Synthesis,spectroscopic, DFT,biological studies and molecular docking of oxovanadium (IV), copper (II) and iron (III) complexes of a new hydrazone derived from heterocyclic hydrazide

A new Schiff base hydrazone (Z)‐2‐(2‐aminothiazol‐4‐yl)‐N′‐(2‐hydroxy‐3‐methoxybenzylidene) acetohydrazide (H₂L) and its chelates [VO (HL)₂]·5H₂O, [Cu (HL)Cl(H₂O)]·2H₂O and [Fe(L)Cl(H₂O)₂]·3H₂O have been isolated and characterized using different physico‐chemical methods, for example infrared (IR), electron paramagnetic resonance (EPR), thermogravimetric analysis and DTG in the solid state, and ¹H‐NMR, ¹³C‐NMR and UV in solution. Magnetic and UV–visible measurements proposed that the coordination environments are square pyramidal, tetrahedral and octahedral geometries for oxovanadium (IV), Cu (II) and Fe (III), respectively. The ligand acts as mono‐negative NO towards oxovanadium (IV) and Cu (II) ions, and bi‐negative ONO for Fe (III) ion. The geometries of the ligand and its complexes were performed using Gaussian 9 program with density functional theory. The EPR spectral data of oxovanadium (IV) and Cu (II) chelates confirmed the mentioned geometries. The molecular modeling was done, and illustrated bond lengths, bond angles, molecular electrostatic potential, Mulliken atomic charges and chemical reactivity for the inspected compounds. Theoretical IR and ¹H‐NMR of the free ligand were calculated. Furthermore, thermodynamic and kinetic parameters for thermal decomposition steps were studied. Docking study of H₂L was applied against the proteins of both bacterial strains Staphylococcus aureus and Escherichia coli, as well as the protein of xanthine oxidase as antioxidant agent by Schrödinger suite program utilizing XP glide protocol. Furthermore, antimicrobial, antioxidant and DNA‐binding activities of the compounds have been carried out.     

Synthesis,structure, and urease inhibitory activities of Co(III), Mn(II) and Zn(II) complexes with hydrazone derived from protocatechuic acid

[Co^III(L₁)₂·H₂O]NO₃ (1), [Mn^II(L₁)₂·H₂O] (2), and [Zn^II(L₁)₂·H₂O] (3) with a hydrazone derived from protocatechuic acid (HL₁ = C₁₅H₁₃N₃O₃) were designed, synthesized, and characterized by C, H, N elemental analyses, single-crystal X-ray diffraction, and IR spectra, which revealed that the three complexes are similar structures. Docking study has been done. The urease inhibitory activities of the three complexes were tested. Complexes 1 and 3 showed strong inhibitory activity against jack bean urease with IC₅₀ values of 45.9 and 11.64 μM. Complex 2 had no obvious inhibitory activity to urease; the IC₅₀ was > 50 μM.     

Structural,DFT/B3LYP and molecular docking studies of binuclear thiosemicarbazide Copper (II) complexes and their biological investigations

Thiosemicarbazide copper (II) complexes; [Cu₂(HL¹)₂(H₂O)₂Cl₂].H₂O (1) and [Cu₂(HL²)₂(H₂O)₂Cl₂].2H₂O (2) (where H₂L¹ = 2-picolinoyl-N-(pyridin-2-yl)hydrazine-1-carbothioamide and H₂L² = 2-(2-(2-aminothiazol-4-yl)acetyl)-N-(pyridin-2-yl)hydrazine-1-carbothioamide) have been synthesized and characterized. Analytical and spectroscopic data revealed that ligands behaves as monobasic tetradentate with octahedral geometry. In addition, the optimized geometry of the ligands and their complexes was approved with the Jaguar 9.1 program in the Schrödinger set using DFT (density functional theory) to predict chemical processes and to estimate the properties of the material made by the hybrid functional density system B3LYP. Furthermore, the thermal degradation curves of complexes were discussed in order to determine the kinetic and thermodynamic parameters by various approaches. Additionally, the antioxidant (using the DPPH and SOD methods) and the antibacterial potency of the compounds were examined. Also, docking study of ligands and their complexes was carried out against Staphylococcus aureus gram +ve, gram -ve bacterial strains of Escherichia coli and Candida albicans using the XP glide protocol of Schrödinger suite.     

