Phosphorescence quenching of l(-)-tryptophan in dimethyl sulfoxide at 77 K by trivalent lanthanide ions

Abstract

Quenching of the corrected phosphorescence emission of tryptophan in dimethyl sulfoxide by trivalent lanthanide ions Ln 3+ can be interpreted in terms of a static model leading to triplet quenching constants k Q T ranging from 1.3 × 10 1 to 9.1 × 10 1 M −1. The values of k Q T increase with increasing spectral overlap and J values of the ground state of the appropriate lanthanide ions. The phosphorescence lifetime of tryptophan is virtually independent of [Ln 3+] and has a value of 6.15 ± 0.25 s, in agreement with the static model of triplet quenching.