. The prominent interaction patterns of 1 and 2 with CT-DNA were examined by employing electronic absorption and emission spectral titrations, cyclic voltammetry and viscosity measurements. All the results show that CT-DNA binds with both copper (II) complexes 1 and 2 . Furthermore, protein binding ability in vitro of complexes 1 and 2 with both BSA and HSA were carried out using multispectroscopic techniques and a static quenching pattern was observed in both cases. Molecular docking study was employed to ascertain the exact mechanism of action of 1 and 2 with DNA and protein molecules (BSA and HSA). In vitro cytotoxicity activity of complexes 1 and 2 toward AGS and A549 was evaluated using MTT assay which demonstrates that both complexes 1 and 2 have superior prospectus to act as anticancer agents. Communicated by Ramaswamy H. Sarma.- Published
- 2019
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15. In-vitro evaluation studies of 7-chloro-4-aminoquinoline Schiff bases and their copper complexes as cholinesterase inhibitors.
- Author
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Zanon VS, Lima JA, Cuya T, Lima FRS, da Fonseca ACC, Gomez JG, Ribeiro RR, França TCC, and Vargas MD
- Subjects
- Animals, Cells, Cultured, Cholinesterase Inhibitors chemistry, Coordination Complexes chemistry, Coordination Complexes pharmacokinetics, Drug Evaluation, Preclinical, In Vitro Techniques, Mice, Molecular Docking Simulation, Spectrum Analysis methods, Aminoquinolines chemistry, Cholinesterase Inhibitors pharmacology, Coordination Complexes pharmacology, Copper chemistry, Schiff Bases chemistry
- Abstract
Alzheimer's disease (AD) is one of the most common age-related neurodegenerative disorders. Aggregation of amyloid-β peptide into extracellular plaques with incorporation of metal ions, such as Cu
2+ , and reduction of the neurotransmitter acetylcholine levels are among the factors associated to the AD brain. Hence, a series of 7-chloro-4-aminoquinoline Schiff bases (HLa-e) were synthesized and their cytotoxicity and anti-cholinesterase activity, assessed for Alzheimer's disease. The intrinsic relationship between Cu2+ and the amyloidogenic plaques encouraged us to investigate the chelating ability of HLa-e. Dimeric tetracationic compounds, [Cu2 (NH La-e)4 ]Cl4 , containing quinoline protonated ligands were isolated from the reactions with CuCl2 ·2H2 O and fully characterized in the solid state, including an X ray diffraction study, whereas EPR data showed that the complexes exist as monomers in DMSO solution. The inhibitory activity of all compounds was evaluated by Ellman's spectrophotometric method in acetylcholinesterase (AChE) from Electrophorus electricus and butyrylcholinesterase (BChE) from equine serum. HLa-e and [Cu(NH Ld)2 ]Cl2 were selective for AChE (IC50 = 4.61-9.31 μM) and were not neurotoxic in primary brain cultures. Docking and molecular dynamics studies of HLa-e inside AChE were performed and the results suggested that these compounds are able to bind inside AChE similarly to other AChE inhibitors, such as donepezil. Studies of the affinity of HLd for Cu2+ in DMSO/HEPES at pH 6.6 and pH 7.4 in μM concentrations showed formation of analogous 1:2 Cu2+ /ligand complexes, which may suggest that in the AD-affected brain HLd may scavenge Cu2+ and the complex, also inhibit AChE., (Copyright © 2018. Published by Elsevier Inc.)- Published
- 2019
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16. 5-Nitroimidazole-derived Schiff bases and their copper(II) complexes exhibit potent antimicrobial activity against pathogenic anaerobic bacteria.
- Author
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Oliveira AA, Oliveira APA, Franco LL, Ferencs MO, Ferreira JFG, Bachi SMPS, Speziali NL, Farias LM, Magalhães PP, and Beraldo H
- Subjects
- Anti-Bacterial Agents chemical synthesis, Anti-Bacterial Agents chemistry, Copper chemistry, Crystallography, X-Ray, Electrochemical Techniques, Microbial Sensitivity Tests, Models, Molecular, Molecular Structure, Nitroimidazoles chemistry, Schiff Bases chemistry, Anti-Bacterial Agents pharmacology, Bacteria, Anaerobic drug effects, Copper pharmacology, Nitroimidazoles pharmacology, Schiff Bases pharmacology
- Abstract
In the present work a family of novel secnidazole-derived Schiff base compounds and their copper(II) complexes were synthesized. The antimicrobial activities of the compounds were evaluated against clinically important anaerobic bacterial strains. The compounds exhibited in vitro antibacterial activity against Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides vulgatus, Bacteroides ovatus, Parabacteroides distasonis and Fusubacterium nucleatum pathogenic anaerobic bacteria. Upon coordination to copper(II) the antibacterial activity significantly increased in several cases. Some derivatives were even more active than the antimicrobial drugs secnidazole and metronidazole. Therefore, the compounds under study are suitable for in vivo evaluation and the microorganisms should be classified as susceptible to them. Electrochemical studies on the reduction of the nitro group revealed that the compounds show comparable reduction potentials, which are in the same range of the bio-reducible drugs secnidazole and benznidazole. The nitro group reduction potential is more favorable for the copper(II) complexes than for the starting ligands. Hence, the antimicrobial activities of the compounds under study might in part be related to intracellular bio-reduction activation. Considering the increasing resistance rates of anaerobic bacteria against a wide range of antimicrobial drugs, the present work constitutes an important contribution to the development of new antibacterial drug candidates.
- Published
- 2018
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17. Photocytotoxic Copper(II) Complexes with Schiff-Base Scaffolds for Photodynamic Therapy.
- Author
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Lin RK, Chiu CI, Hsu CH, Lai YJ, Venkatesan P, Huang PH, Lai PS, and Lin CC
- Subjects
- Antineoplastic Agents chemistry, Antineoplastic Agents therapeutic use, Apoptosis drug effects, Cell Line, Tumor, Crystallography, X-Ray, Humans, Molecular Structure, Organometallic Compounds chemistry, Organometallic Compounds therapeutic use, Photochemotherapy, Photolysis, Antineoplastic Agents pharmacology, Carcinoma, Basal Cell drug therapy, Copper chemistry, Organometallic Compounds pharmacology, Schiff Bases chemistry
- Abstract
Photodynamic therapy (PDT) is a promising and minimally invasive method for the treatment of superficial diseases, and photosensitizers with high phototoxicity indices (defined as (IC
50 dark )) are essential for the development of ideal photosensitizing properties for this technology. Herein, we report a series of photocytotoxic copper(II) complexes [Cu(50 irradiation )) are essential for the development of ideal photosensitizing properties for this technology. Herein, we report a series of photocytotoxic copper(II) complexes [Cu(R QYMP)(dppn)] (R QYMP=N,N,O-tridentate Schiff-base derivatives, dppn=benzo[i]dipyrido[3,2-a;2',3'-c]phenazine), the structures of which have been confirmed by mass spectrometry and FTIR spectroscopy. X-ray crystallography revealed that the CuN4 O core of the [Cu(cumyl QYMP)(dppn)](ClO4 ) (4). This can be attributed to the formation of reactive oxygen species, cell apoptosis, and caspase-3 activation, indicating high potential of complex 4 as a photosensitizer candidate in PDT. Thus, copper complexes bearing suitable Schiff-base ligands with a dppn co-ligand may be considered for the design of efficient metal-based anticancer agents for PDT.3-OMe QYMP)(dppn)](ClO4 ) (4). This can be attributed to the formation of reactive oxygen species, cell apoptosis, and caspase-3 activation, indicating high potential of complex 4 as a photosensitizer candidate in PDT. Thus, copper complexes bearing suitable Schiff-base ligands with a dppn co-ligand may be considered for the design of efficient metal-based anticancer agents for PDT., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2018
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18. Antitumor activity of pyrrolizines and their Cu(II) complexes: Design, synthesis and cytotoxic screening with potential apoptosis-inducing activity.
