1-(4-Nitrophenyl)-benzimidazolium-based ratiometric chromogenic probes for cyanide ion

1,3- and 1,4-bis-[1-(4-nitrophenyl)-benzimidazolium-3-methylene]benzene-based molecular probes interact selectively with cyanide ion to switch the absorbance from 270 nm to 376 nm and elaborate ratiometric chromogenic probes for the estimation of 1–270 μM cyanide ion—the desirable concentration range for practical applications.