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Abstract A Pd(II) complex of tetradentate Schiff base ligand, bis(5-methoxysalicylidene)-4-methyl benzene-1,2-diamine (H 2 L) was prepared from Pd(OAc) 2 in refluxing acetonitrile. The complex was characterized using FT-IR, lH NMR, 13C{1H} NMR spectroscopic techniques, elemental analyses (CHN). Also, its molecular structure was determined by single-crystal X-ray diffraction. The crystal structure data showed a tetradentate mode of coordination for Schiff base, through N 2 O 2 donor sets. In addition, DFT calculations at M06-2X/Def2-TZVP level of theory were conducted to obtain electronic and structural properties of the studied species. NBO-CMO analysis combined with TD-DFT method was done to interpret electronic transitions by determining their included occupied and virtual orbitals. NBO-CMO data show that there are MMCT and LMCT in the studied complex. All theoretical data are in line with the experimental results. Highlights • Synthesis, characterization and spectral properties of new Pd(II) Schiff base complex. • Geometry distorted square-planar around Pd(II). • Structural and DFT studies of the new Pd(II) complex. [ABSTRACT FROM AUTHOR]

Abstract A new Schiff base, HL , derived from condensation reaction of 2,4-dihydroxybenzaldehyde and 4-amino-3-methyl-1 H -1,2,4-triazole-5(4 H)-thione together with its Ni(II) complex have been synthesized and characterized by several spectroscopies methods. The optimized geometries, assignment of the IR bands and NMR chemical shifts as well as exploring of the frontier orbitals of two synthesized compounds have been calculated using the density functional theory (DFT) procedures. The most stable tautomer of the HL Schiff base and kinetics of its tautomerization have been explored theoretically. In the square planar structure of the [Ni(L)Cl] complex, the anionic L - acts as a NOS tridentate ligand. The chloro ligand is positioned trans to the azomethine nitrogen. The DFT-computed IR frequencies and NMR chemical shifts are good in agreement with their corresponding experimental values, approving validity of the optimized geometries for two investigated compounds. The [Ni(L)Cl] complex exhibits high catalytic activities in a three-component cyclocondensation for synthesis of the tetrahydrobenzo [ b ]pyrans. Graphical abstract Image 1 Highlights • A new 1,2,4-triazole Schiff base and its Ni(II) complex have been newly synthesized. • Optimized geometries and assignments of the IR and NMR spectra have been computed using the DFT methods. • The synthesized Schiff base (HL) acts as a NOS tridentate ligand. • The chloro ligand occupies the 4th coordination position of the square [Ni(L)Cl] complex. • Catalytic behavior of the [Ni(L)Cl] complex has been investigated. [ABSTRACT FROM AUTHOR]

Abstract A Schiff base ligand HL has been synthesized by the condensation of an equimolar amount of 2-hydroxy-4-methoxybenzaldehyde and 3-amino-1,2,4-triazole and characterized by elemental analysis, IR, 1H NMR, 13C NMR and ESI-mass spectrometry. The metal complexes 1–4 have been synthesized by the reaction of ligand with Co(II), Ni(II), Cu(II) and Zn(II) chlorides in ethanol in the molar ratio 1:1. All the metal complexes 1–4 were characterized by elemental analysis, molar conductance, electronic spectra, IR, and EPR spectra. TGA has been done to check the stability of the synthesized Schiff base ligand HL and its metal complexes 1–4. Spectral data reveals that the ligand HL acts as uninegative tridentate for metal complexes. The geometries of synthesized ligand and its metal complexes were optimized by using Gaussian 09 W program. On the basis of spectral characterization, octahedral geometry has been allocated for Co(II), tetrahedral for Ni(II), tetragonal for Cu(II) and tetrahedral for Zn(II) complexes. The DNA binding studies of metal complex have been investigated by UV absorbance, fluorescence and CD spectrometry. UV absorbance binding studies show that metal complex 1–3 could bind to ctDNA significantly and the results obtained were consistent with the fluorescence and CD spectra. Graphical abstract HOMO and LUMO of Schiff base ligand HL. Image 1 Highlights • Synthesis of 1,2,4-triazole derived Schiff base ligand and its metal complexes. • Characterization by IR, 1H NMR, 13C NMR, ESI-mass, EPR, electronic spectra and TGA. • Ligand HL acts as uninegative tridentate fashion. • Complexes possessed octahedral, tetrahedral, tetragonal, and tetrahedral geometry. • DNA binding of the metal complexes by UV absorbance, fluorescence and CD spectrometry. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A centrosymmetric copper(II) Schiff base complex has been Synthesized. • The Schiff base is trapped in its zwitterionic form. • Supramolecular interactions lead to the formation supra-molecular architecture. • Anion⋯anion interaction between the perchlorate anions have been analyzed. Abstract A centrosymmetric square planar bis-ligand copper(II) complex, [Cu(HL) 2 ](ClO 4) 2 , with a potential tetradentate Schiff base, HL = 2-(2-(ethylamino)ethyliminomethyl)-6-ethoxyphenol, containing pendant side arm, has been prepared and characterized by elemental and spectral analysis and single crystal X-ray diffraction studies. The potential tetradentate Schiff base is trapped in its zwitterionic form and shows a bidentate bonding mode. Several weak forces like hydrogen bonding and C H∙∙∙π interactions lead to the formation of supra-molecular architecture. The existence of an anion⋯anion interaction between the perchlorate anions have been analyzed using DFT calculations, the Bader's theory of atoms-in-molecules (AIM) and the non-covalent interaction index (NCI plot). The O⋯O distance is 2.848(2) Å. [ABSTRACT FROM AUTHOR]

In our current study, Fe (II) complex with 4-4ʹ-methylene bis (2,6-diethyl)aniline-3,5-di-tert-butylsalisilaldimine (HL1) ligand was synthesized by chemical method and the synthesized Fe (II) complex with HL1 ligand was named as Fe(L1)2 complex. Structural, morphological, electronic absorption and photovoltaic properties of Fe(L1)2 complex were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, electronic absorption, and current density (J)-voltage (V) measurements, respectively. The obtained result from the J-V measurement shows that Fe(L1)2 complex synthesized by the chemical method can be used as a promising sensitizer for a dye-sensitized solar cell. [ABSTRACT FROM AUTHOR]

Graphical abstract Seven new water-soluble chiral/achiral SOD-mimicking metal complexes were synthesized and fully characterized. The antioxidant activity of all complexes and their corresponding hybrid proteins were determined. The results show that the water-solubility played a role in improving the antioxidant activity, and the activity was higher when combined with BSA. Abstract Seven new water-soluble chiral/achiral SOD-mimicking metal complexes: NaK[Mn(R -L1)(C 2 H 5 OH) 4 ] (Mn - 1a), NaK[Mn(S -L1)(C 2 H 5 OH) 4 ] (Mn - 1b), NaK[Co(R -L1)]·3H 2 O (Co - 2a), NaK[Co(S -L1)]·3H 2 O (Co - 2b), NaK[(VO)(R -L1)(OH)]·5H 2 O (V - 3a), NaK[(VO)(S -L1)(OH)]·5H 2 O (V - 3b) and [MnL2]·[(CH 3 CH 2) 3 NH] 2 ·5H 2 O (Mn - 4) were synthesized and fully characterized. Furthermore, hybrid protein, binding with complexes and bovine serum albumin (BSA) to enhance the antioxidant activity, were synthesized and evaluated by multispectroscopic techniques. The SOD activities of all complexes and their corresponding hybrid proteins were tested by xanthine/xanthine oxidase method, the antioxidant activity of them were determined by ABTS method. The results show that the SOD activities of the hybrid proteins are higher than that of the corresponding complexes. From the values of the antioxidant activity we obtained, there seems to be some connection between the configuration and antioxidant activity. [ABSTRACT FROM AUTHOR]

