Lighting up zinc: switchable probes for biological imaging

Individual condensation of salicylaldehyde and a variety of different pyridines (equimolar concentration) in polar solution results in a yellowish-orange precipitate (imine-derived product). The study shows that these small-molecule compounds possess turn off and on fluorescence properties upon chelation with Zn²⁺ ions. When reacted with other metal ions, there was no significant increase in the fluorescence intensity of the probes. However, there was multi-fold increase in fluorescence intensity when the probes reacted with Zn²⁺ ions. The probes can be employed as zinc-specific sensors in multiple applications including bioimaging, nanotechnology and environmental sciences.