Electron-transfer induced photo-oxidation of 4,5-dihydro-1,2,4-oxadiazoles: Experimental and computational studies

•Electronic effect of substituents influences the rate of photo-oxidation of dihydrooxadiazoles.•The nature of electron-accepting solvent facilitates the proposed electron-transfer process in this reaction.•Computational (TD/U)B3LYP/6–311++G(d,p) results explain the experimental observations.•The first excited singlet state of dihydrooxadiazoles is involved in the proposed electron transfer step.•Photo-isomerization of trans-5-styryloxadiazole to the corresponding cis-isomer followed by photo-cyclization process.