Electrochemical synthesis for new thiosemicarbazide complexes,spectroscopy, cyclic voltammetry,structural properties,and in silico study

A new thiosemicarbazide derivative ligand (HDCTS) was prepared from the reaction between 2,4‐dinitrophenylhydrazine and 4‐chlorophenyl isothiocyanate. Co(II) and Cu(II) complexes were synthesized from HDCTS derivative by electrochemical method to reach preferable yield in a safe environment. The new complexes as well as the original ligand were fully characterized to establish their chemical formulae. The spectral (infrared, Raman, mass, and ultraviolet–visible), analytical (elemental, thermogravimetric analysis [TGA], and cyclic voltammetry), and conformational techniques were implemented for characterization. According to spectral data and magnetic moments, the octahedral arrangement was proposed around metals through mono‐negative bidentate mode of bonding. TGA discriminates and quantitatively evaluates the presence of water molecules within two complexes. Electrochemical study was interested for all new compounds and suggests the electrode couples to be close for quasi‐reversible behavior. Elaborated conformational study was displayed to extract significant characteristics, which assert firstly on the mode of bonding inside the complexes. The perfect distribution of NH and CS groups inside the optimized structures facilitates their coordination as spectrally proposed. Crystal explorer program was used to investigate the degree of contact between molecules inside crystal packing systems. Effective contribution in surface contact feature was noticed from O and Cl atoms. A certified in silico study concerning the docking feature of new compounds against effective proteins in allergy and inflammation diseases was done. According to data exported, a promising anti‐allergic or anti‐inflammatory efficiency is expected strongly from Cu(II)–DCTS complex.     

Structural,spectroscopic, molecular docking,thermal and DFT studies on metal complexes of bidentate orthoquinone ligand

4‐Triphenylmethyl‐1,2‐benzoquinone (TPMBQ) reacted with some metal ions and the structure of the new compounds had been identified. The metal to ligand ratio was 1:2 which was revealed by elemental analysis. The complexes were found to have octahedral geometry and their thermal stability was studied using thermogravimetric analysis technique. The molar conductance measurements revealed the electrolytic nature of the synthesized chelates. The IR spectra concluded the bidentate nature of the TPMBQ ligand while the ¹H NMR revealed the presence of water molecules. The XRD spectra of Mn (II) and Fe (III) complexes concluded their crystalline structure while Co (II) and Cu (II) chelates refer to amorphous structures. The geometries of the TPMBQ ligand were optimized using Gaussian 09 W; density functional theory B3LYP method. (DFT)/basis set 6–311++G (d, p). HOMO and LUMO energy values for chelates, chemical hardness and electro‐negativity had been calculated. The ligand and its metal complexes had been examined against different kinds of bacteria such as Proteus vulgaris, Escherichia coli, Staphylococcus aurous and Bacillus subtitles to examine their antimicrobial activity. Molecular docking using Auto Dock tools were utilized.     

Synthesis, spectroscopic, and thermal studies of some Hg(II) and Cd(II) coordination compounds of N,N-bis[(E)-3-(phenylprop)-2-enylidene]propanediamine

Some new coordination compounds of cadmium(II) and mercury(II) with N,N-bis[(E)-3-(phenylprop)-2-enylidene]propanediamine (L) as a new bidentate Schiff base ligand with general formula MLX₂ (X = Cl^?, Br^?, I^?, SCN^?, and N₃ ^?) have been prepared. They were characterized by elemental analysis, FT-infrared (FT-IR) and Ultraviolet–Visible spectra, ¹H- and ¹³C-NMR spectra. The reasonable shifts of FT-IR and NMR spectral signals of the complexes with respect to the free ligand confirm well coordination of ligand and anions(X-) in inner sphere coordination mode. The thermal behavior of the complexes from room temperature to 800 °C shows weight loss by decomposition of the anions and ligand segments in the subsequent steps. The results showed that cadmium complexes have no water molecules (neither as lattice nor as coordinated water) and are decomposed in two temperature steps except about cadmium thiocyanate complex that is decomposed in three steps. Final residual contents of cadmium complexes are suggested to be cadmium oxide or sulfide. Mercury complexes were decomposed in three to four temperature steps. Mercury bromide and azide complexes leave out a little amount of mercury oxide in final, while mercury chloride, iodide, and thiocyanate complexes were found to be completely decomposed without any residual matter.     