- Author
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Gouda AM, El-Ghamry HA, Bawazeer TM, Farghaly TA, Abdalla AN, and Aslam A
- Subjects
- Antineoplastic Agents chemical synthesis, Antineoplastic Agents chemistry, Cell Line, Cell Proliferation drug effects, Coordination Complexes chemical synthesis, Coordination Complexes chemistry, Copper chemistry, Dose-Response Relationship, Drug, Drug Screening Assays, Antitumor, Humans, Molecular Structure, Pyrroles chemistry, Structure-Activity Relationship, Antineoplastic Agents pharmacology, Apoptosis drug effects, Coordination Complexes pharmacology, Copper pharmacology, Pyrroles pharmacology
- Abstract
Two novel series including Schiff bases of the pyrrolizine-5-carboxamides and their Cu(II) complexes were designed, synthesized and analysed using spectral and analytical techniques. The analytical results indicated the formation of the complexes in 1:1 or 1:2 (Metal:Ligand) ratio. The geometry around the Cu centers was confirmed to be tetrahedral or octahedral. The cytotoxic activity of the new compounds was evaluated using MCF-7 (human breast adenocarcinoma), A2780 (human ovary adenocarcinoma) and HT29 (human colon adenocarcinoma), in addition to MRC5 (normal human fetal lung fibroblast) cells using the MTT cytotoxicity assay. The Schiff base 12c and the Cu complex 13b were the most active in the two series with IC
50 values in the range of 0.14-2.54 μM against the three cell lines. Also, the Cu complex 13e showed excellent activity against HT29 with IC50 = 0.05μM. 7-Cyano-N-(4-methoxyphenyl)-6-((3-phenylallylidene) amino)-2,3-dihydro-1H-pyrrolizine-5-carboxamide (12c) showed high selectivity (6-13 folds) for cancerous cells over normal cells; and it induced marginal increases in the G1 and S phases of MCF-7 cells during cell cycle analysis, while compound 13b increased the MCF-7 Sub-G1 proapoptotic population, and blocked cells in the G2-M phase in a dose dependent manner. The annexin V apoptosis assay revealed the ability of compounds 12c and 13b to increase the early apoptotic MCF-7 cell populations two and three fold, respectively. Furthermore, these findings were supported by data showing that the two compounds (12c and 13b) elicit cytotoxic activity. Taken together, the data presented in this study warrants further in vitro and in vivo investigations., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)- Published
- 2018
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19. Hybrid pharmacophore approach for bio-relevant di-imines based homobimetallic complexes incorporating functionalized dicarboxylates as co-ligands: Synthesis, spectral and structural activity dependent biological insights (in-vitro DNA and HSA binding, antioxidant and cytotoxicity).
- Author
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Shakir M, Hanif S, Alam MF, Farhan M, and Younus H
- Subjects
- Antineoplastic Agents chemical synthesis, Antineoplastic Agents chemistry, Antineoplastic Agents metabolism, Antineoplastic Agents pharmacology, Cell Line, Tumor, Cell Survival drug effects, Chemistry Techniques, Synthetic, Free Radical Scavengers chemical synthesis, Free Radical Scavengers chemistry, Free Radical Scavengers metabolism, Free Radical Scavengers pharmacology, Humans, Ligands, Models, Molecular, Molecular Conformation, Organometallic Compounds chemical synthesis, Organometallic Compounds chemistry, Protein Binding, Schiff Bases chemistry, Spectrum Analysis, Carboxylic Acids chemistry, Copper chemistry, DNA metabolism, Organometallic Compounds metabolism, Organometallic Compounds pharmacology, Serum Albumin metabolism, Zinc chemistry
- Abstract
Synthesis of bio-efficient homobimetallic complexes, [Cu
2 (L1 )2 (dipic)](NO3 )2 .3H2 O (1), [Zn2 (L1 )2 (dipic)](NO3 )2 .4H2 O (2), [Cu2 (L2 )2 (oxa)](NO3 )2 .4H2 O (3) and [Zn2 (L2 )2 (oxa)] (NO3 )2 .5H2 O (4) was carried out using Schiff bases [(N1 E,N2 E)-N1 ,N2 -bis(5-chlorothiophen-2-ylmethylene)-4-chlorobenzene-1,2-diamine; L1 ] and [(N1 E,N2 E)-N1 ,N2 -bis(5-chlorofuran-2-ylmethylene)-4-chlorobenzene-1,2-diamine; L2 ] as main ligands and dicarboxylate moieties of 2,6-pyridine dicarboxylic acid (H2 -dipic) and oxalic acid (H2 -oxa) as co-ligands, respectively in order to apprehend their structure activity relationships on the basis of pharmacophore hybrid approach. The stoichiometry, geometry, thermal stability, morphology and crystallite size of the compounds were inferred by analytical, spectral (FT-IR,1 H NMR and13 C NMR and Mass), thermal (TGA/DTA), SEM and XRD studies. In-vitro DNA and HSA binding profiles of complexes were analysed by different biophysical measurements. The absorption study divulged that the observed alterations in the physico-chemical properties of complexes upon binding with DNA connoted their intercalative binding mode while fluorescence quenching mechanism was quantified by using Stern Volmer constant (KSV ); 1.73×104 (1), 1.47×104 (2), 5.65×103 (3) and 3.60×103 M-1 (4) which discerned that hybrid pharmacophore active metal complexes (1 and 2) exhibited efficient quenching effect with Ct-DNA in comparison to complexes (3 and 4) due to greater planarity and extent of conjugation (π-π interactions). The intercalative binding mode of complexes is further supported by competitive displacement assay by using fluorogenic dyes (EtBr and Hoechst 33258). The results of HSA fluorescence study divulged static quenching of the complexes (1-4) with KSV values of 7.24×104 (1), 6.03×104 (2), 5.06×104 (3) and 2.85×104 (4) while Kb values; 1.16×105 (1), 2.01×104 (2), 5.84×103 (3) and 8.60×102 (4) suggested them potent avid binder of HSA. Additionally, comparative estimation of scavenging properties using DPPH, superoxide(O2 .- ), hydroxyl (OH- ) and ABTS method and in-vitro cytotoxicity against different cell lines (MCF-7, HeLa and Hep G2) brought out distinct biopotency of complexes due to diverse structural features and chelation effect., (Copyright © 2017 Elsevier B.V. All rights reserved.)- Published
- 2017
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20. Synthesis, characterization and antifungal efficacy of C-coordinated O-carboxymethyl chitosan Cu(II) complexes.
- Author
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Liu W, Qin Y, Liu S, Xing R, Yu H, Chen X, Li K, and Li P
- Subjects
- Chitosan chemistry, Gibberella drug effects, Phyllachorales drug effects, Phytophthora drug effects, Schiff Bases, Spectroscopy, Fourier Transform Infrared, Chitosan analogs & derivatives, Copper chemistry, Fungicides, Industrial chemistry
- Abstract
A novel type of O-carboxymethyl chitosan Schiff bases (O-CSPX) was synthesized via a condensation reaction. After the coordination reaction of cupric ions, Cu(II) complexes (O-CSPX-Cu) were achieved. The theoretical structure of O-CSPX-Cu calculated by Gaussian 09 reveals that the copper ions underwent dsp
2 hybridization, coordinated by the carbon atom in the p-π conjugate group and the oxygen atoms in the acetate ion. Then, the structures were confirmed by FT-IR,1 H NMR, CP-MAS13 C NMR, elemental analysis, DSC and XRD. The antifungal properties of O-CSPX-Cu against Phytophthora capsici (P. capsici), Gibberella zeae (G. zeae) and Glomerella cingulata (G. cingulata) were evaluated at concentrations ranging from 0.05mg/mL to 0.20mg/mL. The experiments indicated that the derivatives have significantly enhanced antifungal activity after copper ion complexation compared with the original chitosan. Moreover, it was shown that 0.20mg/mL of O-CSP3-Cu and O-CSP4-Cu can 100% inhibit the growth of P. capsici. The experimental results reveal that the antifungal efficiency is related to the space steric hindrance on the benzene ring, which may provide a novel direction for the development of copper fungicides., (Copyright © 2016 Elsevier Ltd. All rights reserved.)- Published
- 2017
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21. Effect of substituents on prediction of TLC retention of tetra-dentate Schiff bases and their Copper(II) and Nickel(II) complexes.
