Search

Abstract\nHIGHLIGHTSA new Schiff base inhibitor known as “N, N’ carbonyl- Bis (para-hydroxy benzaldehyde imine)” has been synthesized and characterized by FTIR, NMR, and UV-Visible spectroscopy, the molecule was then assessed for its ability to prevent copper from corroding in a solution of 0.5 M H2SO4 using potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy SEM combined with energy dispersion spectroscopy EDX, and atomic force microscopy AFM. The tested inhibitor exhibits good copper corrosion inhibition performance in a 0.5 M H2SO4 solution. As inhibitor concentration rises, inhibition performance also rises, reaching a maximum inhibitory efficacy of around 84.76 ± 0.69% at 5.10−4 M. The inhibitor was adsorbable to the metal surface and followed the Langmuir isotherm. It has been done such that the addition of KI increased the inhibitory effectiveness, the mixed additives worked together. There is good agreement between the conclusions drawn from theoretical calculations using DFT and MD simulation and actual observations.A new Schiff base inhibitor has been synthesized.The inhibitory efficiency increase with increasing inhibitor concentration.The investigated molecule adsorbs on the copper surface through active centers like N and O.The synthesized molecule has good inhibitory effectiveness with respect to copper corrosion in an acidic medium.A new Schiff base inhibitor has been synthesized.The inhibitory efficiency increase with increasing inhibitor concentration.The investigated molecule adsorbs on the copper surface through active centers like N and O.The synthesized molecule has good inhibitory effectiveness with respect to copper corrosion in an acidic medium. [ABSTRACT FROM AUTHOR]

The incidence of multi-resistant infections has sharply increased. One of the best strategies for developing new drugs is re-engineering existing drugs to enhance their bioavailability and antimicrobial activities. The latest systems focus on designing bioinorganic platforms to develop antimicrobial agents to target drug-resistant microbial strains. Various literature reports highlight metal-based antimicrobial agents unveiling an innovative strategy to tackle microbial agents. One of the significant mechanisms of antibiotic resistance in bacteria is the impermeability of its cell membrane towards antibiotics. Antibiotic-based Schiff base complexes are prime candidates for drug design with minor side effects in this scenario. The enhanced activity of antibiotic Schiff base complexes over their parent compound plays a key role in the emergence of innovative antimicrobials. In this review, we highlight the biological potential aspects of some selected antibiotic-based Schiff base complexes of penicillin, cephalosporins, quinolones, and sulfonamides. Some of the bacteria, especially P. aeruginosa, remain resistant to most of the commercially available antibiotics. Here, the review highlights that Schiff base complexes mediated by antibiotics demonstrate bactericidal activity against these resistant strains. Additionally, their mode of action on the bacterial cell is highlighted. The increased activity of copper, zinc, and silver complexes of different Schiff bases is attributed to their inherent redox chemistry. [ABSTRACT FROM AUTHOR]

Neutral Cu(I) complexes containing Schiff bases as chelating N‐donors and phosphines as P‐donors were efficiently isolated and characterized. The imines were obtained by straightforward condensation between pyrrole‐2‐carboxaldehyde and the corresponding aromatic amines. The structure of most of the Cu(I) species was elucidated through single‐crystal X‐ray diffraction. The Cu(I) complexes exhibited intense absorptions around 400–500 nm ascribed to MLCT transitions. For some Cu(I) derivatives, orange‐ and red‐orange emissions were detected upon excitation with near‐UV and blue irradiation in the solid state. The emission maxima were red‐shifted once the benzothiazole‐derived Schiff base or Xantphos were employed as chelating ligands. Microsecond‐long lifetimes, wide emissions, and large Stokes shifts suggest the involvement of triplet states in the luminescent process. Electrochemical measurements and DFT calculations were employed to rationalize the photoluminescence properties, which were ascribed to mixed 3LC/3MLCT transitions. [ABSTRACT FROM AUTHOR]

In this work, a series of aldehyde‐substituted phthalocyanine compounds (1, 3, and 5) were prepared by the cyclotetramerization of the 4‐(5‐(diethylamino)‐2‐formylphenoxy) phthalonitrile (a) and the corresponding metal salts. Schiff base‐substituted phthalocyanines (2, 4, and 6) were derived from an aldehyde‐substituted phthalocyanine (1, 3, and 5) via the reaction of aldehyde‐substituted phthalocyanines with an amine reagent. The compounds that were obtained were characterized using FT‐IR, 1H {13C} NMR, UV–Vis, and MS spectra (a and 1–6). The inhibitory qualities of synthesized aldehyde and Schiff base‐substituted complexes against the enzymes butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) were assessed. The majority of phthalocyanines exhibited strong enzyme‐inhibiting properties. Out of the six produced phthalocyanines, 3 and 4 displayed the most intriguing profiles as submicromolar selective AChE inhibitors (IC50 = 0.060 μM), whereas 1 demonstrated the most potent BChE inhibitor (IC50 = 0.024 μM). The aggregation studies of CoPcs, CuPcs, and ZnPcs (1–6) were also carried out in this work. [ABSTRACT FROM AUTHOR]

Three new trinuclear complexes containing either nickel(II), copper(II) or zinc(II), [Ni3L2(NO3)2(CH3OH)2]·2CH3OH (1), [Cu3Br2L2] (2), [Zn3L2(NCS)2(CH3OH)2]·0.5CH3OH·0.5H2O (3), and a new dioxidomolybdenum(VI) complex, [MoO2L] (4), have been prepared from the bis-Schiff base N,N'-bis(4-bromosalicylidene)-1,3-propanediamine (H2L) with various metal salts in methanol. The complexes were characterized by elemental analysis, IR and UV–Vis spectra. Molecular structures were confirmed by single crystal X-ray diffraction experiments. The Ni ions in 1 adopt an octahedral coordination environment, bridged by phenolate oxygen and nitrate ligands. The Cu ions in 2 are square pyramidal and square planar, and the Zn ions in 3 are square pyramidal and octahedral. The metal atoms in 2 and 3 are bridged by phenolate oxygen donors. The Mo ion in 4 is octahedral. The Schiff base ligand coordinates to the metal atoms through two phenolate O and two imino N donors. Biological assays revealed that the nickel and copper complexes have effective urease inhibition. [ABSTRACT FROM AUTHOR]

Since the discovery of cisplatin in the 1960s, the search for metallo-drugs that are more efficient than platinum complexes with negligible side effects has attracted much interest. Among the other metals that have been examined for potential applications as anticancer agents is copper. The interest in copper was recently boosted by the discovery of cuproptosis, a recently evidenced form of cell death mediated by copper. However, copper is also known to induce the proliferation of cancer cells. In view of these contradictory results, there is a need to find the most suitable copper chelators, among which Schiff-based derivatives offer a wide range of possibilities. Gathering several metal complexes in a single, larger entity may provide enhanced properties. Among the nanometric objects suitable for such purpose are dendrimers, precisely engineered hyperbranched macromolecules, which are outstanding candidates for improving therapy and diagnosis. In this review article, we present an overview of the use of a particular Schiff base, namely pyridine–imine, linked to the surface of dendrimers, suitable for complexing copper, and the use of such dendrimer complexes in biology, in particular against cancers. [ABSTRACT FROM AUTHOR]

A mesogenic glycine based Schiff base compound of the type, (E)‐methyl 2‐((2‐hydroxy‐4‐(tetradecyloxy)benzylidene)amino)acetate (HL) has been successfully synthesized and characterized using analytical and spectroscopic techniques. The Schiff base compound was evaluated for chemosensor activity towards different metal ions using fluorescence spectroscopy. The experiment reveals highly efficient and selective "turn‐on" and "turn‐off" responses of the fluorescence intensity towards zinc(II) and copper(II), respectively, in presence of other metal ions. The binding constant and the stoichiometry ratio were determined using Benesi‐Hildebrand equation giving 1 : 1 stoichiometry. The limits of detection for both the metal ions were estimated from the fluorescence titration experiments. The reversibility nature of the Schiff base probe was also studied using EDTA as chelating ligand. The compound, HL exhibits two INHIBIT logic gates with chemical inputs (i) Zn2+ (IN1) and Cu2+ (IN2) and (ii) Zn2+ (IN1) and EDTA (IN2). An IMPLICATION logic gate was also obtained when Cu2+ (IN1) and EDTA (IN2) serve as chemical inputs. The compound was found to exhibit potent antibacterial activity and efficient binding interaction with BSA. Molecular docking studies were carried out in order to ascertain the degree of interaction and the nature of binding of the compound with the proteins. [ABSTRACT FROM AUTHOR]

