Acid-Base Properties of the Ground and Excited States of Ruthenium(II) Tris(4′-methyl-2,2′-bipyridine-4-carboxylic Acid)

Chien Hua Su, I-Jy Chang

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The acid dissociation constant, pKa, for the ground and excited states of ruthenium tris(4′-methyl-2,2′-bipyridine-4-carboxylic acid) complex have been measured. The ground state pKa obtained from the pH titration curve of the complex absorption at 454 nm was 2.5. The lifetimes of the excited-state for deprotonated and protonated ruthenium complexes are 595 and 150 ns, respectively. The excited-state pKa* is obtained from the emission titration curve at 630 nm and corrected for the excited-state lifetime to be 4.2. The increase of 1.7 pH units in the acid dissociation constant in the excited-state indicates that the ligand is much more basic in the excited-state. This result confirms the MLCT assignment for the lowest electronic transition of [Ru(mbpyCOOH)3]2+.

Original languageEnglish
Pages (from-to)361-365
Number of pages5
JournalJournal of the Chinese Chemical Society
Volume45
Issue number3
DOIs
Publication statusPublished - 1998 Jan 1

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Ruthenium
Carboxylic Acids
Excited states
Ground state
Acids
Titration
Ligands

Keywords

  • Acid-base
  • Excited-state
  • Ruthenium(II) tris(4′-methyl-2,2′-bipyndine-4-carboxylic acid)

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

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title = "Acid-Base Properties of the Ground and Excited States of Ruthenium(II) Tris(4′-methyl-2,2′-bipyridine-4-carboxylic Acid)",
abstract = "The acid dissociation constant, pKa, for the ground and excited states of ruthenium tris(4′-methyl-2,2′-bipyridine-4-carboxylic acid) complex have been measured. The ground state pKa obtained from the pH titration curve of the complex absorption at 454 nm was 2.5. The lifetimes of the excited-state for deprotonated and protonated ruthenium complexes are 595 and 150 ns, respectively. The excited-state pKa* is obtained from the emission titration curve at 630 nm and corrected for the excited-state lifetime to be 4.2. The increase of 1.7 pH units in the acid dissociation constant in the excited-state indicates that the ligand is much more basic in the excited-state. This result confirms the MLCT assignment for the lowest electronic transition of [Ru(mbpyCOOH)3]2+.",
keywords = "Acid-base, Excited-state, Ruthenium(II) tris(4′-methyl-2,2′-bipyndine-4-carboxylic acid)",
author = "Su, {Chien Hua} and I-Jy Chang",
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T1 - Acid-Base Properties of the Ground and Excited States of Ruthenium(II) Tris(4′-methyl-2,2′-bipyridine-4-carboxylic Acid)

AU - Su, Chien Hua

AU - Chang, I-Jy

PY - 1998/1/1

Y1 - 1998/1/1

N2 - The acid dissociation constant, pKa, for the ground and excited states of ruthenium tris(4′-methyl-2,2′-bipyridine-4-carboxylic acid) complex have been measured. The ground state pKa obtained from the pH titration curve of the complex absorption at 454 nm was 2.5. The lifetimes of the excited-state for deprotonated and protonated ruthenium complexes are 595 and 150 ns, respectively. The excited-state pKa* is obtained from the emission titration curve at 630 nm and corrected for the excited-state lifetime to be 4.2. The increase of 1.7 pH units in the acid dissociation constant in the excited-state indicates that the ligand is much more basic in the excited-state. This result confirms the MLCT assignment for the lowest electronic transition of [Ru(mbpyCOOH)3]2+.

AB - The acid dissociation constant, pKa, for the ground and excited states of ruthenium tris(4′-methyl-2,2′-bipyridine-4-carboxylic acid) complex have been measured. The ground state pKa obtained from the pH titration curve of the complex absorption at 454 nm was 2.5. The lifetimes of the excited-state for deprotonated and protonated ruthenium complexes are 595 and 150 ns, respectively. The excited-state pKa* is obtained from the emission titration curve at 630 nm and corrected for the excited-state lifetime to be 4.2. The increase of 1.7 pH units in the acid dissociation constant in the excited-state indicates that the ligand is much more basic in the excited-state. This result confirms the MLCT assignment for the lowest electronic transition of [Ru(mbpyCOOH)3]2+.

KW - Acid-base

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KW - Ruthenium(II) tris(4′-methyl-2,2′-bipyndine-4-carboxylic acid)

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