- Author
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Stevanović NR, Perušković DS, Gašić UM, Antunović VR, Lolić AĐ, and Baošić RM
- Subjects
- Principal Component Analysis, Quantitative Structure-Activity Relationship, Chromatography, Thin Layer methods, Copper chemistry, Nickel chemistry, Schiff Bases chemistry
- Abstract
The objectives of this study were to gain insights into structure-retention relationships and to propose the model to estimating their retention. Chromatographic investigation of series of 36 Schiff bases and their copper(II) and nickel(II) complexes was performed under both normal- and reverse-phase conditions. Chemical structures of the compounds were characterized by molecular descriptors which are calculated from the structure and related to the chromatographic retention parameters by multiple linear regression analysis. Effects of chelation on retention parameters of investigated compounds, under normal- and reverse-phase chromatographic conditions, were analyzed by principal component analysis, quantitative structure-retention relationship and quantitative structure-activity relationship models were developed on the basis of theoretical molecular descriptors, calculated exclusively from molecular structure, and parameters of retention and lipophilicity., (Copyright © 2016 John Wiley & Sons, Ltd.)
- Published
- 2017
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22. Coordination ability and biological activity of a naringenin thiosemicarbazone.
- Author
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Brodowska K, Correia I, Garribba E, Marques F, Klewicka E, Łodyga-Chruscińska E, Pessoa JC, Dzeikala A, and Chrusciński L
- Subjects
- Cell Line, Tumor, DNA chemistry, HEK293 Cells, Humans, Serum Albumin, Human chemistry, Anti-Bacterial Agents chemistry, Anti-Bacterial Agents pharmacology, Antifungal Agents chemistry, Antifungal Agents pharmacology, Bacteria growth & development, Coordination Complexes blood, Coordination Complexes pharmacology, Copper chemistry, Copper pharmacology, Flavanones chemistry, Flavanones pharmacology, Fungi growth & development, Thiosemicarbazones chemistry, Thiosemicarbazones pharmacology
- Published
- 2016
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23. Ternary copper(II) complexes with amino acid chains and heterocyclic bases: DNA binding, cytotoxic and cell apoptosis induction properties.
- Author
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Ma T, Xu J, Wang Y, Yu H, Yang Y, Liu Y, Ding W, Zhu W, Chen R, Ge Z, Tan Y, Jia L, and Zhu T
- Subjects
- Animals, Antineoplastic Agents chemical synthesis, Antineoplastic Agents chemistry, Antineoplastic Agents metabolism, Cattle, Cell Line, Tumor, Coordination Complexes chemical synthesis, Coordination Complexes chemistry, Coordination Complexes metabolism, DNA metabolism, Humans, Inhibitory Concentration 50, Models, Molecular, Molecular Structure, Phenanthrolines, Phenazines pharmacology, Schiff Bases, Antineoplastic Agents pharmacology, Apoptosis drug effects, Coordination Complexes pharmacology, Copper chemistry
- Abstract
Nowadays, chemotherapy is a common means of oncology. However, it is difficult to find excellent chemotherapy drugs. Here we reported three new ternary copper(II) complexes which have potential chemotherapy characteristics with reduced Schiff base ligand and heterocyclic bases (TBHP), [Cu(phen)(TBHP)]H2O (1), [Cu(dpz)(TBHP)]H2O (2) and [Cu(dppz)(TBHP)]H2O (3) (phen=1,10-phenanthroline, dpz=dipyrido [3,2:2',3'-f]quinoxaline, dppz=dipyrido [3,2-a:2',3'-c]phenazine, H2TBHP=2-(3,5-di-tert-butyl-2-hydroxybenzylamino)-2-benzyl-acetic acid). The DNA-binding properties of the complexes were investigated by spectrometric titrations, ethidium bromide displacement experiments and viscosity measurements. The results indicated that the three complexes, especially the complex 13, can strongly bind to calf-thymus DNA (CT-DNA). The intrinsic binding constants Kb of the ternary copper(II) complexes with CT-DNA were 1.37×10(5), 1.81×10(5) and 3.21×10(5) for 1, 2 and 3 respectively. Comparative cytotoxic activities of the copper(II) complexes were also determined by 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results showed that the ternary copper(II) complexes had significant cytotoxic activity against the human lung cancer (A549), human esophageal cancer (Eca109) and human gastric cancer (SGC7901) cell lines. Cell apoptosis were detected by AnnexinV/PI flow cytometry and by Western blotting with the protein expression of p53, Bax and Bcl-2. All the three copper complexes can effectively induce apoptosis of the three human tumor cells., (Copyright © 2014 Elsevier Inc. All rights reserved.)
- Published
- 2015
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24. Multifunctional composites of chiral valine derivative Schiff base Cu(II) complexes and TiO2.
- Author
-
Takeshita Y, Takakura K, and Akitsu T
- Subjects
- Circular Dichroism, Crystallography, X-Ray, Models, Molecular, Molecular Structure, Oxidation-Reduction, Schiff Bases, Spectrophotometry, Ultraviolet, Ultraviolet Rays, Copper chemistry, Titanium chemistry, Valine chemistry
- Abstract
We have prepared four new Cu(II) complexes containing valine moieties with imidazole ligands at the fourth coordination sites and examined their photo-induced reactions with TiO2 in order of understanding the reaction mechanisms. Under a nitrogen atmosphere, the intermolecular electron transfer reactions (essentially supramolecular interactions) of these systems, which resulted in the reduction of Cu(II) species to Cu(I) ones, occurred after UV light irradiation. In this study, we have investigated the conditions of the redox reactions in view of substituent effects of aldehyde moieties. The results of cyclic voltammetry (CV) on an rotating ring-disk electrode (RRDE) suggested that the substitution effects and redox potentials were correlated. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were also performed to simulate the UV-Vis and circular dichroism (CD) spectra; the results revealed a reasonably good correlation between the substituent effects and the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals (HOMO-LUMO) gaps associated with the most intense transition bands. In addition, we summarized the substitution effects of Cu(II) complexes for their corresponding UV light-induced reactions.
- Published
- 2015
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25. Chelating ability and biological activity of hesperetin Schiff base.
- Author
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Lodyga-Chruscinska E, Symonowicz M, Sykula A, Bujacz A, Garribba E, Rowinska-Zyrek M, Oldziej S, Klewicka E, Janicka M, Krolewska K, Cieslak M, Brodowska K, and Chruscinski L
- Subjects
- Hesperidin, Schiff Bases chemistry, Chelating Agents chemistry, Copper chemistry, DNA chemistry, Flavanones chemistry, Plasmids chemistry
- Abstract
Hydrazone hesperetin Schiff base (HHSB) - N-[(±)-[5,7-dihydroxy-2-(3-hydroxy-4-methoxy-phenyl)chroman-4-ylidene]amino]benzamide has been synthesized and its crystal structure was determined. This compound was used for the formation of Cu(II) complexes in solid state and in solution which were characterized using different spectroscopic methods. The analyses of potentiometric titration curves revealed that monomeric and dimeric complexes of Cu(II) are formed above pH7. The ESI-MS (electrospray ionization-mass spectrometry) spectra confirmed their formation. The EPR and UV-visible spectra evidenced the involvement of oxygen and nitrogen atoms in Cu(II) coordination. Hydrazone hesperetin Schiff base can show keto-enol tautomerism and coordinate Cu(II) in the keto (O(-), N, Oket) and in the enolate form (O(-), N, O(-)enol). The semi-empirical molecular orbital method PM6 and DFT (density functional theory) calculations have revealed that the more stable form of the dimeric complex is that one in which the ligand is present in the enol form. The CuHHSB complex has shown high efficiency in the cleavage of plasmid DNA in aqueous solution, indicating its potential as chemical nuclease. Studies on DNA interactions, antimicrobial and cytotoxic activities have been undertaken to gain more information on the biological significance of HHSB and copper(II)-HHSB chelate species., (Copyright © 2014 Elsevier Inc. All rights reserved.)
- Published
- 2015
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26. Ultra-sensitive quantification of copper in food and water samples by electrochemical adsorptive stripping voltammetry.
