1,1'-二(N-水杨酰腙乙基 )二茂铁及其过渡金属(Ⅱ)的配合物

本文合成了1,1'-二(N-水杨酰腙乙基)二茂铁及其过渡金属配合物,ML.nH~2O[M=Mn(II)、Co(II)、Ni(II)、Cu(II)、Zn(II)和Cd(II)],并用元素分析、UV、IR、^1HNMR、TG-DTA和摩尔电导进行了表征.配体以烯醇式以通过亚胺基氮原子和酰胺基氧负离子与金属离子配位,按摩尔比1:1结合.Ni(II)配合物有一分子DMF配位.大部分配合物比配体热稳定性高.     

Synthesis and Characterization of Metal Complexes of a New Unsymmetrical Tridentate NNS Schiff Base Ligand: X‐ray Crystal Structure Determination of Nickel(II) Complex

A new unsymmetrical tridentate NNS Schiff base ligand, 2‐(2‐nitrophenylthio)‐N‐((pyridine‐2‐yl)methylene)benzenamine (L), and its Mn(II ), Ni(II ), Cu(II ), and Zn(II ) complexes were synthesized. These compounds were characterized by different physicochemical and spectroscopic techniques. The molecular structure of [NiL₂ ](ClO₄ )₂ was determined by single‐crystal X‐ray diffraction. In this complex, two ligands coordinate through azomethine‐N, pyridine‐N, and thioether‐S, forming a mononuclear 6‐coordinate distorted octahedral geometry about a nickel.     

Complex formation of Cu(II), Ni(II), Zn(II), Co(II), and Cd(II) acetates with 3,3′,4,4′,5,5′-hexamethyldipyrrolylmethene

The reactions of complex formation of Cu(II), Co(II), Zn(II), Ni(II), and Cd(II) acetates with 3,3′,4,4′5,5′-hexamethyl-2,2′-dipyrrolylmethene (HL) in DMF were studied by the electronic spectroscopy and calorimetric titration methods at 298.15 K. The main products of the above reactions are [ML₂] chelates. In the case of Cu and Ni salts, the process occurs through the spectrally recorded stage of formation of the heteroligand [ML(AcO)] complexes. The reaction with Cd acetate terminates at the stage of the heteroligand complex formation due to the large radius and decreasing electron affinity of the Cd²⁺ ion. The effect of the metal nature appears in the increasing thermodynamic stability of single-type complexes in the series [ML₂]: Ni(II) < Zn(II) < Co(II) < Cu(II) and [ML(AcO)]: Cd(II) < Ni(II) < Cu(II).     

Theoretical investigation on sulfur‐containing chelating resin‐divalent metal complexes

The complex structures and interactions of sulfur‐containing chelating resin poly[4‐vinylbenzyl‐(2‐hydroxyethyl)]sulfide (PVBS), poly[4‐vinylbenzyl‐(2‐hydroxyethyl)]sulfoxide (PVBSO), and poly[4‐vinylbenzyl‐(2‐hydroxyethyl)]sulfone (PVBSO₂) with divalent metal chlorides (Cu(II), Ni(II), Zn(II), Cd(II), and Pd(II)) were investigated theoretically. Results indicate that PVBS tends to coordinate with metal ions by sulfur and oxygen atoms forming five‐membered ring chelating complexes; while PVBSO and PVBSO₂ prefer to interact with metal ions by the oxygen atom of the sulfoxide or sulfone and hydroxyl group to form six‐membered ring chelating compounds. Theoretical calculations reveal that sulfur atoms of PVBS are the main contributor when coordinate with metal ions, while oxygen atoms also take part in the coordination with Cu(II), Zn(II), and Cd(II). As for PVBSO, the oxygen atoms of sulfoxide group play a key role in the coordination, but sulfur and hydroxyl oxygen also participate in the coordination. Similarly, sulfone group oxygen atoms of PVBSO₂ dominate the coordination of Ni(II), Cu(II), and Pd(II), while the affinities of Zn(II) and Cd(II) are mainly attributed to the hydroxyl oxygen atoms. The computational results are in good agreement with the XPS analysis. Combined the theoretical and experimental results, further understanding of the structural information on the complexes was achieved and the adsorption mechanism was confirmed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Single‐armed salamo‐like dioxime and its multinuclear Cu (II), Zn (II) and Cd (II) complexes: Syntheses,structural characterizations,Hirshfeld analyses and fluorescence properties

