Synthesis and spectroscopic studies of novel mononuclear complexes of cyclic and acyclic Schiff-base derivatives of tridentate and tetradentate coordination with some bivalent transition metal ions

Structural elucidation, theoretical investigation, biological screening and molecular docking studies of metal(II) complexes of NN donor ligand derived from 4-(2-aminopyridin-3-methylene)aminobenzoic acid

Complexes of 4-(((2-aminopyridin-3-yl)methylene)amino)benzoic acid ligand with cobalt(II) (1), nickel(II) (2), copper(II) (3), zinc(II) (4) and palladium(II) (5) are synthesized and characterized by using different spectroscopic methods like, UV-Visible, infrared, ¹H, ¹³C NMR, molar conductance, ESR and elemental analysis. Quantum chemical computations were made using DFT (density functional theory), B3LYP functional and 6-31+ +G(d,p)/SDD basis set in order to determine optimized structure parameters, frontier molecular orbital parameters and NLO properties. Based on DFT and experimental evidence, the complexes ensured that the octahedral geometry have been proposed for complexes 1, 2 and 4, square planar for complexes 3 and 5. All the complexes showed only residual molar conductance values and hence they were considered as non-electrolytes in DMF. In addition, the anti-proliferative activity of the compounds was evaluated against different human cancer cell lines (IMR-32, MCF-7, COLO205, A549, HeLa and HEK 293) and cisplatin is used as a reference drug. Compounds 1 and 4 showed remarkable cytotoxicity in five cancer cell lines tested except MCF-7. Also, the compounds were examined for their in vitro antimicrobial and scavenging activities. The molecular docking results are well corroborated with the experimental anticancer activity results.

Crystal structure of 3,3′-(butane-1,4-diylbis(azanylylidene))bis(1-phenylbut-1-en-1-olato)-κ4 N,N′,O,O′]copper(II), C24H26N2O2Cu

C24H26N2O2Cu, orthorhombic, C2221 (no. 20), a = 11.372(2) Å, b = 19.861(4) Å, c = 9.2904(19) Å, V = 2098.3(7) Å3, Z = 4, R gt(F) = 0.0201, wR ref(F 2) = 0.0580, T = 296(2)K.

Synthesis, spectroscopic studies and inhibitory activity against bacteria and fungi of acyclic and macrocyclic transition metal complexes containing a triamine coumarine Schiff base ligand

Two series of new mono and binuclear complexes with a Schiff base ligand derived from the condensation of 3-acetylcoumarine and diethylenetriamine, in the molar ratio 2:1 have been prepared. The ligand was characterized by elemental analysis, IR, UV-visible, (1)H-NMR and mass spectra. The reaction of the Schiff base ligand with cobalt(II), nickel(II), copper(II), zinc(II) and oxovanadium(IV) lead to mono or binuclear species of cyclic or macrocyclic complexes, depending on the mole ratio of metal to ligand and as well as on the method of preparation. The Schiff base ligand behaves as a cyclic bidentate, tetradendate or pentaentadentae ligand. The formation of macrocyclic complexes depends significantly on the dimension of the internal cavity, the rigidity of the macrocycles, the nature of its donor atoms and on the complexing properties of the anion involved in the coordination. Electronic spectra and magnetic moments of the complexes indicate that the geometries of the metal centers are either square pyramidal or octahedral for acyclic or macro-cyclic complexes. The structures are consistent with the IR, UV-visible, ESR, (1)H-NMR, mass spectra as well as conductivity and magnetic moment measurements. The Schiff base ligand and its metal complexes were tested against two pathogenic bacteria as Gram-positive and Gram-negative bacteria as well as one kind of fungi. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms.

