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 (Cd ²⁺ , Co ²⁺ , Cu ²⁺ , Fe ²⁺ , Hg ²⁺ , Ni ²⁺ , and Zn ²⁺ ) with high affinity in organic-aqueous media (DMSO-HEPES). The chemodosimeters coordinate with the Zn ²⁺ ions in a two-to-one ratio (molecular probe : Zn ²⁺ ) with a log  β 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 Zn ²⁺ ions. Confocal microscopy monitored free Zn ²⁺ ions in the Human Embryonic Kidney cell line HEK293 by coordinating with the chemodosimter.