Direct measurement of intrinsic proton transfer rates in diffusion-controlled reactions

Ehud Pines; Ben Zion Magnes; Matthew J. Lang; Graham R. Fleming

doi:10.1016/S0009-2614(97)01245-1

Direct measurement of intrinsic proton transfer rates in diffusion-controlled reactions

Ehud Pines, Ben Zion Magnes, Matthew J. Lang, Graham R. Fleming

Department of Chemistry

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

128 Scopus citations

Abstract

Acid-base reactions are usually treated as diffusion-controlled. In this study we directly measure the intrinsic proton transfer rates at the reaction contact of several naphthols photoacids-carboxylic base pairs. Deviations from the diffusion-controlled limit result from the finite intrinsic proton transfer rates at contact and these rates correlate well with the total free-energy change following the reactions. The correction was made over 8 ΔpK_a units and yielded k_r⁰=3×10¹¹ s^-1 and G_a⁰=2.9 kcal/mol for the activationless proton transfer rate and the intrinsic free-energy barrier, respectively. A similar behavior is found when the proton dissociation rates of all previously studied naphthol-like photoacids are included in the correlation. The combined correlation, over 11 ΔpK_a units, yielded k_r⁰=2×10¹¹ s^-1 and G_a⁰=2.5 kcal/mol.

Original language	English
Pages (from-to)	413-420
Number of pages	8
Journal	Chemical Physics Letters
Volume	281
Issue number	4-6
DOIs	https://doi.org/10.1016/S0009-2614(97)01245-1
State	Published - 26 Dec 1997

ASJC Scopus subject areas

General Physics and Astronomy
Physical and Theoretical Chemistry

Access to Document

10.1016/S0009-2614(97)01245-1

Cite this

@article{5b4c6ab36e784c3eafb5c8583b1e6762,

title = "Direct measurement of intrinsic proton transfer rates in diffusion-controlled reactions",

abstract = "Acid-base reactions are usually treated as diffusion-controlled. In this study we directly measure the intrinsic proton transfer rates at the reaction contact of several naphthols photoacids-carboxylic base pairs. Deviations from the diffusion-controlled limit result from the finite intrinsic proton transfer rates at contact and these rates correlate well with the total free-energy change following the reactions. The correction was made over 8 ΔpKa units and yielded kr0=3×1011 s-1 and Ga0=2.9 kcal/mol for the activationless proton transfer rate and the intrinsic free-energy barrier, respectively. A similar behavior is found when the proton dissociation rates of all previously studied naphthol-like photoacids are included in the correlation. The combined correlation, over 11 ΔpKa units, yielded kr0=2×1011 s-1 and Ga0=2.5 kcal/mol.",

author = "Ehud Pines and Magnes, {Ben Zion} and Lang, {Matthew J.} and Fleming, {Graham R.}",

note = "Funding Information: This research is supported by Grant No. 92-307 from the US–Israel Binational Science Foundation (BSF), Jerusalem, Israel.",

year = "1997",

month = dec,

day = "26",

doi = "10.1016/S0009-2614(97)01245-1",

language = "English",

volume = "281",

pages = "413--420",

journal = "Chemical Physics Letters",

issn = "0009-2614",

publisher = "Elsevier B.V.",

number = "4-6",

}

TY - JOUR

T1 - Direct measurement of intrinsic proton transfer rates in diffusion-controlled reactions

AU - Pines, Ehud

AU - Magnes, Ben Zion

AU - Lang, Matthew J.

AU - Fleming, Graham R.

N1 - Funding Information: This research is supported by Grant No. 92-307 from the US–Israel Binational Science Foundation (BSF), Jerusalem, Israel.

PY - 1997/12/26

Y1 - 1997/12/26

N2 - Acid-base reactions are usually treated as diffusion-controlled. In this study we directly measure the intrinsic proton transfer rates at the reaction contact of several naphthols photoacids-carboxylic base pairs. Deviations from the diffusion-controlled limit result from the finite intrinsic proton transfer rates at contact and these rates correlate well with the total free-energy change following the reactions. The correction was made over 8 ΔpKa units and yielded kr0=3×1011 s-1 and Ga0=2.9 kcal/mol for the activationless proton transfer rate and the intrinsic free-energy barrier, respectively. A similar behavior is found when the proton dissociation rates of all previously studied naphthol-like photoacids are included in the correlation. The combined correlation, over 11 ΔpKa units, yielded kr0=2×1011 s-1 and Ga0=2.5 kcal/mol.

AB - Acid-base reactions are usually treated as diffusion-controlled. In this study we directly measure the intrinsic proton transfer rates at the reaction contact of several naphthols photoacids-carboxylic base pairs. Deviations from the diffusion-controlled limit result from the finite intrinsic proton transfer rates at contact and these rates correlate well with the total free-energy change following the reactions. The correction was made over 8 ΔpKa units and yielded kr0=3×1011 s-1 and Ga0=2.9 kcal/mol for the activationless proton transfer rate and the intrinsic free-energy barrier, respectively. A similar behavior is found when the proton dissociation rates of all previously studied naphthol-like photoacids are included in the correlation. The combined correlation, over 11 ΔpKa units, yielded kr0=2×1011 s-1 and Ga0=2.5 kcal/mol.

UR - http://www.scopus.com/inward/record.url?scp=0031587575&partnerID=8YFLogxK

U2 - 10.1016/S0009-2614(97)01245-1

DO - 10.1016/S0009-2614(97)01245-1

M3 - Article

AN - SCOPUS:0031587575

SN - 0009-2614

VL - 281

SP - 413

EP - 420

JO - Chemical Physics Letters

JF - Chemical Physics Letters

IS - 4-6

ER -

Direct measurement of intrinsic proton transfer rates in diffusion-controlled reactions

Abstract

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this