Spectral and photochemical properties of bifunctional compounds and their complexes 2. Photocyclization of alpha,omega-bis(diphenylamino) alkanes to alpha,omega-di(carbozolyl)alkanes

Quantum yields of the step-by-step photocyclization of diphenylamine (DPA) derivatives Ph2N-(CH2)(n)-NPh2, n = 3-6, 9, to the corresponding alpha, ome ga-di(carbazolyl)alkanes were measured. At n > 3, the presence of the secon d DPA group had no effect on the cyclization of the first DPA group; howeve r, cyclization of, the second DPA group was retarded after cyclization of t he first DPA group. The effect was explained by quenching of the excited DP A group by the carbazole group newly formed in the semi-cyclic compound. Fo r disubstituted propane (n = 3), the mutual influence of the two groups at both stages of the reaction was found.