Novel Schiff base ligand and its metal complexes with some transition elements. Synthesis,spectroscopic, thermal analysis,antimicrobial and in vitro anticancer activity

A novel Schiff base ligand (H₂L) was prepared through condensation of 2,6‐diaminopyridine and o‐benzoylbenzoic acid in a 1:2 ratio. This Schiff base ligand was characterized using elemental and spectroscopic analyses. A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal complexes of H₂L were prepared and characterized using elemental analysis, spectroscopy (¹H NMR, mass, UV–visible, Fourier transform infrared, electron spin resonance), magnetic susceptibility, molar conductivity, X‐ray powder diffraction and thermal analysis. The complexes are found to have trigonal bipyramidal geometry except Cr(III), Mn(II) and Fe(III) complexes which have octahedral geometry based on magnetic moment and solid reflectance measurements. The infrared spectral studies reveal that H₂L behaves as a neutral bidentate ligand and coordinates to the metal ions via the two azomethine nitrogens. ¹H NMR spectra confirm the non‐involvement of the carboxylic COOH proton in complex formation. The presence of water molecules in all reported complexes is supported by thermogravimetric studies. Kinetic and thermodynamic parameters were determined using Coats–Redfern and Horowitz–Metzger equations. The synthesized ligand and its complexes were screened for antimicrobial activities against two Gram‐positive bacteria (Bacillus subtilis and Staphylococcus aureus), two Gram‐negative bacteria (Escherichia coli and Neisseria gonorrhoeae) and one fungus (Candida albicans). Anticancer activities of the ligand and its metal complexes against human breast cancer cell line (MCF7) were investigated. Copyright © 2016 John Wiley & Sons, Ltd.     

A new carboxylic chelate ligand and its supramolecular complexes formed with sodium ions and alcohol molecules

The new hydrazone ligand 1, featuring a 2-carboxy group at the aromatic ring and a trifluoromethyl structural modification in the pentane-2,4-dione moiety, has been synthesised via the Japp–Klingemann route. The compound is shown to form binuclear multicomponent chelate complexes (2 and 3) composed of two sodium ions, two charge equalising carboxylates of the hydrazone molecule, two more carboxylic hydrazones and two alcohol solvent molecules, with the latter being either EtOH or n-BuOH. X-ray crystal structures of the free hydrazone ligand as well as of the complexes have been studied. They demonstrate for the free ligand a ribbon-type aggregation of carboxylic dimers, while the isomorphous complexes possess a remarkable binuclear structure with the two sodium ions in a distorted octahedral coordination geometry of six oxygen atoms coming, at the equatorial and apical sites, from the hydrazone carbonyl groups and the hydroxyl of the solvent molecules, respectively. The hydrogen bonds owing to the alcohol molecules give rise to the stack formation of the supramolecular cluster. Weak intermolecular contacts involving the fluorine atoms also contribute to the crystalline packing in the case of both the free ligand and the complexes.     

