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Energy transfer from the excited 3*MLCT states to organic acceptors – Temperature effect studies

Paper ID Volume ID Publish Year Pages File Format Full-Text
26858 43982 2014 6 PDF Available
Title
Energy transfer from the excited 3*MLCT states to organic acceptors – Temperature effect studies
Abstract

•Energy transfer processes involving 3*Ir(ppy)3 or 3*Ru(bpy)32+ have been studied.•Solvent and temperature effects have been investigated.•The overall energy transfer rates have been found to be slower than diffusion.•Temperature affects the energy transfer rates through medium viscosity changes.•Magnetic quantum number conservation rule explains the observed deviations.

Energy transfer from the excited (3*D) metal-to-ligand-charge-transfer triplet state (3*MLCT) to selected organic energy acceptor quenchers (A) has been investigated for Ir(ppy)3–chrysene and Ru(bpy)32+–pyrene systems at different temperatures in several organic solvents. For both systems studied, reversible, nearly iso-energetic energy transfer processes 3*D + A ⇌ D + 3*A have been observed. In the presence of an organic quencher, the 3*D emission decays change from the mono-exponential (characteristic for the excited 3*D state of the investigated complexes) to the bi-exponential ones that enables the determination of the kinetic parameters characterizing the investigated forward 3*D + A → D + 3*A and backward 3*D + A ← D + 3*A energy transfer processes. Analysis of the obtained kinetic (rate constants) and thermodynamic (activation energies) data have been performed in the framework of different kinetic models, with the main conclusion that the “classical” Sandros and Balzani models are inadequate for proper description of the experimental results. A much better agreement between theoretical predictions and experimentally found results can be found if the magnetic number conservation rule is implemented in the 3*D + A ⇌ D + 3*A reaction scheme. The obtained results suggest that during the energy transfer processes occurring according to the Dexter mechanism, not only spin but also magnetic quantum number within 3*D…A and D…3*A activated complexes are conserved.

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Keywords
Excited 3*MLCT states; Luminescence decays; Energy transfer processes; Solvent and temperature effects; Magnetic quantum number conservation rule
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Energy transfer from the excited 3*MLCT states to organic acceptors – Temperature effect studies
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 292, 15 October 2014, Pages 10–15
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us