- Author
-
Goudarziafshar H, Nikoorazm M, Mortazavi SS, Abbasi S, and Farmany A
- Subjects
- Adsorption, Animal Husbandry, Electrochemistry, Hydrogen-Ion Concentration, Limit of Detection, Schiff Bases, Copper analysis, Environmental Monitoring methods, Environmental Pollutants analysis, Food Analysis methods, Food Contamination analysis, Water chemistry
- Abstract
A new electrochemical adsorptive stripping voltammetry method was developed for the determination of trace amounts of copper in food and water samples. The study of electrochemical behavior of Cu ion indicated that Cu(II) and Schiff base formed a complex in H₃BO₄-NaOH buffer solution (pH = 7.25). An accumulation potential of -100 mV (vs Ag/AgCl) was applied while the solution was stirred for 60 s. The response curve was recorded by scanning the potential, and the peak current of -0.31 V (vs Ag/AgCl) was recorded. The peak current and concentration of copper accorded with linear relationship in the range of 0.04-120 ng mL(-1). The relative standard deviation (for 12 ng mL(-1) of copper) was 1.73%, and the detection limit was 0.007 ng mL(-1). The possible interference of some common ions was studied. The proposed method was applied to the determination of copper in water, rice, wheat, tea, milk, and tomato with satisfactory results.
- Published
- 2013
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27. Use of polymer-bound Schiff base as a new liquid binding agent of diffusive gradients in thin-films for the measurement of labile Cu²⁺, Cd²⁺ and Pb²⁺.
- Author
-
Fan HT, Liu JX, Sui DP, Yao H, Yan F, and Sun T
- Subjects
- China, Diffusion, Electrolytes, Environmental Monitoring, Hydrogen-Ion Concentration, Ions, Ligands, Membranes, Artificial, Metals chemistry, Metals, Heavy, Polyethyleneimine chemistry, Polymers chemistry, Pyridines chemistry, Reproducibility of Results, Rivers, Schiff Bases, Spectroscopy, Fourier Transform Infrared, Water Pollutants, Chemical chemistry, Water Purification methods, Cadmium chemistry, Copper chemistry, Lead chemistry, Water Pollutants, Chemical analysis
- Abstract
A new diffusive gradients in thin-films (DGT) device with solution of polymer-bound Schiff base (Py-PEI) derived from poly(ethyleneimine) and 2-pyridinecarboxaldehyde as the binding agent (Py-PEI DGT) was developed for measuring labile Cu(2+), Cd(2+) and Pb(2+) in waters. In synthetic solution, uptake percentages of Cu(2+), Cd(2+) and Pb(2+) by Py-PEI DGT were 99.2 ± 4.4%, 103.7 ± 4.8% and 98.7 ± 5.5% of the total metals, respectively. Performance of Py-PEI DGT was independent of pH 4-8.5 and ionic strength 1 × 10(-4)-0.1 mol L(-1). The uptake of labile metals showed agreement with the theoretical values of free ions in EDTA solution, and decreased with increase of humic acid (HA) and dissolved organic carbon (DOC) contents in water due to the complexation of HA and DOC with metals. DGT devices containing different liquid binding agents (Py-PEI, polyacrylate (PA) and poly(4-styrenesulfonate) (PSS)) were deployed in the same solution. The higher uptake percentages of Py-PEI DGT (13.2 ± 1.1, 26.5 ± 2.4 and 62.7 ± 3.2% of total Cu(2+), Cd(2+) and Pb(2+)) were obtained with respective to PSS DGT (6.7 ± 0.6, 9.2 ± 0.9 and 29.6 ± 2.7% of total above metals) and PA DGT (8.9 ± 0.9 and 16.2 ± 1.1% of total Cu(2+) and Cd(2+)) due to its relatively strong binding affinity with metals., (Copyright © 2013 Elsevier B.V. All rights reserved.)
- Published
- 2013
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28. catena-Poly[[[2-(2-chlorophenoxy)-N'-(2-oxidobenzylidene-κO)acetohydrazidato-κ2N',O]copper(II)]-μ-morpholine-κ2N:O].
- Author
-
Wang M and Lian ZX
- Subjects
- Chemistry Techniques, Synthetic, Crystallography, X-Ray, Hydrogen Bonding, Models, Molecular, Molecular Conformation, Morpholines, Schiff Bases, Coordination Complexes chemistry, Copper chemistry
- Abstract
In the title compound, {[Cu(C15H11ClN2O3)(C4H9NO)]n, the Cu(II) cation has square-pyramidal geometry. The morpholine ligand serves as a bridge to link two symmetry-related metal atoms, resulting in an infinite chain structure along the a axis. Adjacent chains are extended into a two-dimensional layered structure via hydrogen bonds formed between morpholine and amide N atoms [N-H···N = 2.971 (3) Å].
- Published
- 2013
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29. Syntheses, structure, and magnetic properties of heteronuclear Cu(II)4Fe(III)4 cluster and Cu(II)8 bimetallacycles.
- Author
-
Hu KQ, Wu SQ, An GY, Cui AL, and Kou HZ
- Subjects
- Coordination Complexes chemical synthesis, Crystallography, X-Ray, Ligands, Magnetics, Molecular Conformation, Schiff Bases, Coordination Complexes chemistry, Copper chemistry, Ferric Compounds chemistry
- Abstract
The compartmental Schiff base ligands N,N'-ethylenebis(3-hydroxysalicylidene) (H(4)L) and N,N'-propylenebis(3-hydroxysalicylidene) (H(4)L') have been employed in the synthesis of a cyclic tetranuclear Cu(II) complex [Cu(4)(L')(2)(MeOH)(3)(H(2)O)]·[Cu(4)(L')(2)(MeOH)(3)] (1), a novel octanuclear Cu(II) complex [Cu(8)(L-L)(2)(H(2)O)(4)(μ(2)-H(2)O)]·3DMF·3H(2)O (2) and a hetero-octanuclear Cu(II)-Fe(III) complex [Cu(4)Fe(4)(L)(4)(H(2)O)(3)(μ(3)-O)(2)]·3DMF·3H(2)O (3). During the formation of the Cu(8) complex (2), a new bis-Schiff base ligand (L-L)(8-) forms via the ortho-para C-C coupling of two H(4)L ligands. The bicyclic complex (2) is comprised of two cyclic Cu(4) units that are similar to that of complex 1. In the Cu(4) unit, the alternate Cu(II) ions are singly bridged by phenoxo groups. The three complexes display overall antiferromagnetic coupling, and the Cu(II)-Cu(II) magnetic coupling constant falls in the range -117.2 to -473.6 cm(-1) for complexes 1 and 2 corresponding to the bridging Cu-O(phenoxide)-Cu bond angles of 124.3-131.0°.
- Published
- 2013
- Full Text
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30. Functionalized mesoporous silica supported copper(II) and nickel(II) catalysts for liquid phase oxidation of olefins.
- Author
-
Nandi M, Roy P, Uyama H, and Bhaumik A
- Subjects
- Catalysis, Oxidation-Reduction, Porosity, Propylamines, Schiff Bases, Silanes chemistry, Alkenes chemistry, Copper chemistry, Nickel chemistry, Silicon Dioxide chemistry
- Abstract
Highly ordered 2D-hexagonal mesoporous silica has been functionalized with 3-aminopropyltriethoxysilane (3-APTES). This is followed by its condensation with a dialdehyde, 4-methyl-2,6-diformylphenol to produce an immobilized Schiff-base ligand (I). This material is separately treated with methanolic solution of copper(II) chloride and nickel(II) chloride to obtain copper and nickel anchored mesoporous materials, designated as Cu-AMM and Ni-AMM, respectively. The materials have been characterized by Fourier transform infrared (FT-IR) and UV-vis diffuse reflectance (DRS) spectroscopy, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), N(2) adsorption-desorption studies and (13)C CP MAS NMR spectroscopy. The metal-grafted mesoporous materials have been used as catalysts for the efficient and selective epoxidation of alkenes, viz. cyclohexene, trans-stilbene, styrene, α-methyl styrene, cyclooctene and norbornene to their corresponding epoxides in the presence of tert-butyl hydroperoxide (TBHP) as the oxidant under mild liquid phase conditions.
