Spectral studies on some pyrimidine derivatives

The electronic absorption spectra of 2-[2'-Thiopyrimidine]-5-nitro-pyridine [I], 1[2'-Thiopyrimidine]-2, 4-dinitrobenzene [II] 2-[2'-Thiopyrimidine]-1, 3, 5-trinitrobenzene [III] and 3-[[2'-Thiopyrimidine] methyl] benzoic acid [IV] were measured in a series of fifteen different solvents. The solvent effects induced spectral shifts in the different peak locations have been analyzed as a function of different solute-solvent interaction mechanisms. Ground state properties of optimum molecular geometries, singlet-singlet electronic transitions have been calculated using the AM1, PM3, ZINDO/S and ab initio/3-21G methods

Steric and mesomeric interaction factors on the electronic spectra of some nitrocresols

The electronic absorption spectra of some mono and di-substituted phenols OHC[6]H[3]XY, where X = NO[2] and Y= CH[3], in 90 percent aqueous ethanol and also in presence of 0.1 N NaOH or 0.1 N HC1 solutions were studied. The spectral behaviour in relation to the different interaction factors between the phenoxy group and the substituent were discussed

Molecular orbital calculations of the electronic structure and spectra of 4-substituted pyridines

HMO and PPP methods have been used to calculate different electronic properties for 4-substituted pyridines in their ground and excited states. Total energies, dipole moments, electronic densities and singlet-singlet excitation energies are reported. The results are compared with experimental values and previous theoretical investigations. The electronic spectra of pyridine and some of its derivative have been studied experimentally and theoretically using different MO methods with different degrees of sophistication ranging from the simple Hueckel method to ab initio calculations. The different Calculated pi electronic properties using the PPP method were found to be in reasonable agreement with the available experimental data. In this paper the results of HMO and PPP calculations of the electronic prosperities of 4-substituted pyridines in their ground and excited states are reported. We aim to study quantitatively the substituent effect on the electronic spectra and other calculated properties in this series of molecules