Three multinuclear Cu (II), Zn (II) and Cd (II) complexes, [Cu₂(L)(μ‐OAc)]·CHCl₂ ( 1 ), [Zn₂(L)(μ‐OAc)(H₂O)]·3CHCl₃ ( 2 ) and [{Cd₂(L)(OAc)(CH₃CH₂OH)}₂]·2CH₃CH₂OH ( 3 ) with a single‐armed salamo‐like dioxime ligand H₃L have been synthesized, and characterized by FT‐IR, UV–vis, X‐ray crystallography and Hirshfeld surfaces analyses. The ligand H₃L has a linear structure and C‐H···π interactions between the two molecules. The complex 1 is a dinuclear Cu (II) complex, Cu1 and Cu2 are all five‐coordinate possessing distorted square pyramidal geometries. The complex 2 also forms a dinuclear Zn (II) structure, and Zn1 and Zn2 are all five‐coordinate bearing distorted trigonal bipyramidal geometries. The complex 3 is a symmetrical tetranuclear Cd (II) complex, and Cd1 is a hexa‐coordinate having octahedral configuration and Cd2 is hepta‐coordinate with a pentagonal bipyramidal geometry, and it has π···π interactions inside the molecule. In addition, fluorescence properties of the ligand and its complexes 1 – 3 have also been discussed.     

Physicochemical characterization of nanobidentate ferrocene‐based Schiff base ligand and its coordination complexes: Antimicrobial,anticancer, density functional theory,and molecular operating environment studies

A novel bidentate Schiff base ligand (HL, Nanobidentate Ferrocene based Schiff base ligand L (has one replaceable proton H)) was prepared via the condensation of 2‐amino phenol with 2‐acetyl ferrocene. The ligand was characterized using elemental analysis, mass spectrometry, infrared (IR) spectroscopy, ¹proton nuclear magnetic resonance (H‐NMR) spectroscopy, scanning electron microscopy (SEM), and thermal analysis. The corresponding 1:1 metal complexes with some transition‐metal ions were additionally characterized by their elemental analysis, molar conductance, SEM, and thermogravimetric ana1ysis (TGA). The complexes had the general formula [M(L)(Cl)(H₂O)₃]xCl·nH₂O (M = Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II)), (x = 0 for Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), x = 1 for Cr(III) and Fe(III)), (n = 1 for Cr(III), n = 3 for Mn(II) and Co(II), n = 4 for Fe(III), Ni(II), Cu(II), Zn(II), and Cd(II)). Density functional theory calculations on the HL ligand were also carried out in order to clarify molecular structures by the B31YP exchange‐correlation function. The results were subjected to molecular orbital diagram, highest occupied mo1ecu1ar orbital–lowest occupied molecular orbital, and molecular electrostatic potential calculations. The parent Schiff base and its eight metal complexes were assayed against four bacterial species (two Gram‐negative and two‐Gram positive) and four different antifungal species. The HL ligand was docked using molecular operating environment 2008 with crystal structures of oxidoreductase (1CX2), protein phosphatase of the fungus Candida albicans (5JPE), Gram(?) bacteria Escherichia coli (3T88), Gram(+) bacteria Staphylococcus aureus (3Q8U), and an androgen‐independent receptor of prostate cancer (1GS4). In order to assess cytotoxic nature of the prepared HL ligand and its complexes, the compounds were screened against the Michigan cancer foundation (MCF)‐7 breast cancer cell line, and the IC₅₀ values of compounds were calculated.     

Gas‐phase ligand exchange of select transition‐metal acetylacetonate and hexafluoroacetylacetonate complexes

Gas‐phase ligand exchange reactions between M(acac)₂ and M(hfac)₂ species, where M is Cu(II) and/or Ni(II), were observed to occur in a double‐focusing reverse‐geometry magnetic sector mass spectrometer. The gas‐phase mixed ligand product, [M(acac)(hfac)]⁺, was formed following the co‐sublimation of either homo‐metal or hetero‐metal precursors. The gas‐phase formation of [Cu(acac)(hfac)]⁺ from hetero‐metal precursors is reported herein for the first time. The [Ni(acac)(hfac)]⁺ complex is also observed for the first time to form following the co‐sublimation of not only Ni precursors, but also from separate Ni and Cu precursors. The corresponding fragmentation patterns of these species are also presented, and the mixed metal mixed ligand product [NiCu(acac)₂(hfac)]⁺ is observed. Copyright © 2008 John Wiley & Sons, Ltd.     