- Published
- 2011
- Full Text
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31. Synthesis and DNA binding studies of Ni(II), Co(II), Cu(II) and Zn(II) metal complexes of N1,N5-bis[pyridine-2-methylene]-thiocarbohydrazone Schiff-base ligand.
- Author
-
Tiwari AD, Mishra AK, Mishra SB, Mamba BB, Maji B, and Bhattacharya S
- Subjects
- Cobalt metabolism, Copper metabolism, DNA, Bacterial chemistry, Electron Spin Resonance Spectroscopy, Escherichia coli genetics, Magnetic Resonance Spectroscopy, Mass Spectrometry, Molecular Structure, Nickel metabolism, Pyridines chemistry, Spectrophotometry, Infrared, Zinc metabolism, Cobalt chemistry, Coordination Complexes chemical synthesis, Coordination Complexes metabolism, Copper chemistry, DNA, Bacterial metabolism, Nickel chemistry, Organometallic Compounds chemical synthesis, Organometallic Compounds metabolism, Schiff Bases, Zinc chemistry
- Abstract
The thiocarbohydrazone Schiff-base ligand with a nitrogen and sulphur donor was synthesized through condensation of pyridine-2-carbaldehyde and thiocarbohydrazide. Schiff-base ligands have the ability to conjugate with metal salts. A series of metal complexes with a general formula [MCl2(H2L)]·nH2O (MNi, Co, Cu and Zn) were synthesized by forming complexes of the N1,N5-bis[pyridine-2-methylene]-thiocarbohydrazone (H2L) Schiff-base ligand. These metal complexes and ligand were characterized by using ultraviolet-visible (UV-Vis), Fourier Transform Infrared (FT-IR), 1H and 13C NMR spectroscopy and mass spectroscopy, physicochemical characterization, CHNS and conductivity. The biological activity of the synthesized ligand was investigated by using Escherichia coli DNA as target. The DNA interaction of the synthesized ligand and complexes on E. coli plasmid DNA was investigated in the aqueous medium by UV-Vis spectroscopy and the binding constant (Kb) was calculated. The DNA binding studies showed that the metal complexes had an improved interaction due to trans-geometrical isomers of the complexes than ligand isomers in cis-positions., (Copyright © 2011 Elsevier B.V. All rights reserved.)
- Published
- 2011
- Full Text
- View/download PDF
32. Cu(II), Co(II), Ni(II), Mn(II), and Fe(II) metal complexes containing N,N'-(3,4-diaminobenzophenon)-3,5-Bu(t)(2)-salicylaldimine ligand: Synthesis, structural characterization, thermal properties, electrochemistry, and spectroelectrochemistry.
- Author
-
Tas E, Kilic A, Durgun M, Küpecik L, Yilmaz I, and Arslan S
- Subjects
- Aldehydes chemistry, Coordination Complexes, Electrochemistry, Ligands, Magnetic Resonance Spectroscopy, Schiff Bases, Spectrophotometry, Infrared, Spectroscopy, Fourier Transform Infrared, Benzophenones chemistry, Cobalt chemistry, Copper chemistry, Ferrous Compounds chemistry, Manganese chemistry, Nickel chemistry, Organometallic Compounds chemical synthesis, Organometallic Compounds chemistry, Salicylates chemistry
- Abstract
The synthesis, structure, spectroscopic and electro-spectrochemical properties of steric hindered Schiff-base ligand [N,N'-(3,4-benzophenon)-3,5-Bu(t)(2)-salicylaldimine (LH(2))] and its mononuclear Cu(II), Co(II), Ni(II), Mn(II) and Fe(II) complexes are described in this work. The new dissymmetric steric hindered Schiff-base ligand containing a donor set of NONO was prepared through reaction of 3,4-diaminobenzophenon with 3,5-Bu(t)(2)-salicylaldehyde. Certain metal complexes of this ligand were synthesized by treating an ethanolic solution of the ligand with an equimolar amount of metal salts. The ligand and its complexes were characterized by FT-IR, UV-vis, (1)H NMR, elemental analysis, molar conductivity and thermal analysis methods in addition to magnetic susceptibility, electrochemistry and spectroelectrochemistry techniques. The tetradentate and mononuclear metal complexes were obtained by reacting N,N'-(3,4-benzophenon)-3,5-Bu(t)(2)-salicylaldimine (LH(2)) with some metal acetate in a 1:1 mole ratio. The molar conductance data suggest metal complexes to be non-electrolytes., (Copyright (c) 2009 Elsevier B.V. All rights reserved.)
- Published
- 2010
- Full Text
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33. The chiral helical structure of a copper(II) complex with a tridentate Schiff base ligand.
- Author
-
Shi WJ
- Subjects
- Crystallography, X-Ray, Hydrogen Bonding, Ligands, Models, Molecular, Schiff Bases, Copper chemistry, Organometallic Compounds chemistry
- Abstract
In the title salt, catena-poly[[[aquacopper(II)]-mu-3-(2-pyridylmethyleneamino)propanoato-kappa4N,N',O:O'] perchlorate], {[Cu(C9H9N2O2)(H2O)]ClO4}n, the monomeric unit contains a square-based pyramidal Cu(II) centre. The four basal positions are occupied by a tridentate anionic Schiff base ligand which furnishes an NNO-donor set, with the fourth basal position being occupied by an O-donor atom from the carboxylate group of an adjacent Schiff base ligand. The coordination sphere is completed by a water molecule at the apical position. Interestingly, each carboxylate group in the ligand forms a syn-anti-configured bridge between two Cu(II) centres, leading to left-handed chiral helicity. The framework also exhibits O-H...O hydrogen bonds involving the water molecules and an O atom of the perchlorate anion.
- Published
- 2009
- Full Text
- View/download PDF
34. Determination of copper in water and plant samples by flame atomic absorption spectrometry after preconcentration on octadecyl silica membrane disks modified with a recently synthesized Schiff's base.
- Author
-
Shamspur T, Mostafavi A, and Sheikhshoaie I
- Subjects
- Hydrogen-Ion Concentration, Indicators and Reagents, Membranes, Artificial, Reference Standards, Schiff Bases, Silicon Dioxide, Solutions, Spectrophotometry, Atomic, Copper analysis, Plants chemistry, Water Supply analysis
- Abstract
A simple, selective, reliable, and sensitive method for the determination of trace amounts of CU2+ ions in aqueous samples is proposed. The Cu2+ ions are adsorbed quantitatively during the passage of aqueous samples through an octadecyl (C18) silica membrane disk modified by a symmetrical tetradentate Schiff base ligand, N,N'-bis(4-phenylazo salicylaldimine) 3-chloro-1,2-phenylenediamine (H2L). The retained Cu2+ ions were then stripped from the disk by elution with the minimal amount of nitric acid solution and determined by flame atomic absorption spectrometry. Various parameters, such as the effect of pH, flow rate, type and amount of eluent, and the effects of various cationic interferences on the recovery of ions were studied. The proposed method permitted large enrichment factors (about 550 and higher). The limit of detection of the method was 1.5 x 10(-2) microg/L. The use of the same disk modified with 6 mg H2L for at least 30 times showed no change in the recovery of Cu2+ ions. The accuracy of the method was confirmed by determination of Cu2+ ions in standard samples [National Institute of Environmental Studies (NIES) No. 2 and Nippon Keikinzoku Kogyo (NKK) No. 920]. The results demonstrated good agreement with certified values.
- Published
- 2008
35. Copper conjugates of nimesulide Schiff bases targeting VEGF, COX and Bcl-2 in pancreatic cancer cells.
- Author
-
Ambike V, Adsule S, Ahmed F, Wang Z, Afrasiabi Z, Sinn E, Sarkar F, and Padhye S
- Subjects
- Animals, Cell Line, Tumor, Cell Proliferation, Electron Spin Resonance Spectroscopy, Humans, Models, Molecular, Spectrophotometry, Infrared, Copper chemistry, Cyclooxygenase 2 chemistry, Proto-Oncogene Proteins c-bcl-2 chemistry, Schiff Bases, Sulfonamides chemistry, Vascular Endothelial Growth Factor A chemistry
- Abstract
Copper conjugates of Schiff base derivatives of nimesulide (1), a well-known cyclooxygenase-2 (COX-2) inhibitor, were synthesized, structurally characterized and evaluated for their COX selectivity indices and cytotoxicities on pancreatic tumor, BxPC-3 (COX-2 positive) and MiaPaCa (COX-2 negative) cell lines. Copper conjugates exhibit distorted square planar geometries as revealed by the single crystal X-ray structure determination of Cu(L1)(2) and show significant growth inhibition in both cell lines (IC50 values 3-26 microM for COX-2 positive and 5-9 microM for COX-2 negative cell line) than the parent nimesulide (35 microM for COX-2 positive and >100 microM for COX-2 negative cell line). The mechanistic pathway for the biological activity involves inhibition of vascular endothelial growth factor (VEGF) and COX inhibition, as well as down regulation of antiapoptotic Bcl-2 and Bcl-(XL) proteins.
