Effect of conjugation and aromaticity of 3,6 di-substituted carbazoles on triplet energy and the implication of triplet energy in multiple-cyclic aromatic compounds.

ABSTRACT: It is well-known that short conjugation is needed to obtain a high triplet energy. Carbazole has 3 fused rings and yet it has a high triplet energy. In order to illuminate the reason behind this, we synthesized a range of carbazole derivatives with substitution at the 3,6-positions. All carbazoles with phenyl moieties substituted at the 3,6-positions exhibit a lower triplet energy than that of carbazole itself. We also quantified the aromaticity of carbazole using the nucleus-independent chemical shift tensor. We discovered that the five-membered heterocyclic aromatic ring in carbazole has reduced aromaticity. This results in a reduced conjugation effect between the five-membered heterocyclic aromatic ring and the neighboring benzene rings. Inspired by this finding, the triplet energies of

SUBMITTER: Woon KL 

PROVIDER: S-EPMC9078734 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature