Photophysical properties of rhenium(I) tricarbonyl complexes containing alkyl- and aryl-substituted phenanthrolines as ligands

Abstract

A number of complexes of the type Re(L-L)(C0)3py+ have been prepared, where L-L is 1,lO-phenanthroline or a phenanthroline derivative containing methyl or phenyl groups and py is pyridine. All of the complexes are highly emissive at room temperature in solution or at 77 K in a glass, and the room-temperature luminescence data are consistent with emission from a 3MLCT state. The emission maximum ranges from 510 to 548 nm in CH*Clz, depending on L-L, and a linear relationship between A, , , and the electrode potentials for oxidation and reduction is evident. Lifetimes in acetonitrile are of the order of several microseconds at room temperature (1.6-1 3 ps), and emission quantum yields are very high (0.17-0.29). Results of photophysical measurements performed at low temperature indicate the presence of two unequilibrated emitting states, a 3MLCT and a 3LC (ligand-centered) state. Time-resolved spectra have established that the 3LC state is the longer-lived of the two and gives a structured spectrum similar to that of the uncoordinated ligand L-L. Both states show a dependence on the substitution pattern, and the contribution of each is determined by the particular L-L. Trends in the room-temperature data may also be accounted for by invoking a multistate model: however, the states are in thermal equilibrium under these conditions.

Photo-ribonucleotide reductase β2 by selective cysteine labeling with a radical phototrigger

“…Spectroscopic studies of ultraviolet-visible absorption and steady-state emission (Fig. 3) show the characteristic features of an electronic structure derived from metal-to-ligand charge transfer (27).…”

Synthesis, structure and characterization of fac-[Re(CO)3]+ complexes derived from hydrazone Schiff bases: DFT–TDDFT investigation on electronic structures

“…It has been reported earlier [11] that the study of electrochemical behavior is an important phenomenon of the complexes involving HOMO and LUMO in the redox processes. In the present case, the complexes are electroactive in acetonitrile solution at Platinum electrode vs SCE.…”

Ligand Variations in [ReX(diimine)(CO)3] Complexes: Effects on Photocatalytic CO2 Reduction

“…[15] Detailed studies have unveiled the remarkable photochemical properties of [ReCl(phen)(CO) 3 ] and related compounds such as [ReX(bipy)(CO) 3 ] (X = Cl -1, X = Br -2). [5,9,16,17] The excited state generated by visible light absorption at 450 to 500 nm has been identified as a metal to ligand charge transfer (MLCT) state, with the photoelectron ejected from a metal-centred π-d into a vacant ligandcentred π* orbital with up to µsec lifetimes. On the basis of the Rehm-Weller approximation [18] the photoexcited molecules are powerful oxidising agents with potentials of +500 to +1200 mV (vs. Ag/AgCl).…”