Selective detection of specific protein-ligand complexes by electrosonic spray-precursor ion scan tandem mass spectrometry

A novel mass spectrometric method for the selective detection of specific protein-ligand complexes is presented. The new method is based on electrosonic spray ionization of samples containing protein and ligand molecules, and mass spectrometric detection using the precursor ion scanning function on a triple quadrupole instrument. Mass-selected intact protein-ligand complex ions are subjected to fragmentation by means of collision-induced dissociation in the collision cell of the instrument, while the second mass analyzer is set to the m/z of protonated ligand ions or their alkali metal adducts. The method allows for the detection of only those ions which yield ions characteristic of the ligand molecules upon fragmentation. Since the scan range of first analyzer is set well above the m/z of the ligand ion, and the CID conditions are established to permit fragmentation of only loosely bound, noncovalent complexes, the method is specific to the detection of protein-ligand complexes under described conditions. Behavior of biologically specific and nonspecific complexes was compared under various instrumental settings. Parameters were optimized to obtain maximal selectivity for specific complexes. Specific and nonspecific complexes were found to show markedly different fragmentation characteristics, which can be a basis for selective detection of complexes with biological relevance. Preparation of specific and nonspecific complexes containing identical building blocks was attempted. Complex ions with identical stoichiometry but different origin showed the expected difference in fragmentation characteristics, which gives direct evidence for the different mechanism of specific versus nonspecific complex ion formation.     

Ligational behaviour of lomefloxacin drug towards Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO(2)(VI) ions: synthesis, structural characterization and biological activity studies

Nine new mononuclear Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO₂(VI) complexes of lomefloxacin drug were synthesized. The structures of these complexes were elucidated by elemental analyses, IR, XRD, UV–vis, ¹H NMR as well as conductivity and magnetic susceptibility measurements and thermal analyses. The dissociation constants of lomefloxacin and stability constants of its binary complexes have been determined spectrophotometrically in aqueous solution at 25 ± 1 °C and at 0.1 M KNO₃ ionic strength. The discussion of the outcome data of the prepared complexes indicate that the lomefloxacin ligand behaves as a neutral bidentate ligand through OO coordination sites and coordinated to the metal ions via the carbonyl oxygen and protonated carboxylic oxygen with 1:1 (metal:ligand) stoichiometry for all complexes. The molar conductance measurements proved that the complexes are electrolytes. The powder XRD study reflects the crystalline nature for the investigated ligand and its complexes except Mn(II), Zn(II) and UO₂(II). The geometrical structures of these complexes are found to be octahedral. The thermal behaviour of these chelates is studied where the hydrated complexes lose water molecules of hydration in the first steps followed by decomposition of the anions, coordinated water and ligand molecules in the subsequent steps. The activation thermodynamic parameters are calculated using Coats–Redfern and Horowitz–Metzger methods. A comparative study of the inhibition zones of the ligand and its metal complexes indicates that metal complexes exhibit higher antibacterial effect against one or more bacterial species than the free LFX ligand. The antifungal and anticancer activities were also tested. The antifungal effect of almost metal complexes is higher than the free ligand. LFX, [Co(LFX)(H₂O)₄]·Cl₂ and [Zn(LFX)(H₂O)₄]·Cl₂ were found to be very active with IC50 values 14, 11.2 and 43.1, respectively. While, other complexes had been found to be inactive at lower concentration than 100 μg/ml.     

Synthesis,spectroscopic, DNA cleavage and antibacterial activity of binuclear schiff base complexes

The binuclear Schiff base complexes are formed newly using different transition metals at their stable oxidation state as Cu(II), Ni(II), and VO(II). 3,3′,4,4′-tetraminobiphenyl and 2-aminobenzaldehyde were condensed to form a new Schiff base ligand having an two N₄ group responsible for better chelating to the metal centers. The ligand and their complexes have been established by analytical, spectral and electrochemical data. The interaction studies of the complexes with CT-DNA were carried out using cyclic voltammetry, viscosity measurements and fluorescence spectroscopy. The free ligand and their metal complexes were screened for their antimicrobial activities against the following species: Klebsiella pneumoniae, Escherichia coli and Staphylococcus aureus. A comparative study of minimum inhibitory concentration (MIC) values of the Schiff base and its complexes indicate that the metal complexes exhibit higher antibacterial activity than the free ligand.     

