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Updated: Nov 16, 2025
Determination of the Photoisomerization Quantum Yield of a Hydrazone Photoswitch
Published on: February 7, 2022
Two RuII Linkage Isomers with Distinctly Different Charge Transfer Photophysics
Jérôme Tisaun1, Baptiste Laramée-Milette2, Joseph S Beckwith3
1Chimie Organique et Photochimie CP 160/08, Université Libre de Bruxelles, Av. Franklin D. Roosevelt 50, 1050 Brussels, Belgium.
Abstract:
The ligand PHEHAT (PHEHAT = 1,10-phenanthrolino[5,6-b]1,4,5,8,9,12-hexaazatriphenylene) presents a structural asymmetry that has a dramatic influence on the photophysical properties depending on the chelation site of the metal ion in the linkage isomers. While [RuII(phen)2HATPHE]2+ behaves classically, like [RuII(bpy)3]2+, [RuII(phen)2PHEHAT]2+ exhibits an unusual behavior. It appears that this complex has two 3MLCT bright states, the lower one being weakly emissive or nonemissive depending on the solvent and temperature. Different photophysical techniques involving a wide range of various temperatures and timescales are essential to analyze this difference. A full photophysical scheme is proposed based on experimental data and density functional theory calculations. While previous studies focused on high temperatures and longer timescale emission, we explore the complexes at very low temperatures and very short times in order to obtain a more complete picture of the intriguing photophysical behavior of these complexes.
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