title: Sensing mechanism for biothiols chemosensor DCO: roles of excited-state hydrogen-bonding and intramolecular charge transfer.
abstract: The biothiols sensing mechanism of (E)-7-(diethylamino)-3-(2-nitrovinyl)-2H-chromen-2-one (DCO) has been investigated using the density functional theory (DFT) and time-dependent DFT methods. The theoretical results indicate that the excited-state intermolecular hydrogen bonding (H-B) plays an important role for the biothiols sensing mechanism of the fluorescence sensor DCO. Multiple H-B interaction sites exist in DCO and in its Michael addition product DCOT, which then induce the formation of the H-B complexes with water molecules, DCOH2 and DCOTH4. In the first excited state, the intermolecular H-Bs between water molecule and DCO in DCOH2 are cooperatively and generally strengthened and thus induced the weak fluorescence emission of DCO, while the cooperative H-Bs between water molecule and DCOT in DCOTH4 are overall weakened and thus responsible for the enhanced fluorescence emission of DCOT. Moreover, the theoretical results suggest that the blue shift of the UV-Vis absorption spectrum of DCOT can be attributed to the relatively weak excited-state intramolecular charge transfer in DCOT compared to DCO.
authors.affiliation: State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116023, People's Republic of China.
authors.forename: Jun-Sheng
authors.initials: JS
authors.lastname: Chen
authors.forename: Ming-Hu
authors.initials: MH
authors.lastname: Yuan
authors.forename: Jia-Pei
authors.initials: JP
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Tian-Shu
authors.initials: TS
authors.lastname: Chu
mesh_terms: D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D015394:Molecular Structure; D013057:Spectrum Analysis; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D013438:Sulfhydryl Compounds; D014867:Water