- Published
- 2007
- Full Text
- View/download PDF
36. Tri- and tetranuclear copper(II) complexes consisting of mononuclear Cu(II) chiral building blocks with a sugar-derived Schiff's base ligand.
- Author
-
Sah AK, Tanase T, and Mikuriya M
- Subjects
- Chemistry, Inorganic methods, Crystallography, X-Ray, Ligands, Molecular Structure, Protons, Schiff Bases, Carbohydrates chemistry, Copper chemistry
- Abstract
A new sugar-derived Schiff's base ligand N-(3-tert-butyl-2-hydroxybenzylidene)-4,6-O-ethylidene-beta-D-glucopyranosylamine (H3L1) has been developed which afforded the coordinatively labile, alcoholophilic trinuclear Cu(II) complex [Cu3(L1)2(CH3OH)(H2O)] (1). Complex 1 has been further used in the synthesis of a series of alcohol-bound complexes with a common formula of [Cu3(L1)2(ROH)2] (R = Me (2), Et (3), nPr (4), nBu (5), nOct (6)). X-ray structural analyses of complexes 2-6 revealed the collinearity of trinuclear copper(II) centers with Cu-Cu-Cu angles in the range of 166-172 degrees . The terminal and central coppers are bound with NO3 and O4 atoms, respectively, and exhibit square-planar geometry. The trinuclear structures of 2-6 can be viewed as the two {Cu(L1)}- fragments capture a copper(II) ion in the central position, which is further stabilized by a hydrogen-bonding interaction between the alcohol ligands and the sugar C-3 alkoxo group. Complex 2 exhibits a strong antiferromagnetic interaction between the Cu(II) ions (J = -238 cm(-1)). Diffusion of methanol into a solution of complex 1 in a chloroform/THF mixed solvent afforded the linear trinuclear complex [Cu(3)(L1)2(CH3OH)2(THF)2] (7). The basic structure of 7 is identical to complex 2; however, THF binding about the terminal coppers (Cu-O(THF) = 2.394(7) and 2.466(7) A) has introduced the square-pyramidal geometry, indicating that the planar trinuclear complexes 2-6 are coordinatively unsaturated and the terminal metal sites are responsible for further ligations. In the venture of proton-transfer reactions, a successful proton transfer onto the saccharide C-3 alkoxo group has been achieved using 4,6-O-ethylidene-d-glucopyranose, resulting in the self-assembled tetranuclear complex, [Cu4(HL1)4] (8), consisting of the mononuclear Cu(II) chiral building blocks, {Cu(HL1)}.
- Published
- 2006
- Full Text
- View/download PDF
37. Synthesis and spectroscopic characterization of copper(II) complexes with the polydentate chelating ligand 4,4'-[1,4-phenylenedi(nitrilo)dipente-2-one.
- Author
-
Shauib NM, Elassar AZ, and El-Dissouky A
- Subjects
- Electron Spin Resonance Spectroscopy, Electrons, Ligands, Metals chemistry, Models, Chemical, Molecular Structure, Oxygen metabolism, Schiff Bases, Spectrophotometry, Infrared, Temperature, Alkenes chemistry, Chelating Agents pharmacology, Copper chemistry, Nitro Compounds chemistry, Spectrophotometry methods
- Abstract
A new series of complexes of 4,4'-[1,4-phenylenenedi(nitilo)]dipenten-2-one, (H(2)L) with CuX(2) x nH(2)O, X = Cl, Br, ClO(4), NO(3) and OAc; n = 1-6 as well as their ethylenediamine adducts have been synthesized and characterized by different physical techniques. The formulation of the complexes is assumed based on their elemental analysis and the molar conductivity. The products are found to be pH-dependent. The IR data showed that the ligand acts as dibasic tetradentate coordinated to copper(II) ions through the enolato-oxygen and the azomethine nitrogen atoms. Electronic, ESR spectra and room temperature magnetic moments indicate that complexes 1-9 are square planar while complexes 10 and 11 are square based pyramidal. The different electronic spectral and ESR parameters are calculated and used to describe the nature of ligand-metal bonding (sigma and pi) as well as to estimate the extent of distortion. A macrocyclic containing copper(II) complex, 12 have been isolated by the reaction of Schiff-base with copper(II)-ethylenediamine mixture. The ligand (H(2)L) is designed as a building block for larger molecules and superamolecular assemblies.
- Published
- 2006
- Full Text
- View/download PDF
38. Designing molecules for PDT: red light-induced DNA cleavage on disulfide bond activation in a dicopper(II) complex.
- Author
-
Dhar S, Nethaji M, and Chakravarty AR
- Subjects
- Copper chemistry, Crystallography, X-Ray, Disulfides chemistry, Ligands, Models, Molecular, Oxygen metabolism, Photochemistry, Photosensitizing Agents chemical synthesis, Photosensitizing Agents chemistry, Schiff Bases, Singlet Oxygen pharmacology, Copper metabolism, DNA radiation effects, Disulfides metabolism, Drug Design, Photochemotherapy, Ultraviolet Rays
- Abstract
The binuclear copper(II) complex [Cu)(RSSR)2](1), where RSSR is a dianionic Schiff base derived from 2-(thioethyl)salicylaldimine having a disulfide bond is prepared, structurally characterized by X-ray crystallography and its photo-induced DNA cleavage activity studied. The Schiff base ligand H2RSSR is also structurally characterized. The crystal structure of shows the discrete dimeric nature of the complex with each metal showing square-planar geometry with a CuN2O2 coordination (Cu...Cu, 5.011(1)A). The tetradentate Schiff base RSSR acts as a linker of two copper centers. The sulfur atoms in the disulfide unit do not show any apparent interaction with the metal ion. Complex 1, which is cleavage inactive in the dark in the presence of reducing agents, shows significant cleavage of supercoiled pUC19 DNA on exposure to UV light of 312 nm or visible light of different wavelengths under aerobic conditions, in the absence of any additives. DNA cleavage data from control experiments reveal involvement of the disulfide unit as a photosensitizer undergoing photo-induced S-S bond cleavage on exposure to UV light and the resulting species activates molecular oxygen to form singlet oxygen (1O2) that causes DNA cleavage following a type-II process. Photo-induced DNA cleavage by 1 on red-light exposure using a CW laser of 632.8 nm or a pulsed ruby laser of 694 nm is proposed to involve sulfide radicals in a type-I process and hydroxyl radicals as the reactive species.
- Published
- 2005
- Full Text
- View/download PDF
39. Novel PVC-based copper(II) membrane sensor based on 2-(1'-(4'-(1''-hydroxy-2''-naphthyl)methyleneamino)butyl iminomethyl)-1-naphthol.
- Author
-
Ganjali MR, Golmohammadi M, Yousefi M, Norouzi P, Salavati-Niasari M, and Javanbakht M
- Subjects
- Edetic Acid, Polyvinyl Chloride, Schiff Bases, Sensitivity and Specificity, Tea chemistry, Copper analysis, Imines chemistry, Ion-Selective Electrodes standards, Naphthols chemistry, Water Pollutants analysis
- Abstract
A copper(II) ion-selective PVC membrane sensor based on 2-(1'-(4'-(1''-hydroxy-2''-naphthyl)methyleneamino)butyl iminomethyl)-1-naphthol (BHNB) as a novel Schiff base containing a sensing material has been successfully developed. The sensor exhibits a good linear response of 29 mV per decade within the concentration range of 10(-1)-10(-6) M of Cu2+. The sensor shows good selectivity for copper(II) ion in comparison with alkali, alkaline earth, transition and heavy metal ions. The BHNB-based sensor is suitable for use with aqueous solutions of pH 3.5-7.0 and displays minimal interference by Sr(II), Cd(II), Hg(II), Zn(II) and Pb(II), which are known to interfere with other previously suggested electrodes. The proposed membrane electrode was used as a sensor for determining the Cu(II) content in black tea samples. It was also applied as an indicator electrode in the potentiometric titration of Cu2+ ions with EDTA.