Synthesis,physico-chemical investigations and biological studies on Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes with p -amino acetophenone isonicotinoyl hydrazone

Complexes of the type [M(painh)(H₂O)₂X], where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); X = Cl₂ or SO₄; painh = p-amino acetophenone isonicotinoyl hydrazone, have been synthesized and characterized by spectral and other physico-chemical techniques. The synthesized complexes are stable powders, insoluble in common organic solvents such as ethanol, benzene, carbon tetrachloride, chloroform and diethyl ether, and are non-electrolytes. Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) studies show that the organic ligand decomposes exothermically through various steps. TGA and Infrared (IR) spectral studies indicate the presence of coordinated water in the metal complexes. Magnetic susceptibility measurements and electronic spectra suggest that Mn(II), Co(II), and Ni(II) complexes are paramagnetic with octahedral geometry, whereas Cu(II) complexes have distorted octahedral geometry. The neutral bidentate ligand bonds through >C=O and >C=N–groups in all the complexes. Electron Spin Resonance (ESR) spectra in the solid state show axial symmetry for [Cu(painh)(H₂O)₂(SO₄)] and elongated rhombic symmetry for [Cu(painh)(H₂O)₂Cl₂], suggesting an elongated tetragonally-distorted octahedral structure for both complexes. X-ray powder diffraction parameters for two complexes correspond to tetragonal and orthorhombic crystal lattices. The metal complexes show fair antifungal activity against Rizoctonia sp., Aspergillus sp., Stemphylium sp., and Penicillium sp. and appreciable antibacterial activity against Pseudomonas sp. and Escherichia coli.     

Synthesis,characterization, biological applications,and molecular docking studies of amino-phenol-derived mixed-ligand complexes with Fe(III), Cr(III), and La(III) ions

A new series of Fe(III), Cr(III), and La(III) mixed-ligand complexes, resulting from the interaction of 2-aminophenol with 2-hydroxy acetophenone (HL₁) as primary ligand and L- histidine (L₂) as a secondary ligand, has been investigated using various physicochemical studies such as elemental analyses, molar conductivity, magnetic moment, infrared, UV/Vis, ¹H NMR, and mass spectroscopic techniques. The microanalytical results indicate that the mixed ligand complexes were designed in a 1:1:1 M ratio. The electronic spectral data indicated that all the synthesized complexes have an octahedral structure. The disc diffusion assay was used to determine the disc inhibition zone (IZ, mm) and minimum inhibitory concentration (MIC, g/mL) of the investigated compounds against the growth of the pathogenic bacterial strains S. aureus, E. faecalis, P. aeruginosa, Klebsiella sp., and E. coli. The MTT test was used to determine the cytotoxicity of these reported compounds against the human hepatocellular liver cancer (HEPG-2) cell lines. The molecular docking study for the compounds against the EGFR tyrosine kinase receptor (PDB code: 1 M17) was conducted to examine the interactions in protein–ligand complexes. Furthermore, the biological activity of the ligand was investigated using quantitative structure–activity relationship studies (QSAR).     

Spectroscopic evaluation of Co(II), Ni(II) and Cu(II) complexes derived from thiosemicarbazone and semicarbazone

Co(II), Ni(II) and Cu(II) complexes were synthesized with thiosemicarbazone (L(1)) and semicarbazone (L(2)) derived from 2-acetyl furan. These complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO corresponds to non-electrolytic nature. All the complexes are of high-spin type. On the basis of different spectral studies six coordinated geometry may be assigned for all the complexes except Co(L)(2)(SO(4)) and Cu(L)(2)(SO(4)) [where L=L(1) and L(2)] which are of five coordinated square pyramidal geometry.     

Spectroscopic studies on Mn(II), Co(II), Ni(II), and Cu(II) complexes with N-donor tetradentate (N4) macrocyclic ligand derived from ethylcinnamate moiety

Manganese(II), cobalt(II), nickel(II), and copper(II) complexes are synthesized with a novel tetradentate ligand, viz. 1,5,9,13-tetraaza-6,14-dioxo-8,16-diphenylcyclohexadecane (L) and characterized by the elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, 1H NMR, IR, electronic, and EPR spectral studies. The molar conductance measurements of the complexes in DMSO correspond to be nonelectrolyte nature for Mn(II), Co(II), and Cu(II) whereas 1:2 electrolytes for Ni(II) complexes. Thus, these complexes may be formulated as [M(L)X(2)] and [Ni(L)]X(2), respectively (where M = Mn(II), Co(II), and Cu(II) and X = Cl- and NO(3-)). On the basis of IR, electronic, and EPR spectral studies an octahedral geometry has been assigned for Mn(II) and Co(II) complexes, square-planar for Ni(II) whereas tetragonal for Cu(II) complexes. The ligand and its complexes were also evaluated against the growth of bacteria and pathogenic fungi in vitro.     