[Cu(5‐ClSal‐Trp)(bpy)]·CH3OH (1) and [Cu(3,5‐ClSal‐Trp)(bpy)]·H2O (2) (5‐ClSal‐Trp: Schiff base derived from 5‐chlorosalicylaldehyde and tryptophan, 3,5‐ClSal‐Trp: Schiff base derived from 3,5‐dichlorosalicylaldehyde and tryptophan, bpy: 2,2′‐bipyridine) have been synthesized and analyzed by CHN analysis, FTIR, electronic absorption spectroscopy, ESI‐MS and XRD techniques. Interaction of the complexes with biomolecules {calf thymus DNA (CT‐DNA) and bovine serum albumin (BSA)} has been researched by fluorescence and electronic absorption spectroscopy. The results show that the complexes can bind via a moderate intercalation binding mode. According to the results obtained with both methods, the logKb and logKSV values of the complexes were found to be very close to each other. BSA quenching mechanism was found to be static. The results showed that the interaction between the complexes and BSA is driven by the hydrogen bond and van der Waals interaction. Additionally, the r values of the complexes (the complex 1 = 0.59 nm and the complex 2 = 0.53 nm) calculated from FRET theory suggested that the distance between the complexes (acceptor) and BSA (donor) is quite close. The complexes exhibited free radical scavenging activity compared to the standard antioxidant β‐carotene and catechin. Antiproliferative efficiency of the complexes on both breast cancer cells (MCF‐7 and MDA‐MB‐231) were also researched using the Sulforhodamine B (SRB) viability assay. It was found that the complex 1 (IC50 = 10.99 μM) exhibited higher cytotoxicity than cisplatin (IC50 = 15.6 μM) against MDA‐MB‐231 cell line. Additionally, intracellular reactive oxygen species (ROS) formation was determined by dihydroethidium (DHE) fluorescent staining. N‐acetylcysteine (NAC) was used as an efficient reactive oxygen species (ROS) scavenger. It was observed that newly synthesized Cu (II) complexes exhibited anti‐growth potential in human breast cancer cells. Additionally, it was determined that the complexes induced reactive oxygen species (ROS) formation in cells in a dose‐dependent manner. [ABSTRACT FROM AUTHOR]

Antibiotic resistance is currently a global health emergency. Metallodrugs, especially metal coordination complexes, comprise a broad variety of candidates to combat antibacterial infections. In this work, we designed a new family of Schiff base zinc(II) complexes with iminopyridine as an organic ligand and different inorganic ligands: chloride, nitrate, and acetate. The antibacterial effect of the Zn(II) complexes was studied against planktonic bacterial cells of Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) strains. The results showed a moderate biocide activity in both types of planktonic bacteria, which arises from the metal complexation to the Schiff base ligand. Importantly, we confirmed the crucial effect of the metal, with Zn(II) improving the activity of Cu(II) counterparts previously reported. On the other hand, the impact of the inorganic ligands was not significant for the antibacterial effect but was relevant for the complex solubility. Finally, as proof of concept of topical antibacterial formulation, we formulated an emulsion containing the most lipophilic Zn(II) complex and confirmed a sustained release for 24 h in a vertical cell diffusion assay. The promising activity of iminopyridine Zn(II) complexes is potentially worth exploring in more detailed studies. [ABSTRACT FROM AUTHOR]

The primary objective of the current framework was to synthesize novel mononuclear 1:1:1 complexes involving FeLG, CoLG, NiLG, CuLG, and ZnLG, where the ligand (L) is identified as 4-[(4-oxo-4,5-dihydro-1,3-thiazol-2-yl)hydrazono]methylphenyl-4-methylbenzenesulfonate, and glycine (G) serves as the coligand. Comprehensive characterization of the investigated complexes was achieved through various analytical techniques, including FTIR, UV-Vis spectroscopy, elemental analysis, mass spectra, magnetic susceptibility measurements, molar conductivity assessments, and thermogravimetric analysis (TGA). The determination of stoichiometry was performed employing the molar ratio technique, revealing the octahedral geometry inherent in the isolated metal complexes. Employing a density functional theory (DFT) approach, the molecular structures of the designated compounds were theoretically elevated, and quantum chemical descriptors were derived to provide a deeper insight into their electronic properties. Furthermore, the inhibitory potential of these compounds against fungal strains and pathogenic bacteria prevalent in the Arab environment was evaluated using the disc diffusion method, emphasizing their role in combating diseases affecting humans, animals, and plants. Notably, the metal complexes exhibited superior antibacterial activity, as evidenced by a higher activity index. Molecular docking investigations were conducted to ascertain the inhibitory effects of the compounds on the 1FJ4 protein, with ZnLG emerging as the compound with the highest binding affinity. These results suggest the promising candidacy of these compounds as antimicrobial agents, particularly in the context of combating bacterial and fungal infections. [ABSTRACT FROM AUTHOR]

A novel coumarin-derived Schiff base fluorescent probe was reported to detect Cu2+ ions in human cells. It was synthesized by the reaction between 7-(diethylamino)coumarin-3-carbohydrazide and pyridoxal 5′-phosphate. The probe has good stability and it exhibited obviously decreasing fluorescent response at λ 490 nm upon addition of Cu(II) ions. The fluorescent probe showed high selectivity for Cu(II) ions compared to other metal ions. The probe has been successfully applied to detect Cu(II) ions in human cells. [ABSTRACT FROM AUTHOR]

Two sulfoxide-containing Schiff bases, (E)-(((2-(methylsulfinyl phenyl) imino)methyl)-4-nitrophenol (HL1) and (E)-3,5-dibromo-2-(((2-(methylsulfinyl phenyl)imino)methyl)phenol (HL2), were prepared by condensation and subsequent oxidation reactions. In the presence of triethylamine, reactions of HL1 with 0.5 equivalent of copper acetate, cobalt acetate, nickel acetate and zinc acetate in ethanol afforded four metal complexes: (η2-N,O-L1)Cu(η3-O,N,O-L1) (1) and (η3-O,N,O-L1)2M (M = Co, 2; Ni, 3; Zn, 4), respectively. Similarly, treatment of HL2 with 0.5 equivalent of cobalt acetate and nickel acetate obtained two cobalt/nickel complexes: (η3-O,N,O-L2)2M (M = Co, 5; Ni, 6). Reactions of HL1 and one equivalent of Ru(PPh3)3Cl2 in tetrahydrofuran in the presence of triethylamine afforded a ruthenium(II) complex, (η3-O,N,S-L1)Ru(PPh3)2Cl (7). The molecular structures of HL1 and 1-7 have been confirmed by single-crystal X-ray diffraction. In addition, the UV–Vis, infrared, and fluorescence spectroscopies of 1–7 along with their electrochemical properties were also investigated. [ABSTRACT FROM AUTHOR]

A new azomethine compound 4-methyl-N-[2-pentafluorophenyliminomethyl)phenyl]methylbenzenesulfamide and a Cu(II) complex based on it are obtained and characterized by 1H NMR, IR spectroscopy and the elemental analysis. Crystal structures of azomethine and its complex are analyzed by single crystal X-ray diffraction (XRD). From the single crystal XRD data it is found that the Cu(II) complex crystallizes in the triclinic space group . The unit cell contains two crystallographically independent mononuclear molecules with similar geometries. In the complex, copper ions have a distorted tetrahedral environment of four nitrogen atoms, which is formed by two bidentate coordinated azomethine ligands. From magnetic measurements it is found that the Cu(II) complex is paramagnetic. [ABSTRACT FROM AUTHOR]

