Spectral, electrochemical and molecular orbital studies on solvatochromic mixed ligand copper(II) complexes of malonate and diamine derivatives

Reactivity and molecular modeling of new solvatochromic mixed-ligand copper(II) chelates of 2-acetylbutyrolactone and dinitrogen bases

A new series of solvatochromic mononuclear mixed ligand chelates with the general formula: Cu(AcBL)(L)X; where AcBL=2-acetylbutyrolactonate, L=N,N,N',N'-tetramethylethylenediamine (Me4en), N,N,N',N'-tetramethylpropylene diamine (Me4pn), 1,10-phenanthroline (Phen) or 2,2'-bipyridyl (Bipy) and X=ClO4-, NO3- or Br- have been synthesized and characterized by the analytical and spectral methods, as well as magnetic and molar conductance measurements. The d-d absorption bands of Me4en-chelates as Nujol mulls or weak donor solvents solutions revealed square-planar, distorted octahedral and/or distorted trigonal bipyramid geometries for the perchlorate, nitrate and bromide chelates, respectively. However, an octahedral structure is identified for chelates in strong donor solvents. Perchlorate chelates show a remarkable color change from violet to green as the Lewis basicity of the donor solvent increases, whereas bromide chelates are mainly affected by the Lewis acidity of solvent. Specific and non-specific interactions of solvent molecules with the chelates were investigated on the basis of unified solvation model. Structural parameters of the free ligands and their Cu(II)-chelates have been calculated on the basis of semiempirical PM3 level and correlated with the experimental data.

Structural, molecular orbital and optical characterizations of binuclear mixed ligand copper (II) complex of phthalate with N,N,N',N'-tetramethylethylenediamine and its applications

A new binuclear mixed ligand complex, [Cu2(Phth)(Me4en)2(H2O)2(NO3)2]·H2O (where, Phth=phthalate, and (Me4en)=N,N,N',N'tetramethylethylenediamine) was synthesized and characterized using analytical, spectral, magnetic, molar conductance, thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and transmission electron microscope (TEM) measurements. The XRD data of Cu(II)-complex was analyzed on the basis of Williamson-Hall (W-H) and compared with TEM results. The results indicate that the complex is well crystalline and correspond to hexagonal crystal structure. Analysis of the absorption coefficient near the absorption edge reveals that the optical band gaps are indirect allowed transition with values of 1.17 and 1.78 eV. The d-d absorption bands of the complex (dissolved in various solvents) exhibit a color changes (solvatochromic). Specific and non-specific interactions of solvent molecules with the complex were investigated using Multiple Linear Regression Analysis (MLRA). Transient photocurrent characteristics of Cu(II)-complex/n-Si heterojunctions indicate that photocurrent under illumination increase with increasing of light intensity and explained by continuous distribution of traps. Structural parameters of the free ligands and their Cu(II)-complex were calculated on the basis of semi-empirical PM3 level and compared with the experimental data. The present copper (II) complex was screened for its antimicrobial activity against some Gram-positive and Gram-negative bacteria and fungus strain.

Structural, molecular orbital and optical characterizations of solvatochromic mixed ligand copper(II) complex of 5,5-Dimethyl cyclohexanate 1,3-dione and N,N,N',N'N″-pentamethyldiethylenetriamine

In this work, a new solvatochromic mononuclear mixed ligand complex with the formula, Cu(DMCHD)(Me5dien)NO3 (where, DMCHD=5,5-Dimethyl cyclohexanate 1,3-dione and (Me5dien)=N,N,N',N'N″-pentamethyldiethylenetriamine was synthesized and characterized by analytical, spectral, magnetic, molar conductance, thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and transmission electron microscope (TEM) measurements. The formation constant-value for copper (II)-DMCHD was found to be much lower than the expected for similar β-diketones, revealing monobasic unidentate nature of this ligand. The d-d absorption bands of the prepared complex exhibit a color changes in various solvent (solvatochromic). Specific and non-specific interactions of solvent molecules with the complex were investigated using Multi Parametric Linear Regression Analysis (MLRA). Structural parameters of the free ligands and their Cu (II) - complex were calculated on the basis of semi-empirical PM3 level and compared with the experimental data. The crystallite size and morphology of Cu(DMCHD)(Me5dien)NO3 were examined using XRD analysis and TEM, revealing that the complex is well crystalline and correspond to the monoclinic crystal structure. The lattice strain and mean crystallite size were estimated by Williamson-Hall (W-H) plot using X-ray diffraction data. The main important absorption parameters such as extinction molar coefficient, oscillator strength and electric dipole strength of the principal optical transitions in the UV-Vis region were calculated. The analysis of absorption coefficient near the fundamental absorption edge reveals that the optical band gaps are direct allowed transitions with values of 2.78 eV and 3.59 eV. The present copper (II) complex was screened for its antimicrobial activity against Staphylococcus Aureus and Bacillus Subtilis as Gram-positive bacteria, Escherichia Coli and Salmonella Typhimurium as Gram-negative bacteria and Candida Albicans as fungus strain.

