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Updated: Jan 8, 2026

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Photo-Migration of Chloride Ions Associated with Amide Substituents on Ruthenium Polypyridyl Complexes
John C Dickenson1, Gerald J Meyer1
1Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
Abstract:
Ruthenium bipyridyl complexes bearing amide or ester functional groups were investigated for chloride ion recognition and migration applications. [Ru(dba)(dtb)2]2+ (Ru-dba) and [Ru(dba)(btfmb)2]2+ (Ru-btfmb), where dba is 4,4'-(CONHC4H10)2-2,2'-bipyridine, dtb is 4,4'-(tert-butyl)2-2,2'-bipyridine, and btfmb is 4,4'-(CF3)2-2,2'-bipyridine, were found to form 1:1 noncovalent assemblies with chloride ions with large equilibrium constants, Keq = 2.2 × 107 M-1. The location of the association was identified by 1H NMR spectroscopy. Chloride association impacted the photoluminescence (PL) maximum, inducing a 650 cm-1 blue shift for Ru-dba and a 490 cm-1 red shift for Ru-btfmb. Infrared (IR) spectroscopy provided evidence of chloride hydrogen bonding to both Ru-dba and Ru-btfmb. Time-resolved IR (TRIR) measurements following the pulsed 532 nm laser excitation of Ru-dba revealed an excited-state absorption at 1645 cm-1, assigned to the amide functional group. In the presence of chloride, the excited-state absorption shifted to lower energy with a time constant of 550 ± 50 ns. No such spectral shifts were observed with Ru-btfmb or the ester complex. A model is proposed wherein an excited-state dipole oriented toward the halide ion induces chloride migration out of the bipyridine plane.
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