M.A. Kamel

Ab initio HF, DFT and experimental (FT-IR) investigation of vibrational spectroscopy of P-N,N-dimethylaminobenzylidenemalononitrile (DBM)

The optimized geometry and vibrational frequencies of P-N,N-dimethylaminobenzylidenemalononitrile (DBM) were obtained by ab initio HF and DFT/B3LYP levels with complete relaxation in the potential energy surface using 6-31++G(d,p) and 6-311++G(d,p) basis sets. The Fourier-transform infrared (FT-IR) spectrum of DBM has been recorded in the region 4000-400 cm(-1). The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR spectrum. The calculated frequencies are in good agreement with the experimental frequencies.

On the spectroscopic analyses of (E)-3-(dicyclopropyl methylene)-dihydro-4-[1-(2,5 dimethylfuran-3-yl) ethylidene]furan-2,5-dione

In this work, a combined experimental and theoretical study on molecular structure and vibrational frequencies of (E)-3-(dicyclopropyl methylene)-dihydro-4-[1-(2,5 dimethylfuran-3-yl) ethylidene] furan-2,5-dione [DCPF] were reported. The FT-IR spectra of DCPF isomers are recorded in the solid phase. The equilibrium geometries, harmonic vibrational frequencies, thermo-chemical parameters, total dipole moment and HOMO-LUMO energies are calculated by density functional theory DFT/B3LYP utilizing 6-311G(d,p) basis set. Results showed that scaled frequencies are in good agreement with experimental values. The HOMOs and the LUMOs energies of DCPF isomers were 3.8 and 2.7eV for E and C isomers,respectively.

FT-IR spectroscopic analyses of 3-Methyl-5-Pyrazolone (MP).

In the present work both experimental and computational FT-IR spectroscopic studies on 3-Methyl-5-Pyrazolone (MP) were reported. Experimental FT-IR spectrum for MP compound is recorded in powder form. Important physical parameters were reported such as structural parameters, vibrational frequencies, entropy, total energy, total dipole moment and HOMO-LUMO energy gap using DFT/B3LYP/6-311G(d,p) basis set. MP molecule has a total dipole moment of 2.83 Debye and HOMO-LUMO energy gap of 5.80 eV. Results indicate also that exposure to UV changes the spin from singlet to doublet state; one can conclude that MP compound may undergo anomalous Zeeman like effect.

Density functional theory (DFT) investigation of molecular structure and frontier molecular orbitals (FMOs) of P-N,N-dimethylaminobenzylidenemalononitrile (DBM)

P-N,N-dimethylaminobenzylidenemalononitrile (DBM) dye belongs to a class of organic compounds known as molecular rotors. Its optimized geometry and frontier molecular orbitals (FMOs), before and after ultraviolet (UV) irradiation, were obtained by DFT/B3LYP level with complete relaxation in the potential energy surface using 6-311++G(d,p) basis set. It is found that the length of C-C bonds of the DBM molecule increases after the UV irradiation, which leads to an increase in its dipole moment making it as a promising material for solar cell applications. Also, its HOMO-LUMO gap decreased from 3.46 to 3.34 eV. From the cyclic voltammetry measurements the value of HOMO-LUMO gap is equal to 3.21 eV. This means that B3LYP/6-311++G(d,p) level of theory is the best one for calculations.

On the spectroscopic analyses of thioindigo dye.

A combined experimental and theoretical study on molecular structure and vibrational frequencies of thioindigo was reported. The FT-IR spectrum of thioindigo is recorded in the solid phase. The equilibrium geometries, harmonic vibrational frequencies, thermo-chemical parameters, total dipole moment and HOMO-LUMO energies are calculated by density functional theory DFT/B3LYP utilizing 6-311G(d,p) basis set. Results showed that cis-isomer is highly recommended to be a promising structure for many applications in optoelectronic devices due to its high calculated dipole moment value (3.44 Debye) which indicates its high reactivity to interact with the surrounding molecules as compared to the trans-isomer which has no dipole moment. Both isomers have a similar HOMO-LUMO energy gap, of 3.02 eV (cis-isomer) and 2.78 eV (trans-isomer).

Spectroscopic analysis of 2-(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-ylimino)-2-(4-nitro-phenyl) acetonitrile

The optimized geometry and vibrational frequencies of 2-(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-ylimino)-2-(4-nitro-phenyl) acetonitrile (DOPNA) were obtained by ab initio DFT/B3LYP level with complete relaxation in the potential energy surface using 6-31G and 6-311G basis sets. The Fourier-transform infrared (FT-IR) spectrum of DOPNA has been recorded in the region 4000-400 cm(-1). The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR spectrum. The calculated frequencies are in comparable agreement with the experimental frequencies. The calculated energy span between the HOMO and the LUMO of DOPNA is 2.94 and 2.87eV by B3LYP/6-31G and B3LYP/6-311G, respectively.