Excited-state intramolecular proton transfer in five-membered hydrogen-bonding systems: 2-pyridyl pyrazoles.
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.
Yu
Wei-Shan
WS
Department of Chemistry, National Taiwan University, 106, Taipei, Taiwan ROC.
Cheng
Chung-Chih
CC
Cheng
Yi-Ming
YM
Wu
Pei-Chi
PC
Song
Yi-Hwa
YH
Chi
Yun
Y
Chou
Pi-Tai
PT
D006860:Hydrogen Bonding; D011522:Protons; D011720:Pyrazoles / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D013053:Spectrophotometry
D011522:Protons; D011720:Pyrazoles; D011725:Pyridines