Synthesis, spectral, crystal structure, thermal behavior, antimicrobial and DNA cleavage potential of two octahedral cadmium complexes: a supramolecular structure

Two new cadmium(II) complexes with the formula of CdL2(NCS)2 and CdL2(N3)2 (in which L is 2,2-dimethyl-N,N'-bis-(3-phenyl-allylidene)-propane-1,3-diamine) have been synthesized and characterized by elemental analysis, molar conductivity measurements, FT/IR, UV-Visible, (1)H and (13)C NMR spectra and X-ray studies. The crystal structure analysis of CdL2(NCS)2 indicated that it crystallizes in orthorhombic system with space group of Pbca. Two Schiff base ligands are bonded to cadmium(II) ion as N2-donor chelate. Coordination geometry around the cadmium ion was found to be partially distorted octahedron. The Cd-Nimine bond distances are found in the range of 2.363(2)-2.427(2)Å while the Cd-Nisothiocyanate bond distances are 2.287(2)Å and 2.310(2)Å. The existence of C-H⋯π and C-H⋯S interactions in the CdL2(NCS)2 crystal leads to a supramolecular structure in its network. Then cadmium complexes were screened in vitro for their antibacterial and antifungal activities against two Gram-negative and two Gram-positive bacteria and also against Candida albicans as a fungus. Moreover, the compounds were subjected for DNA-cleavage potential by gel electrophoresis method. Finally thermo-gravimetric analysis of the complexes was applied for thermal behavior studies and then some thermo-kinetics activation parameters were evaluated.

Synthesis, characterization and experimental, theoretical, electrochemical, antioxidant and antibacterial study of a new Schiff base and its complexes

A new Schiff base ligand was synthesized by reaction of salicylaldehyde with 1,6-bis(4-chloro-2-aminophenoxy)hexane. Then the Schiff base complexes were synthesized by metal salts and the Schiff base. The metal to ligand ratio of metal complexes was found to be 1:1. The Cu(II) complex is proposed to be square planar and the Co(II), Ni(II), Mn(II) and Zn(II) complexes are proposed to be tetrahedral geometry. The Ti(III) and V(III) complexes are proposed to be a capped octahedron in which a seventh ligand has been added to triangular face. The complexes are non-electrolytes as shown by their molar conductivities (ΛM). The structure of metal complexes is proposed from elemental analysis, FT-IR, UV-vis, magnetic susceptibility measurements, molar conductivity measurements, Mass Spectra and thermal gravimetric analysis. In addition antimicrobial and antioxidant studies, cyclic voltammetry of the complexes, theoretical 1H NMR and HOMO-LUMO energy calculations of the new di-functional ligand were done.

Synthesis and characterization of 1,2-bis(2-(5-bromo-2-hydroxybenzilidenamino)-4-chlorophenoxy)ethane and its metal complexes: an experimental, theoretical, electrochemical, antioxidant and antibacterial study

A new Schiff base ligand was synthesized by reaction of 5-bromosalicylaldehyde with 1,2-bis(4-chloro-2-aminophenoxy)ethane. Then the Schiff base complexes were synthesized by the reaction of metal salts and the novel Schiff base. The molar conductivity properties of the complexes were studied and found out that the complexes are nonelectrolytes. The structures of the ligand and its metal complexes were characterized by elemental analysis, FT-IR, UV-VIS, magnetic susceptibility measurements, molar conductivity measurements, and thermal gravimetric analysis. In addition antioxidant, theoretical NMR studies and cyclic voltammetry of the complexes were done. Two methods namely metal chelating activity and diphenylpicrylhydrazyl (DPPH) radical scavenging method were used to determine the antioxidant activity, and antibacterial properties of the compounds were also studied.

Synthesis and characterization of a series of transition metal complexes with a new symmetrical polyoxaaza macroacyclic Schiff base ligand: X-ray crystal structure of cobalt(II) and nickel(II) complexes and their antibacterial properties

