Synthesis and spectroscopic properties of 9-substituted benz[g]indoles

Photolysis of 1,1'-(1,8-naphthylene)-di-1H-1,2,3-triazoles in methanol has given new benz[g]indoles with a triazole ring at 9-position. Similar photolysis of 1-(8-dimethylamino-1-naphthyl)-1H-1,2, 3-triazoles also gives new benz[g]indoles with a dimethylamino group at 9-position. The spectral properties of these compounds were studied in comparison with those of corresponding benz[g]indoles obtained from the similar photolysis of 1-(1-naphthyl)-1H-1,2, 3-triazoles. Since the substituent at 9-position and the pyrrole moiety exist in close proximity in peri- position of the naphthalene ring, unique properties such as the strong intramolecular hydrogen bonding and the restricted rotation of C(sp2)-N(sp3) single bond were observed in the 9-substituted benz[g]indoles.