An ionic liquid tagged schiff base, [1-{2-(2-hydroxybenzylideneamino)ethyl}-3-methylimidazolium]PF6 was synthesized from a functionalized ionic liquid (FIL) 2-aminoethyl-3-methylimidazolium hexafluorophosphate, [2-aemim]PF6 and salicylaldehyde without using any organic solvent. The Schiff base was used as a ligand to trap Mn(II), Co(II), Cu(II) ions from its corresponding metal acetates and to form the new transition metal complexes. The synthesized Mn(II), Co(II), Cu(II) complexes along with the Schiff base were characterized by ESI-MS, PXRD, UV-Visible, FT-IR, 1H NMR spectroscopic and analytical (elemental analysis and magnetic susceptibility measurements) methods. Based on these spectral analysis data tetra coordinated geometries were assigned for the newly synthesized metal(II) complexes. Antibacterial sensitivity of the Schiff base and the Mn(II), Co(II), Cu(II) complexes were evaluated against gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria to assess their minimum zone of inhibition. [ABSTRACT FROM AUTHOR]

The dissociation constants of Schiff bases, (E)-1-[(2,4-dichlorophenylimino)methyl]naphthalen-2-ol, (E)-1-[(2-chloro-4-nitrophenylimino)methyl]naphthalen-2-ol, (E)-1-[(2,4-dimethoxyphenylimino)methyl]naphthalen-2-ol, and their stability constants with the copper(II) metal ion were determined potentiometrically. The experimental conditions were arranged to achieve coordination in aqueous-ethanol solutions [ethyl alcohol (30%) and water (70%) at 25.0±0.1°C and a constant ionic strength of 0.1 mol/dm3 NaCl]. It was detected that each ligand has two dissociation constants, which are associated to the protonated imine nitrogen and the hydroxyl group. The dissociation constants of these ligands and their stability constants of Cu(II) complexes were computed and discussed in relation to their structural configuration, substituents and basicity. The difference in basicity or acidity of these Schiff base ligands were explained in terms of the inductive effect, resonance and steric effect. Keto-enol tautomerism was discussed in the context of hydrogen bonding, basicity of the imine group and hydrogen acidity of the hydroxyl group; a zwitterionic tautomer might develop as well. The chemical species existing in the solution at experimental conditions used were presented with speciation diagrams. The SUPERQUAD program was used to compute dissociation and stability constants as well as the speciation diagrams. The aims of this study was to determine potentiometrically the dissociation constants of the Schiff base ligands used and the stability constants of their complexes with Cu(II). [ABSTRACT FROM AUTHOR]

Novel metal complexes of Au(III), Pd(II), Cu(II), Fe(II) and Mn(II) metals with unique asymmetrical bidentate Schiff base, obtained by condensation reaction between 1-Hydroxy-2-acetonaphthone and 4-Methoxyphenyl ethylamine, 2-(1-((4-methoxyphenethyl)imino)ethyl)naphthalen-1-ol (HL1). Synthesized Schiff base ligand and their metal complexes are well characterized by UV–Vis, FT-IR, NMR, LCMS, ESR, TGA–DSC, XRD and SC-XRD. Analytically proved the structure of metal complexes and ligand. Herein, our reports for the molar ratio of metal to ligand are1:2 in metal complexes with optimization. Interestingly, proved and analysed the interactions between the metal ions and ligand occurring deprotonated oxygen and Schiff base imine nitrogen using FT-IR, NMR, TGA–DSC and XRD. Also the geometries for the metal complexes such as square planar geometries for Au(III), Pd(II), Cu(II) complexes and octahedral geometries for Fe(II) and Mn(II) complexes. Synthesized metal complexes were examined for their in vitro anti-bacterial activity against the gram-negative bacteria E. coli, P. aeruginosa, and gram-positive S. aureus, B. subtilis, as well as their in vitro antifungal activity against the two fungus C. albicans, A. niger. According to the biological investigations, metal complexes are more effective against species of bacteria and fungi than non-complexed ligand. Interestingly, Pd(II) complexes have outstanding antioxidant activity, while Au(III) and Mn(II) complexes exhibit moderate to good antioxidant activity. [ABSTRACT FROM AUTHOR]

Aminoguanidine derivatives are the focus of research because of their various biological activities, such as antiviral, antibacterial, analgesic, antioxidant and anticancer. Their complexes with different metals are also examined and many of them show significant biological activity, too. Besides, some of the complexes show good photoluminescent properties and are used for the preparation of photoelectronic devices. Therefore, the synthesis, physicochemical, structural and thermal characterization of the complexes of 2-acetylpyridine-aminoguanidine (L) with copper (II) are described here. Under different reaction conditions, Cu(II) with L gives three complexes of different compositions. By varying the strength of basicity of the deprotonating agent used, it was proven here that the Schiff base given here could be coordinated in neutral or monoanionic form. In the presence of pyridine, a coordination polymer is obtained, while in the presence of ammonia/lithium acetate two different monomeric complexes were crystallised. Their physicochemical and thermal properties, as well as molecular and crystal structure, are determined. [ABSTRACT FROM AUTHOR]

The main objective of this work was to improve the corrosion resistance of silane coatings, which have recently attracted much attention for their barrier properties. An organic–inorganic hybrid silane coating prepared by the sol–gel process was developed for the corrosion protection of copper in 1 M HCl solution. The hybrid sol was fabricated by mixing tetraethylorthosilicate (TEOS) and triethoxyvinylsilane (TEVS) in an acidic medium. Two Schiff bases, namely [3-(4-methoxyphenyl)isoxazole-5-yl]-methanol (MOPI) and [3-(4-methylphenyl)isoxazole-5-yl]-methanol (MPI), were synthesized and then incorporated into the silane coatings in various concentrations. The structural characterizations of the prepared coatings were performed using scanning electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction, and atomic force microscopy. The corrosion behavior of the coatings was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization. The results indicated that the addition of 1 mM of the MPI and MOPI Schiff bases to the silane coating increased the corrosion resistance from 1.92 to 14.65 and 18.95 kΩ cm2, respectively. The effect of immersion time on the performance of the proposed coatings was also investigated, and increasing immersion time from 1 to 12 and 24 h reduced the protection ability of the coatings. Nevertheless, the corrosion inhibition provided by the Schiff base-containing coatings was satisfying after 24 h of exposure to the corrosive medium. [ABSTRACT FROM AUTHOR]

In this study, we efficiently synthesized a new Schiff base ligand (H2L) along with its mononuclear complex Cu(II) (1). The chemical structures of these compounds were rigorously determined using various analytical techniques, including UV‐ Vis., FT‐IR, 1H NMR, 13 C NMR CHN elemental analysis, single crystal X‐ray diffraction, and quantum calculations. The X‐ray diffraction analysis of the complex revealed the presence of intermolecular interactions characterized by C−H...Br hydrogen bonds, leading to the formation of 2D layers. We conducted a systematic investigation of these intermolecular interactions using HS and QTAIM analysis. Additionally, we affected a comprehensive analysis of H2L, 1, and 2, focusing on their structural, electronic, and optical properties using DFT and TD‐DFT calculations in gas and solvent. The computed parameters closely matched the experimental data, demonstrating good agreement. Reactivity parameters indicated that complex 2 exhibited lower hardness (~1.7 eV) compared to 1 (~1.8 eV) and H2L (~4.4 eV). NLO analysis revealed substantial α and β values for compound 2 in both static and dynamic regimes. Notably, the β values of the title complexes increased with higher solvent polarity. In summary, our investigation highlights the potential of the title complexes as promising candidates for second‐order nonlinear optical materials. [ABSTRACT FROM AUTHOR]

A mononuclear copper(II) complex [CuLa] (1), and three mononuclear nickel(II) complexes [NiLa] (2), [NiLa]·CH3OH (2·CH3OH) and [NiLb] (3), where La and Lb are the dianionic form of N,N'-bis(4-bromosalicylidene)-1,2-cyclohexanediamine (H2La) and N,N'-bis(4-fluorosalicylidene)-1,2-cyclohexanediamine (H2Lb), respectively, were prepared and structurally characterized by spectroscopy method and elemental analyses. The detailed structures were determined by X-ray single crystal diffraction. All the copper and nickel complexes are mononuclear compounds. The metal ions in the complexes are in square planar coordination, with the two phenolate oxygens and two imine nitrogens of the Schiff base ligands. The biological effect of the four complexes were assayed on the bacteria strains Staphylococcus aureus, Escherichia coli and Candida albicans, which show that the substituent groups of the ligands and the metal ions can influence the antimicrobial activities. Complexes 1 and 3 have strong activity against Staphylococcus aureus and Escherichia coli, which are comparable to the reference drug tetracycline. [ABSTRACT FROM AUTHOR]

