Monobasic Bidentate Ligand Research Articles

Synthesis and Characterization of Coordination Behavior of Diclofenac Sodium Drug Toward Hg(II), Pb(II), and Sn(II) Metal Ions: Chelation Effect on Their Thermal Stability and Biological Activity

Diclofenac sodium compound has great biological, medical, industrial, and coordination applications. Most of its metal complexes have antibacterial and antifungal effects. A general survey of previous literature concerning the interaction of transition metals with diclofenac compound was given. From this survey, it is appeared that deep chemical studies were needed to through lighter on the complexing ability and chemical properties, due to presence of active groups such as amino, hydroxyl, carbonyl, and carboxyl groups. Therefore the present work was aimed mainly to study the spectroscopic, stability, and related thermodynamic parameters, structural, thermal, molar conductivity, and biological properties of the diclofenac sodium with selected metal ions such as Hg(II), Pb(II), and Sn(II). The used of theoretical concepts and experimental techniques were discussed. Solid complexes have been prepared and characterized by IR, UV-Vis, elemental analysis CHN, and 1H-NMR. Diclofenac reacts with Hg(II), Pb(II), and Sn(II) by molar ratio (2:1) (diclofenac:metal ion). IR, UV-Vis, spectra indicate that diclofenac behaves as a monobasic bidentate ligand coordinated to the metal ions via the deprotonated carboxylate O and carbonyl groups. The Hg(II), Pb(II), and Sn(II) complexes of diclofenac are found to have high activity against bacteria, especially Bacillus subtilis, and fungi, especially Aspergillus niger, whereas the Pb(II) complex is more active than the Sn(II) and Hg(II) complexes.

Supramolecular spectral studies on metal–ligand bonding of novel quinoline azodyes

A series of novel bidentate azodye quinoline ligands were synthesized with various p-aromatic amines like p-(OCH3, CH3, H, Cl and NO2). All ligands and their complexes have been characterized on the basis of elemental analysis, IR, 1H and 13C NMR data and spectroscopic studies. IR and 1H NMR studies reveal that the ligands (HLn) exists in the tautomeric azo/hydrazo form in both states with intramolecular hydrogen bonding. The ligands obtained contain NN and phenolic functional groups in different positions with respect to the quinoline group. IR spectra show that the azo compounds (HLn) act as monobasic bidentate ligand by coordinating via the azodye (NN) and oxygen atom of the phenolic group. The ESR (g|| and g⊥) and bonding α2 parameters of the copper ion were greatly affected by substituting several groups position of ring of quinoline and p-aromatic ring. The ESR spectra of copper complexes in powder form show a broad signal with values in order g||>g⊥>ge>2.0023. The value of covalency factor β and orbital reduction factor K accounts for the covalent nature of the complexes. All complexes possessed an octahedral and square planar geometry. The thermal properties of the complexes were investigated using TGA and DSC. It is found that the change of substituent affects the thermal properties of complexes.

HIGHER-COORDINATE COMPLEXES OF SILICON(IV) WITH N-SALICYLIDENE-2-AMINOPYRIDINE: SYNTHESIS, CHARACTERIZATION, REACTIVITY, AND ANTIBACTERIAL STUDIES

A series of novel higher-coordinate complexes of silicon(IV) X3Si{O-C6H4–2-[CH = N(C5H4N)]}(1–6) with coordination spheres consisting of substituents X = (OEt, Ph, Cl, and NCS) and bidentate Schiff base ligand HO-C6H4–2-[CH = N(C5H4N)] derived from 2-aminopyridine and salicyldehyde have been synthesized and characterized by elemental analyses, infrared spectroscopy, 1H, 13C NMR spectroscopy, and mass spectrometry. The spectral data showed that the Schiff base acted as a monobasic bidentate ligand via imine nitrogen and phenolic oxygen atoms. The thermal stability of complexes (1–6) was studied by thermogravimetric analysis. The antibacterial activities of compounds (1–6) were screened against both Gram-negative bacteria (Escherichia coli and Vibrio cholerae) and Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus). Graphical :

Synthesis and characterization of ligational behavior of curcumin drug towards some transition metal ions: Chelation effect on their thermal stability and biological activity

Complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with curcumin ligand as antitumor activity were synthesized and characterized by elemental analysis, conductometry, magnetic susceptibility, UV–Vis, IR, Raman, ESR, 1H-NMR spectroscopy, X-ray diffraction analysis of powdered samples and thermal analysis, and screened for antimicrobial activity. The IR spectral data suggested that the ligand behaves as a monobasic bidentate ligand towards the central metal ion with an oxygen’s donor atoms sequence of both OH and CO groups under keto–enol structure. From the microanalytical data, the stoichiometry of the complexes 1:2 (metal:ligand) was found. The ligand and their metal complexes were screened for antibacterial activity against Escherichia Coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa and fungicidal activity against Aspergillus flavus and Candida albicans.

Synthesis, spectral and thermal studies of some polymeric mixed ligand uracil–hydrazide complexes with transition metal ions

Polymeric mixed ligand complexes of the type [MCl(ur)(Bh)(H2O)] n and [M(ur)(Inh)(H2O)2] n , where, M = Co(II), Ni(II), Cu(II) and Zn(II), UR = uracil, Bh = benzoic acid hydrazide and Inh = isonicotinic acid hydrazide, have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, thermo grams (TGA) studies, electronic, IR and ESR spectral studies. The magnetic moments and electronic spectral studies indicate high spin 6-coordinate octahedral geometry for all the complexes. ESR spectral studies on copper(II) complexes in solid state show a tetragonal octahedral environment around the metal ion and as the ground state. IR studies suggest that uracil behaves as monobasic bidentate ligand bonding through N(1) and C(4)=O groups to different metal atoms forming a polymeric framework. The ligand Bh bonds to metal through –NH2 and >C=O groups while Inh through –NH2 and a deprotonated C–O− groups. TGA studies of some of the complexes show multi-step decomposition pattern of their organic frameworks.

Synthesis, spectral characterization and thermal studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with 2-amino benzoic acid- and 2-hydroxy benzoic acid thiophen-2-ylmethylene hydrazide

A series of metal complexes of Co(II), Ni(II), Cu(II) and Zn(II) with 2-amino benzoic acid thiophen-2-ylmethylene hydrazide (Habth) and 2-hydroxy benzoic acid thiophen-2-ylmethylene hydrazide (Hhbth) have been synthesized. The complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, electronic, IR, NMR, ESR spectra and thermal studies (TGA and DTA). Molecular structure of the Habth ligand was determined by single crystal X-ray diffraction technique. Habth acts as a monobasic bidentate ligand in all its complexes bonding through a deprotonated CO− and CN groups whereas, Hhbth acts as a monobasic bidentate in its Co(II) and Ni(II) complexes, bonding through a deprotonated CO− and CN groups and as monobasic tridentate in Cu(II) and Zn(II) complexes bonding through CO, CN and deprotonated (CO)− groups with the metal ion. Electronic spectra suggest a square planar geometry for Co(II), Ni(II) and Cu(II) complexes of Habth and Co(II) and Ni(II) complexes of Hhbth. However, the Cu(II) and Zn(II) complexes of Hhbth have octahedral geometry. The ESR spectra of Cu(II) complex of Hhbth in the solid state and in DMSO frozen solution show axial signals and suggest the presence of unpaired electron in dx2-y2 orbital of Cu(II). The Cu(II) complex of Habth in solid state shows isotropic signal, whereas, axial signal in DMSO frozen solution in the range of tetragonally distorted octahedral geometry due to interactions of DMSO molecules at axial positions. Thermal studies of some of the metal complexes show a multi-step decomposition pattern of bonded ligands in the complex.