A new symmetrical [N4O2] hexadentate Schiff base ligand, (E)-N-(pyridin-2-ylmethylene)-2-(3-(2-((E)-pyridin-2-lmethyleneamino)phenoxy)naphthalen-2-yloxy)benzenamine, abbreviated to L, and its complexes of Ni(II), Cu(II), Zn(II), Co(II), Cd(II) and Mn(II) have been synthesized in the presence of metal ions. The complexes were structurally characterized by elemental analyses, IR, UV-Vis, NMR and molar conductivity. The crystal structures of two complexes, [NiL(ONO2)2]·2H2O and [CoLCl2]CH3OH·0.5H2O, have been determined by a single crystal X-ray diffraction study. In these complexes, the ligand is coordinated in a neutral form via pyridine and azomethine nitrogen atoms. The metal ions complete their six coordination with two coordinated nitrate or chloride ions, forming a distorted octahedral geometry. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Enterococcus faecalis, Bacillus cereus and Staphylococcus epid and also against the three Gram-negative bacteria: Citrobacter freundii, Enterobacter aerogenes and Salmonella typhi. The activity data show that the complexes are more potent antibacterials than the parent Schiff base.

Tetra- and hexadentate Schiff base ligands and their Ni(II), Cu(II) and Zn(II) complexes. Synthesis, spectral, magnetic and thermal studies

Tetradentate N(2)O(2), N(4) Schiff bases, 1,2-bis(4-oxopent-2-ylideneamino) benzene (BOAB), 1-(4-oxopent-2-ylideneamino-2-[(2-hydroxyphenyl)ethylideneamino] benzene (OAHAB), 7,16-bis(4-chlorobenzylidene)-6,8,15,17-tetra-methyl-7,16-dihydro -5,9,14,18-tetraza-dibenzo[a,h] cyclo tetradecene (BCBDCT), 7,16-bis(2-hydroxy-benzylidene)-6,8,15,17-tetramethyl-7,16-dihydro-5,9,14,18-tetraza-dibenzo [a,h] cyclo tetradecene (BHBDCT) and hexadentate N(4)O(2) Schiff bases, 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(2-hydroxybenzylidene) pentane (BHAPHP), 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(4-chlorobenzylidene) pentane (BHAPCP) were prepared and characterized by elemental analysis, IR, UV-Vis, (1)H NMR and mass spectra. The solid complexes of the prepared Schiff base ligands with Ni(II), Cu(II) and Zn(II) ions were isolated and characterized by elemental and thermal analyses, IR, electronic and ESR spectra as well as conductance and magnetic susceptibility measurements. The results showed that most complexes have octahedral geometry but few can attain the tetrahedral arrangement. The TG analyses suggest high stability for most complexes followed by thermal decomposition in different steps. The kinetic and thermodynamic parameters for decomposition steps in Cu(II) complexes thermograms have been calculated.

Synthesis, spectroscopic and thermal studies of some IIB group complexes with a new N2-Schiff base ligand

Synthesis, spectroscopic and thermal studies of some complexes of a new N(2)-Schiff base ligand of N(1),N(2)-bis((E)-2-methyl-3-phenylallylidene)ethane-1,2-diamine (L) with a general formula of MLX(2) (M = Zn(II), Cd(II) and Hg(II); X = Cl(-), Br(-), I(-), SCN(-) and N(3)(-)) are described. The ligand and its complexes were characterized by elemental analysis, molar conductance, UV-vis spectra, FT-IR spectra, MS, (1)H NMR and (13)C NMR spectra. The conductivity measurement as well as spectral data indicated that the complexes are non-electrolyte. (1)H and (13)C NMR spectra have been studied in DMSO-d(6) and/or CDCl(3). The thermal behavior of the complexes shows weight loss by decomposition of the anions and ligand segments in the subsequent steps. Activation thermodynamic parameters of decomposition such as E*, ΔH*, ΔS* and ΔG* were calculated from TG curves.