Ni(II) and Cu(II) complexes of bidentate thiosemicarbazone ligand: Synthesis,structural, theoretical,biological studies and molecular modeling

The conventional condensation and refluxing process was employed to synthesize Ni(II) and Cu(II) complexes of Methylcarbamatethiosemicarbazone ligand. Reactions were carried out at the pH of 7. The molar ratio of the ligand and metal salt was 2:1. The structures of the synthesized metal complexes were suggested by different analytical techniques such as magnetic susceptibility, molar conductance, IR, EPR and UV spectroscopy. Experimental studies confirmed the octahedral geometry for all the complexes. The geometry of the ligand and complexes were also confirmed by theoretical studies. The complexes were investigated for biological action against pathogenic fungi (C. krusei, C. albican) and bacteria (S. aureus, E. coli). The antimicrobial results confirmed superior inhibition potential of the metal complexes as compared with the parent ligand. The enhanced antimicrobial activities might be due to the chelation. Molecular-docking assays confirmed the strong interaction of ligand with target antimicrobial protein DNA gyrase-B.     

Preparation,Characterization, Biological Activity and 3D Molecular Modeling of Mn(II), Co(II), Ni(II), Cu(II), Pd(II) and Ru(III) Complexes of Some Sulfadrug Schiff Bases

Mn(II), Co(II), Ni(II), Cu(II), Pd(II) and Ru(III) complexes of Schiff bases derived from the condensation of sulfaguanidine with 2,4‐dihydroxy benzaldehyde ( HL1 ), 2‐hydroxy‐1‐naphthaldehyde ( HL2 ) and salicylaldehyde ( HL3 ) have been synthesized. The structures of the prepared metal complexes were proposed based on elemental analysis, molar conductance, thermal analysis (TGA, DSC and DTG), magnetic susceptibility measurements and spectroscopic techniques (IR, UV‐Vis, and ESR). In all complexes, the ligand bonds to the metal ion through the azomethine nitrogen and α‐hydroxy oxygen atoms. The structures of Pd(II) complex 8 and Ru(III) complex 9 were found to be polynuclear. Two kinds of stereochemical geometries; distorted tetrahedral and distorted square pyramidal, have been realized for the Cu(II) complexes based on the results of UV‐Vis, magnetic susceptibility and ESR spectra whereas octahedral geometry was predicted for Co(II), Mn(II) and Ru(III) complexes. Ni(II) complexes were predicted to be square planar and tetrahedral and Pd(II) complexes were found to be square planar. The antimicrobial activity of the ligands and their metal complexes was also investigated against the gram‐positive bacteria Staphylococcus aures and Bacillus subtilis and gram‐negative bacteria, Escherichia coli and Pesudomonas aeruginosa, by using the agar dilution method. Chloramphenicol was used as standard compound. The obtained data revealed that the metal complexes are more or less, active than the parent ligand and standard. The X‐ray crystal structure of HL3 has been also reported.     

Synthesis,crystal structures and spectral characterization of Cu(II) and Mn(II) complexes of 4-hydroxy-3-methoxybenzaldehyde: antioxidant properties and molecular docking studies

[Cu(L)₂(H₂O)₂] (1) and [Mn(L)₂(H₂O)₂] (2) (HL = 4-hydroxy-3-methoxybenzaldehyde) were synthesized and characterized using elemental, spectral (FTIR, ESI-MS, UV–visible, fluorescence and EPR), thermal, cyclic voltammetric, powder, and single crystal X-ray crystallographic studies. Spectral and X-ray data ascertained the structural features, binding modes of ligand and distorted octahedral geometry around the metal ions. Cyclic voltammetric studies confirmed the formation of a quasi reversible redox couple in solution. Crystal structure analysis of 1 and 2 reveal the presence of non-covalent interactions, resulting in a 1-D polymeric chain. Antioxidant properties (using DPPH and hydrogen peroxide assay) and molecular docking studies (using 1BNA) are also examined. The binding free energies (calculated from docked models), ?270 (1) and ?295 kJ mol^?1 (2), suggest that the complexes reasonably bind to DNA, and the DNA-binding affinity of 2 is stronger than that of 1.     

