Fluorescence self-quenching of substituted N,α-diphenylnitrones in various solvents

Photophysical and photochemical properties for N,α-diphenylnitrone 1a, α-p-methoxyphenyl-N-phenylnitrone 1b, N-(t-butyl)-α-phenylnitrone 1c, cis-α-cyano-N,α-diphenylnitrone 1d, trans-α-cyano-N,α-diphenylnitrone 1e, α-methoxycarbonyl-N,α-diphenylnitrone 1f and α-ethoxycarbonyl-N,α-diphenylnitrone 1g were investigated. Photolysis studies in polar and protic solvent such as ethanol revealed that the singlet-state formation was preferred in nitrones and this was confirmed by the fluorescence investigations. Absorption and fluorescence spectra indicated considerable shifts with variation in polarity of the solvent.