Synthesis and chemosensitivity of a new iminium salt toward a cyanide anion.

A short, high-yielding route to pyranylidene Iminium (Imi) salts using a new pyrylium salt reaction between N,N-Dimethylformamide (DMF) and acetic anhydride is reported. The Imi salt-sensing behavior toward various anions has been investigated using UV-Visible spectroscopy. The Imi salt demonstrates high selectively for CN(-) when various other anions, such as CN(-), Cl(-), Br(-), I(-), SCN(-), ClO4(-), NO3(-), HSO4(-), PF6(-) and N3(-), are present because it is highly reactive towards nucleophiles. The selective detection of CN(-) with the Imi unit gave rise to a significant hypochromic shift in the CH3CN solution at λmax=444nm and 423nm and creation of new peak at 252nm. These studies indicated that CN(-) had high affinity toward Imi, forming a 1:1 complex; this observation agrees with the current understanding of these materials.