Spectroscopic, thermal and biological studies of the coordination compounds of sulfasalazine drug: Mn(II), Hg(II), Cr(III), ZrO(II), VO(II) and Y(III) transition metal complexes

The complexations of sulfasalazine (H3Suz) with some of transition metals have been investigated. Three types of complexes, [Mn(HSuz)-2(H2O)4] x 2H2O, [M(HSuz)-2(H2O)2] x xH2O (M=Hg(II), ZrO(II) and VO(II), x=4, 8 and 6, respectively) and [M(HSuz)-2(Cl)(H2O)3] x xH2O (M=Cr(III) and Y(III), x=5 and 6, respectively) were obtained and characterized by physicochemical and spectroscopic methods. The IR spectra of the complexes suggest that the H3Suz behaves as a bidentate ligand. The thermal decomposition of the complexes as well as thermodynamic parameters (DeltaE*, DeltaH*, DeltaS* and DeltaG*) were estimated using Coats-Redfern and Horowitz-Metzger equations. In vitro antimicrobial activities of the H3Suz and the complexes were tested.     

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.     

Spectroscopic,electrochemical, theoretical characterization and biological evaluation of a ferrocenyl-substituted unsymmetric azine ligand and its Cu(II) complex

Ferrocenyl-substituted unsymmetrical azine and its Cu(II) complex were prepared. The redox active ferrocene-based azine was obtained by condensation of 1-[(E)-hydrazono]-5-bromo-2-hydroxybenzene with ferrocene carboxaldehyde. The ferrocenyl ligand and its Cu(II) complex were characterized by IR, UV–vis, NMR, X-ray, magnetic susceptibility, molar electrical conductivity measurements, and TG techniques. The redox behaviors of the ferrocene compounds were investigated by cyclic voltammetry. Structural parameters and spectroscopic properties of the ligand and the Cu(II) complex were calculated by employing density functional theory (DFT) and time-dependent DFT and compared with available experimental data. We found slightly stronger binding ability for Cu(II) complex than the free ligand. DNA binding abilities for ferrocenyl-substituted unsymmetrical azine ligand and its Cu(II) complex are higher than some reported ferrocene compounds. We also studied DNA cleavage, superoxide and DPPH radical scavenging abilities of the compounds. Furthermore, the synthesized organometallic compounds can be bound to DNA through an intercalative mode.     

Supramolecular assembly of hydrogen bonding,ESR studies and theoretical calculations of Cu(II) complexes

A series of copper(II) complexes were synthesized by the reaction of copper(II) chlorid with 1‐phenyl‐3methyl‐(3‐dervitives phenylhydrazo)‐5‐pyrazolone (HL_n) yields 1:1 and 1:2 (M:L) complexes depending on the reaction conditions. The elemental analysis, spectral (IR, ¹H NMR, UV‐Vis and ESR), conductance and magnetic measurements were used to characterize the isolated complexes. The IR spectral data indicate that the metal ions are coordinated through the oxygen of the keto and nitrogen of hydrazone groups. The UV‐Vis spectra, magnetic moments and ESR studies indicate square planar geometry for Cu(II) complexes ( 1–3 ) by NO monobasic bidentate and the two monobasic trans bidentate in octahedral geometry for Cu(II) complexes ( 4–6 ). It is found that the change of substituent affects the theoretical calculations of Cu(II) complexes. Molecular docking was used to predict the binding between the ligands (HL_n) and the receptors of prostate cancer mutant (2Q7K), breast cancer mutant (3HB5), crystal structure of E. coli (3T88) and crystal structure of S. aureus (3Q8U). The molecular and electronic structures of Cu(II) complexes and quantum chemical calculations were studied. According to intramolecular hydrogen bond leads to increasing of the complexes stability.     

Spectroscopic,morphology and electrical conductivity studies on Co(II), Ni(II), Cu(II) and Mn(II)-oxaloyldihydrazone complexes

