Molecular keypad locks based on gated photochromism and enhanced fluorescence by protonation effects.

Being a "lock-unlock" system, gated photochromism is generally applied in nondestructive readout for optical memory materials. In the presented paper, we successfully constructed molecular keypad locks by introduction of the gated photochromism. A series of diarylethenes compounds (DAEs) based on fluorescent 5-methoxy-2-pyridyl thiazoles, were prepared and then characterized as photochromic fluorescent switches. Protoantion of the reported DAEs resulted in both protonation-locked photo-reactivities, i.e., gated photochromism, and enhancement of fluorescence. Molecular keypad locks were then successfully constructed, which are also featured by "one-key" lock operation.