Jump to main content
Jump to site search

Issue 2, 2015
Previous Article Next Article

A questionable excited-state double-proton transfer mechanism for 3-hydroxyisoquinoline

Author affiliations

Abstract

Two excited state proton transfer mechanisms of 3-hydroxyisoquinoline (3HIQ) in cyclohexane and acetic acid (ACID) were investigated based on the time-dependent density functional theory (TDDFT), suggesting a different double-proton transfer mechanism from the one proposed previously (J. Phys. Chem. B, 1998, 102, 1053). Instead of the formation of keto–enol complexes for 3HIQ self-association in cyclohexane, our theoretical results predicted that 3HIQ self-association exists in two forms: the normal form (enol/enol) and the tautomer form (keto/keto) in cyclohexane. A high barrier (37.023 kcal mol−1) between the 3HIQ enol monomer and 3HIQ keto monomer form indicated that the 3HIQ keto monomer in the ground state should not exist. In addition, the constructed potential energy surfaces of the ground state and excited state have been used to explain the proton transfer process. Upon optical excitation, the enol/enol form is excited to the first excited state, then transfers one proton, in turn, transition to the ground state to transfer another proton. A relatively low barrier (8.98 kcal mol−1) demonstrates two stable structures in the ground state. In view of the acetic acid solvent effect, two protons of 3HIQ/ACID transfer along the dihydrogen bonds in the first excited state, which is a different transfer mechanism to 3HIQ self-association. In addition, the proton transfer process provides a possible explanation for the fluorescence quenching observed.

Graphical abstract: A questionable excited-state double-proton transfer mechanism for 3-hydroxyisoquinoline

Back to tab navigation

Publication details

The article was received on 15 Sep 2014, accepted on 12 Nov 2014 and first published on 17 Nov 2014


Article type: Paper
DOI: 10.1039/C4CP04135F
Author version
available:
Download author version (PDF)
Phys. Chem. Chem. Phys., 2015,17, 1142-1150

  •   Request permissions

    A questionable excited-state double-proton transfer mechanism for 3-hydroxyisoquinoline

    J. Zhao, J. Chen, Y. Cui, J. Wang, L. Xia, Y. Dai, P. Song and F. Ma, Phys. Chem. Chem. Phys., 2015, 17, 1142
    DOI: 10.1039/C4CP04135F

Search articles by author

Spotlight

Advertisements