- Published
- 2003
- Full Text
- View/download PDF
40. The superoxide dismutase-like activity of some copper(II) complexes derived from tridentate Schiff bases.
- Author
-
Bergendi L, Krätsmár-Smogrovic J, Duracková Z, and Zitnanova I
- Subjects
- Catalysis, Free Radicals, Humans, Models, Chemical, Models, Molecular, Neutrophils drug effects, Neutrophils metabolism, Organometallic Compounds chemistry, Oxidation-Reduction, Oxygen metabolism, Antioxidants metabolism, Copper metabolism, Free Radical Scavengers, Organometallic Compounds metabolism, Schiff Bases, Superoxide Dismutase metabolism, Superoxides metabolism
- Abstract
Oxygen free radicals are the final or intermediate products of many metabolic reactions. Of greatest significance to the organism are superoxide anion radical (O2-.), hydrogen peroxide (H2O2), hydroxyl radical (.OH), singlet oxygen (1O2) etc. A proper ratio between both production and breakdown of oxy-radicals is essential for the maintenance of a dynamic equilibrium of vital processes. The superoxide dismutases protect cells against toxic influence of the superoxide. In addition, some square-pyramidally pentacoordinated copper(II) complexes, derived from tridentate Schiff bases of the N-salicylideneaminoalcanoate type, show remarkable SOD-like activity. A selected set of complexes of this type have been tested: potassium [aqua-(N-salicylideneglutamato) cuprate] (L- and D,L-form), potassium [(isothiocyanato)-(N-salicylideneglycinato) cuprate], potassium [(isothiocyanato)-(N-salicylidene-D,L-alaninato) cuprate], potassium [(isothiocyanato)-(N-salicylidene-beta-alaninato) cuprate] and potassium [(isocyanato)-(N-salicylideneglycinato) cuprate]. Our results suggest that the copper complexes are not only antioxidants, but may also possess anti-inflammatory, cytostatic and radioprotective properties.
- Published
- 1991
- Full Text
- View/download PDF
41. Schiff base copper(II) chelate as a tool for immobilization of protein.
- Author
-
Moriya K, Tanizawa K, and Kanaoka Y
- Subjects
- Chelating Agents, Chemical Phenomena, Chemistry, Proteins analysis, Subtilisins isolation & purification, Copper, Proteins isolation & purification, Schiff Bases
- Abstract
In our previous report a new methodology for intermolecular cross-linking or bridging of protein utilizing a spontaneous chelate formation process was proposed. In this paper the reliability of the process as a tool for protein immobilization has been further evaluated. The chromatographic behavior of tryptophan in a column packed with Sepharose coupled with salicylaldehyde residue showed that the alpha-amino acid was bound tightly to the gel in the presence of copper(II) ion and was eluted by the addition of ethylenediaminetetraacetate (EDTA). It was also proved that subtilisin modified with an alpha-amino acid residue was immobilized on the column, and this binding was reversed by the addition of EDTA as well.
- Published
- 1989
- Full Text
- View/download PDF
42. EPR non-detectable copper in pyridoxal biogenic amine Schiff base complexes.
- Author
-
Sharrock P, Nepveu-Juras F, Massol M, and Haran R
- Subjects
- Electron Spin Resonance Spectroscopy, Pyridoxal Phosphate, Schiff Bases, Copper, Octopamine, Pyridoxal
- Published
- 1979
- Full Text
- View/download PDF
43. Immobilized chymotrypsin by means of Schiff base copper(II) chelate.
- Author
-
Moriya K, Tanizawa K, and Kanaoka Y
- Subjects
- Aldehydes, Animals, Catalysis, Cattle, Chymotrypsinogen, Enzyme Activation, Hydrolysis, Kinetics, Schiff Bases, Chelating Agents, Chymotrypsin, Copper, Enzymes, Immobilized
- Abstract
A new method for cross-linking of protein was proposed in our previous work. The method is based on the spontaneous chelate formation process involving three components, salicylaldehyde moiety, alpha-amino acid residue and copper(II). In this paper versatility of the method as a purpose of immobilization of enzyme was described. Chymotrypsin-salicylaldehyde conjugate was immobilized to the agarose gel attached alpha-amino acid residue in the presence of copper(II) ion The enzyme was not eluted from the gel by washing with a copper free buffer though it was exclusively eluted by a medium containing EDTA. Catalytic activity of the chymotrypsin salicylaldehyde conjugate was not changed upon the immobilization. The method was proposed as a new tool for reversible immobilization of enzyme.
- Published
- 1989
- Full Text
- View/download PDF
44. Schiff base copper(II) chelate as a tool for intermolecular cross-linking and immobilization of protein.
- Author
-
Moriya K, Tanizawa K, and Kanaoka Y
- Subjects
- Aldehydes, Gels, Macromolecular Substances, Chelating Agents, Copper, Cross-Linking Reagents, Schiff Bases, Serum Albumin, Bovine
- Abstract
A new method for intermolecular cross-linking or bridging of protein has been proposed. The method is based on the spontaneous chelate formation process involving three components, salicylaldehyde, alpha-amino acid residue and copper(II). Reliability of the process as a tool for protein cross-linking was evaluated by chromatographic procedures. Behavior of salicylaldehyde in a column packed with Sepharose attached alpha-amino acid residue showed that salicylaldehyde was bound tightly to the gel in the presence of copper(II) ion and was eluted by the addition of EDTA. The association was shown strong enough to be applied for the purpose of cross-linking of proteins. It was also proved that BSA salicylaldehyde conjugate was immobilized specifically to the column, and the process was reversed by the addition of EDTA as well. The method is proposed to be useful not only for immobilization of enzyme but also for cross-linking of proteins since the method is free from unexpected random coupling products which are unavoidable with bifunctional cross-linking reagents.
- Published
- 1989
- Full Text
- View/download PDF
45. [Physico-chemical study of the reaction between transition metal ions and Schiff bases. Polarographic study of complexes of copper(II) with salicylidene-beta-alanine].
- Author
-
Inamul-Khakv
- Subjects
- Chemical Phenomena, Chemistry, Mathematics, Polarography, Alanine analogs & derivatives, Copper, Schiff Bases, beta-Alanine analogs & derivatives
- Abstract
Copper complexes of salicylidene-alanine have been studied by polarographic method of analysis in aqueous medium and at constant ionic strength. The reduction of copper in different concentrations of schiff base at the dropping mercury electrode was found to be diffusion controlled but irreversible. The kinetic parameters (alpha and ks) were evaluated by the method of Ayabe and Matsuda. The composition and stability constants of the complex were determined by DeFord and Hume's method as modified by Vleck.
- Published
- 1980
46. Six cobalt(II), zinc(II), nickel(II) and copper(II) complexes based on bis-benzimidazolyl bidentate ligands with phenolyl ether linkers: synthesis, structural studies and recognition of HSO4-.