Conventional and microwave synthesis,spectral, thermal and antimicrobial studies of some transition metal complexes containing 2-amino-5-methylthiazole moiety

Schiff base metal complexes of Cr(III), Co(II), Ni(II) and Cu(II) derived from 5-chlorosalicylidene-2-amino-5-methylthiazole (HL¹) and 2-hydroxy-1-naphthylidene-2-amino-5-methylthiazole (HL²) have been synthesized by conventional as well as microwave methods. These compounds have been characterized by elemental analysis, FT-IR, FAB-mass, molar conductance, electronic spectra, ¹H-NMR, ESR, magnetic susceptibility, thermal, electrical conductivity and XRD analyses. The complexes exhibit coordination number 4 or 6. The complexes are coloured and stable in air. Analytical data reveal that all the complexes exhibit 1:2 (metal:ligand) ratio. IR data show that the ligand coordinates with the metal ions in a bidentate manner through the phenolic oxygen and azomethine nitrogen. FAB-mass and thermal data show degradation pattern of the complexes. The thermal behaviour of metal complexes shows that the hydrated complexes lose water molecules of hydration in the first step; followed by decomposition of ligand molecules in the subsequent steps. XRD patterns indicate crystalline nature for the complexes. The Schiff bases and metal complexes show good activity against the Gram-positive bacteria; Staphylococcus aureus and Gram-negative bacteria; Escherichia coli and fungi Aspergillus niger and Candida albicans. The antimicrobial results also indicate that the metal complexes are better antimicrobial agents as compared to the Schiff bases.     

Coordination complexes incorporating pyrophosphate: Structural overview and exploration of their diverse magnetic,catalytic and biological properties

Current attention continues to revolve around the chemistry and biochemistry associated with polyphosphate anions because of their importance in biology. A pivotal intermediate within this family is the pyrophosphate tetraanion, P₂O₇^4?. Considering its biological relevance and the multidentate nature that makes it an ideal ligand in the field of the coordination chemistry, there is a growing interest in the use of this anion in building new class of molecules/compounds for different purposes. While the total number of characterized structures still remains modest, several new pyrophosphate-containing coordination complexes have been reported in the last decade, as well as different solid-state structures. This review focuses on the structural, magnetic, and biological properties of coordination complexes incorporating the pyrophosphate ligand reported to date.     

Calcium-Ligand Cooperation Promoted Activation of N2O,Amine, and H2 as well as Catalytic Hydrogenation of Imines,Quinoline, and Alkenes

Bond activation and catalysis using s-block metals are of great significance. Herein, a series of calcium pincer complexes with deprotonated side arms have been prepared using pyridine-based PNP and PNN ligands. The complexes were characterized by NMR and X-ray crystal diffraction. Utilizing the obtained calcium complexes, unprecedented N₂O activation by metal-ligand cooperation (MLC) involving dearomatization-aromatization of the pyridine ligand was achieved, generating aromatized calcium diazotate complexes as products. Additionally, the dearomatized calcium complexes were able to activate the N−H bond as well as reversibly activate H₂, offering an opportunity for the catalytic hydrogenation of various unsaturated molecules. DFT calculations were applied to analyze the electronic structures of the synthesized complexes and explore possible reaction mechanisms. This study is an important complement to the area of MLC and main-group metal chemistry.     