The bidentate (N, O) donor Schiff base, methyl‐4‐(2‐hydroxybenzylidene‐amino) benzoate (HL), was synthesized for the synthesis of CuL2 complex. Their structures were characterized by single crystal X‐ray diffraction and spectroscopic methods. The important structural features of ligand HL are (space group: Pca21; a = 6.1434(7) Å; b = 7.1021(7) Å; c = 28.963(3) Å; α = 90.00°; β = 90.00°, and γ = 90.00°) and of CuL2 are (space group: P21/n; a = 15.763(7) Å; b = 8.1921(5) Å, and c = 20.1955(8) Å; α = 90.00°; β = 96.547(4)°, and γ = 90.00°). The DFT/TD‐DFT studies were performed to evaluate the structure optimization, MEP plot, and electronic spectroscopy data as well as the HOMO‐LUMO energy and also other electronic descriptor properties. The DNA and BSA binding property of both the ligand and complex were studied employing a variety of spectroscopic methods, viscosity experiments, and gel electrophoresis technique. Their biophysical study including 3D fluorescence, FRET calculation, and anisotropy measurements with BSA were studied by spectrofluorometric methods. The molecular docking simulation of the ligand HL and CuL2 was executed with DNA and BSA to observe their different weak and strong binding interactions and to compare their binding aptitude with biomolecules and experimental results. The software "PASS" for drug likeness prediction and "ADMET" for bioactivity were implemented to get an idea about the antineoplastic and bioactivity aspects of HL and CuL2 complex. The anticancer property of the Cu(II) complex was measured by MTT assay against human breast carcinomas (MCF‐7) cancer cell line and as well as normal human embryonic kidney cells (HEK293) and is less toxic and comparable anticancer activity compared to cisplatin and oxaliplatin. The annexin V‐FITC, propidium iodide assay by flow cytometric method, and reactive oxygen species (ROS) production assay by DCFDA were assessed in presence of the HL and CuL2 for their cell death mechanism proceed via either apoptosis or necrosis. [ABSTRACT FROM AUTHOR]

Biopolymeric Schiff bases of chitosan and metal-based hydrogels have recently gained much attraction in biological applications. Herein, we successfully synthesized a novel binary blended hydrogel film [vanillin crosslinked chitosan (Cs)/locust bean gum (LBG)] and then synthesized its complexes with Fe(III), Zn(II) & Cu(II) metal ions by solution casting method. The synthesis of Schiff base and its metal complexes was confirmed by UV–Vis spectroscopy, FTIR, and XRD. The interactions between the polymeric chains, thermal stability, surface morphology, and the presence of the metal ions in the films were examined by FTIR, TGA, SEM, and EDX. The synthesized hydrogels were evaluated for their mechanical strength and swelling behaviors. Fe(III), Zn(II) and Cu(II) metal ions in the synthesized hydrogel films endowed conductive properties to the hydrogel. The antibacterial tests indicated that all hydrogels and their metal complexes have potent antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa bacteria strains. Finally, these innovative hydrogel films can be promising candidates for biomedical applications and soft electronics. [ABSTRACT FROM AUTHOR]

Copper is the third most abundant essential transition metal ion in the human body. It's responsible for important activities in many living things, but excessive intake of Cu2+ can lead to a range of diseases. A colorimetric and turn‐off fluorescent probe (E)‐2‐(5‐(benzothiazol‐2‐yl)‐2‐(diethylamino)‐4‐hydroxybenzylidene)‐N‐phenylhydrazine‐1‐carbothioamide (ZTR) was designed and synthesized by thiosemicarbazone Schiff base as a specific complexes site strategy to achieve highly specific Cu2+ detection. The fluorescence of the probe ZTR solution fell dramatically when Cu2+ was added, and its appearance changed from dazzling blue to nearly colorless. The simple structure and readily available fluorescent probe provide a novel approach for the quantitative detection of Cu2+ in the linear range from 0 to 0.12 μM, with a detection limit down to 16 nM, and with high selectivity for Cu2+ over 15 other metal ions. Job's plot analysis showed that probe ZTR and Cu2+ formed a 1:1 coordination complex. In addition, because of its low detection limits and fast response time, the created fluorescent molecule was effectively used to study the target ions on test paper strips and in water samples.)) [ABSTRACT FROM AUTHOR]

Three copper(II) and cobalt(III) complexes, [CuL(dca)]n (1), [CuL(N3)]n (2) and [CoL(N3)2(DMF)] (3), where L is the monoanionic form of the Schiff base (((2-(pyrrolidin-1-yl)ethyl)imino)methyl)naphthalen-2-ol (HL), and dca is dicyanamide, have been prepared and characterized by elemental analyses, IR and UV-Vis spectroscopy, as well as single crystal X-ray diffraction. The Cu atoms in complexes 1 and 2 are in square pyramidal coordination, and the Co atom in complex 3 is in octahedral one. Complexes 1 and 2 inhibit the Jack bean urease with IC50 values of 0.25 ± 0.14 and 0.32 ± 0.15 μmol L-1, respectively. Complex 3 show weak activity on Jack bean urease with percentage inhibition of 37%. [ABSTRACT FROM AUTHOR]

Two new copper(II) complexes, [CuL] (1) and [Cu4Cl2L2(N3)2]·CH3OH (2), derived from the bis-Schiff base N,N'-bis(4-bromosalicylidene)propane-1,2-diamine (H2L) have been prepared and characterized by spectroscopy methods, as well as single crystal X-ray determination. The Cu atom in the mononuclear complex 1 is in square planar coordination. The outer and inner Cu atoms in the phenolate and azide co-bridged tetranuclear complex 2 are in square planar and square pyramidal coordination, respectively. The antibacterial activities of the Schiff base and the two copper complexes have been assayed on the bacteria Staphylococcus aureus and Escherichia coli, and the yeast Candida parapsilosis. [ABSTRACT FROM AUTHOR]

A series of novel macroacyclic Schiff base ligands and their Cu (II) complexes were synthesised via reacting dicarbonyls of varying chain lengths with S-methyl dithiocarbazate (SMDTC) and S-benzyl dithiocarbazate (SBDTC) followed by coordination with Cu (II) ions. X-ray crystal structures were obtained for compound 4, an SBDTC-diacetyl analogue, and Cu7, an SMDTC-hexanedione Cu (II) complex. Anticancer evaluation of the compounds showed that Cu1, an SMDTC-glyoxal complex, demonstrated the highest cytotoxic activity against MCF-7 and MDA-MB-231 breast cancer cells with IC50 values of 1.7 µM and 1.4 µM, respectively. There was no clear pattern observed between the effect of chain length and cytotoxic activity; however, SMDTC-derived analogues were more active than SBDTC-derived analogues against MDA-MB-231 cells. The antibacterial assay showed that K. rhizophila was the most susceptible bacteria to the compounds, followed by S. aureus. Compound 4 and the SMDTC-derived analogues 3, 5, Cu7 and Cu9 possessed the highest antibacterial activity. These active analogues were further assessed, whereby 3 possessed the highest antibacterial activity with an MIC of <24.4 µg/mL against K. rhizophila and S. aureus. Further antibacterial studies showed that at least compounds 4 and 5 were bactericidal. Thus, Cu1 and 3 were the most promising anticancer and antibacterial agents, respectively. [ABSTRACT FROM AUTHOR]

