Effects of europium spectral probe interchange in Ln-dyads with cyclen and phen moieties. Issue 13 (12th March 2019)

• Record Type: Journal Article
• Authors: Bao, Guochen; Liu, Zhenyu; Luo, Yuxia; Wong, Ka-Leung; Tanner, Peter A.
• Is Part Of: Dalton transactions. Volume 48:Issue 13(2019)
• Page Start: 4314
• Page End: 4323
• Publication Date: 2019-03-12
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c9dt00533a
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Antenna-lanthanide energy transfer is investigated via a bimetallic complex with one silent and one probe lanthanide ion, when their positions are interchanged in the complex. Abstract : Herein, we have investigated spectral structure and intensity changes in a bimetallic lanthanide complex comprising La 3+ and Eu 3+, with the ions coordinated to silent and antenna ligands, when their positions are interchanged. Comparison of the fluorescence decay of a ligand in the presence and absence of La 3+ has enabled internal nonradiative decay rates to be determined. The effects upon Eu 3+ emission spectra resulting from changes in its environment at a distance of ∼10 Å, and upon changing from the solid state to solution, were also investigated. Conclusive results to these investigations were achieved from the electronic excitation spectra, emission spectra and emission decay measurements ofcyc-phen, cycLn 1 -phLn 2, cycLn-phen andphLn (Ln = La, Eu; cyc = substituted 1, 4, 7, 10-tetrazacyclododecane; phen = 1, 10-phenanthroline; ph = phen(pdtc)3, pdtc = pyrrolidine-1-carbodithioate) recorded in the solid state, at 298 K and ∼10 K, and in solution. Ligand fluorescence was observed in all cases at room temperature, and phosphorescence was observed at 77 K, except forcyc-phen . The phosphorescence lifetimes of the La 3+ complexes extend up to 180 ms. Our results support the concept that the lowest excited states of the complexes are localized on individual ligands, in the present case phen, rather than delocalized over the entire molecule.