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Dipole moments of indoles in their ground and the first excited singlet states

1986; Elsevier BV; Volume: 135; Linguagem: Inglês

10.1016/0166-1280(86)80050-1

1872-7999

Cyril Párkányi, Subba Rao Oruganti, Abdou O. Abdelhamid, László von Szentpály, Babacar Ngom, Jean‐Jacques Aaron,

Free Radicals and Antioxidants

The ground-state dipole moments of seven substituted indoles (3-acetylindole, 5- bromoindole, 3-formylindole, 2-indolecarboxylic acid, 5- indolecarboxylic acid, 5-methoxy-2-indolecarboxylic acid, and 5-nitroindole) have been measured at room temperature (298 K) in several solvents (benzene, dioxane, n-butyl ether). Their first excited singlet-state dipole moments have been determined by means of the equations of Bakhshiev and Chamma-Viallet, using the variation of the Stokes shift with the solvent dielectric constant-refractive index term. A comparison of the two sets of dipole moments indicates that the first excited singlet state of indoles is more polar than the ground state. The effect of substituents is discussed. The experimental values of dipole moments of selected indoles are compared with those calculated by the PPP (LCI-SCF-MO) method.