In this study, new mixed ligand Cu(II), Ni(II) and Pd(II) metal complexes were synthesized and characterized by NMR (for ligand), UV‐Vis, elemental analysis, FT‐IR, molar conductivity techniques. While the octahedral structure is recommended for Cu(II) and Ni(II) complexes, the square plane structure is recommended for the Pd(II) complex. The compounds lack conductivity traits indicating their non‐electrolyte nature in solution. Photoluminescence properties of the synthesized mixed ligand complexes were investigated. These three complexes showed emission bands when excited at their maximum absorbances. The excitation/emission bands of the Pd(II) complex shifted to higher (red) wavelengths when compared to the Cu(II) and Ni(II) complexes. The Pd(II) complex showed the Stokes shift of 26 nm. These metal complexes were screened for their anticancer activities against the colon cancer (DLD‐1) and lung cancer (A549) cell lines. The results show that these complexes have antiproliferative activity. In particular, two of the complexes (Pd(II) and Cu(II)) were found to have a higher cytotoxic effect than the positive control drug cisplatin with low IC50 values. [ABSTRACT FROM AUTHOR]

Synthesis of three different new sulfonamide compounds (L1–L3) and their Cu(II) complexes were carried out. Their structures were characterized by spectroscopic methods such as Fourier transform infrared, Proton nuclear magnetic resonance and elemental analysis. Cu(II) complexes were screened for Gram-positive, Gram-negative bacteria and against yeast using the microdilution method. In particular, CuL2 was found to have significant antimicrobial effects on Gram (–), Gram (+) and eukaryotic yeast. The results showed that CuL2 exhibited better antimicrobial activity than other complexes. Depending on the antimicrobial activity results, time killing experiments of CuL2, the most effective complex, were performed. [ABSTRACT FROM AUTHOR]

Three new mixed Ni(II), Co(II) and Cu(II) complexes have been created using 2-((2-mercaptophenylimino)methyl)-4- methoxyphenol and 1,10-phenanthroline. FT-IR, Elemental analysis, magnetic susceptibility, UV-Vis and molar conductivity technique have all been used to explore the structural characterisation of these compounds. Magnetic susceptibility readings for the L-Cu, L-Ni, and L-Co complexes were 1.97 BM, 2.92 BM, and 2.84 BM, respectively. The L-Co complex is thought to be antiferromagnetic. The structures of the mixed ligand metal complexes are thought to be octahedral geometry. There are no conductivity properties in the complexes; however, they exhibit molar conductivities that range from 2.46 to 9.04 μS/cm. [ABSTRACT FROM AUTHOR]

The efficient synthesis of amino acid Schiff base copper(II) complexes using a microfluidic device was successfully achieved. Schiff bases and their complexes are remarkable compounds due to their high biological activity and catalytic function. Conventionally, products are synthesized under reaction conditions of 40 °C for 4 h using a beaker-based method. However, in this paper, we propose using a microfluidic channel to enable quasi-instantaneous synthesis at room temperature (23 °C). The products were characterized using UV–Vis, FT–IR, and MS spectroscopy. The efficient generation of compounds using microfluidic channels has the potential to significantly contribute to the efficiency of drug discovery and material development due to high reactivity. [ABSTRACT FROM AUTHOR]

Two new one-dimensional (1-D) end-to-end azido and thiocyanato bridged Cu(II) coordination polymers, [Cu(L)(µ-1,3-N3)]n(ClO4)n (1) and [Cu(L)(µ-1,3-NCS)]n(ClO4)n (2) with a morpholine-based tridentate N,N,N-donor Schiff base ligand (1-methyl-1H-imidazol-2-yl)-N-[2-(morpholin-4-yl)ethyl]methanimine, L) have been synthesized. Compounds 1 and 2 have been characterized by elemental analyses and spectroscopic techniques. The X-ray single crystal structures of 1 and 2 show the formation of regular zigzag chains with µ-1,3-azido and µ-1,3-thiocyanate bridges, respectively. Variable temperature (2–300 K) magnetic studies indicate that 1 shows a ferromagnetic intrachain exchange interaction with g = 2.135(2) and J = 2.13(2) cm−1, while in 2 this interaction is antiferromagnetic with g = 2.1412(3) and J = –0.277(2) cm−1. X-band EPR spectra of 1 and 2 in frozen (143 K) DMF solution corroborate our magnetic studies. [ABSTRACT FROM AUTHOR]

A new asymmetrically substituted ONOO Schiff base ligand N-(2′-hydroxy-1′-naphthylidene)-3-amino-2-naphthoic acid (nancH2) was prepared from the condensation of 2–hydroxy–1–naphthaldehyde and 3–amino–2–naphthoic acid. nancH2 reacts with Cu2(O2CMe)4·2H2O in the presence of Gd(O2CMe)3·6H2O to afford a uniform one-dimensional homometallic chain, [CuII(nanc)]n (1). The structure of 1 was elucidated via single crystal X-ray diffraction studies, which revealed that the Cu(II) ions adopt distorted square planar geometries and are coordinated in a tridentate manner by an [ONO] donor set from one nanc2− ligand and an O− of a bridging carboxylate group from a second ligand. The bridging carboxylato group of the nanc2− ligand adopts a syn, anti-η1:η1:μ conformation linking neighboring Cu(II) ions, forming a 1D chain. The magnetic susceptibility of 1 follows Curie–Weiss law in the range 45–300 K (C = 0.474(1) emu K mol-1, θ = +7.9(3) K), consistent with ferromagnetic interactions between S = ½ Cu(II) ions with g = 2.248. Subsequently, the data fit well to the 1D quantum Heisenberg ferromagnetic (QHFM) chain model with g = 2.271, and J = +12.3 K. DFT calculations, implementing the broken symmetry approach, were also carried out on a model dimeric unit extracted from the polymeric chain structure. The calculated exchange coupling via the carboxylate bridge (J = +13.8 K) is consistent with the observed ferromagnetic exchange between neighbouring Cu(II) centres. [ABSTRACT FROM AUTHOR]

We report two complexes [Cu(LI)2] (1) and [Cu(LII)2] (2) (HLI = N-cyclohexyl-3-methoxysalicylideneimine, HLII = N-cyclohexyl-3-ethoxysalicylideneimine). The ligands in both complexes are trans-1,5-N,O-coordinated, yielding a square planar CuN2O2 coordination core. The molecule of 1 is planar with two cyclohexyl groups oriented to the opposite sites of the planar part of a molecule, while the molecule of 2 is significantly bent with two cyclohexyl groups oriented to the same convex site of a molecule. It was established that both complexes in MeOH absorb in the UV region due to intraligand transitions and LMCT. Furthermore, the UV-vis spectra of both complexes revealed two low intense shoulders in the visible region at about 460 and 520 nm, which were attributed to d–d transitions. Both complexes were predicted to belong to a fourth class of toxicity with the negative BBB property and positive gastrointestinal absorption property. According to the molecular docking analysis results, both complexes are active against all the applied SARS-CoV-2 proteins with the best binding affinity with Nsp 14 (N7-MTase), PLpro and Mpro. The obtained docking scores of complexes are either comparable to or even higher than those of the initial ligands. Complex 1 was found to be more efficient upon interaction with the applied proteins in comparison to complex 2. Ligand efficiency scores for the initial ligands, 1 and 2 were also revealed. [ABSTRACT FROM AUTHOR]

The conjugated Schiff base (E)-1-(1H-Indol-3-yl)-N-(6-methylbenzo[d]thiazol-2-yl) methanimine (L1) was synthesised by reflux method and complexation with divalent Co, Ni, Cu and Zn. Further it was characterised by using 1H-NMR, FT-IR, UV/vis. and ESI-MS spectroscopy. The Schiff bases were tridentate coupled to the metal ions using N,N,N donor sites. After that, the biological activity of synthetic ligand (L1) and their metal complexes has been evaluated. Antibacterial properties of all target compounds were investigated in vitro. The prepared compounds prevent the pathogen from forming biofilms and regulate its growth. The disc diffusion method was used to investigate the inhibitory effects of the Schiff base ligands on bacterial growth. These investigations indicated that L1-Zn(II) complexes and ligands L1-Ni(II) had positive effects on Gram (-ve) Escherichia coli (E. Coli - MTCC 1610) and Gram (+ve) Micrococcus luteus (M. luteus MTCC-4300). [ABSTRACT FROM AUTHOR]

