A molecular chemodosimeter to probe "closed shell" ions in kidney cells.

Two quinidine-functionalized coumarin molecular probes have been synthesized and have been found to bind metal cations (Cd2+, Co2+, Cu2+, Fe2+, Hg2+, Ni2+, and Zn2+) with high affinity in organic-aqueous media (DMSO-HEPES). The chemodosimeters coordinate with the Zn2+ ions in a two-to-one ratio (molecular probe : Zn2+) with a log ß of 10.0 M-2. Upon the addition of the closed-shell metal ions studied, a fluorescence turn-on via an excimer formation is seen at 542 nm due to the quinaldine moiety adopting a syn arrangement when coordinated to the metal Zn2+ ions. Confocal microscopy monitored free Zn2+ ions in the Human Embryonic Kidney cell line HEK293 by coordinating with the chemodosimter.