Abstract 2-amino-3-(4-hydroxyphenyl) N-[(1E)-(2-hydroxyphenyl)methylene]propanehydrazide (amph , LH 2) and Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes were synthesized and characterized based on the elemental analyses, molar conductance, TGA, magnetic susceptibility, 1H and 13C NMR, UV–Vis, IR, EPR and mass spectroscopic, cyclic voltammetric, SEM, TEM and powder XRD data. Formation of complexes having 1:1 metal:ligand stoichiometry was envisaged from elemental and TG studies. On the basis of the magnetic and spectral studies, distorted octahedral geometry had been assigned for all the complexes in which the ligand acted as a tridentate species bonding through the carbonyl-O, azomethine-N and phenolate/phenolic-O. The molecular geometries of the metal complexes were also optimized using the hybrid functional B3LYP and the segmented all-electron relativistically contracted def2-SVP as the basis set for the DFT calculations. The ligand and all the complexes showed irreversible redox behavior. The complexes were observed to bind CT-DNA through intercalative mode. The ligand was active against bacterial strains Bacillus subtilis , Pseudomonas aeruginosa and Escherichia coli while the complexes would exhibit selectiveness in their activities. Graphical abstract Image 1 Highlights • The Schiff base was synthesized from L-Tyrosine Hydrazide. • The ligand forms 1:1 transition metal complexes in which it acts as a tridentate species. • All complexes have tetragonally distorted octahedral geometry. • The ligand and complexes exhibit irreversible redox behaviour. • The ligand and complexes possess antimicrobial activities against some bacterial strains and the complexes bind CT-DNA by intercalative modes. [ABSTRACT FROM AUTHOR]

Two novel cationic Ru(III) complex compounds with Schiff bases, N-phenyl-5-X-salicylideneimine (where X = H or Br) and indazole have been synthesized and characterized by various spectral and electrochemical analysis. The existence of molecular ions M+ at m/z 730.1652 and 887.9818 corresponding to [C40H32N6O2Ru]+ and [C40H30Br2N6O2Ru]+, respectively, was obtained by mass spectra analysis. The coordination of the ligands in the Ru(III) octahedral environment occurs through imine nitrogen, deprotonated phenolic oxygen atom from the Schiff bases as well as via the free electronic pair on the nitrogen atom in indazole. Furthermore, the effect of the cationic Ru(III) complexes on the Briggs-Rauscher oscillating reaction was preliminary studied and monitored potentiometrically. [ABSTRACT FROM AUTHOR]

Abstract New transition metal complex of Pt(II) of the Schiff base ligand with (E)-2-((1-(thiophen-2-yl)ethylidene)amino)phenol HL have been synthesized using the ultrasonic irradiation and characterized by physicochemical and spectroscopic methods. The IR spectrum of Pt(II) complex showed that the coordination in metal ions via the imine N and S atoms. Magnetic and UV–Vis spectra showed that the geometrical structure of Pt(II) complex is square planar. The molar conductance data revealed that Pt(II) complex is non-electrolyte. The thermodynamic parameters for thermal decomposition of Pt(II) complex was calculated from analysis of the TG-DTG curves using Hörowitz–Metzger method. The fluorescence of the ligand HL and its Pt(II) complex in different solvents and pH conditions have also been studied in detail. The quenching of the fluorescence intensity of the ligand can be noted obviously, in the presence of Pt(II) ion. Geometry optimization of the compounds was calculated by semiempirical molecular orbital theory PM3 method using Hyperchem 7.52 program. Graphical abstract Image 1 Highlights • Synthses of novel Pt(II) Schiff base complex by ultrasonic method. • Spectroscopic studies suggested that Pt(II) complex possess a square planar geometry. • The Schiff base ligand HL and its Pt(II) complex was exhibited fluorescent properties. • Molecular orbital calculations were performed using hyper Chem 7.52 program. [ABSTRACT FROM AUTHOR]

The recent environmental awareness has been the motivation for the growing preference for environmentally friendly and water‐based systems in chemical synthesis. In the present work, ZnO nanoparticles were synthesized via a novel method without any water‐insoluble compounds. At the first step, a binary Zn Schiff‐base complex was prepared from sodium salicylaldehyde‐5‐sulfonate, L‐alanine, and zinc acetate. Then, a ternary Zn complex containing the Schiff‐base, chelating, and Phen ligands was synthesized from the as‐synthesized binary Zn Schiff base and 1,10‐phenanthroline monohydrate. This intermediate product showed high water solubility and long‐term stability. Finally, ZnO nanoparticles were synthesized through the calcination of the ternary complex powder at 400, 500, and 600 °C. Combining X‐ray diffraction (XRD) and energy dispersive spectroscopy (EDS) results, it was concluded that the samples contained the ZnO phase without any impurity phases, but Fourier transform infrared (FTIR) spectra implied the presence of a remaining impurity. According to the XRD, FTIR, and photoluminescence (PL) analyses, the as‐synthesized samples differed in terms of the defect content and lattice strain. The sample calcined at 500 °C possessed the lowest defect content and lattice strain. Transmission electron microscopy (TEM) imaging revealed the formation of ZnO nanoparticles with particles sizes of <20, ~50, and ~100 nm for samples heat‐treated at the different temperatures. A ternary zinc complex containing a Schiff‐base, chelating, and Phen ligands was prepared as an intermediate product, the treatment of which at 500 °C led to the formation of ZnO nanoparticles (ZnO NPs) with the minimum number of point defects and a high degree of crystallinity. Water‐based chemistry was successfully utilized to synthesize ZnO NPs with a bandgap of 3.13–3.19 eV and particle size of 20–100 nm. A series of water‐soluble materials and a water‐based method were utilized. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • New zinc complexes from the Schiff-base ligands were synthesized and characterized. • The interaction with CT-DNA was investigated using various spectroscopic methods. • The cytotoxicities of dinuclear Zn complex are higher than trinuclear complexes. Abstract Three new zinc(II) complexes, namely, [Zn 2 (H 2 L1) 2 (OAc) 2 ] (1), [Zn 3 (H 2 L1) 2 (OAc) 4 ] (2) and {[Zn 3 (H 2 L2) 2 (OAc) 4 ]·C 2 H 5 OH·DMF} (3) [(H 3 L1 = Schiff-base derived from salicylaldehyde and 2-amino-2-ethyl-1,3-propanediol and H 3 L2 = Schiff-base derived from 5-chlorosalicylaldehyde and 2-amino-2-ethyl-1,3-propanediol)], were synthesized and characterized using elemental analyses, infrared spectroscopy and X-ray diffraction. Single crystal structure analysis reveals that complex 1 is five-coordinated distorted square pyramidal configuration. Complexes 2 and 3 exhibit the similar trinuclear structure. And the alkoxy groups in the ligands are play an important role in the formation of supramolecular networks of complexes 1 – 3. The interaction of the complexes 1 – 3 with calf thymus (CT) DNA was investigated using UV–visible (UV–Vis), circular dichroism spectra (CD), fluorescence, viscosity and thermal denaturation methods. The intrinsic binding constants for the complexes are found to order of 104 indicating that the complexes are good metallo-intercalators. Complex 1 shows maximum binding affinity (K b : 7.64 × 104) compared to others. The all complexes can bind to CT-DNA via intercalative mode. The MTT assay show that the cytotoxicity of dinuclear complex 1 is more effective with HeLa cancerous cells. All the experimental results are suggestive that the nuclearity and configuration of zinc complexes have significant influence on their properties. [ABSTRACT FROM AUTHOR]