Four new complexes of copper(II), nickel(II) and zinc(II), [CuL2] (1), [Ni3L2(4-BrSal)2(CH3COO)2(CH3OH)2]-2CH3OH (2), [ZnBr2(HL)2] (3) and [ZnL(dca)]n (4), where L is 5-bromo-2-((cychlopentylimino)methyl)phenolate, HL is the zwitterionic form of 5-bromo-2-((cychlopentylimino)methyl)phenol, 4-BrSal is the monoanionic form of 4-bromosalicylaldehyde, dca is dicyanamide anion, were synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopy. The structures of the complexes were further confirmed by single crystal X-ray structure determination. Complex 1 is a mononuclear copper(II) compound, with a crystallographic two-fold rotation axis symmetry. The Cu atom is in distorted square planar coordination. Complex 2 is a trinuclear nickel(II) compound, with an inversion center symmetry. The Ni atoms are in octahedral coordination. Complex 3 is a mononuclear zinc(II) compound, while complex 4 is a dca bridged polymeric zinc(II) compound. The Zn atoms are in tetrahedral coordination. The compounds were assayed for their antimicrobial activities. [ABSTRACT FROM AUTHOR]

The current study intends to develop a novel, simple and selective colorimetric method to identify the presence of copper on the basis of a newly-synthesized Schiff base prepared from the condensation of 1,3-phthalaldehyde with 2-aminophenol. The new chromogenic agent was studied using elemental analysis, IR, NMR, MS, and UV-VIS absorption. The new chelate produces a stable colored complex with Cu(II) ions with a 1:1 composition using the continuous variation method. The colored complex exhibited a strong absorption peak at 440 nm and this phenomenon empowers copper analysis to be conducted in natural water, and pharmaceutical solutions directly via the colorimetric method. The author analyzed and optimized all the factors that tend to influence the sensitivity of the method. Such factors include pH, time, the concentration of the ligand and temperature. The process, proposed in the study, was then evaluated in terms of precision, accuracy and selectivity. The study outcomes are as follows: linear dynamic range 0.8-22 μg mL-1; limit of quantitation 0.970 μg mL-1; and limit of detection 0.293 μg mL-1. [ABSTRACT FROM AUTHOR]

Schiff base ligand [3-(2-hydroxyphenylimino)-1,3-dihydroindol-2-one] was synthesized by the condensation reaction of isatin with 2-aminophenol. The Schiff base and its metal complexes with Co(II), Ni(II), and Cu(II) and ions were permeated by 1H NMR, IR, elemental analysis, ESI-MS spectroscopy, electronic spectroscopy, and some physicochemical measurements. The Schiff base behaved as a tridentate ligand in all metal complexes and was linked by azomethine nitrogen (=C=N). Supported by analytical data the metal-ligand stoichiometry in the formation of complexes was found as 1 : 2 molecular ratio. Based on analytical data allied with spectroscopic studies spilled that the Cu(II) complex preferred tetrahedral geometry, while Ni(II) and Co(II) complexes offered square planar and octahedral geometry, respectively. The complexes were undergone thermal analysis (TGA and DTG); complexes were found thermally stable up to 200°C. All the stable assembled compounds were assessed for antibacterial competency. The ligand and the complexes were played mild to sturdy antibacterial activity against numerous pathogenic bacterial species, although growth inhibitory activities of complexes were enhanced comparatively than their respective ligands. Additionally, molecular docking analysis and quantum computational calculations based on the density functional theory (DFT) approach were used to study the molecular characteristics of the novel complexes and provide in-depth insights into their involvement in their ability to restrict bacterial growth. [ABSTRACT FROM AUTHOR]

The newly synthesized biphenyldicarboxylic acid Schiff base and its complexes with Cu(II) were synthesized, and their spectroscopic and structural analysis was performed. The reaction of the ligand and copper(II) acetate in different solvents resulted in the formation of two solvatomorphic complexes, one with MeOH, and the other with DMF molecules, in the crystal lattice. The differences in the results of the thermal analysis could be explained by the different polarities of the solvents present. SC-XRD analysis revealed that the ligand is coordinated as a dianion, in a pentadentate manner, through two phenoxide oxygen atoms, two azomethine nitrogen atoms, and with the oxygen atom of one carboxylate functioning as a bridge that connects the monomeric units. The coordination polyhedron was described with several parameters obtained from different methods of calculation. The presence of different solvents in the crystal structure results in differences in the H-bond networks, and an overall different crystal packing of the structural units in the obtained complexes. [ABSTRACT FROM AUTHOR]

Interest in developing selective and sensitive metal sensors for environmental, biological, and industrial applications is mounting. The goal of this work was to develop a sensitive and selective sensor for certain metal ions in solution. The goal was achieved via (i) preparing the sensor ((E)-2-((pyridine-3-ylimino)methyl)phenol) (3APS) using microwave radiation in a short time and high yield and (ii) performing spectrophotometric titrations for 3APS with several metal ions. 3APS, a Schiff base, was prepared in 5 min and in a high yield (95%) using microwave-assisted synthesis. The compound was characterized by FTIR, XRD, NMR, and elemental analysis. Spectrophotometric titration of 3APS was performed with Al(III), Ba(II), Cd(II), Co(II), Cu(II), Fe(III), Mn(II), Ni(II), and Zn(II). 3APS showed good abilities to detect Al(III) and Fe(III) ions fluorescently and Cu(II) ion colorimetrically. The L/M stoichiometric ratio was 2:1 for Cu(II) and 1:1 for Al(III) and Fe(III). Low detection limits (μg/L) of 324, 20, and 45 were achieved for Cu(II), Al(III), and Fe(III), respectively. The detection of aluminum was also demonstrated in antiperspirant deodorants, test strips, and applications in secret writing. 3APS showed high fluorescent selectivity for Al(III) and Fe(III) and colorimetric selectivity towards Cu(II) with detection limits lower than corresponding safe drinking water guidelines. [ABSTRACT FROM AUTHOR]

A bis-Schiff base N,N'-ethylene-bis(3-bromosalicylaldimine) (H2L) was prepared from 3-bromosalicylaldehyde and ethane-1,2-diamine. With H2L as ligand, a new copper(II) complex [CuL] (1) and a new cobalt(III) complex [CoL(NCS) (DMF)] (2) were prepared and characterized by physico-chemical methods and single crystal X-ray analysis. X-ray analysis indicates that the Cu atom in complex 1 is in square planar coordination, and the Co atom in complex 2 is in octahedral coordination. The compounds were tested in vitro for their antibacterial activities on Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas fluorescens. Both complexes have effective activities on the bacteria. [ABSTRACT FROM AUTHOR]

An ultrasound-assisted synthesis has been used for the preparation of novel benzothiazole Schiff bases (1-3) as ligands for Zn(II) and Cu(II) metal complexes. In this class of Schiff base ligands, the isolated complexes 1a and 2a appear to be the only ones that have structures which include both the Schiff base ligand and the hydrolysis product 2-aminobenzothiazole in the same complex molecule. The aldehydes formed by Schiff base hydrolysis formed a rare example of a trans-isomer in pentacoordinated 2,4-disubstituted benzaldehyde complexes. [ABSTRACT FROM AUTHOR]

[Display omitted] • New copper(I) Schiff base complex was synthesized and characterized. • Crystal structure of Cu(I) complex by single crystal X-ray diffraction technique was examined. • Catalytic activity of the Cu(I) complex was executed in the first-time synthesis of new tetrahydropyrimidine derivatives. • A mechanism for the catalytic reaction was suggested and investigated by density functional theory (DFT). Herein, we report the synthesis and spectroanalytical characterization of one-dimensional polymeric Cu(I) complex [Cu(L2Br)I] n , incorporating N,N′ -bis(2-bromobenzylidene)ethane-1,2-diamine Schiff base ligand, L2Br. Single crystal X-ray diffraction (SC-XRD) was used to examine the specific organization of atoms in the complex. The results showed that the Cu ion was coordinated only through the N donor sites of the Schiff base. The complex's tetrahedral shape was distorted, as demonstrated by the bond angles around the metal atom. The natural bond orbital and atoms in molecules investigations were also carried out in order to gain greater knowledge of the Cu(I) complex's intermolecular charge transfer characteristics. The redox nature of the the complex was assessed by the cyclic voltammetry (CV) technique. The Cu(I)/Cu(II) redox arrangement has been observed to exhibit characteristics consistent with a quasi-reversible method. Furthermore, the catalytic activity of the Cu(I) complex was executed in the first-time synthesis of new tetrahydropyrimidine derivatives by treating various aryl nitriles with 2,2-dimethyl-1,3-propanediamine under conventional thermal conditions. A mechanism for the catalytic reaction was suggested and investigated by density functional theory (DFT). [ABSTRACT FROM AUTHOR]

