Dual role of silver in a fluorogenic N-squaraine probe based on Ag(I)-ππ interactions

Abstract

[eng] In the presence of Ag(I), the monoanion of cyano-N-squaraine (I) generates an intense fluorescence turn-on response. Experimental evidence and DFT calculations reveal a sequence of deprotonation-coordination events in which the Ag(I) ions play a dual role as a Lewis acid and coordinating metal. The observed effect is highly selective for Ag(I) compared to other metals.