Chelation of specific metal ions imparts coplanarity and fluorescence in two imidazo[1,2-a]pyridine derivatives: Potential chemosensors for detection of metal ions in aqueous and biosamples.

Synthesis and chelation induced fluorescence emission from two imidazo[1,2-a]pyridine derivatives are described. The nonfluorescent molecule 1 containing N and O donor atoms, achieves coplanarity upon interactions with trivalent cations Al, Fe and Cr, that favors fluorescence emission. Molecule 2 containing two N donor atoms attains coplanarity upon interaction with the only Zn and becomes fluorescent. Both molecules 1 and 2 form a 1:1 complex with interacting metal ions. Other trivalent metal ions (including Bi and In) and common divalent metal ions (including Hg and Cd) fail to form any complex with 1 or 2, and they do not interfere in the detection of Zn, Al, Fe or Cr ions. Noninterference of other metal ions renders 1 and 2 suitable for the detection of fungal cells contaminated with Zn, Al, Fe or Cr ions.