Studies on the effect of solvents on the electronic absorption spectra of 4-phenylmorpholine and 1-phenylpyrrole

Abstract

The Ultraviolet-Visible (UV) spectra of 4-phenylmorpholine and 1-phenylpyrrole in different solvents have been studied. The molar absorptivities and oscillator strengths were determined. Also, quantum chemical calculations were carried out using time-dependent density functional theory with Beck-3-Lee-Yang-Parr exchange-correlation functional with a 6-31G* basis set (TDDFT/B3LYP/6- 31G*) for the optimized structures of the compounds. On the basis of this, the dipole moment, dihedral angle, oscillator strength, and singlet excited state of these compounds were determined in different solvents of different polarities. It was found that the bands are both n→Π* and Π→Π* transitions for the compounds. The value of the dipole moment and dihedral angles of the compounds increase with increasing polarities of solvents, and it could be predicted theoretically that 4- phenylmorpholine is more planar and reactive than 1-phenylpyrrole. There is a strong agreement between the experimental and theoretical results obtained for 4-phenylmorpholine, while there is a slight disagreement between the experimental and theoretical results in the number of transitions observed for 1-phenylpyrrole due to the collapsing of bands in the excited state in the experimental section.