Synthesis, spectroscopic characterization and biological activity of 2-(p-toluidino)-N′-(2-hydroxbenzylidene) acetohydrazide complexes

Ti(IV), VO(II), Ni(II), Co(II), Mn(II), Cu(II), Zn(II), Cd(II), Sn(II), ZrO(II), UO2(II) Fe(III), Ru(III), Ho(III) and Yb(III) complexes of 2-(p-toluidino)-N-(2-hydroxbenzylidene) acetohydrazide have been prepared and characterized on the basis of various spectroscopic techniques like electronic, EPR, FT-IR and 1 H NMR studies, elemental analysis, magnetic properties and thermo-gravimetric analysis, and also by the aid of molar conductivity measurements. It is found that the Schiff base behaves as a monobasic tridentate, monobasic bidentate or dibasic tridentate ligand bonding to the metal ions via the oxygen atom of carbonyl oxygen atom in the enolic or ketonic form, azomethine nitrogen atom and/or oxygen atom of deprotonated phenolic hydroxyl group with 1 : 1 or 1 : 2 metal to ligand stoichiometry. Octahedral geometries have been assigned for Ni(II), Co(II), Mn(II), Fe(III) and Ru(III) complexes, tetragonally distorted octahedral geometry has been suggested for Cu(II) complexes, while square pyramidal geometry has been proposed for VO(II) complexes. The compounds were subjected to antimicrobial activity screening using Well diffusion method. Complexes (2), (8), (9), (10), (11), (13), (15) and (16) exhibit inhibitory effect towards fungus (Aspergillus niger) more than the parent ligand. However complexes (6), (2), (11), (12), (9), (16), (13), (5), (18), (15), (19), (8) and (7) are noticeable for antibacterial activity at the same concentration.

Synthesis, structural and corrosion inhibition studies on cobalt(II), nickel(II), copper(II) and zinc(II) complexes with 2-acetylthiophene benzoylhydrazone

Cobalt(II), nickel(II), copper(II) and zinc(II) complexes with 2-acetylthiophene benzoylhydrazone have been synthesized and characterized by elemental analyses, magnetic susceptibility measurements, electronic, IR, NMR and ESR spectral techniques. The molecular structures of ligand and its copper(II) complex have been determined by single crystal X-ray diffraction technique. The Cu(II) complex possesses a CuN 2O 2 chromophore with a considerable delocalization of charge. The structure of the complex is stabilized by intermolecular π–π stacking and C–H⋯π interactions. Hatbh acts as a monobasic bidentate ligand in all the complexes bonding through a deprotonated C–O − and >C N groups. Electronic spectral studies indicate an octahedral geometry for the Ni(II) complex while square planar geometry for the Co(II) and Cu(II) complexes. ESR spectrum of the Cu(II) complex exhibits a square planar geometry in solid and in DMSO solution. The trend g || > g ⊥ > 2.0023 indicates the presence of an unpaired electron in the d x 2 - y 2 orbital of Cu(II). The electro-chemical study of Cu(II) complex reveals a metal based reversible redox behavior. The Ni(II) complex shows exothermic multi-step decomposition pattern of the bonded ligand. The ligand and its most of the metal complexes show appreciable corrosion inhibition properties for mild steel in 1 M HCl medium. [Co(atbh) 2] complex exhibited the greatest impact on corrosion inhibition among the other compounds.

Supramolecular structure and substituents effect on the spectral studies of dioxouranium(VI) azodyes complexes

Abstract The synthesis of several coordination azo compounds of dioxouranium(VI) heterochelates with bidentate azo compounds derived from 4-alkylphenylazo-5-sulfo-8-hydroxyquinoline (HL n ) ligands, are described. The ligands and structural composition of azo complexes were confirmed and characterized by various physico-chemical techniques. The bonding sites of the azo compounds are deduced from IR and 1 H NMR spectra and the ligands were found to bond to the UO 2 2 + ion in a bidentate fashion. The ligands obtained contain N N and phenolic functional groups in different positions with respect to the quinoline group. IR spectra show that the azo compounds (HL n ) acts as a monobasic bidentate ligand by coordinating via the azo nitrogen atom of azodye ( N N ) and oxygen atom of the phenolic group forming thereby a six-membered chelating ring and concomitant formation of an intramolecular hydrogen bond. The υ 3 frequency of UO 2 2 + has been shown to be an excellent molecular probe for studying the coordinating power of the ligands. The values of υ 3 of the prepared complexes containing UO 2 2 + were successfully used to calculate the force constant, F UO (1n 10 −8 N/A) and the bond length R UO (in A) of the U O bond. A strategy based upon both theoretical and experimental investigations has been adopted. The theoretical aspects are described in terms of the well-known theory of 5d-4f transitions. Wilson’s, matrix method, Badger’s formula, and Jones and El-Sonbati equations were used to calculate the U O bond distances from the values of the stretching and interaction force constants. The most probable correlation between U O force constant to U O bond distance were satisfactorily discussed in term of Badger’s rule and the equations suggested by Jones and El-Sonbati. The effect of Hamette’s constant is also discussed.

