Deactivation of excited 1-amino-5,6,7,8-tetrahydronaphthalene in various solvents
Fluorescence emission of 1-amino-5,6,7,8-tetrahydronaphthalene is quenched by pyridine at 300 and 77 K and the mechanism involves π-electron delocalization via a hydrogen bond. The probable effect of conformational changes in the molecule also needs to be considered. In polar solvents ethanol and methanol which form hydrogen-bonding chains a significant role is played by resonance transfer from the aminotetrahydronaphthalene and its methyl derivative NN-dimethylaminotetrahydronaphthalene to pyridine in quenching the fluorescence emission of the molecules. Triethylamine quenches fluorescence of aminotetrahydronaphthalene at 300 K but not at 77 K. Possible deactivation process may involve ion-pair formation. Reaction schemes for quenching by pyridine and triethylamine are described. From the non-exponential nature of phosphorescence decay at 77 K formation of hydrogen bond complex between aminotetrahydronaphthalene in the triplet state and the quenchers is inferred.