Dipyridophenazine Complexes of Ru(II): Versatile Optical Sensors for Small and Large Molecules

摘要

Bis(phenanthroline)dipyridophenazineruthenium(II), [Ru(phen){sub}2dppz]{sup}(2+), exhibits unusual optical properties compared to other derivatives of [Ru(bpy){sub}3]{sup}(2+). [Ru(phen){sub}2dppz]{sup}(2+) does not exhibit photoluminescence in water, but does emit brightly at ～610 nm in the presence of nonaqueous solvents or hydrated polymers like DNA and Nafion. We have observed this "light switch" effect upon binding [Ru(phen){sub}2dppz]{sup}(2+) to a protein with a hydrophobic pocket (chymotrypsin), suggesting that we may be able to develop optical probes of protein tertiary structure. We have also prepared derivatives of [Ru(phen){sub}2dppz]{sup}(2+) that have ancillary ligands other than phenanthroline, and find that these molecules change color upon exposure to small molecules; the environmental parameters we have been able to assess so far include Lewis acidity, the nature of hydrated counterions, polarity, and hydrogen-bond donation ability.