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J. Phys. Chem. B 2008, 112, 2700-2711
Meta and Para Effects in the Ultrafast Excited-State Dynamics of the Green Fluorescent Protein Chromophores1 Kyril M. Solntsev,*,† Olivier Poizat,*,‡ Jian Dong,† Julien Rehault,‡ Yongbing Lou,§,| Clemens Burda,§ and Laren M. Tolbert*,† School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, Laboratoire de Spectrochimie Infrarouge et Raman (UMR 8516 de l’UniVersite´ et du CNRS), Centre d’Etudes et de Recherches Lasers et Applications (FR 2416 du CNRS), Baˆ t. C5, UniVersite´ des Sciences et Technologies de Lille, 59655 VilleneuVe d’Ascq, France, and Center for Chemical Dynamics and Nanomaterials Research, Department of Chemistry, Case Western ReserVe UniVersity, CleVeland, Ohio 44106 ReceiVed: September 25, 2007; In Final Form: December 10, 2007
Femtosecond transient absorption and fluorescence upconversion experiments have been performed to investigate the photoinduced dynamics of the meta isomer of the green fluorescent protein chromophore, m-HBDI, and its O-methylated derivative, m-MeOBDI, in various solvent mixtures at neutral, acidic, and basic pH. The para isomer, p-HBDI, and its O- and N-methylated derivatives, p-MeOBDI and p-HBDIMe+, were also studied for comparison. In all cases, fast quenching of the excited S1 state by internal conversion (IC) to the ground state was observed. In the para compounds, IC, presumably promoted by the internal twisting, arises in