Synthesis, spectral and thermal studies of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complex dyes based on hydroxyquinoline moiety

A series of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of azo-compounds containing hydroxyl quinoline moiety have been synthesized and characterized by elemental analysis, molar conductance, magnetic moments, IR, electronic and ESR spectral studies. The results revealed the formation of 1:1 and 1:2 (L:M) com- plexes. The molar conductance data reveal that the chelates are nonelectrolyte. IR spectra indicate that the azodyes behave as monobasic bidentate or dibasic tetradentate ligands through phenolate or carboxy oxygen, azo N for 1:1 (L:M) complexes beside phenolate oxygen and quinoline N atoms for 1:2 (L:M) complexes. The thermal analyses (TG and DTA) as well as the solid electrical conductivity measurements are also studied. The molecular parameters of the ligands and their metal complexes have been calculated.

2-(Phenylamino)acetohydrazide로부터 유도된 Hydrzone 리간드와 그들의 착물의 합성, 특성 및 항균활성

VO(II), ZrO(II), Hf(IV), (II), Sn(II), V(V), Ru(III), Cd(II), Ho(III) and Yb(III) complexes of N'-(2-hydroxybenzyl)-2-(phenylamino)acetohydrazide (, 1) and N'-((3-hydroxy-naphthalen-2-yl)methylene)-2-(phenylamino)-acetohydrazide (, 13) have been synthesized and characterized by elemental analyses, NMR, IR, UV-Vis, conductance, thermal analyses (DTA and TG). The spectral data showed that the ligands behave as neutral bidentate, monobasic bidentate, monobasic tridentate or bibasic tridentate ligand bonded to the metal ions through the azomethine nitrogen atoms, phenolic hydroxyl group in protonated or deprotonated form and enolic or ketonic carbonyl group. The ligands and their metal complexes exhibit higher antifungal and antibacterial inhibitory effects than parent ligands and the solution of metal ions. Most of metal complexes exhibit higher antifungal activity than standard antifungal drug (amphotricene B). It is also clear that the ligands and their metal complexes have higher antifungal activity than antibacterial activity.

Polymer complexes. LIII. Supramolecular coordination modes and structural of novel sulphadrug complexes

Novel polymer complexes of copper(II), palladium(II), platinum(II) and cadmium(II) containing homopolymer [4-acrylamido benzene sulphonyl guanidine; (HL)] and various anions (SO 4 2−, CH 3COO −, NO 3 −, Br − or Cl −) have been designed and carried out. Their structures were investigated by elemental analyses, spectral (IR, UV–vis, 1H NMR and ESR) and magnetic moments. The modes of interactions between the ligand and the metals were discussed, where oxygen (of O S O group) and nitrogen atom [of imino nitrogen (NH/N) of the guanidine group] are involved in chelation. The homopolymer shows two types of coordination behaviour. In mononuclear polymer complexes 4 and 6– 10, it acts as a neutral bidentate ligand chelated through the NH and O atoms, whereas in the polymer complexes 1– 3, 5 and 11, monobasic bidentate ligand is coordinated through the –N and –O atoms. The poly-chelates are of 1:1/1:2 (metal–homopolymer) stoichiometry and exhibit four coordination. On the basis of electronic spectral data and magnetic susceptibility measurement square planar geometry has been proposed. The ESR spectral data provided information about their structure on the basis Hamiltonian parameters and degree of covalency. From the electron paramagnetic resonance and spectral data, the orbital reduction factors were calculated.

Synthesis, characterization, catalytic and antimicrobial activities of RuII complexes of Schiff bases derived from 2-substituted benzoicacid (2-oxo-1 ,2-dihydro-indol-3-ylidene) hydrazides

A new ruthenium(II) Schiff base complexes of the type [RuX(CO)(EPh 3 )(B)(L)] (where X = H or CI; B = EPh 3, py; E = P/As; L = monobasic bidentate ligand) have been synthesized. All the complexes were characterized by physicochemical and spectroscopic methods. An octahedral geometry has been proposed for all the complexes. The new complexes have been tested to find out their catalytic activity for the oxidation of alcohols to corresponding carbonyl compounds. Further the ligands and complexes were subjected to antimicrobial activity studies.