The gas‐phase ligand exchange of copper and nickel acetylacetonate,hexafluoroacetylacetonate and trifluorotrimethylacetylacetonate complexes

The gas‐phase ligand‐exchange reactions between Cu(II) and Ni(II) complexes containing the acetylacetonate (acac), hexafluoroacetylacetonate (hfac), and trifluorotrimethylacetylacetonate (tftm) ligands were investigated using a triple quadrupole mass spectrometer. The gas‐phase mixed‐ligand products of [Cu(acac)(tftm)]⁺, [Ni(acac)(tftm)]⁺, [Cu(hfac)(tftm)]⁺, and [Ni(hfac)(tftm)]⁺ were formed following the co‐sublimation of either homo‐metal or hetero‐metal precursors. The gas‐phase formation of [Cu(acac)(tftm)]⁺, [Cu(hfac)(tftm)]⁺, [Ni(acac)(tftm)]⁺, and [Ni(hfac)(tftm)]⁺ complexes is reported herein for the first time. The corresponding fragmentation patterns of these species along with those of Cu(tftm)₂ and Ni(tftm)₂ are also presented. Mass‐selected ion‐neutral reactions were investigated. Copyright © 2009 John Wiley & Sons, Ltd.     

Salisaldehyde-2-aminobenzimidazole schiff base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)

New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method. This revised version was published online in July 2006 with corrections to the Cover Date.     

Antimicrobial and anticancer activities of Schiff base ligand and its transition metal mixed ligand complexes with heterocyclic base

A new Schiff base ligand (HL) was prepared via a condensation reaction of quinoline‐2‐carboxaldhyde with 2‐aminophenol in a molar ratio of 1:1. Its transition metal mixed ligand complexes with 1,10‐phenanthroline (1,10‐phen) as co‐ligand were also synthesized in a 1:1:1 ratio. HL and its mixed ligand complexes were characterized using elemental analysis, infrared, ¹H NMR, mass and UV–visible spectroscopies, molar conductance, magnetic measurements, solid reflectance, thermal analysis, electron spin resonance and X‐ray diffraction. Molar conductance measurements showed that all complexes have an electrolytic nature, except Cd(II) complex. From elemental and spectral data, the formulae [M(L)(1,10‐phen)(H₂O)]Cl_x?nH₂O (where M = Cr(III) (x = n = 2), Mn(II) and Ni(II) (x = 1, n = 2), Fe(III) (x = n = 2), Co(II), Cu(II) and Zn(II) (x = 1, n = 2)) and [Cd(L)(1,10‐phen)Cl]?3H₂O for the metal complexes have been proposed. The geometric structures of complexes were found to be octahedral. Powder X‐ray diffraction reflected the crystalline nature of the complexes; however, the Schiff base is amorphous. HL and its mixed ligand complexes were screened against Gram‐positive bacteria (Streptococcus pneumoniae and Bacillus subtilis) and Gram‐negative bacteria (Pseudomonas aeruginosa and Escherichia coli). Antifungal activity was determined against Aspergillus fumigatus and Candida albicans, the data showing that most complexes had activity less than that of the Schiff base while Mn(II), Fe(III) and Ni(II) complexes showed no significant antifungal activity. The anticancer activity of HL and its metal complexes was also studied against breast and colon cell lines. The metal complexes showed IC₅₀ higher than that of HL, especially the Cu(II) complex which showed the highest IC₅₀ against breast cell line.     

