Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5398247 | Journal of Luminescence | 2016 | 6 Pages |
Abstract
Nanosecond laser flash photolysis and time resolved luminescence were used to study the photophysical processes for Eu((i-Bu)2PS2)3Phen (1) and Eu(C4H8NCS2)3Phen (2) complexes in acetonitrile. These complexes show a very weak red Eu3+ luminescence in spite of the fact that the phenanthroline molecule in triplet state is a good antenna to excite the red luminescence of many Eu(III)-Phen complexes. To determine the reasons of this effect the photoprocesses in solutions, containing the (i-Bu)2PS2â or C4H8NCS2â ions and free phenanthroline molecule, have been studied with the use of laser flash photolysis (266Â nm). It was shown that the phenanthroline in triplet excited state (TPhen*) deprives the electron from these dithiolate ions with a high rate constants close to 109Â Mâ1Â sâ1. The transient spectra of phenanthroline anion-radical and dithiolate radicals were recorded which are in a good agreement with literature data. Since the effective concentration of dithiolate ions (Lâ) in the coordination sphere of 1 and 2 complexes is close to 10Â M the time of electron transfer between Lâ and TPhen* is in the range of 100Â ps or less. As the laser flash photolysis of solutions of 1 and 2 complexes with a 10Â ns time resolution failed to detect the spectra of phenanthroline anion-radical and dithiolate radicals, it indicates that the time of back electron transfer is less than 10â8Â s. Thus, the very weak red luminescence of 1 and 2 complexes is due to the electron transfer between ligands in the coordination sphere which successfully suppresses the energy transfer from the phenanthroline triplet state to Eu3+ ion.
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Related Topics
Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Arkady S. Kupryakov, Victor F. Plyusnin, Vyacheslav P. Grivin, Julia A. Bryleva, Stanislav V. Larionov,