Ground and Singlet Excited State Pyridinic Protonation of N9-Methylbetacarboline in Water-N,N-Dimethylformamide Mixtures
Autor: | María A. Muñoz, Manuel Balón, Antonio Sánchez Coronilla, Carmen Carmona |
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Rok vydání: | 2009 |
Předmět: |
Time Factors
Sociology and Political Science Hydrogen Clinical Biochemistry chemistry.chemical_element Protonation Photochemistry Excimer Biochemistry Fluorescence Absorption Cations Singlet state Nitrogen Compounds Spectroscopy Chemistry Hydrogen bond Water Dimethylformamide Hydrogen Bonding Clinical Psychology Models Chemical Excited state Steady state (chemistry) Protons Ground state Law Social Sciences (miscellaneous) Carbolines |
Zdroj: | Journal of Fluorescence. 19:1025-1035 |
ISSN: | 1573-4994 1053-0509 |
DOI: | 10.1007/s10895-009-0502-y |
Popis: | The ground and the singlet excited state pyridinic protonation of 9-methyl-9H-pyrido[3,4-b]indole, MBC, in water-N,N-dimethylformamide mixtures has been studied by absorption, steady state and time resolved fluorescence measurements. These proton transfer reactions elapse by a stepwise mechanism modulated by different hydrogen bonded adducts and exciplexes formed by water molecules and the pyridinic nitrogen atom of the MBC. Based in the present and previous studies, a general mechanistic Scheme for the ground and the singlet excited state MBC pyridinic protonation has been proposed. Accordingly, in the ground state, upon increasing the water proportion of the water-N,N-dimethylformamide mixtures, a hydrogen bonded complex, HBC, its hydrogen bonded proton transfer complex, PTC, a pre-cationic complex, PC, and the cation, C, are progressively formed. In the excited state, MBC, HBC and PC behave as independent fluorophores. Excited state cations, C*, are mainly formed by direct excitation of the ground state cations and, in minor proportion, by the excited state reaction of the PTC* through the CL* exciplex. |
Databáze: | OpenAIRE |
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