Mononuclear Co(III), Ni(II) and Cu(II) complexes of tridentate di‐tert‐butylphenylhydrazone: Synthesis,characterization, X‐ray crystal structures,Hirshfeld surface analysis,molecular docking and in vivo anti‐inflammatory activity

A new hydrazone (LH₂) derived from the condensation of 2‐(4‐fluorobenzamido)benzohydrazide with 3,5‐di‐tert‐butyl‐2‐hydroxybenzaldehyde was used to synthesize Co(III), Ni(II) and Cu(II) complexes. These were characterized using various physicochemical, thermal, spectroscopic and single‐crystal X‐ray diffraction techniques. All the complexes crystallize in a monoclinic crystal system with P2₁/n space group and Z = 4. Structural studies of [Co(L)(LH)]?H₂O indicate the presence of both amido and imidol tautomeric forms of the ligand, resulting in a distorted octahedral geometry around the Co(III) ion. On the other hand, in the [Ni(L)(DMF)] and [Cu(L)(H₂O)] complexes, the ligand coordinates to the metal through imidol form resulting in distorted square planar geometry, in which the fourth position is occupied by the oxygen of coordinated DMF in [Ni(L)(DMF)] and by a water molecule in [Cu(L)(H₂O)]. Hirshfeld surface calculations were performed to explore hydrogen bonding and C―H???π interactions. Molecular docking studies were carried out to study the interaction between the synthesized compounds and proteins (cyclooxygenase‐2 and 5‐lipoxygenase). The complexes along with the parent ligand were screened for their in vivo anti‐inflammatory activity, using the carrageenan‐induced rat paw oedema method. The complexes show significant anti‐inflammatory potencies.     

Spectral,thermal and magnetic investigations of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 4-methylphthalates

Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 4-methylphthalates were investigated and their composition, solubility in water at 295 K and magnetic moments were determined. IR spectra and powder diffraction patterns of the complexes prepared with molar ratio of metal to organic ligand of 1.0:1.0 and general formula: M [ CH₃C₆H₃(CO₂)₂]·nH₂o (n=1-3) were recorded and their decomposition in air were studied. During heating the hydrated complexes are dehydrated in one (Mn, Co, Ni, Zn, Cd) or two steps (Cu) and next the anhydrous complexes decompose to oxides directly (Cu, Zn), with intermediate formation of carbonates (Mn, Cd), oxocarbonates (Ni) or carbonate and free metal (Co). The carboxylate groups in the complexes studied are mono- and bidentate (Co, Ni), bidentate chelating and bridging (Zn) or bidentate chelating (Mn, Cu, Cd). The magnetic moments for paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.92, 5.05, 3.36 and 1.96 M.B., respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

Coordination behaviour,molecular docking,density functional theory calculations and biological activity studies of some transition metal complexes of bis‐Schiff base ligand

Coordination compounds of Mn (II), Fe (III), Co (II), Ni (II), Cu (II) and Cd (II) ions were synthesized from reaction with Schiff base ligand 4,6‐bis((E)‐(2‐(pyridin‐2‐yl)ethylidene)amino)pyrimidine‐2‐thiol (HL) derived from the condensation of 4,6‐diaminopyrimidine‐2‐thiol and 2‐(pyridin‐2‐yl)acetaldehyde. Microanalytical data, magnetic susceptibility, infrared and ¹H NMR spectroscopies, mass spectrometry, molar conductance, powder X‐ray diffraction and thermal decomposition measurements were used to determine the structure of the prepared complexes. It was found that the coordination between metal ions and bis‐Schiff base ligand was in a molar ratio of 1:1, with formula [M (HL)(H₂O)₂] X_n (M = Mn (II), Co (II), Ni (II), Cu (II) and Cd (II), n = 2; Fe (III), n = 3). Diffuse reflectance spectra and magnetic susceptibility measurements suggested an octahedral geometry for the complexes. The coordination between bis‐Schiff base ligand and metal ions was through NNNN donor sites in a tetradentate manner. After preparation of the complexes, biological studies were conducted using Gram‐positive (B. subtilis and S. aureus) and Gram‐negative (E. coli and P. aeruginosa) organisms. Metal complexes and ligand displayed acceptable microbial activity against both types of bacteria.     