- Author
-
Zhixiang Zhao, Yue Yang, Linhai Hu, Jianhua Wang, Jie Yu, and Qingxiang Liu
- Subjects
- *
COPPER , *ETHER synthesis , *FLUORESCENCE spectroscopy , *BINDING constant , *METAL complexes , *SCHIFF bases - Abstract
Three bis-benzimidazolyl bidentate ligands with phenolyl ether linkers, 1,n-bis[2-(1H-1,3-benzimidazol-1-ylmethyl)phenoxy]alkane (L1: n = 1, L2: n = 3, L3: n = 4), and their six metal complexes were synthesized by the reactions of the respective ligands with metal salts. The six metal complexes included two cobalt(II) complexes ([Co(L1)(NO3)2] (1) and [Co(L3)(LA)]n (6) (LA = maleate)), two copper(II) complexes ([Cu(L1)(SO4)]2 (4) and [Cu(L3)(SO4)]2 (5)), one zinc(II) complex ([Zn(L1)(NO3)2] (2)) and one nickel(II) complex ([Ni(L2)(NO3)2] (3)). Complexes 1 and 2 had one 16-membered macrometallocycle, and complex 3 had one 18-membered macrometallocycle. In complexes 4 and 5, two SO42- joined two macrometallocycles together (16-membered macrometallocycle for 4 and 19-membered macrometallocycle for 5). In complexes 1-5, each macrometallocycle was constructed from one ligand and one metal ion. In complex 6, 19-membered macrometallocycles were connected together by maleate groups (LA) to form a 1D polymeric chain, where each 19-membered macrometallocycle was constructed from one L3 and one Co(II) ion. In crystal packings of complexes 1-6, H-bonds, π--π interactions and C--H•••π contacts participated in the formation of 2D supramolecular layers and 3D supramolecular architectures. The conformations of complexes 1-6 were also analyzed. Additionally, the recognition performance of complex 1 as a chemosensor for HSO4- was studied through fluorescence spectra, UV/vis spectra, 1H NMR titrations, HRMS spectra and IR spectra. The large binding constant (1.81 x 104 M-1) showed that there was a strong acting force between 1 and HSO4-, and the low detection limit (1.40 x 10-7 mol L-1) indicated that the detection of 1 for HSO4- was sensitive. The experimental results showed that complex 1 can effectively differentiate HSO4- from other anions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
47. Six cobalt(II), zinc(II), nickel(II) and copper(II) complexes based on bis-benzimidazolyl bidentate ligands with phenolyl ether linkers: synthesis, structural studies and recognition of HSO4-.
- Author
-
Zhixiang Zhao, Yue Yang, Linhai Hu, Jianhua Wang, Jie Yu, and Qingxiang Liu
- Subjects
COPPER ,ETHER synthesis ,FLUORESCENCE spectroscopy ,BINDING constant ,METAL complexes ,SCHIFF bases - Abstract
Three bis-benzimidazolyl bidentate ligands with phenolyl ether linkers, 1,n-bis[2-(1H-1,3-benzimidazol-1-ylmethyl)phenoxy]alkane (L
1 : n = 1, L2 : n = 3, L3 : n = 4), and their six metal complexes were synthesized by the reactions of the respective ligands with metal salts. The six metal complexes included two cobalt(II) complexes ([Co(L1 )(NO3 )2 ] (1) and [Co(L3 )(LA)]n (6) (LA = maleate)), two copper(II) complexes ([Cu(L1 )(SO4 )]2 (4) and [Cu(L3 )(SO4 )]2 (5)), one zinc(II) complex ([Zn(L1 )(NO3 )2 ] (2)) and one nickel(II) complex ([Ni(L2 )(NO3 )2 ] (3)). Complexes 1 and 2 had one 16-membered macrometallocycle, and complex 3 had one 18-membered macrometallocycle. In complexes 4 and 5, two SO4 2- joined two macrometallocycles together (16-membered macrometallocycle for 4 and 19-membered macrometallocycle for 5). In complexes 1-5, each macrometallocycle was constructed from one ligand and one metal ion. In complex 6, 19-membered macrometallocycles were connected together by maleate groups (LA ) to form a 1D polymeric chain, where each 19-membered macrometallocycle was constructed from one L3 and one Co(II) ion. In crystal packings of complexes 1-6, H-bonds, π--π interactions and C--H•••π contacts participated in the formation of 2D supramolecular layers and 3D supramolecular architectures. The conformations of complexes 1-6 were also analyzed. Additionally, the recognition performance of complex 1 as a chemosensor for HSO4 - was studied through fluorescence spectra, UV/vis spectra, 1H NMR titrations, HRMS spectra and IR spectra. The large binding constant (1.81 x 104 M-1 ) showed that there was a strong acting force between 1 and HSO4 - , and the low detection limit (1.40 x 10-7 mol L-1 ) indicated that the detection of 1 for HSO4 - was sensitive. The experimental results showed that complex 1 can effectively differentiate HSO4 - from other anions. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
48. Contents list.
- Subjects
- *
NICKEL phosphide , *RHODAMINES , *SCHIFF bases , *FORMIC acid , *COPPER , *INDOLE compounds , *TRANSITION metals , *FRIEDEL-Crafts reaction , *POLYMERS - Abstract
The article focuses on recent advancements in chemistry, highlighting the development of new materials and chemical processes. Topics include the synthesis of insensitive energetic materials with enhanced detonation performance, the use of vanadium(V) complexes for syndiospecific ring-opening metathesis polymerization (ROMP) of cyclic olefins, and the exploration of metal-support interactions to enhance catalytic activity for hydrogen production.
- Published
- 2024
- Full Text
- View/download PDF
49. Synthesis and characterization of copper(II) complexes: their catalytic behavior towards alcohol oxidation using NaOCl as the oxidant.
- Author
-
Roy, Suparna, Barma, Arpita, Muhuri, Debasmita, Ghosh, Pritam, and Roy, Partha
- Subjects
- *
COPPER , *ALCOHOL oxidation , *BENZYL alcohol , *SCHIFF bases , *OXIDIZING agents , *SINGLE crystals , *SODIUM hypochlorite - Abstract
Two mononuclear complexes, [Cu(L1)2] (complex 1) and [Cu(HL2)2](NO3)2 (complex 2) where HL1 is 1-((cyclohexylmethylimino)methyl)-naphthalen-2-ol and HL2 is 4-bromo-2-((2-morpholinoethylimino)methyl)phenol, have been synthesized under mild conditions and characterized by different standard analytical methods. Single crystal X-ray diffraction analysis shows that the copper atoms in both copper(II) complexes are in a square planar geometry. These complexes have been used as catalysts in the oxidation of benzyl alcohol and benzyl alcohol with various substituents in the presence of NaOCl as the terminal oxidant. The results show that complex 1 acts as a better catalyst than the other with the highest yield of 91% in the case of 4-methoxy benzyl alcohol oxidation. The copper complex transfers the oxygen of sodium hypochlorite to the alcohol to produce the aldehyde. The use of NaOCl as an oxidant in alcohol oxidation is rare although it is cheap and nonexplosive. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Novel Copper (II) Complexes with Fluorine-Containing Reduced Schiff Base Ligands Showing Marked Cytotoxicity in the HepG2 Cancer Cell Line.
- Author
-
Oboňová, Bianka, Valentová, Jindra, Litecká, Miroslava, Pašková, Ľudmila, Hricovíniová, Jana, Bilková, Andrea, Bilka, František, Horváth, Branislav, and Habala, Ladislav
- Subjects
- *
CYTOTOXINS , *SCHIFF bases , *COPPER , *LIGANDS (Biochemistry) , *SERUM albumin - Abstract
Several novel copper (II) complexes of reduced Schiff bases containing fluoride substituents were prepared and structurally characterized by single-crystal X-ray diffraction. The complexes exhibited diverse structures, with the central atom in distorted tetrahedral geometry. The biological effects of the products were evaluated, specifically their cytotoxicity, antimicrobial, and antiurease activities, as well as affinity for albumin (BSA) and DNA (ct-DNA). The complexes showed marked cytotoxic activities in the HepG2 hepatocellular carcinoma cell line, considerably higher than the standard cisplatin. The cytotoxicity depended significantly on the substitution pattern. The best activity was observed in the complex with a trifluoromethyl group in position 4 of the benzene ring—the dichloro[(±)-trans-N,N′-bis-(4-trifluoromethylbenzyl)-cyclohexane-1,2-diamine]copper (II) complex, whose activity (IC50 28.7 μM) was higher than that of the free ligand and markedly better than the activity of the standard cisplatin (IC50 336.8 μM). The same complex also showed the highest antimicrobial effect in vitro. The affinity of the complexes towards bovine serum albumin (BSA) and calf thymus DNA (ct-DNA) was established as well, indicating only marginal differences between the complexes. In addition, all complexes were shown to be excellent inhibitors of the enzyme urease, with the IC50 values in the lower micromolar region. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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