Complexation and Thermal Studies of Uric Acid with Some Divalent and Trivalent Metal Ions of Biological Interest in the Solid State

Nine new [metal uric acid] complexes [M(Ua) n ]°·XH 2 O have been synthesized. These complexes have been characterized by elemental analysis, X-ray diffraction (XRD), magnetic susceptibility ( w eff. ), FTIR spectra, thermal analysis (TG & DTA), and electronic spectra (UV/visible). Uric acid (HUa) coordinates as a bidentate ligand to Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Al(III), Cr(III) and Fe(III) through the protonated N-7 within the imidazole ring and O-6 within the pyrimidine ring. Uric acid forms neutral metal urate complexes with all the above metal ions. The quantitative compositions were determined as [M(Ua) 2 ·(H 2 O) 2 ]°·XH 2 O where M(II)=Mn, Fe, Co, Ni, Cu, Zn and X=2, 4, 2, 4, 2, 2, respectively. The M(II) complexes exhibit an isostructural octahedral coordination with N-7, O-6 of two uric acid ligand molecules, and O of two water molecules. Compositions were also determined as [M(Ua) 3 ]°·YH 2 O where M(III)=Al, Cr, Fe and Y=6, 3, 3 respectively. All the M(III) complexes form an isostructural octahedral coordination with N-7 and O-6 of three uric acid ligand molecules. Iron(III) complexes prepared with N 1 , N 3 and N 9 -methyl uric acid yielded brown complexes with a metal ligand ratio of 1 3, while N 7 -methyl uric acid did not yield a complex due to blockage of N-7 with a methyl group.     

Synthesis, characterization and biological activities of Cu(II), Co(II), Mn(II), Fe(II), and UO2(VI) complexes with a new Schiff Base hydrazone: O-hydroxyacetophenone-7-chloro-4-quinoline hydrazone

The Schiff base hydrazone ligand HL was prepared by the condensation reaction of 7-chloro-4-quinoline with o-hydroxyacetophenone. The ligand behaves either as monobasic bidentate or dibasic tridentate and contain ONN coordination sites. This was accounted for be the presence in the ligand of a phenolic azomethine and imine groups. It reacts with Cu(II), Ni(II), Co(II), Mn(II), UO(2) (VI) and Fe(II) to form either mono- or binuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, NMR, Mass, and UV-Visible spectra. The magnetic moments and electrical conductance of the complexes were also determined. The Co(II), Ni(II) and UO(2) (VI) complexes are mononuclear and coordinated to NO sites of two ligand molecules. The Cu(II) complex has a square-planar geometry distorted towards tetrahedral, the Ni(II) complex is octahedral while the UO(2) (VI) complex has its favoured heptacoordination. The Co(II), Mn(II) complexes and also other Ni(II) and Fe(III) complexes, which were obtained in the presence of Li(OH) as deprotonating agent, are binuclear and coordinated via the NNNO sites of two ligand molecules. All the binuclear complexes have octahedral geometries and their magnetic moments are quite low compared to the calculated value for two metal ions complexes and thus antiferromagnetic interactions between the two adjacent metal ions. The ligand HL and metal complexes were tested against a strain of Gram +ve bacteria (Staphylococcus aureus), Gram -ve bacteria (Escherichia coli), and fungi (Candida albicans). The tested compounds exhibited high antibacterial activities.     

Aminopyridinate–FI Hybrids,Their Hafnium and Titanium Complexes,and Their Application in the Living Polymerization of 1‐Hexene

Based on two well‐established ligand systems, the aminopyridinato (Ap) and the phenoxyimine (FI) ligand systems, new Ap‐FI hybrid ligands were developed. Four different Ap‐FI hybrid ligands were synthesized through a simple condensation reaction and fully characterized. The reaction of hafnium tetrabenzyl with all four Ap‐FI hybrid ligands exclusively led to mono(Ap‐FI) complexes of the type [(Ap‐FI)HfBn₂]. The ligands acted as tetradentate dianionic chelates. Upon activation with tris(pentafluorophenyl)borane, the hafnium‐dibenzyl complexes led to highly active catalysts for the polymerization of 1‐hexene. Ultrahigh molecular weights and extremely narrow polydispersities support the living nature of this polymerization process. A possible deactivation product of the hafnium catalysts was characterized by single‐crystal X‐ray analysis and is discussed. The coordination modes of these new ligands were studied with the help of model titanium complexes. The reaction of titanium(IV) isopropoxide with ligand 1 led to a mono(Ap‐FI) complex, which showed the desired fac‐mer coordination mode. Titanium (IV) isopropoxide reacted with ligand 4 to give a complex of the type [(ApH‐FI)₂Ti(OiPr)₂], which featured the ligand in its monoanionic form. The two titanium complexes were characterized by X‐ray crystal‐structure analysis.     