Graphical abstract A new mononuclear octahedral cobalt(III) complex with pendant Schiff base has been synthesized and characterized by single crystal X-ray diffraction experiment. Solid state supramolecular interactions of the complex have been explored. The complex was found to be active towards catechol oxidase and phenoxazinone synthase mimicking activity. Abstract A new cobalt(III) complex, [Co(L-κ-N,N,O)(L-κ-N,O)(NCS)]·0.5H 2 O, with a pendant Schiff base {HL = 2((2-morpholinoethylimino)methyl)-6-ethoxyphenol} has been synthesized and characterized by elemental and several spectral analyses. Single crystal X-ray diffraction studies confirmed its structure. Extended supra-molecular assemblies were generated in the complex through weak noncovalent interactions. The complex was found to exhibit catechol oxidase and phenoxazinone synthase mimicking activity. [ABSTRACT FROM AUTHOR]

Mixed μ -azido-Schiff-base palladacycles [Pd{ C , N - κ 2 -(4-R)C 6 H 3 CH = N-C 6 H 3 -2,6- i -Pr 2 }( μ 2 -N 3 )] 2 (R = H, 1 ; OMe, 2 ) served as a metal-template for the synthesis of unusual dicarbodiimido bridged complexes [( μ 2 -NCN-Xyl)Pd{ C , N - κ 2 -(4-R)C 6 H 3 CH = NC 6 H 3 -2,6- i -Pr 2 }] 2 (R = H; OMe) and mixed tetrazolato-isocyanido complexes [Pd( C , N - κ 2 -(4-R)C 6 H 3 CH = NC 6 H 3 -2,6- i -Pr 2 )(CN 4 -Xyl)(CN-Xyl)] (R = H; OMe). Reactions of ethyl isothiocyanate with 1 and 2 gave the ditetrazole-thiolato bridged Pd complexes [( μ 2 -SCN 4 -C 2 H 5 )Pd( C , N - κ 2 -(4-R)C 6 H 3 CH = NC 6 H 3 -2,6- i -Pr 2 )] 2 . All these complexes were fully characterized by FT-IR, NMR spectroscopy, elemental analysis and/or X-ray crystallography. [ABSTRACT FROM AUTHOR]

The titanium(IV) complexes of Schiff bases derived from aroylhydrazine e.g. benzoylhydrazine, salicyloylhydrazine, nicotinic acid hydrazide with aldehyde or ketone are reported and characterized based on UV–vis spectroscopy, (Infra-red) IR spectra, 1 H NMR spectra, mass spectra, magnetic susceptibility and molar conductance measurements. Complexes are found to possess 1:2 (metal:ligand) stoichiometry. The prepared ligands were act as dibasic tridentate ligands. On the basis of experimental evidences octahedral geometry has been proposed for prepared complexes. Geometry was confirmed by the optimized structure obtained from computational study. The synthesized ligands, in comparison to their titanium(IV) complexes, were also screened for their microbial and antioxidant properties. [ABSTRACT FROM AUTHOR]

One new nickel(II) complex, [Ni(L)] (1), was synthesized from the Schiff base ligand derived from pyrrole-2-carboxaldehyde and 1,3-diaminopropane. Complex 1 was characterized by elemental analysis, IR, UV-Vis and ESI mass spectroscopy, cyclic voltammetry, and single-crystal X-ray structure analysis. Crystallographic results show that two Ni(II) monomeric moieties are present with similar structural features but with slightly different bond lengths and bond angles. The geometry around the Ni(II) center is distorted square planar. DNA-binding properties of complex 1 were well explored by employing UV-Vis and fluorescence spectral methods, cyclic voltammetry, and by viscosity measurements. Similarly the protein-binding study was studied by multispectroscopic techniques using both BSA and HSA. The cytotoxicity study of the compound has also been evaluated. Notably, the in vitro cytotoxicity of complex 1 on two cancer cell lines (AGS and A549) demonstrates that complex 1 has very good anticancer activity. MTT assay, cell-cycle analysis, and annexin-V assay have been performed to know the extent of effect of complex 1 as anticancer agent. Further, in silico molecular docking study revealed that the nickel(II) complex fits into the minor groove of duplex DNA by hydrophobic interaction with functional groups of B-DNA. [ABSTRACT FROM AUTHOR]

The reaction of Ln(NO 3 ) 3 ·6H 2 O (Ln = Gd, Tb) and Cu(O 2 CMe) 2 ·H 2 O with the polydentate Schiff base ligand OH C 10 H 7 CH NC(C 2 H 5 )(CH 2 OH) 2 (H 3 L) in Me 2 CO afforded the heptanuclear heterometallic complexes [Cu 5 Ln 2 (O 2 CMe) 2 (NO 3 ) 4 (L) 2 (HL) 2 ] (Ln = Gd ( 1 ), Tb ( 2 )) which were characterized by single-crystal X-ray crystallography ( 1 ) and powder XRD measurements ( 2 ). Both complexes are isomorphous and consist of a central core {Cu II 5 Ln III 2 (μ 3 -OR) 6 (μ 3 -O 2 CMe) 2 } 8+ described as two distorted centrosymmetrically related cubane subunits, {Cu II 3 Ln III (μ 3 -OR) 3 (μ 3 -O 2 CMe)} 5+ , with the common apex, Cu(1), residing on an inversion center. Peripheral ligation and bridging is provided by two triply and two doubly deprotonated Schiff base ligands, two μ 3 -acetates and four chelate nitrates. Magnetic susceptibility measurements revealed the presence of dominant ferromagnetic interactions for both complexes. The magnetocaloric effect of 1 was examined via isothermal magnetization measurements under various applied fields and the maximum entropy change was found equal to 15.7 J kg −1  K −1 at 2 K for Δ H  = 5 T. Ac susceptibility measurements of 2 revealed slow magnetic relaxation process suggesting the presence of single-molecule magnet behavior. [ABSTRACT FROM AUTHOR]

A new complex of oxovanadium, VOL has been synthesized from Schiff base ligand obtained by the condensation of o -phenylenediamine and 5-bromo-salicylaldehyde. All new compounds have been characterized by 1 H NMR, IR spectra, UV–Vis spectroscopy, elemental analysis and mass spectrometry. The molar conductance data revealed that the metal complex is a non-electrolyte. Thermal analysis techniques (TGA/DTA) of the ligand and the complex were performed. The proposed structures for the free ligand and the corresponding vanadium complex were corroborated by the use of geometry optimization and conformational analysis. The solid state structure of complex VOL was fully determined by single crystal X-ray diffraction analysis. Similar electrochemical behavior for both the ligand and the corresponding complex have been observed by cyclic voltammetry (CV). The complex gave a metal-based one-electron quasi-reversible redox couple at 606 mV/SCE corresponding to the VO IV /VO V redox process which was consistent with the hydrodynamic voltammograms. Additional peaks in the CVs that were growing with the scan rate have been attributed to consecutive one-electron reduction of the ligand. The catalytic activity of the oxovanadium Schiff base complex VOL was tested in the oxidation reaction of cyclohexene. The efficiency of the catalyst was influenced by the nature of the oxidant. The results showed that the complex was highly active and selective for cyclohexenone in optimized conditions. [ABSTRACT FROM AUTHOR]

In this paper, the formation of Schiff base compounds has been explained by the templating effect of a metal ion modulated by counter anions. It is shown that a dicondensed Schiff ligand can utilize the N2O2 compartment to form a stable copper complex. However, in the presence of a strongly coordinating thiocyanate ion, the dicondensed ligand is converted to the corresponding monocondensed ligand to yield a square planar copper(II) complex coordinated by the NNO donor set of the Schiff base and the terminal thiocyanate coligand. This template approach provides a methodology to trap the monocondensed ligand HL2 [2-((E)-(3-aminopropylimino)methyl)-6-methoxyphenol] as its Cu(II) compound [CuL2(NCS)]. We report herein the crystal structure and spectroscopic studies of this newly synthesized complex. [ABSTRACT FROM AUTHOR]

