Indole derivatives R 0140 Derivatives of Indole. Part 143. Synthesis of Photochromic Derivatives of 2-Arylindoles. -During exposure to UV light the light-yellow solution of title derivatives (V) and (VIII) becomes dark-green as a result of ring opening and transformation to betaines. -(GOGRICHIANI, E. O.; KATSADZE, E. A.; GAVTADZE, N. G.; SAMSONIYA, S. A.; DUERR, H.; Chem. Heterocycl.