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Query: EC:3.4.24.64 (
MPP
)
1,876
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Studies of 2-(1H-pyrazol-5-yl)pyridine (PPP) and its derivatives 2-(4-methyl-1H-pyrazol-5-yl)pyridine (
MPP
) and 2-(3-bromo-1H-pyrazol-5-yl)pyridine (
BPP
) by stationary and time-resolved UV/Vis spectroscopic methods, and quantum chemical computations show that this class of compounds provides a rare example of molecules that exhibit three types of photoreactions: 1) excited-state intramolecular proton transfer (ESIPT) in the syn form of
MPP
, 2) excited-state intermolecular double-proton transfer (ESDPT) in the dimers of PPP in nonpolar media, as well as 3) solvent-assisted double-proton transfer in hydrogen-bonded 1:1 complexes of PPP and
MPP
with alcoholic partners. The excited-state processes are manifested by the appearance of a dual luminescence and a bimodal irreversible kinetic coupling of the two fluorescence bands. Ground-state syn-anti equilibria are detected and discussed. The fraction of the higher-energy anti form varies for different derivatives and is strongly dependent on the solvent polarity and hydrogen-bond donor or acceptor abilities.
...
PMID:Three modes of proton transfer in one chromophore: photoinduced tautomerization in 2-(1H-pyrazol-5-yl)pyridines, their dimers and alcohol complexes. 2294 37
