Studies on 1,n-dicarbazolylalkanes and related species: Model compounds of polyvinylcarbazole

Dimer model compounds of polyvinylcarbazole (1,n-dicarbazolylalkanes, where n = 1 through 5) were prepared by a substitution reaction of the potassium salt of carbazole with the corresponding 1,n-dibromoalkane. Flash photolysis on electron donor-acceptor (EDA) molecules of these dimer compounds with tetranitromethane (TNM) generated radical cations which combined through 2nd order kinetics with nitrogen dioxide (from dissociative electron capture of TNM). Noticeable interactions were observed between carbazoles when n = 1, 3 and 4. This photochemical nitration reaction, monitored by NMR after fixed irradiation times, showed formation of mononitro derivatives as primary photoproducts, followed by dinitration at longer irradiation times. Nitration products from these irradiations were isolated and characterized using standard techniques. Studies were also carried out under dark conditions both before and after irradiation. No reaction was apparent when dimer compounds and TNM were stored in the dark without irradiation. However, solution studies monitoring the reaction mixture after irradiation (stored in the dark) revealed that additional nitration of the dimer compounds occurs under dark conditions, possibly through a radical chain reaction.;Also, unreacted 1,1-dicarbazolylmethane shows a gradual breakdown via a stable iminium ion which leads to carbazole and other degradation products. EDA complexes of the dimer compounds were studied using both tetracyanoethylene (TCNE) and TNM as electron acceptors. EDA complexes of these model compounds with TCNE showed 1:1 stoichiometry using the method of continuous variations. EDA complexes with both TNM and TCNE showed K...