title: Synthesis and Photophysical Properties of Aza[n]helicenes.
abstract: Synthesis and study of aza[7]helicene and aza[9]helicene is presented in this paper. Photo-dehydrocyclization of the 3,6-bis-styryl derivative of carbazole leading to sterically less demanding aza[7]helicene resulted in smooth reaction, and only the desired angular-angular product was detected. However, in the case of aza[9]helicene, along with the expected angular-angular cyclization, three other products involving linear mode of cyclization were also isolated and characterized. In this case, the helical compound aza[9]helicene was predominantly formed at lower concentration while the other isomers were obtained at higher concentration. All of the compounds formed by angular-angular, angular-linear, and linear-linear modes of cyclization were fully characterized, and their photophysical properties were investigated.
authors.affiliation: Department of Chemistry, Faculty of Science, M. S. University of Baroda , Vadodara 390 002, India.
authors.forename: Gourav M
authors.initials: GM
authors.lastname: Upadhyay
authors.affiliation: Department of Chemistry, Faculty of Science, M. S. University of Baroda , Vadodara 390 002, India.
authors.forename: Harish R
authors.initials: HR
authors.lastname: Talele
authors.affiliation: Department of Chemistry, Faculty of Science, M. S. University of Baroda , Vadodara 390 002, India.
authors.forename: Ashutosh V
authors.initials: AV
authors.lastname: Bedekar