• Different electronic and steric effects of amine backbone led to linear-type M-Dy-M, one-dimensional (1D) chain and interlayer-type structures of complexes. • Align the magnetic easy axis of lanthanide ions as closely as possible with the direction of M-M facilitating the mitigation of quantum tunneling of magnetization. • Notable hysteresis loops at maximum temperature of 3.5 K, 7.5 K, and 4 K are observed for Cu 2 Dy, Zn 2 Dy and Ni 2 Dy complexes, respectively. Series of 3d-4f heterotrinuclear complexes [ M Dy M ] (M =Zn, Cu, Ni) with formula [Cu 2 (L1) 2 DyCl 2 (H 2 O)]·Cl·MeCN (1), [Cu 2 (L2) 2 DyCl 2 ] n (2), [Cu 2 (L3) 2 DyCl 2 (MeOH) 2 ]·Cl·(MeOH) 3 (3), [Zn 2 (L1) 2 DyCl 2 (H 2 O)]·Cl·MeCN (4) and [Ni 2 (L1) 2 DyCl 3 ]·(CH 2 Cl 2) 2 (5) were constructed by three hexadentate compartment Schiff bases (L1 = N ,N'-bis(3-methoxysalicylidene)-2,2-dimethylpropane-1,3-diamine; L2 = N ,N'-bis(3-methoxysalicylidene)-1,3-propanediamine; L3 = N ,N'-bis(2‑hydroxy-3-methoxybenzylidene)-1,2-phenylenediamine). Different electronic and steric effects of amine backbone lead to linear-type M -Dy- M , one-dimensional (1D) chain and interlayer-type structures of complexes 1 – 5 , respectively. Among these, complexes 1, 4 and 5 were constructed as the M -Dy- M linear-type coordination configuration containing diamagnetic zinc(II) ions and paramagnetic copper(II) ions or nickel(II) ions respectively. Molecular magnetic studies reveal that complexes 1, 4, 5 and chain complex 2 exhibited significant single-molecule magnets (SMMs) behavior and the notable hysteresis loops at maximum temperature of 3.5 K, 3 K, 7.5 K, and 4 K are observed, which are comparable among the outstanding heteronuclear (d/f) SMMs constructed by Schiff base ligands. Series of 3d-4f heterotrinuclear [MDyM] SMMs were constructed, different electronic and steric effects of amine backbone lead to very different structure and displaying significant magnetic relaxation with hysteresis loops at maximum temperature of 3.5 K, 3 K, 7.5 K, and 4 K, respectively, which are comparable among the outstanding heteronuclear (d/f) SMMs constructed by Schiff base ligands. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • New benzhydrazone based Schiff base metal(II) complexes were synthesized and characterized. • DNA binding experiments revealed complexes bind to DNA through the intercalation binding mode. • DNA cleavage investigation displayed Cu(II) complexes completely destroy the DNA instead of cleavage. • Ni(II) complex has (IC 50 2.38 ± 2.2 µg/mL) a strong ability to inhibit the growth of MCF-7 cell line. Bivalent mononuclear transition metal complexes of cobalt, nickel, copper and zinc were synthesized from (E)-2-(1-(2-(2-hydroxybenzoyl)hydrazono)ethoxy)benzoic acid. The FTIR, 1H NMR, 13C NMR, HR-Mass, UV–Vis., EPR, Powder XRD and SEM analysis were employed to investigate the structural features of synthesized compounds. The spectral data confirmed the square planar geometry of the complexes. The EPR spectra of the Cu(II) complex supported the proposed geometry. Powder X-ray diffraction (PXRD) analysis and scanning electron microscopy (SEM) imaging revealed that the complexes consist of nano-sized grains exhibiting a polycrystalline structure. The in vitro antimicrobial efficacy of the compounds was evaluated against various bacterial and fungal strains using the well diffusion method. The in vitro antibacterial activity demonstrated that all synthesized compounds were biologically active, and Zn(II) complex exhibited the highest inhibitory activity against S. aureus (gram-positive bacteria). For antioxidant activity, the free ligand and its metal chelates were evaluated using the standard DPPH method, revealing that the Co(II) complex displayed least inhibitory concentration value (IC 50 = 16 ± 2.3 μg/mL) indicating the highest antioxidant activity. DNA interaction studies showed intercalation between complexes and DNA, and the Cu(II) complex exhibited a higher binding affinity of 2.78 ± 0.34 × 105 M−1. The DNA cleavage ability of the compounds was assessed using gel electrophoresis, demonstrating the effective cleavage of the pBR322 plasmid DNA. The Schiff base and its complexes were subjected to an anticancer evaluation against the human breast cancer cell line (MCF-7) using the MTT assay method. The percentage cell inhibition of the compounds was calculated. [ABSTRACT FROM AUTHOR]

Reaction of the Schiff base 2,4-difuloro-6-(((2-(pyrrolidin-1-yl)ethyl)imino)methyl)phenol (HL) with copper salts and some bridging ligands afforded five complexes, [CuClL] (1), [Cu(μ-Br)L] n (2), [Cu(μ-Br)(μ 1,5 -dca)L] n ·nCH 3 OH (3), [Cu(μ 1,3,5 -dca)L] n (4) and [Cu(μ 1,3 -N 3)L] n (5) (dca = dicyanoamide). These complexes have been analyzed and characterized by the means of elemental analysis, infrared and electronic spectra, as well as single crystal X-ray diffraction. The Cu atom in the mononuclear complex 1 is in square planar coordination, in the bromido-bridged polynuclear complex 2 is in square pyramidal coordination, in the bromido and dca co-bridged polynuclear complex 3 is in square pyramidal coordination, in the dca bridged polynuclear complex 4 is in octahedral coordination, and in the azido bridged polynuclear complex 5 is in square pyramidal coordination. The Schiff base ligand coordinates to the CuII ions through the phenolate oxygen, imine nitrogen and pyrrolidine nitrogen atoms. The biological study revealed that the complexes have good antimicrobial activity against the bacteria strains B. subtilis , S. aureus , E. coli and P. fluorescens. [Display omitted] Reaction of the Schiff base 2,4-difluoro-6-(((2-(pyrrolidin-1-yl)ethyl)imino)methyl)phenol (HL) with copper salts and some bridging ligands afforded five complexes, [CuClL] (1), [Cu(μ-Br)L] n (2), [Cu(μ-Br)(μ 1,5 -dca)L] n ·nCH 3 OH (3), [Cu(μ 1,3,5 -dca)L] n (4) and [Cu(μ 1,3 -N 3)L] n (5) (dca = dicyanoamide). These complexes have been analyzed and characterized by the means of elemental analysis, infrared and electronic spectra, as well as single crystal X-ray diffraction. The Cu atom in the mononuclear complex 1 is in square planar coordination, in the bromido-bridged polynuclear complex 2 is in square pyramidal coordination, in the bromido and dca co-bridged polynuclear complex 3 is in square pyramidal coordination, in the dca bridged polynuclear complex 4 is in octahedral coordination, and in the azido bridged polynuclear complex 5 is in square pyramidal coordination. The Schiff base ligand coordinates to the CuII ions through the phenolate oxygen, imine nitrogen and pyrrolidine nitrogen atoms. The biological study revealed that the complexes have good antimicrobial activity against the bacteria strains B. subtilis , S. aureus , E. coli and P. fluorescens. [ABSTRACT FROM AUTHOR]

