Effect of Non-hydrogen Bonding Solvents on the Electronic Spectra of Aromatic N-Oxides

Abstract

The strong π-π* absorption bands of pyridine N-oxide, 4-nitropyridine N-oxide, acridine N-oxide and N-methylbenzaldoxime were measured in various solvents, and the frequency shifts induced by solvents were quantitatively analyzed by applying the McRae’s theory of the solvent effect. On the other hand, the fluorescence spectra of acridine N-oxide have also been recorded in various solvents, and the solvent effect has been discussed in connection with that of the absorption spectra. The results show that the π-electron transfer from the oxygen atom to the ring is much greater in the excited state than in the ground state.