In this study, a new Schiff base ligand [2-{[4-amino-5-(3,4,5-trimethoxy-benzyl)-pyrimidin-2-ylimino]-methyl}-6-methoxy-phenol, C22H24N4O5] and its bismuth(III) complex [BiC22H22N4O5Cl] were synthesized using o-vanillin and trimethoprim in anhydrous solvents. Chemical analysis, elemental analysis, spectrum analysis and TG-DSC analysis were employed to characterize the compositions and structures of the two new compounds. In particular, the metabolic thermogenic curves of Schizosaccharomyces pombe (S. pombe) and Helicobacter pylori (H. pylori) cells treated by the two new compounds at different concentrations were monitored by an isothermal microcalorimeter at 32.00 and 37.00 °C, respectively. On the basis of the metabolic thermogenic curves, some important biothermokinetic parameters such as the microbial growth rate constant (k), inhibition ratio (I) and half inhibition concentration (IC50) were estimated. The experimental results indicated that both the Schiff base ligand and its bismuth(III) complex could inhibit the growth metabolism of S. pombe and H. pylori, but the inhibitory abilities of the two compounds were as follows: the Schiff base ligand > the complex for S. pombe and the Schiff base ligand < the complex for H. pylori, respectively. More importantly, the results also found that the Schiff base bismuth(III) complex exhibited bidirectional biological effect and hormesis effect on H. pylori cell line, i.e., the complex can stimulate the growth metabolism of H. pylori at low concentration, while inhibiting its growth at high concentration. [ABSTRACT FROM AUTHOR]

A series of chromone Schiff base complexes were prepared and analytically as well as spectroscopically characterized. The ligand was found to act as a monobasic tridentate ligand bonded covalently or coordinatively to the metal ion via deprotonated hydroxyl group, azomethine nitrogen atom and carbonyl oxygen atom of antipyrine moiety. Both electronic spectra and magnetic measurements indicated an octahedral or a distorted octahedral geometry around the metal ions for all metal complexes except the nickel complex, which had a tetrahedral geometry. In addition, the ability of the newly prepared compounds to activate the tumour suppressor p53 in cancer cells was studied, with zinc and copper complexes showing promising activities for p53 ubiquitination compared with diphenylimidazole (reference drug). [ABSTRACT FROM AUTHOR]

In this work, a new Schiff base ligand (HL: 5-bromo-2-((allylimino)methyl)phenol) was prepared from the reaction of 5-bromo salicylaldehyde and allylamine. Then, three new Schiff base complexes, ZnL 2 (1), NiL 2 (2) and CoL 3 (3) , were synthesized through the reaction of Zn(NO 3 ) 2 ·6H 2 O, Ni(OAC) 2 ·4H 2 O, and CoCl 2 ·6H 2 O with the new Schiff base ligand in methanol or chloroform. The ligand and its related complexes were characterized by elemental analysis, FT-IR, UV-Vis spectroscopy, and 1 H- NMR technique. The molecular structures of complexes (1 – 3) were determined by the single crystal X-ray diffraction technique. The crystallographic data revealed that complexes 1 and 2 are four-coordinated by two phenolate oxygen and two imine nitrogen atoms of two Schiff base ligands. On the other hand, the metal center is six-coordinated by three phenolate oxygen and three imine nitrogen atoms of three Schiff base ligands in 3 . Eventually, DFT calculations and the study of electrochemical properties were performed on the new three complexes. [ABSTRACT FROM AUTHOR]

A series of copper(II)‐Schiff bases‐functionalized polyacrylonitrile fiber catalysts were successfully prepared using copper acetate as copper source and characterized by elemental analysis, fourier‐transfer infrared spectroscopy, ultraviolet‐visible spectroscopy, X‐ray photoelectron spectroscopy and inductively coupled plasma analysis. Excellent physical strength and thermal stability of the fiber catalysts were demonstrated by scanning electron microscopy, X‐ray diffraction, thermogravimetric/differential scanning calorimetry analysis and mechanical strength measurements. Furthermore, these catalysts were successfully applied to one‐pot multicomponent copper‐catalyzed azide‐alkyne cycloaddition (CuAAC) reaction and aldehyde, alkyne, amine (A3) coupling reaction in which the influences of different substituent groups on the catalytic activities of fiber catalysts were investigated in detail. Among them, the bis[N‐ethyl‐3,5‐di‐tert‐butyl‐salicylideneiminato]copper(II)‐functionalized polyacrylonitrile fiber (PANS2F−Cu) as a green, efficient catalyst exhibited the best catalytic activity for its high hydrophobic micro‐environment can aggregate the reactants to the catalytic sites and accelerate the reaction. In addition, the PANS2F−Cu has performed well in scaled‐up experiment and shown excellent recyclability (at least ten times), and these enable it to have great potential for further applications. [ABSTRACT FROM AUTHOR]

The condensation of 2‐acetylferrocene with 4‐nitro‐1,2‐phenylenediamine in a 1:1 molar ratio, resulting in formation of a novel bi‐dentate organometallic Schiff base ligand (L), (2‐(1‐((2‐amino‐5‐nitrophenyl)imino)ethyl)cyclopenta‐2,4‐dien‐1‐yl)(cyclopenta‐2,4‐dien‐1‐yl)iron. Also, its Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes have been synthesized. The stoichiometric ratios of the prepared compounds were estimated using elemental analysis (C, H, N, M), molar conductivity, FT‐IR, UV‐Vis, 1H‐NMR, SEM and mass spectral analysis. Furthermore, their TG and DTG properties were studied. The geometrical structure of the complexes was found to be octahedral. From spectral analysis, the Schiff base coordinated to metal ions through the azomethine and amine groups. DFT‐based molecular orbital energy calculations of the synthesized ligand have been studied, in which the ligand was theoretically optimized. The Schiff base and its metal complexes have been screened for their antimicrobial activities against different bacterial and fungal species by using disc diffusion method. The anticancer activities of the ligand and its metal complexes have also been studied towards breast cancer (MCF‐7) and human normal melanocytes (HFB‐4) cell lines. Molecular docking was also used to identify the interaction between the Schiff base ligand and its Cd(II) complex with the active site of the receptors of breast cancer mutant oxidoreductase (PDB ID: 3HB5), crystal structure of Staphylococcus aureus (PDB ID: 3Q8U) and yeast‐specific serine/threonine protein phosphatase (PPZ1) of Candida albicans (PDB ID:5JPE). [ABSTRACT FROM AUTHOR]

We report the synthesis, structure and magnetic properties of a series of MnIII complexes with N,N′‐ethylenebis(5‐methoxysalicylideneiminate) (5MeO‐salen) and acetate ligands, namely, [Mn2(5MeO‐salen)2(CH3COO)]X [X = ClO4– (1), PF6– (2), CF3SO3– (3)]. The [Mn(5MeO‐salen)]+ cations form oxo‐bridged dimers, the further assembly of which by acetate groups leads to zigzag chains. There are two alternating types of dimeric {Mn2O2} units, each of which is intrinsically ferromagnetic or anisotropic but mutually coupled antiferromagnetically along the chain. Magnetostructural analyses were performed with the help of ab initio calculations to elucidate the subtle effects of local magnetic anisotropy combined with exchange effects. A qualitative mechanism for the exchange coupling is advanced on the basis of the ab initio calculations to explain the ferromagnetism inside the phenoxo‐bridged dimeric units and the antiferromagnetic behaviour of the acetate bridge. [ABSTRACT FROM AUTHOR]

