title: Photophysical processes involved within the bichromophoric system 9-benzotriazole-1-ylmethyl-9H-carbazole and its role as an artificial photosynthetic device.
abstract: From both steady state and fluorescence lifetime measurements it reveals that due to photoexcitation of benzotriazole (BZ) part of the bichromophore, 9(1-H-benzotriazole-lylmethyl)-9H-carbazole (BHC), singlet-singlet energy transfer takes place to populate the lowest excited singlet of carbazole (CZ). CZ, thus being excited indirectly via energy transfer process, undergoes strong charge transfer (CT) reaction with the surrounding polar medium acetonitrile (ACN). On the other hand, very weak CT band was apparent when CZ part, within BHC, was directly excited. In less polar tetrahydrofuran (THF) and polar benzonitrile (BN) environment, lack of formation of CT band strongly suggests in favor of the electron-accepting behavior of ACN. Moreover, by measuring the emission spectra of BHC in microcrystals and of 30 bilayers mixed LB film at high mole fraction of BHC molecules, the possibility of excimer formation or aggregation has been ruled out. Thus, BHC, when dissolved in ACN, acts as a triad system of BZ-CZ-ACN where BZ acts as an antenna molecule and CZ as a reaction center. The possible role of the bichromophoric system BHC as an artificial photosynthetic or solar energy conversion device has been hinted.
authors.affiliation: Department of Spectroscopy, Indian Association for the Cultivation of Science, 2A and 2B Raja S C Mullick Road, Jadavpur, Kolkata 700032, West Bengal, India.
authors.forename: Paulami
authors.initials: P
authors.lastname: Mandal
authors.forename: Tapas
authors.initials: T
authors.lastname: Misra
authors.forename: Asish
authors.initials: A
authors.lastname: De
authors.forename: Sanjib
authors.initials: S
authors.lastname: Ghosh
authors.forename: Shyamal Roy
authors.initials: SR
authors.lastname: Chaudhury
authors.forename: Joydeep
authors.initials: J
authors.lastname: Chowdhury
authors.forename: Tapan
authors.initials: T
authors.lastname: Ganguly
mesh_terms: D000097:Acetonitriles; D052160:Benzothiazoles / Q000737:chemistry*; D002227:Carbazoles / Q000737:chemistry*; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010777:Photochemistry; D010788:Photosynthesis; D013050:Spectrometry, Fluorescence; D013696:Temperature
chemical_list: C519058:9-benzotriazole-1-ylmethyl-9H-carbazole; D000097:Acetonitriles; D052160:Benzothiazoles; D002227:Carbazoles; C041514:carbazole; C032159:acetonitrile