A spectroscopic study of the excited state proton transfer processes of (8-bromo-7-hydroxyquinolin-2-yl)methyl-protected phenol in aqueous solutions

Jinqing Huang, Adna P. Muliawan, Jiani Ma, Ming De Li, Hoi Kei Chiu, Xin Lan, Davide Deodato, David Lee Phillips, Timothy Dore

Research output: Contribution to journalArticle

Abstract

A combination of spectroscopic methods and density functional theory (DFT) computations was used to study the excited state proton transfer (ESPT) processes of (8-bromo-7-hydroxyquinolin-2-yl)methyl-protected phenol (BHQ-OPh). Characterization of the prototropic forms of BHQ-OPh in different solvent environments revealed that the neutral form predominates in acetonitrile and in 1 : 1 acetonitrile/water (pH 5.0), whereas the anionic form predominates in 1 : 1 acetonitrile/PBS (pH 7.4). Both the neutral and anionic forms were significantly populated in 1 : 1 acetonitrile/water. Upon irradiation in acetonitrile the triplet neutral form was observed, whereas the triplet anionic form was detected in 1 : 1 acetonitrile/PBS (pH 7.4). The existence of the triplet tautomeric form of BHQ-OPh in both 1 : 1 acetonitrile/water and 1 : 1 acetonitrile/water (pH 5.0), and the ESPT processes from the neutral to the anionic to the tautomeric forms in the excited state were observed using time-resolved spectroscopy. A reaction mechanism in 1 : 1 acetonitrile/water and 1 : 1 acetonitrile/water (pH 5.0) was proposed based on the spectroscopic and DFT computational results. A comparison of the results for BHQ-OPh with those of BHQ-OAc reveals that the initial prototropic states and photochemical processes are similar. The understanding gained of the initial photo-induced processes of BHQ-based photoremovable protecting groups (PPGs) is useful for the design of new quinolinyl-based PPGs for specialized applications.

Original languageEnglish (US)
Pages (from-to)575-584
Number of pages10
JournalPhotochemical and Photobiological Sciences
Volume16
Issue number4
DOIs
StatePublished - Jan 1 2017

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Proton transfer
Phenol
Excited states
phenols
acetonitrile
aqueous solutions
protons
excitation
Water
water
Density functional theory
8-bromo-7-hydroxyquinoline
density functional theory
Irradiation
Spectroscopy
irradiation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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A spectroscopic study of the excited state proton transfer processes of (8-bromo-7-hydroxyquinolin-2-yl)methyl-protected phenol in aqueous solutions. / Huang, Jinqing; Muliawan, Adna P.; Ma, Jiani; Li, Ming De; Chiu, Hoi Kei; Lan, Xin; Deodato, Davide; Phillips, David Lee; Dore, Timothy.

In: Photochemical and Photobiological Sciences, Vol. 16, No. 4, 01.01.2017, p. 575-584.

Research output: Contribution to journalArticle

Huang, Jinqing ; Muliawan, Adna P. ; Ma, Jiani ; Li, Ming De ; Chiu, Hoi Kei ; Lan, Xin ; Deodato, Davide ; Phillips, David Lee ; Dore, Timothy. / A spectroscopic study of the excited state proton transfer processes of (8-bromo-7-hydroxyquinolin-2-yl)methyl-protected phenol in aqueous solutions. In: Photochemical and Photobiological Sciences. 2017 ; Vol. 16, No. 4. pp. 575-584.
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AU - Ma, Jiani

AU - Li, Ming De

AU - Chiu, Hoi Kei

AU - Lan, Xin

AU - Deodato, Davide

AU - Phillips, David Lee

AU - Dore, Timothy

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