title: Excited-state intramolecular proton transfer in five-membered hydrogen-bonding systems: 2-pyridyl pyrazoles.
abstract: The excited-state intramolecular proton transfer (ESIPT) reaction in five-membered N-H...N hydrogen-bonding systems has been explored through design and syntheses of a series of 5-(2-pyridyl) 1-H-pyrazoles 1a-d. The ESIPT mechanism was confirmed through spectroscopy, relaxation dynamics, and corresponding methylated analogues. The results demonstrate for the first time a unique system among ESIPT molecules, in which ESIPT incorporates an appreciably large energy barrier fine-tuned by the skeletal reorganization. This makes 1a-d systems ideal models for probing the reaction potential energy surface.
authors.affiliation: Department of Chemistry, National Taiwan University, 106, Taipei, Taiwan ROC.
authors.forename: Wei-Shan
authors.initials: WS
authors.lastname: Yu
authors.forename: Chung-Chih
authors.initials: CC
authors.lastname: Cheng
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Cheng
authors.forename: Pei-Chi
authors.initials: PC
authors.lastname: Wu
authors.forename: Yi-Hwa
authors.initials: YH
authors.lastname: Song
authors.forename: Yun
authors.initials: Y
authors.lastname: Chi
authors.forename: Pi-Tai
authors.initials: PT
authors.lastname: Chou
mesh_terms: D006860:Hydrogen Bonding; D011522:Protons; D011720:Pyrazoles / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D013053:Spectrophotometry
chemical_list: D011522:Protons; D011720:Pyrazoles; D011725:Pyridines