Cobalt (II), nickel (II), copper (II) and manganese (II) complexes of dihydrazone derived from the condensation of oxaloyldihydrazide with 2-hydroxybenzaldehyde have been synthesized. The dihydrazone ligand/chelates were characterized on the basis of their elemental analyses, spectral (UV–Vis., FT-IR, mass, ¹H NMR), magnetism, thermal (TGA) measurements and structures of the compounds have been established. The surface morphology of the desired complexes was studied by SEM. The ligand is coordinated to the Ni(II), Co(II), Mn(II) and Cu(II) centers in bi, tetra, penta and hexadentate way giving mono-nuclear complexes except in case of manganese and copper the bi-nuclear complexes were formed. The nickel complex has tetrahedral geometry while the other complexes are suggested to have octahedral configurations. The prepared samples have been assayed for their electrical activities. The electrical activity (DC and AC conductivity) for ligand and its metal complexes has been examined at different frequencies (1, 10, 100 kHz) in the temperature ranges 303–573 and 300–625 K, respectively. The DC and AC conductivity are viewed as thermally activated process at higher temperatures and a marked increment was seen in case of Mn(II) complex. The dielectric permittivity was determined in the temperature area of 300–625 K and diminished with augmentation of frequency proposing a typical behavior of dielectrics.     

Synthesis,characterization, biological screening and molecular docking of Zn(II) and Cu(II) complexes of 3,5-dichlorosalicylaldehyde-N4-cyclohexylthiosemicarbazone

A 3,5-dichlorosalicylaldehyde-N⁴-cyclohexylthiosemicarbazone (C₁₄H₁₆Cl₂N₃OS) and its complexes [Zn(dsct)(phen)]·DMF ( 1 ), [Zn(dsct)(bipy)]·DMF ( 2 ), [Cu(dsct)(bipy)]·DMF ( 3 ) (phen = 1,10-phenathroline, bipy = 2,2’bipyridine) were synthesized and characterized by CHN analysis, FT-IR, UV–vis and NMR spectra. The molecular structure of the thiosemicarbazone (H₂dsct) and its complexes have been resolved using single crystal XRD studies. In the complexes, thiosemicarbazone exist in the thioiminolate form and acts as dideprotonated tridentate ligand coordinating through phenolic oxygen, thioiminolate sulfur and azomethine nitrogen. The antibacterial activity of the prepared compounds were screened against Escherichia coli, Salmonella typhi, Enterobacter aerogenes, Shigella dysentriae, Bacillus cereus, Staphylococcus aureus. All the complexes showed activity against bacterial strains E.coli and Salmonella typhi. The thiosemicarbazone showed activity against three bacterial strains such as E. coli, Enterobacter aerogenes and Shigella dysentriae. Complex 2 showed very good antibacterial activity as compared to standard drug (Ampicillin) against the bacterial strain, Salmonella typhi. Finally, the thiosemicarbazone and its complexes have been used to accomplish molecular docking studies against an Epidermal Growth Factor Receptor (EGFR) and breast cancer mutant 3hb5-oxidoreductase to determine the most preferred mode of interaction. The results confirm that the complex [Cu (dsct)(bipy)]·DMF( 3 ) showed the highest docking score as compared to other complexes under study. The [Cu(dsct)(bipy)]·DMF( 3 ) complex was evaluated for their anticancer activities against breast cancer cell line (MCF-7) and normal L929 (Mouse Fibroblast) cell line. It was found that the compound showed an LC₅₀ of 6.25 μg/mL against breast cancer cell line (MCF-7).     

Spectroscopic investigation,DFT, fluorescence,molecular docking and biological studies of divalent and trivalent binuclear complexes prepared from benzoyl thiosemicarbazide derivative of 2‐benzylmalonohydrazide

The binuclear Cr (III), Mn (II) and Fe (III) complexes of N,N′‐(2,2′‐(2‐benzylmalonyl)bis (hydrazine‐1‐carbonothioyl))dibenzamide (H₄BPCD), which derived from the combination of 2‐benzylmalonohydrazide suspension with benzoyl‐isothiocyanate, have been isolated and investigated by the necessary analytical and spectroscopic techniques. The IR studies show that H₄BPCD dispose as a mono‐negative hexadentate ligand (NOS)₂ towards Mn (II) ion and tetra‐negative hexadentate (NOS)₂ towards both Cr (III) and Fe (III) ions. The values of molar conductance in DMSO suggested the non‐electrolytic nature for all complexes. The magnetic measurements and the electronic transitions data confirmed the hexa‐coordinate geometry of complexes. The DFT geometry optimization of all compounds and IR comparative study of both theoretical and experimental of H₄BPCD were carried out. Moreover, the H₄BPCD and its Cr (III) complex displayed intra ligand (π → π*) fluorescence emission spectra which corroborate their photoactive nature. The coordinated and crystalline water molecules have been investigated by (TG/DTG) studies. The kinetic and thermodynamic parameters were computed using Horowitz‐ Metzger, Coats‐Redfern and Broido methods. Biological studies of DNA binding, minimum inhibitory concentration, in vitro determination of SOD‐like activity and MTT‐cytotoxicity assay as well as molecular docking studies were tested for the ligand and its complexes.     