Since their development in the 1930s, Schiff-base complexes have played an important role in the field of coordination chemistry. Here, we report the synthetic, spectral, structural, magnetic and electrochemical studies of two new pentacoordinated neutral chloro-iron(III) complexes (3,5) supported by dianionic [N2O2]2- tetradentate Schiff-base ligands unsymmetrically substituted by either a pair of acceptor (F and NO2) or donor (ferrocenyl and OCH3) groups. The electron-withdrawing Schiff-base proligand 2 and the complexes 3 and 5 were prepared in good yields (79-86%). Complex 3 was readily obtained upon reaction of 2 with anhydrous iron chloride under basic conditions, while the bimetallic derivative 5 was synthesized by condensation of the free amino group of the ferrocenyl-containing O,N,N-tridentate half-unit 4 with 5-methoxysalicylaldehyde in the presence of FeCl3. The three new compounds were characterized by elemental analysis, FT-IR, UV-Vis, mass spectrometry and in the case of 2 by multinuclear NMR spectroscopy. The crystal structures of 3 and 5 revealed that in the two five-coordinate monomers, the iron atom showed distorted square-pyramidal geometry, with the N and O atoms of the Schiff-base ligand occupying the basal sites and the chlorine atom at the apex of the pyramid. Magnetic measurements showed a high-spin configuration (S = 5/2) for the Fe(III) ion in 3 and 5. Reduction associated with the Fe(III)/Fe(II) redox couple occurred at -0.464 and -0.764 V vs. Ag/Ag+, and oxidation taking place at the Schiff-base ligand was observed at 1.300 and 0.942 V vs. Ag/Ag+ for 3 and 5, respectively. A high-electronic delocalization of the Schiff-base ligand substituted by fluoro and nitro groups stabilizes the Fe(II) oxidation state and shifts the redox potential anodically. [ABSTRACT FROM AUTHOR]

An ionic coordination complex of manganese(III), [Mn(HL) 2 (CH 3 OH) 2 ][Mn(HL) 2 (N 3 ) 2 ] (where H 2 L = 1-(5-hydroxy-3-oxapentyliminomethyl)-3-ethoxyphenol), has been synthesized. Elemental analyses and spectroscopic techniques have been used to characterize the complex. The structure has been determined by the single crystal X-ray diffraction study. The complex consists of a complex cation, [Mn(HL) 2 (CH 3 OH) 2 ] + and a complex anion, [Mn(HL) 2 (N 3 ) 2 ] − . Each of them has six-coordinate centrosymmetric manganese(III) centre and is significantly elongated due to the Jahn–Teller distortion at the d 4 manganese(III) center. Hirshfeld surface analysis was used for visually analyzing intermolecular interactions in the solid state structure of the complex. Fingerprint plot reveals the percentage of intermolecular contacts (O⋯H, C⋯H and N⋯H) in it. The complex is found to show efficient catalytic activity towards aerial oxidation of 3,5-di -tert -butylcatechol (3,5-DTBC) and o -aminophenol with K cat values 292.44 and 215.58 h −1 respectively. [ABSTRACT FROM AUTHOR]

Two mononuclear Schiff base complexes, [Zn(L) 2 ] ( 1 ) and [Cu(L) 2 ] ( 2 ) are synthesized involving bidentate N,O-donor ligand viz. 2-((E)-(3-methoxypropylimino)methyl)-6-methoxyphenol. Different spectroscopic tools like FTIR, UV–Vis, 1 H NMR, 13 C NMR etc. have been deployed to characterize complexes 1 and 2 . Complex 1 has been analyzed using single crystal X-ray diffraction analysis method. Complexes 1 and 2 show affinity towards A-T rich sequence of DNA which is further supported by molecular docking analysis. Interestingly, only complex 2 exhibits oxidative DNA cleavage activity in presence of H 2 O 2 which is investigated by gel electrophoresis method. Complex 1 is found to be nontoxic whereas complex 2 is cytotoxic. [ABSTRACT FROM AUTHOR]

This study highlights the synthesis and characterization of Schiff base ligands namely 1-ferrocenyl-3- (2-furyl) propenone diamino (thio) urea and selected metal complexes including Pb(Ⅱ), Bi(Ⅲ), Cu(Ⅱ), Cr(Ⅲ), Ba(Ⅱ), Cd (Ⅱ), Fe(Ⅱ), Ni(Ⅱ), Sn(Ⅱ), Nd(Ⅱ) as a central metal. The stoichiometric ratios of the prepared complexes were estimated using complementary techniques such as elemental analyses (C,H,N), FT-IR and molar conductivity. Furthermore, their physicochemical studies were carried out using thermal TGA. Antimicrobial activities of both the Schiff base ligand and its metal complexes were tested against strains of Gram (-ve) , such as E. coli and S. aureus and MRSA , C. albicans and A. flavus fungi. The investigated Schiff base complexes showed higher activity and stability than their corresponding Schiff base ligands and the addition of ferrocene group also achieved the function of drug superposition. Moreover, the prepared Schiff base ligand and its Cu(II) and Cd(II)and Ni(II) complexes have been evaluated for their anticancer activities against two cancer cell lines namely mouse leukemia cells (P-388) and lung cancer (A-549) cell lines. [ABSTRACT FROM AUTHOR]

Four new cyclopentadienylruthenium(II)-acetophenone-4( N )-substituted thiosemi-carbazone complexes, with the general formula [Ru(ƞ 5 -C 5 H 5 )(H-Aptsc)PPh 3 ].Cl ( 1 ), [Ru(ƞ 5 -C 5 H 5 )(H-Apmtsc)PPh 3 ].Cl ( 2 ), [Ru(ƞ 5 -C 5 H 5 )(H-Ap-etsc)PPh 3 ].Cl ( 3 ) and [Ru(ƞ 5 -C 5 H 5 )(H-Ap-ptsc)PPh 3 ].Cl ( 4 ) were synthesised and characterised ( 1 H NMR, 13 C NMR, IR and electronic spectroscopy). The molecular structure of representative complexes 2 and 3 was confirmed by single crystal X-Ray diffraction technique. The binding ability of complexes ( 1 – 4 ) to calf-thymus DNA (CT DNA) and Bovine Serum Albumin (BSA) has been explored by absorption and emission titration methods. Based on the observations, an electrostatic and an intercalative binding mode have been proposed for the complexes with CT-DNA. The BSA protein binding studies have been monitored by quenching of tryptophan and tyrosine residues in the presence of complexes and static type of quenching mechanism has been proposed. In vitro free radical scavenging activity was performed by DPPH radical. The complexes ( 1–4 ) exhibited highest scavenging activity than conventional standard vitamin C (IC 50 = 5.65 ± 0.12). Further, antibacterial activity of the complexes has been screened against four pathogenic bacteria such as Salmonella paratyphi , Staphylococcus aureus , Escherichia coli and Bacillus subtilis . From the results it is found that all the complexes exhibited significant activity against the pathogens and among them, complex 3 exhibited higher activity. [ABSTRACT FROM AUTHOR]

Syntheses, structures, electronic properties and bio-catalytic activities of oxovanadium(IV) complexes [VOL 1 ,VOL 2 ] containing N,O-donor Schiff base ligands (L 1 = 2,2′-{cyclohexane-1,2-diylbis[nitrilo( E )methylylidene]}bis[5-(prop-2-yn-1-yloxy)phenol] and L 2 = 2,2′-{1,2-phenylenebis[nitrilo( E )methylylidene]}bis[5-(prop-2-yn-1-yloxy)phenol]) are presented. The single crystal XRD analyses show distorted square pyramidal based geometry for VOL 1 and VOL 2 . The structure and electronic properties of the complexes were analyzed using DFT and TD-DFT calculations. The topological analysis of the electron density was carried out to analyze the bonding nature in the complexes. The bio-relevant catalytic activities (catecholase, phenoxazinone synthase and haloperoxidases) of the complexes have been investigated. The X-band EPR studies show that the oxidation of 3,5-DTBC and 2-aminophenol catalyzed by VOL 1 and VOL 2 are due to the formation of ligand-centered radical pathway. DFT studies support the ligand-centered radical formation in the reduced metal complexes with significant elongation of the imine bond length. [ABSTRACT FROM AUTHOR]