Synthesis,characterization, cyclic voltammetry,and antimicrobial properties of N-(5-benzoyl-2-oxo-4-phenyl-2H-pyrimidine-1-yl)-malonamic acid and its metal complexes

A new heterocyclic compound, N-(5-benzoyl-2-oxo-4-phenyl-2H-pyrimidin-1-yl)-malonamic acid, was synthesized from N-aminopyrimidine-2-one and malonyldichloride. Bis-chelate complexes of the ligand were prepared from acetate/chloride salts of Cu(II), Co(II), Ni(II), Mn(II), Zn(II), Cd(II), Fe(III), Cr(III), and Ru(III) in methanol. The structures of the ligand and its metal complexes were characterized by microanalyses, IR, NMR, API-ES, UV-Vis spectroscopy, magnetic susceptibility, and conductometric analyses. Octahedral geometry was suggested for all the complexes, in which the metal center coordinates to ONO donors of the ligand. Each ligand binds the metal using C=O, HN, and carboxylate. The cyclic voltammograms of the ligand and the complexes were also discussed. The compounds were evaluated for their antimicrobial activities against Gram-positive and Gram-negative bacteria, and fungi using microdilution procedure. The antimicrobial studies showed that Cu(II), Fe(III), and Ru(III) complexes exhibited good antibacterial activity against Gram-positive bacteria with minimum inhibitory concentrations between 20 and 80 µg mL^?1. However, the ligand and the complexes possess weak efficacy against Gram-negative bacterium and Candida strains. As a result, we suggest that these complexes containing pyrimidine might be a new group of antibacterial agents against Gram-positive bacteria.     

Syntheses and structural characterizations of 24-membered dimetal (Mn, Ni, Fe) macrocyclic complexes and the C-S bond formation between acetylacetone and a mercapto N-heterocycle

An organic ligand 2,5-di(3-pentanedionylthio)-1,3,4-thiadiazole (H2L) reacts with metal (Mn, Ni, Fe) salts, resulting in 24-membered dimetal macrocyclic complexes [MnL(H2O)(dmso)](2).2dmso, [NiL(H2O)(dmf)](2).2dmf, [MnL(dmf)2]2 and [Fe2L2(solvent)2(SO4)] (solvent=dmso; H2O ; dmf). Di-manganese macrocyclic complexes [MnL(dmf)(dmso)]2 and [MnL(H2O)2](2).6H2O can also be obtained directly by aerobic assembly reaction of MnCl2, dipotassium 1,3,4-thiadiazole-2,5-dithiolate (K2tdadt) and acetylacetone (H2acac) in various solvents, accompanying a C-S bond formation between acetylacetone and the mercapto N-heterocycle. Disulfide has been considered as the intermediate in the assembly reaction. Meanwhile an assembly reaction including MnCl2, 2-mercaptobenzimidazole and H2acac has produced an organic compound 2-(3-pentanedionylthio)benzimidazole with a new C-S bond. These dimetal complexes have similar macrocyclic structures, in which solvent molecules and sulfate coordinate to the octahedral metal in trans-configuration, whereas a pair of water molecules are located in octahedral cis-positions for owing to a small steric effect. A host cavity of sufficiently large size exists in the macrocyclic structure to trap the solvent molecules and the sulfate anion. The IR spectra have been used to assign the solvent molecules trapped and the sulfate anion which is shown as a bridged bidentate ligand. Thermal analyses show the stability of the macrocyclic backbone below 200 degrees C and gradual release processes of the trapped solvent molecules. Decomposition and oxidation of the dimetal macrocycle backbone occur at 300-500 degrees C, resulting in a metal sulfate. Further decomposition led to metal oxide at 500-600 degrees C.     

