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

• Synthesis of a new pyranylidene iminium (Imi) salt in high yields (92%).
• Pyranylidene iminium (Imi) salt can be used to determine CN− ion with high selectivity.
• Imi salt attracts the nucleophilic CN− ion to form the cyano-enone structure.
• Selective binding leads to ∼171 nm [423–252 nm] hypsochromic (blue) shift.
• The binding mechanism and product identity were confirmed using FT-IR studies.

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 = 444 nm and 423 nm and creation of new peak at 252 nm. 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.

Figure optionsDownload as PowerPoint slide