Transition Metal Complexes of Mn(II),Co(II) and Ni(II) with Schiff base derived from 4-chloroaniline and Salicylaldehyde were synthesized and characterized by conductivity measurement, magnetic susceptibility, infrared spectra, metal-ligand ratio determination and solubility test. The Schiff base and its metal complexes were tested for antibacterial activity against Staphylococcus aureus and Escherichia coli and fungal activity against Aspergillus f la vus and Mucor species. The low molar conductance values range (16-28.1Ohm-1 cm2mol1) indicated that all the complexes are non electrolytes. The magnetic susceptibility revealed that all the complexes are paramagnetic in nature. The metal-ligand ratio was found to be 1:2 in all the complexes. The infrared spectra suggested that the Schiff base behaves as a bidentate ligand. The antimicrobial studies revealed moderate activity against the tested organism when compared with the standards (Ciprofloxacin and Ketoconazole), and this activity increases by increasing concentration. And also the Metal Complexes showed higher activity than free Ligand due to chelation. [ABSTRACT FROM AUTHOR]

Complexes of Mn(II), Fe(II) and Co(II) containing N, N'-bis[o-anisaldehyde]p-phenylenediamine tetradentate Schiff base as primary ligand and glycine as secondary bidentate ligand have been synthesized by reflux in 1:1:1 mole ratio and characterized both analytically and spectroscopically. Molar conductance measurement (69.02 to 86.30£T1cm2mor1) of the complexes indicated they are weak electrolyte and magnetic susceptibility measurement shows values in range of 4.53 to 5.59BM indicating their paramagnetism. The infrared data suggested that the Schiff base coordinated via the two nitrogen atoms of the azomethine groups (1628 to 1680 cm-1) and the oxygen atoms of the adjacent methoxy groups (1341 to 1389 cm-1), while glycine coordinated via the nitrogen atom of the amino group (3060-3324 cm-1) and the oxygen atom of the carboxylate anion. Based on the analytical and spectroscopic data the complexes may be assigned an octahedral geometries and molecular formulae of the form [M(L)Gly], where M = Mn, Fe and Co, L =Schiffbase and Gly = glycine. The Schiff base and its mixed ligand complexes were screened for antimicrobial activity against Staphylococcus aureus, Escherichia coli, Salmonella typhi, Mucor inducus and Aspergiilus fumigatus. The complexes exhibited enhanced antimicrobial activity (10mm to 18mm) at 60 pg/disc as compared to 10mm activity of the uncoordinated Schiffbase at the same concentration. [ABSTRACT FROM AUTHOR]

Herein, we synthesized a new nano-scale Schiff base Ni(II) complex in water as a green solvent and at ambient temperature. The compound was characterized using FT-IR and elemental analysis. Also, its molecular structure was determined by single crystal X-ray diffraction technique. The MTT assay results indicated that the anticancer activity of the compound is affected by its size. Finally, binding ability of the nano-scale Ni(II) Schiff base complex with calf thymus DNA and human serum albumin was investigated using combination of experimental (UV–Vis, fluorescence, circular dichroism (CD) and viscosity) and computational (molecular docking, molecular dynamics simulation and qm/mm) methods. The estimated binding constants for the DNA-complex and HSA-complex were about 10 4 M − 1 . Molecular docking studies revealed the binding of Ni(II) complex to the minor groove of DNA and warfarin binding site of protein by formation of hydrogen bond, π-cation and hydrophobic interactions. MD simulation studies revealed that complexation with NiL 2 changed the structure of HSA when compared to free protein. Finally, the ONIOM results showed that the structural parameters of the compound changed along with binding to DNA and HSA, indicating the strong interaction between the compound and these biomacromolecules. [ABSTRACT FROM AUTHOR]

Three new N 2 O 4 -donor bis-Schiff base Co(II) complexes, Co(C 36 H 34 N 2 O 8 )·2CH 3 OH ( 1 ), Co(C 28 H 34 N 2 O 8 S 2 )·H 2 O ( 2 ) and Co(C 40 H 36 N 4 O 8 )·3CH 3 OH ( 3 ) with distorted octahedral six-coordinate Co(II) centers were synthesized and determined by single crystal X-ray analysis. The X-ray crystallography shows that the metal atoms of three complexes are all six-coordinate with two nitrogen atoms from C N groups, two oxygen atoms from ether groups and two carboxylic oxygen atoms in the mono-ligand, forming a distorted octahedral geometry. Theoretical studies of the three complexes were carried out by density functional theory (DFT) Becke's three-parameter hybrid (B3LYP) method employing the 6-31G basis set. The DFT studies indicate that the calculation is in accordance with the experimental results. Moreover, inhibition of jack bean urease by Co(II) complexes 1–3 have also been investigated. At the same time, a docking analysis using a DOCK program was conducted to determine the probable binding mode by inserting the complexes into the active site of jack bean urease. The experimental values and docking simulation exhibited that the complex 3 showed strong inhibitory activity (IC 50 = 16.43 ± 2.35 μM) and the structure-activity relationships were further discussed. [ABSTRACT FROM AUTHOR]

New tetradentate mononuclear nickel(II) [NiL] and pentadentate binuclear copper(II) [Cu 2 L 2 H 2 O], H 2 O Schiff base complexes have been synthesized. The crystal structures of [NiL] and [Cu 2 L 2 H 2 O], H 2 O have been determined by X-ray diffraction method showing distorted square-planar geometry for [NiL] and distorted tetragonal pyramid geometry for [Cu 2 L 2 H 2 O], H 2 O . In both complexes, the dehydroacetic acid functional group engages in a deprotonated manner and coordination occurs through the nitrogen atoms of the imine function and the phenolic oxygen. Density Functional Theory calculations are carried out for the determination of the optimized structures. The fundamental vibrational wave numbers are calculated and a good agreement between observed and calculated wave numbers is achieved. [ABSTRACT FROM AUTHOR]

Novel [Fe(4-benzyl-2-hydroxyphenyl-propylidene)ethylene-diamine], and [Fe (2,4,6-trihydroxy-benzyl-4-metoxiphenyl-methylidene)ethylene-diamine] complexes were synthesized by reacting Fe salt with the indicated Schiff-base ligands. The compounds were characterized byFe Mössbauer spectroscopy, FTIR, UV-VIS, TG-DTA-DTG, MS, AFM, XRD, cyclic voltammetry and biological activity measurements. 295 K and 78 K Mössbauer spectra revealed that iron is dominantly in high spin Fe state in both complexes while simultaneously a minor low spin Fe was also present in both complexes, furthermore a minor high spin Fe was observed in [Fe(2,4,6-trihydroxy-benzyl-4-metoxiphenyl- methylidene) ethylene-diamine], too. [ABSTRACT FROM AUTHOR]

The Cu, Ni, and Со complexes based on the following new azomethine compounds containing azobenzene groups in the ortho- or para-positions of the amine fragment are synthesized: 2-allyl-6-[( E)-[4-( E)-phenylazophenyl]iminomethyl]phenol (HL), 2-allyl-6-[( E)-[4-methyl-2-[( E)-phenylazo]- p-tolylazo] iminomethyl]phenol (HL), 5-methoxy-2-[( E)-[4-[( E)-phenylazo]phenyl]iminoethyl]phenol (HL), and 5-methoxy-2-[( E)-[4-methyl-2-[( E)- p-tolylazo]phenyl]iminomethyl]phenol (HL). The structures of the complexes are determined by the data of IR and Н NMR spectroscopy (for the azomethine compounds), X-ray absorption spectroscopy, and magnetochemistry. The coordination centers of all Cu complexes have a distorted square structure. A direct dependence of the geometry of the coordination polyhedron on the position of azobenzene groups in the amine fragments of the ligands is found for the Ni and Co complexes. The octahedral environment of the nickel and cobalt ions takes place in the case of the ortho-position of the amine fragment, whereas the square environment for the Ni complexes or the tetrahedral environment for the Co complexes is observed at the para-position. The molecular structures of two azomethines HL and HL are determined by X-ray diffraction analysis (CIF files CCDC nos. 1552836 (HL) and 1552837 (HL)). [ABSTRACT FROM AUTHOR]