Cyclometallated platinum(II) complexes: oxidation to, and C-H activation by, platinum(IV)

A series of cyclometallated phenylpyridine platinum(II) complexes have been synthesised with a systematic variation in both the phenylpyridine and the ancillary ligand. Oxidation of one of the cyclometallated species leads to a number of isomeric platinum(IV) complexes, all of which eventually isomerize to a single compound. The route to these new compounds has been demonstrated to involve an initial slow oxidation followed by a rapid C-H activation to give doubly cyclometallated complexes. The solid state structures of a number of both the platinum(II) and the platinum(IV) species have been solved; many of the structures exhibited extended interactions that result in complex three dimensional packing.     

Water molecules inside protein structure affect binding of monosaccharides with HIV‐1 antibody 2G12

Water molecules inside biomolecules constitute integral parts of their structure and participate in the functions of the proteins. Some of the X‐ray crystallographic data are insufficient for analyzing a series of ligand–protein complexes in the same condition. We theoretically investigated antibody binding abilities of saccharide ligands and the effects of the inner water molecules of ligand–antibody complexes. Classical molecular dynamics and quantum chemical simulations using a model with possible water molecules inside the protein were performed with saccharide ligands and Human Immunodeficiency Virus 1 neutralizing antibody 2G12 complexes to estimate how inner water molecules of the protein affect the dynamics of the complexes as well as the ligand–antibody interaction. Our results indicate the fact that d ‐fructose's strong affinity to the antibody was partly due to the good retentiveness of solvent water molecules of the ligand and its stability of the ligand's conformation and relative position in the active site. © 2016 Wiley Periodicals, Inc.     

Chiral heterocyclic ligands. XVI: Synthesis and crystal structures of four metal complexes of a tridentate,biheterocyclic ligand derived from l-cysteine

The readily available homochiral ligand (1) was used to prepare four mononuclear nickel and cobalt complexes with a 2:1 ligand:metal ratio. X-ray crystal structures of these revealed that in all cases the N,N,O-tridentate ligand adopts facial coordination to the metal with the pyridine rings trans-disposed and the carboxylate and amine groups cis. The individual crystal structures of these compounds differ significantly in the way the complexes pack, which is mediated by hydrogen bonding involving the cations, anions and water molecules as well as, in one case, π-stacking.     

Azo dye with nitrogen donor sets of atoms and its metal complexes: Synthesis,characterization, DFT,biological, anticancer and Molecular docking studies

An azo derivative was synthesized by coupling diazotized 2,6‐diaminopyridine with p‐dimethyl amino benzaldehyde and this new ligand formed a series of metal complexes with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) salts. These complexes were characterized on the basis of elemental analyses, molar conductance, infrared spectroscopy, UV–Vis, ¹H NMR, mass spectrometry, electronic spectra, magnetic susceptibility and ESR spectral studies, conductivity measurements, thermogravimetric analyses (TG‐DTG). The molecular and electronic structure of the azo ligand was optimized theoretically and the quantum chemical parameters were calculated. The ligand and its metal complexes were subjected to X‐ray powder diffraction study. The thermal stability of the ligand and its metal complexes was examined by thermogravimetry. The ligand and its complexes were tested for their in vitro antimicrobial activity, some of the complexes showed good antimicrobial activities against some selected bacterial and fungal strains. Anticancer activity of the ligand and its metal complexes are evaluated against human cancer (MCF‐7 cells viability). Molecular docking was used to predict the binding between azo ligand and the receptors of nucleoside diphosphate kinase of Staphylococcus aureus (3Q8U) and (3HB5) which is breast cancer mutant oxidoreductase. The docking study provided useful structural information for inhibition studies.