Studies on some salicylaldehyde Schiff base derivatives and their complexes with Cr(III), Mn(II), Fe(III), Ni(II) and Cu(II)

The formation constants of some transition metal ions Cr(III), Mn(II), Fe(III), Ni(II) and Cu(II) binary complexes containing Schiff bases resulting from condensation of salicylaldehyde with aniline (I), 2-aminopyridine (II), 4-aminopyridine (III) and 2-aminopyrimidine (IV) were determined pH-metrically in ethanolic medium (80%, v/v). The formation constants were determined for all binary complexes. The important infrared (IR) spectral bands corresponding to the active groups in the four ligands and the solid complexes under investigation were studied. The solid complexes have been synthesized and studied by thermogravimetric analysis. The thermal dehydration and decomposition of these complexes were studied kinetically using the integral method applying the Coats-Redfern equation. It was found that the thermal decomposition of the complexes follow second order kinetics. The thermodynamic parameters of the decomposition are also reported. The electronic absorption spectra of the investigated ligands were carried out to determine the pK(a) values spectrophotometrically.     

Synthesis,structural studies and antituberculosis evaluation of new hydrazone derivatives of quinoline and their Zn(II) complexes

The quinoline hydrazone ligands were synthesized through multi-step reactions. The 2-hydroxy-3-formylquinoline derivatives (1a–1c) were prepared from acetanilide derivatives as starting materials using Vilsmeier–Haack reaction. Then the condensation of 2-hydroxy-3-formylquinoline derivatives with hydrazide derivatives (2a–2c) yielded quinoline hydrazone ligands (3a–3i). The synthesis of a new series of Zn(II) complexes carried out by refluxing with these quinoline hydrazone ligands (3a–3i) is reported. The molecular structures of the ligands (3a–3i) and the Zn complexes were characterized by elemental analysis and spectral studies like FT-IR, ¹H and ¹³C NMR, MS, UV–Visible and fluorescence. The preliminary results of antituberculosis study showed that most of the Zn(II) complexes 4a–4i demonstrated very good antituberculosis activity while the ligands 3a–3i showed moderate activity. Among the tested compounds 4e and 4g were found to be most active with minimum inhibitory concentration (MIC) of 8.00 μM and 7.42 μM respectively against Mycobacterium tuberculosis (H37 RV strain) ATCC No-27294 which is comparable to “first and second line” drugs used to treat tuberculosis.     

Synthesis of Co(II), Cu(II), Hg(II), UO2(II) and Pb(II) binuclear nanometric complexes from multi‐donor ligand: Spectral,modeling, quantitative structure–activity relationship,docking and antitumor studies

New synthesis of Co(II), Cu(II), Hg(II), UO₂(II) and Pb(II) binuclear nanometric complexes derived from multi‐donor ligand is reported. Structural and molecular formulae of all isolated complexes were established. Bi‐negative hexa‐dentate mode of ligand was proposed for the two central atoms in all complexes. Infrared, UV–visible, magnetic moments, electron paramagnetic resonance, thermogravimetric analysis and elemental analysis were used to build all structural formulae. X‐ray diffraction and scanning electron microscopy were used to determine the morphological features of the compounds and to compute particle sizes. Theoretical computations were implemented to support the proposed formulae. Kinetic study was executed over suitable stages to clarify the comparative stabilities. The DFT/B3LYP method, using the Gaussian 09 program, was utilized for optimizing the distribution of atoms over all compounds except the UO₂²⁺ complex. This exclusion refers to an inability to find a suitable method. Significant parameters were estimated using frontier energies (highest occupied and lowest unoccupied molecular orbitals) and data log file. A quantitative structure–activity relationship study applying HyperChem was executed for the organic compound tautomer forms to give a significant view about their biological character. AutoDock tools 4.2 were used to investigate the biological trend of organic compounds (keto and enol) against three types of proteins. The types were chosen related to in vitro investigation: breast, prostate and liver carcinoma proteins. IC₅₀ values indicated insignificant inhibition activity towards all carcinoma cell lines under investigation, except for the Hg(II) complex which displayed distinct activity against breast carcinoma compared with reference drug (doxorubicin).