A mixture of copper(II) chloride dihydrate and ligands derived from amantadine and 5-halogenated salicylaldehyde in anhydrous methanol generated two novel complexes CHClCuNO ( I) and CHBrCuNO ( II), respectively. The complexes were characterized by melting point, elemental analysis, molar conductance, IR, UV-Vis, and single-crystal X-ray diffraction (CIF files nos. 1435429 ( I), 1435430 ( II)). Single-crystal X-ray diffraction analysis reveals that both complexes crystallize in monoclinic system, P2/ c space group. Each asymmetric unit consists of two mononuclear copper(II) complex molecules and each complex molecule includes one copper(II) atom two corresponding deprotonated ligands. The central copper(II) atom is four-coordinated via two nitrogen atoms and two oxygen atoms from the corresponding Schiff base ligands, forming a distorted tetrahedral geometry. Electrochemical properties of the complexes were studied by cyclic voltammetry. [ABSTRACT FROM AUTHOR]

The ring opening transformation of three substituted 2-(2-pyridyl)benzothiazolines of general formula [(C 6 H 4 NCS)(C 5 H 4 N)R] (R = C 5 H 4 N, 1 ; R = C 6 H 5 , 2 ; R = H, 3 ) was studied by their reaction with metal chlorides of Ni(II), Pd(II), and Pt(II). In these reactions, the anionic tridentate Schiff bases { L n } − coordinated to metal ions were identified. Seven metallic complexes of type [M( L n )Cl] [M = Pd, n = 1, R = C 5 H 4 N, ( 1a ); n = 2, R = C 6 H 5 , ( 2a ); n = 3, R = H, ( 3a ). M = Pt, n = 1, R = C 5 H 4 N, ( 1b ); n = 2, R = C 6 H 5 , ( 2b ); n = 3, R = H, ( 3b ), and M = Ni, R = C 6 H 5 , ( 2c )] were characterized in solution by NMR and vibrational spectroscopy in solid state. Crystal structures of benzothiazolines 1 and 2 and complexes 1a – 3a , 1b ·DMSO, and 2c were analyzed by X-ray diffraction studies. In all cases, mononuclear complexes with a distorted square planar geometry were obtained. For compounds 1 – 3 , the predominance of the benzothiazoline (ring form) over the Schiff base (open form) as well as the formation of the [Pd( L n )Cl] (n = 1–3) complexes were studied by DFT calculations at the PBEPBE/(Def2-TZVP,SDD) level in gas phase. [ABSTRACT FROM AUTHOR]

A novel inclusion Zn(II) complex with water guest molecule is synthesized from 6,6′-diethoxy-2,2′-[2,2-dimethylpropane-1,3-diylbis(nitrilomethylidyne)]-diphenol salen-type Schiff base (H 2 L) and is characterized through single crystal XRD studies, IR, UV–Vis methods. Thermal profile is studied using TG-DTG–DSC method. Single crystal XRD analysis reveals a rare open book structure for the complex and an interesting star-like supramolecular assembly. The emission properties of the complex is compared with that of the ligand, pseudo-inclusion and inclusion compounds from Zn(II) and Pd(II) ions prepared from the same ligand. Hirshfeld surface for the compounds were mapped with various functions and further quantification of intermolecular interactions was made through the generation of 2D finger print plots. To dissect the nucleophilic and electrophilic regions on the molecular surface, ESP plots of the compounds are generated. Further DFT calculations are done at B3LYP/def2-TZVP level of theory to optimize the geometry of the compounds and to compare frontier orbitals and charge distribution among the compounds. Molecular docking of the compounds with B-DNA dodecamer and Human Serum Albumin (HSA) is performed to gain an insight on the structure–activity relationship of these compounds. [ABSTRACT FROM AUTHOR]

Ag(I) complexes with a series of optically active Schiff bases derived from (1 R ,2 R )(-)cyclohexanediamine and different aldehydes were obtained and characterized by 1 H, 13 C, NMR in a solution and in the solid state, UV–Vis, fluorescence, and IR spectroscopy. X-ray crystal structure of (1 R ,2 R )(-)chxn(5-Br-3OCH 3 baH) 2 ( 4 ) was solved. Moreover, intermolecular interactions in the crystal structure of (1 R ,2 R )(-)chxn(5-Br-3OCH 3 baH) 2 were analyzed using 3D Hirshfeld surfaces and the related 2D fingerprint plots. The obtained complexes have been used for preparation of thin layers on Si(1 1 1) to test the possibility of their use as the fluorescent materials. Thin layers of silver(I) complexes were deposited on Si(1 1 1) using the spin coating method and characterized by scanning electron microscopy (SEM/EDS), atomic force microscopy (AFM), and fluorescence spectroscopy. [Ag(1 R ,2 R )(-)chxn(5-Br-3OCH 3 baH) 2 NO 3 ] ( 4a ) complex exhibited significantly increase of the fluorescence intensity in comparison with ligand ( 4 ). The fluorescence of silver complexes solutions was observed between 395 and 470 nm. For silver(I) layers, from intraligand transitions (depending on the exciton wavelengths), the most intensive bands were observed between 390 and 560 nm. The intensity of the fluorescence bands registered for the layers obtained at 1100 rpm or 2000 rpm/min and 30 s time was highest. [ABSTRACT FROM AUTHOR]

A new Schiff base ligand was synthesized by the reaction of 4-acetyl-5,6-diphenyl-3(2H)-pyridazinone with ethylenediamine. A series of binary copper(II) Schiff base complexes have been synthesized by using various copper(II) salts; AcO − , NO 3 − , ClO 4 − , Cl − and Br − . Ternary complexes were synthesized by using auxiliary ligands (L′) [N,O-donor; 8-hydroxyquinoline and glycine or N , N -donor; 1,10-phenanthroline, bipyridyl and 2-aminopyridine]. The structures of the Schiff base and its complexes were characterized by elemental and thermal analyses, IR, electronic, mass, 1 H NMR and ESR spectra in addition to conductivity and magnetic susceptibility measurements. The obtained complexes include neutral binuclear complexes as well as neutral and cationic mononuclear complexes according to the anion used and the experimental conditions. The ESR spin Hamiltonian parameters of some complexes were calculated and discussed. The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. Kinetic parameters (Ea, A, ΔH, ΔS and ΔG) of the thermal decomposition stages were evaluated using Coats–Redfern equations. The antimicrobial activity of the Schiff base and its complexes was screened against Gram–positive bacteria ( Staphylococcus aureus and Bacillus subtilis ), Gram–negative bacteria ( Salmonella typhimurium and Escherichia coli ), yeast ( Candida albicans ) and fungus ( Aspergillus fumigatus ). The antitumor activity of the Schiff base and some of its Cu(II) complexes was investigated against HepG-2 cell line. [ABSTRACT FROM AUTHOR]

