Medium effects on the photophysical properties of terbium(III) complexes with pyridine-2,6-dicarboxylate

Photochem Photobiol Sci. 2002 Dec;1(12):925-33. doi: 10.1039/b206370k.

Abstract

Emission quantum yields and excited-state lifetimes of mono-, bis- and tris-complexes of terbium(III) with pyridine-2,6-dicarboxylate (DPA) have been measured for aqueous solutions as a function of pH and in the presence of six different anions: bromide, chloride, sulfate, perchlorate, acetate and nitrate. The state of ligation of the terbium ion had a more dramatic effect on photophysical properties of the complexes in comparison with the alteration of other medium parameters. An increase in the number of DPA ligands, coordinated with Tb3+ (from zero to three) resulted in an increase in the emission quantum yield from 0.06 to approximately 0.4, with concurrent prolongation of the excited-state lifetime from 0.5 to approximately 2 ms. It was determined that both an increase in the non-radiative decay rates and a decrease in the values of the radiative decay rate constants, contribute to the luminescence quenching that was detected when the number of DPA ligands was decreased and/or the media acidified. The purpose of this investigation is to aid in the establishment of optimal conditions for conducting terbium(III)-based emission assays for DPA, which is found in the coats of endospores.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Anions / chemistry
  • Carboxylic Acids / chemistry*
  • Hydrogen-Ion Concentration
  • Kinetics
  • Ligands
  • Luminescent Measurements
  • Organometallic Compounds / chemistry*
  • Photochemistry
  • Pyridines / chemistry*
  • Quantum Theory
  • Spectrophotometry, Ultraviolet / methods
  • Terbium / chemistry*

Substances

  • Anions
  • Carboxylic Acids
  • Ligands
  • Organometallic Compounds
  • Pyridines
  • Terbium