Synthesis and thermal studies of tetraaza macrocylic ligand and its transition metal complexes. DNA binding affinity of copper complex

A Tetraaza Macrocylic Ligand (H2L) and its complexes, [Cd(H2L)(OH2)2](NO3)(2)·1/2OH2 (I), [Co(H2L)(OH2)](NO3)(2)·1/2OH2 (II), [Cu(H2L)(NO3)2]·3/2OH2 (III) and [Ni(H2L)(NO3)(OH2)]NO3·OH2 (IV), have been synthesized and characterized on the basis of elemental analysis, molar conductivity, 1H NMR, UV-vis, FT-IR and mass spectroscopy. All results confirm that the prepared compounds have 1:1 metal-to-ligand stoichiometry, octahedral configuration and the ligand behaves as a neutral tetradendate towards the metal ions. [CdL(OH2)2] (V), [CoL(OH2)2] (VI), [CuL(OH2)2] (VII) and [Ni(H2L)(NO3)2] (VIII) were synthesized pyrolytically in solid state from corresponding compounds (I-IV). Analytical results of complexes (V-VIII) show that the ligand behaves either as a neutral tetradendate or dianionic tetradentate ligand towards the metal ions. The binding of H2L and its copper complex (III) to DNA has been investigated by ultraviolet absorption spectroscopy. The experiments indicate that H2L and its copper complex (III) can bind to DNA through an intercalative mode. The H2L and its copper complex (III) exhibited anti-tumor activity against Ehrlich Acites Carcinoma (E.A.C) at the concentration of 100 μg/ml.

Synthesis and spectral characterization of 14- and 16-membered tetraazamacrocyclic Schiff base ligands and their transition metal complexes and a comparative study of interaction of calf thymus DNA with copper(II) complexes

14 and 16 membered Schiff base macrocyclic ligands, 7,14-dimethyl-5,12-di(N-amino)-2-methylphenyl-1,4,8,11-tetraaza-cyclotetradecane-4,7,11,14-tetraene (L(1)) and 8,16-dimethyl-6,14-di(N-amino)-2-methylphenyl-1,5,9,13-tetraaza-cyclohexadecane-5,8,13,16-tetraene (L(2)) were synthesized by condensation reaction between 2'-methyleacetoacetanilide and aliphatic diamines. The metal complexes of the types, [ML(1)](NO(3))(2) and [ML(2)(NO(3))(2)] [M = Co(II), Ni(II), Cu(II) and Zn(II)] were prepared by interaction of ligands, L(1) or L(2) with hydrated metal(II) nitrates. The ligands and their complexes were characterized by elemental analysis, IR, (1)H and (13)C NMR, EPR, UV-Vis spectroscopy, magnetic susceptibility, conductivity measurements and ESI-mass spectral studies. The results of elemental analyses, ESI-mass and conductivity measurements confirmed the stoichiometry of ligands and their complexes while the characteristic absorption bands and resonance peaks in IR and NMR spectra confirmed the formation of ligand frameworks around the metal ions. The square planar geometry for complexes derived from ligand L(1) and octahedral environment for complexes derived from ligand L(2) with distortion in Cu(II) complex have been confirmed on the basis of results of electronic and electron spin resonance spectral studies and magnetic moment measurements. Absorption and fluorescence spectral studies revealed different binding mode for complex, [CuL(1)](NO(3))(2) as compared with [CuL(2)(NO(3))(2)] on interaction with calf thymus DNA.

Synthesis and spectroscopic studies of some cadmium(II) and mercury(II) complexes of an asymmetrical bidentate Schiff base ligand

Synthesis and spectroscopic studies on four-coordinate complexes of cadmium(II) and mercury(II) halides with a new asymmetrical bidentate Schiff base ligand of N,N'-bis[alpha-methylcinamaldehydene]propane-1,2-diamine(L) are described. The ligand and its complexes were characterized by elemental analysis, molar conductance, UV-visible spectra, FT-IR spectra, MS, (1)H NMR and (13)C NMR spectra. The complexes are non-electrolytes in DMF. The electronic spectra of the complexes were recorded in DMF solution. (1)H and (13) C NMR spectra been studied in CDCl(3). The molar conductance as well as spectral properties indicated the complexes do not dissociate in DMF and retain their coordination. FT-IR and NMR spectra of the complexes exhibit downfield as well as upfield shifts of the free ligand resonances that show change in geometry during the coordination. The suggested structure of the complexes is pseudo-tetrahedral. Molecular structures of the complexes have been optimized by MM+ calculations that supported pseudo-tetrahedral geometry around the metal (II) ions.