Olusegun Ayobami Odunola

Synthesis and Characterization of Nickel(II) Complexes of Benzoic Acid and Methyl Substituted Benzoic Acid Hydrazides and X‐Ray Structure of Ni[C6H5CONHNH2]3Cl2·3CH3OH

Nickel(II) complexes of benzoic acid hydrazides (BAH) and o, m, and p‐substituted methylbenzoic acid hydrazides (MBAH) have been prepared and characterized by elemental analysis, room temperature magnetic susceptibility measurements, infrared and electronic reflectance spectral studies. The biological activities of the compounds and x‐ray structure of Ni[C6H5CONHNH2]3Cl2·3CH3OH are also reported. The microanalyses showed that the hydrazides reacted with the nickel(II) salts in 1:3 (metal:ligand) molar ratio. The hydrazide ligand behaves as a neutral bidentate chelating ligand with coordination involving the carbonyl oxygen and the amino nitrogen of the hydrazide moiety. The effective magnetic moments (μeff), infrared and electronic spectra of the compounds are consistent with a six‐coordinate pseudo‐octahedral arrangement of the ligands around the nickel ion. The x‐ray diffraction analysis of Ni[C6H5CONHNH2]3Cl2·3CH3OH showed that it crystallizes as a triclinic system with a P‐1 space group, a=10.2289(5), b=12.0707(6), c=14.0477(7) Å, α=67.5540(10)°, β=69.2360(10)°, γ=73.7860(10)°. The nickel ion is coordinated by three units of benzoic acid hydrazide with the chloride ions and the methanol solvates uncoordinated in the crystal lattice. The compounds show some measurable activity against selected bacteria and fungi.

SYNTHESIS AND STRUCTURAL FEATURES OF COPPER(II) COMPLEXES OF BENZOIC ACID AND METHYL SUBSTITUTED BENZOIC ACID HYDRAZIDES AND X-RAY STRUCTURE OF Cu[C6H5CONHNH2]2(NO3)2

ABSTRACT The synthesis, spectroscopic, magnetic and biological activities of copper(II) complexes of benzoic acid hydrazides (BAH) and o, m, and p-substituted methylbenzoic acid hydrazides (MBAH) and the single crystal X-ray structure for bis(benzoic acid hydrazide)copper(II) nitrate {Cu[BAH]2-(NO3)2} (BAH=Benzoic acid hydrazide) are reported. The composition of the ligands was established by elemental analyses, 1H NMR, and GC-MS. Magnetic susceptibility, electronic and infrared spectral data are consistent with a mononuclear square-planar geometry with bidentate coordination of the hydrazide ligands to give essentially a CuN2 2 chromophore. Cu[BAH]2(NO3)2 crystallizes from methanol solution under ambient temperature in a monoclinic system with a P21/c space system. The copper atom has a nearly regular, four-coordinated, square-planar arrangement with the nitrate anions being uncoordinated in the crystal lattice. The compounds did not show significant activity against selected bacteria and fungi.

Spectroscopic and Magnetic Properties of Zn(II), Cd(II) and Hg(II) Carboxylates

Abstract Complexes of 3,5-dimethylbenzoic (3,5-DMB), 3,5-dinitro-benzoic (3,5-DNB) and 2,4,6-trimethylbenzoic (2,4,6-TMB) acids with Zn(II), Cd(II), and Hg(II) ions have been synthesized and characterized by elemental analysis, infrared, conductance and magnetic susceptibility measurements. Most of the complexes show a 1:2 metal to ligand stoichiometry. The infrared spectra suggest that the carboxylate ions are coordinated to the central metal atom in a bidentate or bridging fashion except in Hg(2,4,6-TMB)2 where there is some evidence of unidentate coordination. The conductance measurements show that the compounds are non-electrolytes. The magnetic susceptibility data of the complexes are presented.

Synthesis, Characterization, and Crystal Structures of [Cu(phen)2Cl]Cl. 6.5H2O and [Cu(phen)2Br]Br

Two mixed-ligand complexes of copper(II) with 1,10-phenanthroline and halides [Cu(phen)2Cl]Cl.6.5H2O (1) and [Cu(phen)2 Br]Br (2), have been synthesized and characterized by microanalysis, spectroscopic, magnetic and single-crystal X-ray diffraction studies. The two complexes are isostructural in which the coordination geometry about the copper(II) ion is that of a trigonal bipyramid, with the central copper atom bound to one chloride (I) and one bromide (2) atom and four nitrogen atoms of the two phenanthroline ligands. The result of IR, electronic spectra, electron spin resonance (ESR) and magnetic measurements are discussed.