Synthesis, molecular modeling, thermal and spectral studies of metal complexes of hydrazone derived from 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione and thiosemicarbazide

Metal complexes with the general formula [ML(H2O)(CH3OH)x]·nH2O·(CH3OH)y(NO3)z [M=Cu(II), Ni(II), Co(II), VO(IV), Cr(III), Cd(II), Zn(II) or UO2(VI); x=0-2; y=0,1; z=0,1; n=0-2, 6 and L=hydrazone (H2L) derived from condensation of thiosemicarbazide with 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione. The synthesized ligand and its metal complexes have been characterized on the basis of elemental analyses, spectral and magnetic studies as well as thermal gravimetric analysis (TGA). The deprotonated ligand acts as a dibasic tridentate (ONS) via phenolate oxygen, azomethine (CN), and thiolate (C-S) groups. Copper(II) complex exhibits square planar geometry. Nickel(II), chromium(III) and dioxouranium(VI) complexes exhibit octahedral geometry. Cobalt(II), cadmium(II) and zinc(II) complexes showed tetrahedral geometry, whereas oxovanadium(IV) reveals square pyramidal geometry. Thermal analysis are investigated and showed either three or four thermal decomposition steps. Kinetic parameters (Ea, A, ΔH, ΔS and ΔG) of the thermal decomposition stages have been evaluated using Coats-Redfern equations. The molecular parameters of the ligand and its metal complexes have been calculated and correlated with the experimental data such as IR and TGA results.

Conversion of CO2into Cyclic Carbonates in the Presence of Metal Complexes as Catalysts

The sterically hindered salicylaldimine ligands N,N‘-(1,5-diaminonaphthalene)-3,5-but2-salicylaldimine (L1), N,N‘-(2,7-diaminofluaren)-3,5-but2-salicylaldimine (L2) and N,N‘-(1,8-diaminonaphthaline)-3,5-but2-salicylaldimine (L3) have been synthesised by the condensation of 1,5-diaminonaphthalene, 2,7-diaminofluarene, and 1,8-diaminonaphthaline with 3,5-di-tert-butylsalicylaldehyde, respectively. Dinuclear M(II) complexes of L1and L2and mononuclear M(II) complexes of L3have been prepared using Cu(II), Ni(II), Co(II), and Mn(II) salts and characterised. The synthesised sterically-hindered, salen-type complexes were tested as catalysts for the formation of cyclic carbonates from CO2and liquid epoxides (propylene oxide, epichlorohydrine, 1,2-epoxybutane and styrene oxide), which served as both reactant and solvent. Ligand structure and the type of metal centre have a marked influence on the catalytic activity. Mn(II) complexes showed the highest catalytic activity.

Spectroscopic, solvent influence and thermal studies of ternary copper(II) complexes of diester and dinitrogen base ligands

New mixed-ligand copper(II) complexes containing the bidentate dinitrogen ligands [N,N,N',N'-tetramethylethylenediamine (tmen), 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen)] and the bidentate dioxygen ligands [diethylmalonate (DEM), ethylacetoacetate (EAA) and ethylbenzoylacetate (EBA)] were prepared. The complexes were characterized by elemental analysis, infrared, mass and ESR spectral data, magnetic and molar conductance measurements and thermal gravimetric analysis. From the investigation, the geometries of the complexes are square planar for perchlorate complexes and a square pyramid or octahedral for the nitrate complexes. Solvatochromic behavior of the Cu(II) complexes indicates strong solvatochromism of their solutions in polar and non-polar solvents. The observed solvatochromism is due to the solute-solvent interaction between the chelate cation and the solvent molecules.