Syntheses,characterization and biological studies of zinc(II), copper(II) and cobalt(II) complexes with Schiff base ligand derived from 2‐hydroxy‐1‐naphthaldehyde and selenomethionine

Novel zinc(II), copper(II), and cobalt(II) complexes of the Schiff base derived from 2‐hydroxy‐1‐naphthaldehyde and D, L ‐selenomethionine were synthesized and characterized by elemental analysis, IR, electronic spectra, conductance measurements, magnetic measurements and powder XRD. The analytical data showed the composition of the metal complex to be ML(H₂O), where L is the Schiff base ligand and M = Co(II), Cu(II) and Zn(II). IR results confirmed the tridentate binding of the Schiff base ligand involving azomethine nitrogen, naphthol oxygen and carboxylato oxygen atoms. ¹H NMR spectral data of lithium salt of the Schiff base ligand [Li(HL)] and ZnL(H₂O) agreed with the proposed structures. The conductivity values of complexes between 12.50 and 15.45 S cm² mol^?1 in DMF suggested the presence of non‐electrolyte species. The powder XRD studies indicated that Co(II) complex is amorphous, whereas Cu(II) and Zn(II) complexes are crystalline. The results of antibacterial and antifungal screening studies indicated that Li(HL) and its metal complexes are active, but CuL(H₂O) is most active among them. Copyright © 2010 John Wiley & Sons, Ltd.     

Coordination compounds of some transition metal ions with new Schiff base ligand derived from dibenzoyl methane. Structural characterization,thermal behavior,molecular structure,antimicrobial, anticancer activity and molecular docking studies

Series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes were prepared with tetradentate Schiff base ligand derived by condensation of 2‐aminophenol with dibenzoylmethane. The novel Schiff base H₂L (2–2′‐((1Z,1Z’)‐(1,3‐diphenyl propane‐1,3 diylidene) bis (azanylylidene) diphenol) and its binary metal complexes were characterized by physicochemical procedures i.e. elemental analysis, FT‐IR, UV–Vis, thermal analyses (TGA/DTG), mass spectrometry, magnetic susceptibility and conductometric measurements. On the basis of these studies, an octahedral geometry for all these complexes was proposed expect Ni(II) complex which had tetrahedral geometry. Molar conductivity values revealed that the complexes were electrolytes except Mn(II), Zn(II) and Cd(II) complexes were non electrolytes. The ligand bound to the metal ions via two azomethine N and two phenolic OH as indicated from the IR and ¹H NMR spectral study. The molecular and electronic structures of H₂L and its zinc complex were optimized theoretically and the quantum chemical parameters were calculated. The antimicrobial activity against a number of bacterial organisms as Streptococcus pneumonia, Bacillus Subtilis, Pseudomonas aeruginosa and Escherichia coli and fungi as Aspergillus fumigates, Syncephalastrum racemosum, Geotricum candidum and Candida albicans by disk diffusion method were screened for the Schiff base and its complexes. The Cd(II) complex has potent antimicrobial activity. Anticancer activity of the Schiff base ligand and its metal complexes were evaluated in human cancer (MCF‐7 cells viability). The Cr(III) complex exhibited higher activity than other complexes and ligand. Molecular docking was used to predict the binding between Schiff base ligand (H₂L) and its Zn(II) complex and the receptors of RNA of amikacin antibiotic (4P20) and human‐DNA‐Topo I complex (1SC7). The docking study provided useful structural information for inhibition studies.     

Interaction of pyridine‐2,5‐dicarboxylic acid with heavy metal ions in aqueous solutions

Interactions between pyridine‐2,5‐dicarboxylic acid and Zn(II), Ni(II), Pb(II), Cd(II), and Cu(II) were characterized in aqueous solutions (20°C; I = 0.4 (KNO₃)) by means of d.c.‐polarography, spectrophotometry, and ¹H NMR spectroscopy. Polarography was used to determine the concentration of free metal ions in the presence of 10‐fold excess ligand in weakly alkaline solutions, and to determine stability constants for the Zn(II), Cd(II), and Cu(II) complexes with pyridine‐2,5‐dicarboxylic acid. ¹H NMR spectroscopy was used to further characterize complex formation. © 2005 Wiley Periodicals, Inc. 16:285–291, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20123     

Spectroscopic and magnetic evidence of coordination properties of bioactive diethyl (pyridin-4-ylmethyl)phosphate ligand with chloride transition-metal ions

