Taher S. Kassem

Synthesis, Electrochemical Behavior, Spectral, and Magnetic Studies of Copper(II) Complexes with Ferrocene-Containing Hydrazones

ABSTRACT A new series of copper(II) complexes of the stoichiometry [L2Cu]·nH2O and [(HL)2CuCl2]·2H2O, where HL is 1-acetyl-ferrocene-benzoylhydrazone, 1-acetylferrocene-4-chlorobenzoyl-hydrazone, 1-acetylferrocene-4-hydroxy-benzoylhydrazone or 1-acetylferrocene-4-methylbenzoylhydrazone, HL1, HL2, HL3 or HL4, respectively, were synthesized and characterized. IR data showed that all ligands act as monobasic or neutral bidentates coordinated to copper ion via the oxygen and azomethine N atoms. ESR spectra and magnetic data showed that [(L1)2Cu]·-H2O and [(L3)2Cu]·2H2O are polymeric exhibiting magnetic exchange interaction. ESR data also indicate that all complexes are associated with a d x 2−y 2 ground state. The electrochemical behavior of the free ligands and their copper(II) complexes were studied and are discussed.

Synthesis of two new silver(I) complexes with 3-bromoquinoline: Molecular structure, spectroscopic characterizations and DFT studies.

Two new Ag(+) complexes with 3-bromoquinoline (3BrQ) have been synthesized and characterized using elemental analysis, FTIR, NMR and mass spectra. The studied complexes have the formula [Ag(3BrQ)(OAC)]; 1 and [Ag(3BrQ)3(TCA)]; 2 where OAC and TCA are acetate and trichloroacetate, respectively. Based on the DFT calculations, 1 and 2 showed distorted trigonal planar and distorted tetrahedral coordination geometry. The electronic properties such as dipole moment (μ), polarizability (α0), HOMO and LUMO energies are calculated using the same level of theory. These electronic parameters were used to predict the nonlinear optical properties of the studied compounds. The studied silver complexes were predicted to be better nonlinear optical materials than urea. The electronic spectra of these complexes are calculated using the TD-DFT calculations. The infrared vibrational spectra were assigned based on the potential energy distribution (PED) analysis. The calculated (1)H NMR chemical shift values using GIAO approach showed good agreement with the experimental data. The intramolecular charge transfer interactions of the title molecules were studied by natural bond orbital (NBO) analysis.

Molecular structure and spectral properties of ethyl 3-quinolinecarboxylate (E3Q) and [Ag(E3Q)2(TCA)] complex (TCA=Trichloroacetate).

A new [Ag(E3Q)2(TCA)] complex; (E3Q=Ethyl 3-quinolinecarboxylate and TCA=Trichloroacetate) has been synthesized and characterized using elemental analysis, FTIR, NMR and mass spectroscopy. The molecular geometry and spectroscopic properties of the complex as well as the free ligand have been calculated using the hybrid B3LYP method. The calculations predicted a distorted tetrahedral arrangement around Ag(I) ion. The vibrational spectra of the studied compounds have been assigned using potential energy distribution (PED). TD-DFT method was used to predict the electronic absorption spectra. The most intense absorption band showed a bathochromic shift and lowering of intensity in case of the complex (233.7 nm, f=0.5604) compared to E3Q (λmax=228.0 nm, f=0.9072). The calculated (1)H NMR chemical shifts using GIAO method showed good correlations with the experimental data. The computed dipole moment, polarizability and HOMO-LUMO energy gap were used to predict the nonlinear optical (NLO) properties. It is found that Ag(I) enhances the NLO activity. The natural bond orbital (NBO) analyses were used to elucidate the intramolecular charge transfer interactions causing stabilization for the investigated systems.

How assembly matters to catalysis and thermal conductivity mediated by CuO nanoparticles

CuO nanostructures (NSs) of different morphologies were prepared, applied as catalysts for the pyrolysis of sugarcane bagasse (PSCB), and applied for thermally-conductive nanofluids. Both size and shape of the prepared NSs ranged from 5 to 1000 nm, and from nanodots (NDs) to spindle nano-aggregates (NAs), respectively. The catalytic activity of these NSs towards the PSCB was followed up by thermogravimetric analysis (TGA), where they increased the percentage of total weight loss, and lowered the decomposition temperatures of PSCB. The Coats-Redfern kinetic model showed a decline in activation energy by 57 and 9-43 kJ mol-1 for NDs and NAs, respectively. Colloidal dispersions of CuO NDs and NAs in monoethylene glycol (MEG) were prepared with volume fractions ([Formula: see text]) of 0.01-0.04%, where thermal conductivity improved with increasing [Formula: see text]. At all values of [Formula: see text], the best enhancements were exerted by NDs. The nature of assembly impacted the catalyzed PSCB and the thermal conductivity of MEG. This behavior depends to a large extent on the NAs that expose a different fraction of crystal facets of different reactivities and surface areas, not on the constituent nanorods (NRs).