Optical spectroscopic properties of europium, terbium-ruhemann's purple complexes, time-resolved luminescence imaging and applications
Luminescent lanthanide ions such as Eu^^ and Tfc^* show emission enhancement, when complexed with Ruhemann's Purples, RPs, (reaction products of ninhydrin and ninhydrin analogs with amino acids) via intramolecular energy transfer from the RP ligands (good absorbers) to the ions. This luminescence enhancement is due to the absorption enhancement of the Eu-RP and Tb-RP complexes and to the high quantum luminescence efîiciency of the Eu^'^ and Tb'^^ ions. We present the optical spectroscopic features (absorption, excitation, emission spectra, and emission lifetimes) of the complexes formed with RPs and Eu or Tb. The stoichiometry of these complexes and the mechanism of intramolecular energy transfer are also addressed. Substituent effects on lanthanide emission enhancement, and some applications of these complexes are presented as well.