A series of five chloride coordination compounds of diethyl (pyridin-4-ylmethyl)phosphate (4-pmOpe) ligand, i.e. [CuCl₂(4-pmOpe)₂], [NiCl₂(4-pmOpe)₄], [CoCl₂(4-pmOpe)], [ZnCl₂(4-pmOpe)₂], and [CdCl₂(4-pmOpe)₂], was prepared and studied. Stoichiometry and stereochemistry of the compounds was confirmed by spectroscopic and magnetic studies as well as by elemental analyses. The 4-pmOpe ligand has a capacity to coordinate to metal ions by means of phosphoryl oxygen and/or nitrogen of pyridine atoms. In Cu(II), Ni(II), and Zn(II) compounds, 4-pmOpe adopts the monodentate coordination mode, bonding metal centers through the pyridine nitrogen atom only. On the contrary, in Co(II) and Cd(II) compounds, 4-pmOpe acts as N,O-bridging ligand forming polynuclear structures. Magnetic studies (1.8–300 K) indicate mononuclear structure of the Co(II) and Ni(II) compounds and suggest existence of a very weak exchange coupling between metal centers in crystal lattice.     

Molecular structure,molecular docking,thermal, spectroscopic and biological activity studies of bis‐Schiff base ligand and its metal complexes

Coordination compounds of Fe(III), Zn(II), Ni(II), Co(II), Cu(II), Cd(II) and Mn(II) ions were synthesized from the ligand [4,4′‐((((ethane‐1,2‐diylbis(oxy))bis(2,1‐phenylene))bis(methanylylidene))bis(azanylylidene))diphenol]ethane (H₂L) derived from the condensation of bisaldehyde and 4‐aminophenol. Microanalysis, magnetic susceptibility, infrared, ¹H NMR and mass spectroscopies, molar conductance, X ray powder diffraction and thermal analysis were used to confirm the structure of the synthesized chelates. According to the data obtained, the composition of the 1:1 metal ion–bis‐Schiff base ligand was found to be [M(H₂L)(H₂O)₂]Cl_n (M = Zn(II), Ni(II), Co(II), Cu(II), Cd(II) and Mn(II), n = 2; Fe(III), n = 3). Magnetic susceptibility measurements and reflectance spectra suggested an octahedral geometry for the complexes. Central metals ions and bis‐Schiff base coordinated together via O2 and N2 donor sites which as evident from infrared spectra. The Gaussian09 program was applied to optimize the structural formula for the investigated Schiff base ligand. The energy gaps and other important theoretical parameters were calculated applying the DFT/B3LYP method. Molecular docking using AutoDock tools was utilized to explain the experimental behaviour of the Schiff base ligand towards proteins of Bacillus subtilis (5 h67), Escherichia coli (3 t88), Proteus vulgaris (5i39) and Staphylococcus aureus (3ty7) microorganisms through theoretical calculations. The docked protein receptors were investigated and the energies of hydrogen bonding were calculated. These complexes were then subjected to in vitro antibacterial studies against several organisms, both Gram negative (P. vulgaris and E. coli) and Gram positive (S. pyogones and B. subtilis). The ligand and metal complexes exhibited good microbial activity against the Gram‐positive and Gram‐negative bacteria.     

New azo‐azomethine‐based transition metal complexes: Synthesis,spectroscopy, solid‐state structure,density functional theory calculations and anticancer studies

A novel tetradentate azo‐Schiff base ligand (H₂L) was synthesized by 2:1 molar condensation of an azo‐aldehyde and ethylenediamine. Its mononuclear Cu(II), Ni(II), Co(II) and Zn(II) complexes were prepared and their structures were confirmed using elemental analysis, NMR, infrared and UV–visible spectroscopies and molar conductivity measurements. The results suggest that the metal ion is bonded to the tetradentate ligand through phenolic oxygens and imine nitrogens of the ligand. The solid‐state structures of the azo‐Schiff base ligand and its Cu(II) complex were determined using single‐crystal X‐ray diffraction studies. The azo‐Schiff base ligand lies on a crystallographic inversion centre and thus the asymmetric unit contains half of the molecule. X‐ray data revealed that keto–amine tautomer is favoured in the solid‐state structure of the ligand. In the structure of the Cu(II) complex, the Cu(II) ion is coordinated to two phenolate oxygen atoms and two imine nitrogen atoms of the azo‐Schiff base ligand with approximate square planar geometry. The anticancer activity of the synthesized complexes was investigated for human cancer cell line (MCF‐7) and cytotoxicity of the synthesized compounds was determined against mouse fibroblast cells (L929). The ligand and its complexes were found to show antitumor activity. The synthesized metal complexes were optimized at the B3LYP/LANL2DZ level and a new theoretical formula for MCF‐7 cells was also derived.