A Novel Schiff base, 3-(((4-chlorophenyl)imino)methyl)benzene-1,2-diol ( HL 1 ) was successfully synthesized along with a structurally similar Schiff base 3-(((4-bromophenyl)imino)methyl)benzene-1,2-diol ( HL 2 ). Both the Schiff bases were used to synthesize their zinc (II) and cobalt (II) complexes. These compounds were characterized by FTIR, 1 H NMR, 13 C NMR and elemental analysis. Metal complexes were confirmed by TGA. Crystals of Schiff bases were also characterized by X-ray analysis and experimental parameters were found in line with the theoretical parameters. Quantum mechanical approach was also used to fine useful structural parameters and to ensure the geometry of metal complexes. The photometric behaviors of all the synthesized compounds were investigated in a wide pH range using BR buffers. The appearance of isosbestic points indicated the existence of Schiff bases in more than one isomeric form. Moreover, these compounds were screened for enzyme inhibition; antibacterial, cytotoxic and in vivo antidiabetic activities and compounds were found active against one or other activity. Results indicate that Zn L 2 2 is a good inhibitor of alkaline phosphatase enzyme and possess highest potential against diabetes, blood cholesterol level and cancer cells. This effort just provides preliminary data for some biological properties. Further investigations are required to precisely determine mechanistic pathways of their use towards drug development. [ABSTRACT FROM AUTHOR]

New mixed ligand complexes of transition metals were synthesized from a Schiff base (L1) obtained by the condensation reaction of oxamide and furfural as primary ligand and 2,2′-bipyridine (L2) as secondary ligand. The ligands and their metal complexes were studied using various spectroscopic methods. Also thermal analyses were conducted. The mixed ligand complexes were found to have formulae [M(L1)(L2)]Cl m⋅ nH2O (M = Cr(III) and Fe(III): m = 3, n = 0; M = Cu(II) and Cd(II): m = 2, n = 1; M = Mn(II), Co(II), Ni(II) and Zn(II): m = 2, n = 0). The resultant data revealed that the metal complexes have octahedral structure. Also, the mixed ligand complexes are electrolytic. The biological and anticancer activities of the new compounds were tested against breast cancer (MCF-7) and colon cancer (HCT-116) cell lines. The results showed high activity for the synthesized compounds. [ABSTRACT FROM AUTHOR]

A novel tetradentate dianionic Schiff base ligand, N, N′-bis(2-carboxyphenylimine)-2,5-thiophenedicarboxaldhyde (H2L) and some first row d-transition metal chelates (Co(II), Cu(II), Ni(II) and Zn(II)) were synthesized and characterized using various physicochemical and spectroscopic methods. The spectroscopic data suggested that the parent Schiff base ligand coordinates through both deprotonated carboxylic oxygen and imine nitrogen atoms. The free Schiff base and its metal chelates were screened for their antimicrobial activities for various pathogenic bacteria and fungi using the agar well diffusion method. The antibacterial and antifungal activities of all the newly synthesized compounds are significant compared to the standard drugs ciprofloxacin and nystatin. The antioxidant activities of the compounds were determined by reduction of 1,1-diphenyl-2-picrylhydrazyl and compared with that of vitamin C as a standard. DNA binding ability of the novel Schiff base and its complexes was investigated using absorption spectroscopy, fluorescence spectroscopy, viscosity measurements and thermal denaturation. The obtained results clearly demonstrate that the binding affinity with calf thymus DNA follows the order: Cu(II) complex > Ni(II) complex > Zn(II) complex > Co(II) complex >H2L. Furthermore, the DNA cleavage activity of the newly synthesized ligand and its metal complexes was investigated using supercoiled plasmid DNA (pUC18) gel electrophoresis. [ABSTRACT FROM AUTHOR]

Reliable compounds with low toxicity are tempting potential chemotherapeutics. With an aim of achieving less toxic but more potent metallodrugs, four new-generation hydrophilic Cu(II) and Zn(II) complexes with DNA-targeting properties were synthesized and characterized using various physicochemical data. The excellent DNA binding and cleavage results confirmed the mode of binding of DNA with the complexes and their ability to denature it. The profound in vitro cytotoxicity exhibited by complex 3 against a panel of cell lines (HeLa, MCF-7 and HepG-2) along with NHDF (normal human dermal fibroblasts) with distinct activity towards HepG-2 and low toxicity to NHDF prompted in vivo studies of induced hepatocellular carcinoma-affected Swiss albino rats. On evaluating various serum hepatic, biological and histopathological parameters, complex 3 showed excellent activity in restoring the damaged liver to normal. As a means of identifying the pathway of DNA damage, flow cytometric evaluation of cell cycle analysis was performed, which revealed S phase arrest-induced apoptosis in HepG-2 cells by complex 3, making it a cell cycle-specific drug. [ABSTRACT FROM AUTHOR]

The synthesis of monomeric pentacoordinated diorganotin(IV) complexes derived from pyridoxal hydrochloride and 4- or 5- R-substituted ortho-aminophenols is described. The complexes were characterized using UV-visible, infrared, mass, 1H NMR, 13C NMR and 119Sn NMR spectral techniques. The molecular structure of three complexes was established using X-ray diffraction: 3b and 3d show a distorted trigonal bipyramidal geometry, in which the basal plane is defined by the butyl groups and the iminic nitrogen atom, whereas the oxygen atoms from the aromatic ring occupy axial positions; in contrast, complex 3e exhibits a square pyramidal geometry. The cytotoxic activity of all complexes against human cell lines U-251 (glioblastoma), K-562 (chronic myelogenous leukemia), HCT-15 (human colorectal cancer), MCF-7 (human breast cancer) and SKLU-1 (non-small-cell lung cancer) was evaluated, and the inhibitory percentage values indicated higher activity than the reference standard, cisplatin. Acute toxicity studies were performed in vivo for the prepared complexes to determine the lethal medium dose (LD50) after intraperitoneal administration to mice. [ABSTRACT FROM AUTHOR]

Mn(III)-pentadentate Schiff base complex supported on multi-walled carbon nanotubes as a recyclable and reusable, green and nano-heterogeneous catalyst was designed and fully characterized using infrared spectroscopy, X-ray diffraction, scanning electron microscopy, , inductively coupled plasma mass spectrometry, and thermogravimetric analysis. A facile, eco-friendly, mild and green procedure was developed for the one-pot three-component synthesis of tetrahydrobenzo[ b]pyrans via tandem Knoevenagel-Michael cyclocondensation reactions between aromatic aldehydes, 1,3-diones and malononitrile using a catalytic amount of Mn(III)-pentadentate Schiff base complex supported on MWCNTs as an efficient recyclable heterogeneous catalyst under solvent-free conditions at room temperature. This process has the advantages of easy availability, stability, recyclability and eco-friendliness of the catalyst, short reaction times, high to excellent yields and simple work-up procedure. [ABSTRACT FROM AUTHOR]

A copper(II)-vanillin complex was immobilized onto MCM-41 nanostructure and was used as an inexpensive, non-toxic and heterogeneous catalyst in the synthesis of symmetric aryl sulfides by the cross-coupling of aromatic halides with S8 as an effective sulfur source, in the oxidation of sulfides to sulfoxides using 30% H2O2 as a green oxidant and in the synthesis of 5-substituted 1 H-tetrazoles from a smooth (3 + 2) cycloaddition of organic nitriles with sodium azide (NaN3). The products were obtained in good to excellent yields. This catalyst could be reused several times without loss of activity. Characterization of the catalyst was performed using Fourier transform infrared, energy-dispersive X-ray and atomic absorption spectroscopies, X-ray diffraction, thermogravimetric analysis, and scanning and transmission electron microscopies. [ABSTRACT FROM AUTHOR]

Novel Schiff base [ N′, N′″-(((ethane-1,2-diylbis(oxy))bis(2,1-phenylene))bis(methanylylidene))di(benzohydrazide)] was formed by the condensation reaction of benzohydrazide with 2,2′-(ethane-1,2-diylbis(oxy))dibenzaldehyde. Its reaction with various metal ions was studied and the structures of the new products were characterized using common analytical and spectroscopic methods. All the metal complexes have pronounced anticancer activities. The antimicrobial activities against Gram-negative and Gram-positive bacteria were investigated. [ABSTRACT FROM AUTHOR]