Comparison of the rate of excited-state proton transfer from photoacids to alcohols and water

Ron Simkovitch; Shay Shomer; Rinat Gepshtein; Michal E. Roth; Doron Shabat; Dan Huppert

doi:10.1016/j.jphotochem.2013.12.009

Comparison of the rate of excited-state proton transfer from photoacids to alcohols and water

Ron Simkovitch, Shay Shomer, Rinat Gepshtein, Michal E. Roth, Doron Shabat, Dan Huppert

School of Chemistry

Tel Aviv University

Research output: Contribution to journal › Article › peer-review

Abstract

Steady-state and time-resolved techniques were employed to study the excited-state proton-transfer (ESPT) rate of two newly synthesized photoacids - quinone cyanine diindolium (QCy7) and its dipicolinium analog (QCy9) - in three protic solvents, water, methanol and ethanol. The ESPT rate constant k _PT of QCy7, whose pKa*∼-6.5 in water, methanol and ethanol is 1.2 × 10¹³ s^-1, 8 × 10¹¹ s ^-1, 7 × 10¹¹ s^-1 respectively. k _PT for QCy9 (pKa*∼-8.5), is 10¹³ s^-1 for all three protic solvents used. We qualitatively explain these results and also the previously found solvent dependence of k_PT of weaker photoacids by adiabatic and non-adiabatic proton-transfer formalism.

Original language	English
Pages (from-to)	90-101
Number of pages	12
Journal	Journal of Photochemistry and Photobiology A: Chemistry
Volume	277
DOIs	https://doi.org/10.1016/j.jphotochem.2013.12.009
State	Published - 1 Mar 2014

Keywords

Fast reactions
Photoacids
Protic solvents
Proton transfer
Quinone cyanine

All Science Journal Classification (ASJC) codes

General Chemistry
General Chemical Engineering
General Physics and Astronomy

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10.1016/j.jphotochem.2013.12.009

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title = "Comparison of the rate of excited-state proton transfer from photoacids to alcohols and water",

abstract = "Steady-state and time-resolved techniques were employed to study the excited-state proton-transfer (ESPT) rate of two newly synthesized photoacids - quinone cyanine diindolium (QCy7) and its dipicolinium analog (QCy9) - in three protic solvents, water, methanol and ethanol. The ESPT rate constant k PT of QCy7, whose pKa*∼-6.5 in water, methanol and ethanol is 1.2 × 1013 s-1, 8 × 1011 s -1, 7 × 1011 s-1 respectively. k PT for QCy9 (pKa*∼-8.5), is 1013 s-1 for all three protic solvents used. We qualitatively explain these results and also the previously found solvent dependence of kPT of weaker photoacids by adiabatic and non-adiabatic proton-transfer formalism.",

keywords = "Fast reactions, Photoacids, Protic solvents, Proton transfer, Quinone cyanine",

author = "Ron Simkovitch and Shay Shomer and Rinat Gepshtein and Roth, \{Michal E.\} and Doron Shabat and Dan Huppert",

note = "Funding Information: We thank professor A. Nitzan for helpful discussions. This work was supported by grants from the James-Franck German-Israeli Program in Laser-Matter Interaction and by the Israel Science Foundation .",

year = "2014",

month = mar,

day = "1",

doi = "10.1016/j.jphotochem.2013.12.009",

language = "الإنجليزيّة",

volume = "277",

pages = "90--101",

journal = "Journal of Photochemistry and Photobiology A: Chemistry",

issn = "1010-6030",

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TY - JOUR

T1 - Comparison of the rate of excited-state proton transfer from photoacids to alcohols and water

AU - Simkovitch, Ron

AU - Shomer, Shay

AU - Gepshtein, Rinat

AU - Roth, Michal E.

AU - Shabat, Doron

AU - Huppert, Dan

N1 - Funding Information: We thank professor A. Nitzan for helpful discussions. This work was supported by grants from the James-Franck German-Israeli Program in Laser-Matter Interaction and by the Israel Science Foundation .

PY - 2014/3/1

Y1 - 2014/3/1

N2 - Steady-state and time-resolved techniques were employed to study the excited-state proton-transfer (ESPT) rate of two newly synthesized photoacids - quinone cyanine diindolium (QCy7) and its dipicolinium analog (QCy9) - in three protic solvents, water, methanol and ethanol. The ESPT rate constant k PT of QCy7, whose pKa*∼-6.5 in water, methanol and ethanol is 1.2 × 1013 s-1, 8 × 1011 s -1, 7 × 1011 s-1 respectively. k PT for QCy9 (pKa*∼-8.5), is 1013 s-1 for all three protic solvents used. We qualitatively explain these results and also the previously found solvent dependence of kPT of weaker photoacids by adiabatic and non-adiabatic proton-transfer formalism.

AB - Steady-state and time-resolved techniques were employed to study the excited-state proton-transfer (ESPT) rate of two newly synthesized photoacids - quinone cyanine diindolium (QCy7) and its dipicolinium analog (QCy9) - in three protic solvents, water, methanol and ethanol. The ESPT rate constant k PT of QCy7, whose pKa*∼-6.5 in water, methanol and ethanol is 1.2 × 1013 s-1, 8 × 1011 s -1, 7 × 1011 s-1 respectively. k PT for QCy9 (pKa*∼-8.5), is 1013 s-1 for all three protic solvents used. We qualitatively explain these results and also the previously found solvent dependence of kPT of weaker photoacids by adiabatic and non-adiabatic proton-transfer formalism.

KW - Fast reactions

KW - Photoacids

KW - Protic solvents

KW - Proton transfer

KW - Quinone cyanine

UR - http://www.scopus.com/inward/record.url?scp=84892754160&partnerID=8YFLogxK

U2 - 10.1016/j.jphotochem.2013.12.009

DO - 10.1016/j.jphotochem.2013.12.009

M3 - مقالة

SN - 1010-6030

VL - 277

SP - 90

EP - 101

JO - Journal of Photochemistry and Photobiology A: Chemistry

JF - Journal of Photochemistry and Photobiology A: Chemistry

ER -

Comparison of the rate of excited-state proton transfer from photoacids to alcohols and water

Abstract

Keywords

All Science Journal Classification (ASJC) codes

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