Optomechanical trans-to-cis and cis-to-trans isomerization and unusual photophysical behavior of fac-[Re(CO)3(phen)(CNstpy)]+

Unusual high photoassisted quantum yields for cis-to-trans (Φ254 nm = 0.27 ± 0.05) isomerization of CNstpy coordinated to fac-[Re(CO)3(phen)(CNstpy)]+ were determined along with trans-to-cis ones (Φ313 nm = 0.58 ± 0.02; Φ365 nm = 0.61 ± 0.06; Φ404 nm = 0.42 ± 0.02). Additionally, in contrast to other similar rhenium(I) complexes, the cis photoproduct is quasi non-emissive and comparable to the trans-complex. The cis-to-trans photoisomerization is due to the deactivation from the ILcis-CNstpy excited state in competition to the usual 3MLCTRe→phen luminescence. These efficient cis to trans and trans to cis photoisomerization can be conveniently used in light powered molecular machines.