• Cu(II) and Zn(II) Schiff base complexes were characterized by X-ray crystallography, FT-IR, and CHN. • The DNA/BSA binding was studied by UV–vis & PL method, CV, CD, electrophoresis & docking simulation. • MTT assay showed the complexes cytotoxicity against three cancer cell lines. • Zn(II) complex performed as an efficient turn-off sensor for CrO 4 2− ion in water medium. • Cu(II) complex showed a high catecholase activity. Synthesis, characterization, X-ray crystallography, and the interaction with BSA/FS-DNA are reported for two new complexes, [{CuII 2 L(NCS) 2 }(μ 1,3 -NCS)] n (1) and [ZnII 2 L(μ 1,1 -N 3)(N 3) 2 ] (2) (where L =[2,6-bis{N-(2-pyridylethThis section comprises references that occur in the reference list but not in the body of the text. Please position each reference in the text or, alternatively, delete it.yl)formidoyl}-4-methylphenol]). Characterization of the complexes was performed using elemental analysis, UV–vis, and FT-IR spectroscopy. X-ray analysis revealed a thiocyanate-bridged 1-D polymeric structure for complex 1 and a homodinuclear monophenoxo- and azido-bridged structure for complex 2. ‌‌Binding affinity and interaction mode with BSA/FS-DNA were investigated for both complexes using absorption and emission spectroscopy, viscosity measurement, circular dichroism, agarose gel electrophoresis, electrochemical study, and docking simulation. The EtBr replacement experiments clarified an effective binding affinity, K b = 0.53 × 106 M−1 and K b = 3.5 × 106 M−1 for complex 1 and 2, respectively, and intercalation as the dominant binding mode for both complexes. Furthermore, the cytotoxicity detection test of the complexes against AGS, MCF-7, PC3 cancer, and NIH/3T3 normal cell lines has shown a moderate selective anticancer activity against MCF-7 and AGS in complex 1. Both complexes triggered apoptosis-programmed cell death. Also, complex 2 showed a sensitive and selective turn-off fluorescence behavior (K b = 1.1 × 1010 M−1) toward CrO 4 2− among various anions with LOD of 5 × 10−7 M. Moreover, the ability of complex 1 to catalyze the oxidation of 3,5-di‑ tert ‑butyl catechol (3,5-DTBCH 2) to its related quinone, was investigated and it showed an acceptable enzymatic activity. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Schiff bases are suitable for synthesizing of coordination complexes. • Schiff base complexes are used in pharmaceutical industries as drugs. • Environmental issues can be overcome by essential elements like Cu(II) and Ni(II) • Mononuclear complexes serve as ligands for synthetic polynuclear metal complexes. • Metal complexes exhibit square planar geometry and thermodynamic stability. The present work aims to synthesize and characterize new Schiff base metal complexes (Cu(II) and Ni(II)) derived from 4,5-Dichloro- o -phenylenediamine and 3,5-Dichloro-2-hydroxyacetophenone. The synthesized Schiff base and their complexes have been characterized with the support of more than a few standard physicochemical techniques such as elemental analysis, spectroscopic, thermal, and cyclic voltammetry studies. Further the molecular structures are ascertained by computational methods like density functional theory (DFT) methods. The newly synthesized Schiff base ligand acts as ONNO donor tetradentate chelate and coordinated through an azomethine nitrogen and phenoxo oxygen atom to the Cu(II) and Ni(II). Moreover, all the newly prepared compounds exhibit moderate biological activity such as antibacterial. The synthesized compounds were screened for their antibacterial by the disc agar diffusion method. Spectral analysis exhibits square planar geometry for Cu(II) & Ni(II) mono and binuclear complexes. The antimicrobial results indicate that the homo binuclear copper (II) complex was more active than the other mono and binuclear complexes. The theoretical DFT calculations were applied to verify the molecular geometry of chelators and their complexes. The DFT optimized geometries of the complexes are in agreement with experimental observations. [ABSTRACT FROM AUTHOR]

[Display omitted] • A dinuclear Cu(II) complex with oxazolidine ligand and two Schiff base complexes with the same ligand were synthesized by "one-pot" method and characterized. The self-assembly process of these complexes were monitored by ESI-MS. • This is the first report of oxazolidine complex/ tetrabutylammonium halide co-catalyst in for the cycloaddition of CO 2 and epoxides reaction. • The catalytic explore for the cycloaddition of CO 2 and different reaction substrates and preliminary kinetic studies shows that the reaction is a intramolecular Lewis acid-base catalytic mechanism. Catalytic chemical fixation of carbon dioxide to high value-added chemicals has attracted extensive attention and the discovery of new catalytic system has always been a research hotspot in carbon dioxide chemistry. Three complexes were synthesized by using 2-quinoline formaldehyde and tris-base precursor through Schiff base reaction and characterized. Compound Co[L 1 ] 2 Cl 2 ·2H 2 O (1) and compound Ni[L 1 ] 2 Cl 2 ·2H 2 O (2) are two mononuclear complex with derived schiff base ligand (L 1 = 2-(hydroxymethyl)-2-((quinolin-2-ylmethylene)amino)propane-1,3-diol), while compound Cu 2 [L 2 ] 2 Cl 2 ∙2CH 3 OH (3) is a dinuclear complex containing derived deprontonated ligand (L 2 = (2-(quinolin-2-yl)oxazolidine-4,4-diyl)dimethanol) The self-assembly process of these complexes were monitored by ESI-MS. The catalytic explore for the cycloaddition of CO 2 and different reaction substrates and preliminary kinetic studies shows that all complexes are active and the reaction is an intramolecular Lewis acid-base catalytic mechanism. This is the first report of oxazolidine complex/ tetrabutylammonium halide catalyst in for cycloaddition of epoxides and CO 2 reaction and the complex 3 is more active than the other two complexes, which provides new notions for the design and solicitation of Schiff base/oxazolidine catalysts. [ABSTRACT FROM AUTHOR]

Herein, we document the development of a novel organoselenium-based Schiff base, 2-((4-((2-hydroxy-4-nitrobenzylidene)amino)phenyl)selanyl)- N -phenylacetamide (HOASe), to selectively separate zinc and copper from food samples. To the best of our knowledge, OSe compound has never been used in microextraction procedures before, until today. HOASe was synthesized from aniline by a simple four-step procedure. The structure of HOASe was elucidated by various spectroscopic techniques (e.g., IR, MS, 1H- and 13C NMR). After that, HOASe was used to extract Cu2+ and Zn2+ by ultrasonic-assisted dispersive liquid-liquid microextraction based on the solidification of floating organic drop (UA-DLLME-SFOD) combined with flame atomic absorption spectrometry. Important experimental parameters including amount of the extraction solvent, initial pH, amount of HOASe, ultrasonication time, centrifugation, and salt addition, were studied and optimized to offer quantitative separation of the analytes. The detection limits and the linear ranges for Cu2+ and Zn2+ were 1.9, 8.0 – 400.0, and 2.4, 6 – 150 μg L-1, respectively. The method's greenness and applicability were assessed using the Analytical GREEnness metric methodology and the Blue Applicability Grade Index, respectively. Finaly, this approach was used for quantification of Cu2+ and Zn2+ in food samples and, therefore, can be further developed for food safety and quality control programs. [Display omitted] • A novel organoselenium-based Schiff base was prepared and characterized. • It was used as ligand for UA-DLLME-SFOD of Cu2+ and Zn2+ • The procedure is simple, precise, and accurate. • The LODs were 1.9 and 2.4 μg L-1 for Cu2+ and Zn2+, respectively. • The procedure was applied for determination of Cu2+ and Zn2+ in foods by FAAS. [ABSTRACT FROM AUTHOR]

Two novel coordination polymers {[Cu4(H2dam-dap)4(ClO4)2]·2ClO4}n (1) and [Cu3(H2dam-dap)2(N3)2(NO3)2]n (2) have been obtained through the copper salts and 3-(3-Amino-propylimino)-butan-2-one oxime (H3dam-dap) ligand, which was synthesized by one-pot reaction in the preparation process of complexes. Single-crystal X-Ray analysis shows that complex 1 displays a cage-like 12-MC-4 metallacrown structural unit with the sides exhibiting Cu–N–O repeat units, and the cage-like structures have been linked into one 1D chain by the bridges of ClO4− anions; 2 possesses trinuclear [Cu3(H2dam-dap)2]4+ unit with three Cu ion locating in a linear arrangement, and the adjacent trinuclear units are linked into a 2D coordination polymer by bridging nitrate anions. Magnetic studies reveal that 1 displays ferromagnetic coupling between metal centres, and 2 exhibits antiferromagnetic interaction and field-induced frequency-dependent behavior. [ABSTRACT FROM AUTHOR]