Synthesis, Characterization, and Structural Studies of Nickel(II) Complexes of Some New Substituted Acid Hydrazides

The syntheses, spectroscopic, magnetic, and antimicrobial and theoretical studies of a new series of hydrazides; RCOCH 2 CONHNH 2 (R = CH 3 , C 3 H 7 , C 6 H 5 ) variously described as acetoacetic (AAAH), butyrylacetic (BUTAH) and benzoylacetic (BENZAH) acid hydrazides and its nickel(II) complexes are reported. Microanalyses, room temperature magnetic susceptibility measurements infrared and electronic reflectance spectra are consistent with a distorted six coordinate octahedral geometry for the complexes. The modeled compounds using semi-empirical method PM3 and density functional theory (DFT) shows a good correlation of crystallographic data. The compounds show appreciable activity against gram +ve and gram-ve bacteria.

Tailoring of energy levels in (2Z)-2-cyano-2-[2-[(E)-2-[2-[(E)-2-(p-tolyl)vinyl]thieno[3,2-b]thiophen-5-yl]vinyl]pyran-4-ylidene]acetic acid derivatives via conjugate bridge and fluorination of acceptor units for effective D–π–A dye-sensitized solar cells: DFT–TDDFT approach

Density functional theory (DFT) was employed to investigate the role of fused thiophene and bridged thiophene π-linkers as well as acceptor unit fluorination in modifying the properties of dye sensitizers for dye-sensitized solar cells (DSSCs). A series of novel (2Z)-2-cyano-2-[2-[(E)-2-[2-[(E)-2-(p-tolyl)vinyl]thieno[3,2-b]thiophen-5-yl]vinyl]pyran-4-ylidene]acetic acid derivatives were simulated using DFT and time-dependent density functional theory to calculate their electronic and optical properties, population analysis, global reactivity index and light harvesting efficiency. The results showed that dyes with bridged thiophene π-linker have narrower energy bandgap (Eg) and longer absorption wavelength (λmax) than those with fused thiophene π-linker. Also, fluorination of the acceptor unit of the dyes enhanced the electron accepting ability of 2-cyano-2-pyran-4-ylidene-acetic acid by lowering the lowest unoccupied molecular orbital (LUMO) energy, which leads to lower Eg, lower chemical hardness (η), and longer wavelength. Therefore, incorporation of fluorine atoms at the acceptor unit makes the conduction-band potential more favorable, leading to effective charge separation and charge transfer between donor and acceptor.

Synthesis, Characterization, and Quantum Chemical Studies of Ru(phen)2Cl2.2H2O and Ru(bipy)2Cl2.2H2O With 2,6-Diacetylpyridinedihydrazone

The mixed-ligand complexes of Ru(phen)2Cl2.2H2O and Ru(bipy)2Cl2.2H2O with 2,6-diacetylpyridinedihydrazone were prepared and characterized using elemental analyses and spectroscopic techniques. Semi-empirical (PM3) and ab initio (HF/3-21G*) methods were used for the calculations of geometries, heat of formation, binding and stabilization energies. The elemental analyses were satisfactory when compared with the calculated values. The infrared and UV-Vis spectra as well as the fragmentation patterns in the mass spectra were consistent with octahedral Ru(II) complex. The conductivity measurements confirmed the 1:2 electrolyte nature of the complexes. The theoretical studies revealed higher stabilization and binding energies for the [Ru(phen)2L]2+ species which indicated that it is thermodynamically more stable.

Synthesis and Characterization of Mn(II), Co(II) and Ni(II) Cyanobenzoates

Abstract Mn(II), Co(II), and Ni(II) complexes of 2-, 3-, and 4-cyanobenzoates have been synthesized and characterized by analytical, conductivity, magnetic susceptibility measurements, infrared and electronic reflectance spectral studies. The analytical data show a stoichiometry of the complexes to be MY2 and the infrared spectra suggest bridging bidentate coordination of the carboxylate to the metal ions. The complexes were non-electrolytes. Octahedral coordination around the metal ions in most of the complexes is proposed.