Synthesis, Spectroscopic Characterization, and In Vitro Antimicrobial Potency of Sulfur-Bonded Complexes of Boron(III)

The present article describes the synthesis and characterization of tetracoordinated boron (III) complexes with monobasic bidentate ligands (L 1 H, L 2 H, L 3 H, L 4 H, L 5 H, and L 6 H) having the general formulae PhB(L)(OH) and PhB(L) 2 . The 1:1 and 1:2 reactions of phenyl boronic acid with monobasic bidentate ligands resulted in the formation of colored solids. The complexes have been characterized by elemental analysis, molecular weight determinations, and IR and NMR ( 1 H, 13 C and 11 B) spectroscopy, as well as UV-vis spectral studies. Based on these studies, a tetrahedral geometry has been proposed for the resulting complexes. The ligands, along with their complexes, have been screened in vitro against a number of pathogenic fungal and bacterial strains. The studies indicate that the boron chelates are more potent than the parent ligands.

Synthesis, spectroscopic investigations, and biological activity of metal complexes of N-benzoylthiosemicarbazide

N-Benzoylthiosemicarbazide, HL, was obtained by fusion of benzoylhydrazide and ammonium thiocyanate. Reactions of HL with cobalt(II), nickel(II), copper(II), zinc(II), iron(III), cadmium(II), oxovanadium(IV), and dioxouranium(VI) in 1 : 1 molar ratio yield the corresponding complexes. The N-benzoylthiosemicarbazide may act as a neutral or monobasic bidentate ligand coordinated through NS or NO sites. The structures of the HL ligand and its complexes were identified by elemental analysis, infrared, electronic, mass, 1H-NMR, and ESR spectra as well as magnetic susceptibility and molar conductivity measurements. Different geometries were obtained for the metal complexes. The ligand and its metal complexes were investigated for antibacterial and antifungal properties. Two Gram-positive bacteria, Staphylococcus aureus and Streptococcus pyogenes, two Gram-negative, bacteria, Pseudomonas fluorescens and Pseudomonas phaseolicola and two fungi, Fusarium oxysporum and Aspergillus fumigatus, were used in this study. The metal complexes were more effective than the free ligand.

Synthesis, spectral, electrochemical and catalytic properties of Cu(II), Ni(II) and Co(II) complexes containing N, O donors

Metal(II) chelates of Schiff bases derived from the condensation of multi-substituted aniline with mono- and di-substituted salicylaldehyde have been prepared and characterized by 1H NMR, IR, electronic, EPR, magnetic and cyclic voltammetry measurements. The complexes are of the type M(X-DPMP) 2 [(M = Cu(II), Ni(II) or Co(II)), DPMP = 2-[(2,6-diisopropylphenylimino)methyl]phenol, X = Br, Cl, I, BrCl]. The Schiff bases behave as monobasic bidentate ligand in their complexes. The spectral data indicate that the ligand coordinates through the phenolic oxygen and the azomethine nitrogen atoms. The observed A || values in the Cu(II) complexes indicate a tetrahedrally distorted square planar structure. The cyclic voltammetric redox potential of copper(II) and nickel(II) complexes suggest the existence of irreversible pairs in acetonitrile. Cu(Br-DPMP) 2 was found to be an efficient catalyst for cyanosilylation of aldehydes under mild conditions.

