title: Dual Fluorescence in GFP Chromophore Analogues: Chemical Modulation of Charge Transfer and Proton Transfer Bands.
abstract: Dual fluorescence of GFP chromophore analogues has been observed for the first time. OHIM (o-hydroxy imidazolidinone) shows only a charge transfer (CT) band, CHBDI (p-cyclicamino o-hydroxy benzimidazolidinone) shows a comparable intensity CT and PT (proton transfer) band, and MHBDI (p-methoxy o-hydroxy benzimidazolidinone) shows a higher intensity PT band. It could be shown that the differential optical behavior is not due to conformational variation in the solid or solution phase. Rather, control of the excited state electronic energy level and excited state acidity constant by functional group modification could be shown to be responsible for the differential optical behavior. Chemical modification-induced electronic control over the relative intensity of the charge transfer and proton transfer bands could thus be evidenced. Support from single-crystal X-ray structure, NMR, femtosecond to nanosecond fluorescence decay analysis, and TDDFT-based calculation provided important information and thus helped us understand the photophysics better.
authors.affiliation: Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata , Mohanpur, West-Bengal 741246, India.
authors.forename: Tanmay
authors.initials: T
authors.lastname: Chatterjee
authors.affiliation: Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata , Mohanpur, West-Bengal 741246, India.
authors.forename: Mrinal
authors.initials: M
authors.lastname: Mandal
authors.affiliation: Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata , Mohanpur, West-Bengal 741246, India.
authors.forename: Ananya
authors.initials: A
authors.lastname: Das
authors.affiliation: Department of Spectroscopy, Indian Association for the Cultivation of Science , 2A and 2B Raja S. C. Mullick Road, Kolkata, West Bengal 700032, India.
authors.forename: Kalishankar
authors.initials: K
authors.lastname: Bhattacharyya
authors.affiliation: Department of Spectroscopy, Indian Association for the Cultivation of Science , 2A and 2B Raja S. C. Mullick Road, Kolkata, West Bengal 700032, India.
authors.forename: Ayan
authors.initials: A
authors.lastname: Datta
authors.affiliation: Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata , Mohanpur, West-Bengal 741246, India.
authors.forename: Prasun K
authors.initials: PK
authors.lastname: Mandal
mesh_terms: D004579:Electron Transport; D049452:Green Fluorescent Proteins / Q000737:chemistry*; D008958:Models, Molecular; D011487:Protein Conformation; D011522:Protons; D013050:Spectrometry, Fluorescence
chemical_list: D011522:Protons; D049452:Green Fluorescent Proteins