The pOH jump: Determination of deprotonation rates of water by 6-methoxyquinoline and acridine

E. Pines; D. Huppert; M. Gutman; N. Nachliel; M. Fishman

doi:10.1021/j100281a061

The pOH jump: Determination of deprotonation rates of water by 6-methoxyquinoline and acridine

E. Pines, D. Huppert, M. Gutman, N. Nachliel, M. Fishman

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

60 Scopus citations

Abstract

6-Methoxyquinoline (6MQ) and acridine are known to become more basic when excited to their lowest singlet state. We utilized a direct time-resolved subnanosecond technique and steady-state fluorescence to determine the acid-base kinetics of these excited compounds ΦN* + H₂O ⇄ ΦN*H⁺ + OH^- (k₁, k_-1). The protonation rates (k₁) were found to be 5.2 × 10⁶ M^-1 s^-1 and 0.2 × 10⁶ M^-1 s^-1 for 6MQ (pK* = 11.8) and acridine (pK* = 10.7), respectively. The neutralization rate (k_-1) was found to be diffusion controlled (6MQ) k_-1 = 3.1 × 10¹⁰ M^-1 s^-1. The deuterium isotope effects were found to be k₁^H/k₁^D = 3.5 and k_-1^H/k_-1^D = 2.2. The protonation rate increased in the presence of metal cations; for acridine in 2 M Mg(NO₃)₂ solution k₁ = 73 × 10⁶ M^-1 s^-1.

Original language	English
Pages (from-to)	6366-6370
Number of pages	5
Journal	Journal of Physical Chemistry
Volume	90
Issue number	23
DOIs	https://doi.org/10.1021/j100281a061
State	Published - 1 Jan 1986
Externally published	Yes

ASJC Scopus subject areas

General Engineering
Physical and Theoretical Chemistry

Access to Document

10.1021/j100281a061

Cite this

@article{41a845831dba4f61a2d0572b536fbf1e,

title = "The pOH jump: Determination of deprotonation rates of water by 6-methoxyquinoline and acridine",

abstract = "6-Methoxyquinoline (6MQ) and acridine are known to become more basic when excited to their lowest singlet state. We utilized a direct time-resolved subnanosecond technique and steady-state fluorescence to determine the acid-base kinetics of these excited compounds ΦN* + H2O ⇄ ΦN*H+ + OH- (k1, k-1). The protonation rates (k1) were found to be 5.2 × 106 M-1 s-1 and 0.2 × 106 M-1 s-1 for 6MQ (pK* = 11.8) and acridine (pK* = 10.7), respectively. The neutralization rate (k-1) was found to be diffusion controlled (6MQ) k-1 = 3.1 × 1010 M-1 s-1. The deuterium isotope effects were found to be k1H/k1D = 3.5 and k-1H/k-1D = 2.2. The protonation rate increased in the presence of metal cations; for acridine in 2 M Mg(NO3)2 solution k1 = 73 × 106 M-1 s-1.",

author = "E. Pines and D. Huppert and M. Gutman and N. Nachliel and M. Fishman",

year = "1986",

month = jan,

day = "1",

doi = "10.1021/j100281a061",

language = "English",

volume = "90",

pages = "6366--6370",

journal = "Journal of Physical Chemistry",

issn = "0022-3654",

publisher = "American Chemical Society",

number = "23",

}

TY - JOUR

T1 - The pOH jump

T2 - Determination of deprotonation rates of water by 6-methoxyquinoline and acridine

AU - Pines, E.

AU - Huppert, D.

AU - Gutman, M.

AU - Nachliel, N.

AU - Fishman, M.

PY - 1986/1/1

Y1 - 1986/1/1

N2 - 6-Methoxyquinoline (6MQ) and acridine are known to become more basic when excited to their lowest singlet state. We utilized a direct time-resolved subnanosecond technique and steady-state fluorescence to determine the acid-base kinetics of these excited compounds ΦN* + H2O ⇄ ΦN*H+ + OH- (k1, k-1). The protonation rates (k1) were found to be 5.2 × 106 M-1 s-1 and 0.2 × 106 M-1 s-1 for 6MQ (pK* = 11.8) and acridine (pK* = 10.7), respectively. The neutralization rate (k-1) was found to be diffusion controlled (6MQ) k-1 = 3.1 × 1010 M-1 s-1. The deuterium isotope effects were found to be k1H/k1D = 3.5 and k-1H/k-1D = 2.2. The protonation rate increased in the presence of metal cations; for acridine in 2 M Mg(NO3)2 solution k1 = 73 × 106 M-1 s-1.

AB - 6-Methoxyquinoline (6MQ) and acridine are known to become more basic when excited to their lowest singlet state. We utilized a direct time-resolved subnanosecond technique and steady-state fluorescence to determine the acid-base kinetics of these excited compounds ΦN* + H2O ⇄ ΦN*H+ + OH- (k1, k-1). The protonation rates (k1) were found to be 5.2 × 106 M-1 s-1 and 0.2 × 106 M-1 s-1 for 6MQ (pK* = 11.8) and acridine (pK* = 10.7), respectively. The neutralization rate (k-1) was found to be diffusion controlled (6MQ) k-1 = 3.1 × 1010 M-1 s-1. The deuterium isotope effects were found to be k1H/k1D = 3.5 and k-1H/k-1D = 2.2. The protonation rate increased in the presence of metal cations; for acridine in 2 M Mg(NO3)2 solution k1 = 73 × 106 M-1 s-1.

UR - http://www.scopus.com/inward/record.url?scp=0000018635&partnerID=8YFLogxK

U2 - 10.1021/j100281a061

DO - 10.1021/j100281a061

M3 - Article

AN - SCOPUS:0000018635

SN - 0022-3654

VL - 90

SP - 6366

EP - 6370

JO - Journal of Physical Chemistry

JF - Journal of Physical Chemistry

IS - 23

ER -

The pOH jump: Determination of deprotonation rates of water by 6-methoxyquinoline and acridine

Abstract

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this