1-naphthylazo derivatives of some 1,3-dicarbonyl compounds and their Cu (II), Ni(II) and Zn(II) complexes

The coupling of diazotized 1-aminonaphthalene with 1,3-dicarbonyl compounds (acetylacetone, methylacetoacetate and acetoacetanilide) yielded a new series of bidentate ligand systems (HL). Analytical, IR, 1H-NMR and mass spectral data indicate that the compounds exist in the intramolecularly hydrogen bonded keto-hydrazone form. With Ni(II), Cu(II) and Zn(II), these potential monobasic bidentate ligands formed [ML2] type complexes. The IR, 1H- -NMR and mass spectral data of the complexes are consistent with the replacement of the chelated hydrazone proton of the ligand by a metal ion, thus leading to a stable six-membered chelate ring involving the hydrazone nitrogen and the hydrogen bonded carbonyl oxygen. The Ni(II) and Zn(II) chelates are diamagnetic, while the Cu(II) complexes are paramagnetic. In the metal complexes of the naphthylazo derivatives of acetylacetone and methylacetoacetate, the acetyl carbonyl is involved in coordination, whereas in the chelates of the naphthylazo derivative of acetoacetanilide, the anilide carbonyl is bonded with the metal ion.

Studies on some lanthanide(III) complexes with 4-hydroxyantipyrine

Seven new lanthanide(III) complexes with 4-hydroxyantipyrine were synthesized. These complexes were characterized by elemental analysis, molar conductance, magnetic moment measurements, FT-IR, electronic and 1HNMR spectra, X-ray powder diffraction, and thermogravimetric studies. The ligand, 4-hydroxyantipyrine (hap), contained carbonyl oxygen and hydroxyl oxygen as potential donor sites. On coordination, deprotonation occurred and as a result, hap acted as a monobasic bidentate ligand. A coordination number 6 was assigned to the lanthanide(III) ions in these complexes with orthorhombic structure. All the complexes were thermally stable ∼150 °C and underwent decomposition in three stages with the formation of Ln 2O 3 as the final residues.

Synthesis, Characterization and Biological Activities of Cu(II), Co(II), Ni(II), Mn(II) and Fe(III) Complexes with Schiff Base Derived from 3‐(4‐Chlorophenoxymethyl)‐4‐amino‐5‐mercapto‐1,2,4‐triazole

Coordination complexes of Cu(II),Co(II), Ni(II), Mn(II) and Fe(III)with Schiff bases derived from 3‐(4‐chlorophenoxymethyl)‐4‐amino‐5‐mercapto‐1, 2, 4‐triazole and substituted aldehydes have been synthesized. The complexes were characterized by elemental analysis, conductivity measurements, magnetic susceptibility data, electronic, IR, ESR and 1H NMR spectral data. On the basis spectroscopic studies, the Schiff base is monobasic bidentate ligand having the composition ML2(2H2O) Where M = Cu(II), Co(II), Ni(II) ,Mn(II), ML2(H2O)Cl Where M = Fe(III). Various physicochemical data suggest a six coordinated octahedral geometry for Cu(II),Co(II), Ni(II), Mn(II) and Fe(III) complexes. The antibacterial activities of ligand and its complexes were screened by cup plate method.

Role of a Novel Mixed-Valence-Ligand on the Structures of Supramolecular Polymeric Complexes

The design of supramolecular polymer complexes of ruthenium, rhodium and uranium based on the homopolymer N-acryloyl-1-ethyl-2-thiourea (AETH) has been pursued. AETH shows three types of coordination behaviour. It acts as a neutral bidentate ligand coordinating through its thiocarbonyl sulphur and carbonyl oxygen atoms in both the mixed valence paramagnetic trinuclear polymer complexes ((1) and (2)) and mononuclear polymer complexes ((3)–(5)). On the other hand, it behaves as a monobasic bidentate ligand coordinating through CS and enolic (C–O) bonds in the mixed ligand poly-chelates (PAETH), which are obtained from the reaction of AETH with RuCl3 · x H2O in the presence of N-heterocyclic base consisting of polymer complexes ((7) and (8)). The mononuclear compound (6) acts as a monobasic and neutral bidentate ligand coordinating through CO and imino atoms. Monomeric distorted octahedral or trimeric chlorine-bridge pseudo-octahedral structures are proposed for these polymer complexes. The stoichiometries of the poly-chelates are 1:1, 1:2 and 3:2 (metal/homo-polymer) and exhibit six-coordinations. The amine homo-polymer exchange reactions of coordination poly-chelate in symmetrical and unsymmetrical bidentate homo-polymer complexes have been investigated and the ligand field parameters were also calculated. The homo-polymer and its polymer complexes have been characterized using a variety of physiochemical techniques.