Experimental studies on the UV-spectra of substituted pyridine N-oxides and their perchlorates in acetonitrile

Abstract

Simple and, if formed, semiperchlorates of substituted pyridine N-oxides have been synthesised and the spectra of N-oxides and salts have been recorded in acetonitrile solution. For basic enough N-oxides homoconjugated cations are observed spectrophotometrically while for the remaining ones such individuals have not been observed even for large concentrations of salts. In the spectra of substituted pyridine N-oxides and their proton complexes the same bands can be noted as for pyridine N-oxide and its complexes with proton. For N-oxides containing groups which can exert some mesomeric effect the characteristic N-oxide redox band observed for pyridine N-oxide at 275 nm is strongly red-shifted, owing to conjugation.