A novel bifunctional-group salamo-like multi-purpose dye probe based on ESIPT and RAHB effect: Distinction of cyanide and hydrazine through optical signal differential protocol

Abstract

A novel bifunctional-group multi-purpose dye probe p-TNS has been designed and synthesized. The probe p-TNS has unique excited-state intramolecular proton transfer (ESIPT) and resonance-assisted hydrogen bonding (RAHB) coupled system, was confirmed to detect cyanide and hydrazine by blocking the ESIPT effect. Cyanide can change the fluorescence of the solution from bright green to orange-red (116 nm Stokes shift), while hydrazine causes the bright green fluorescence to be quenched. The recognition mechanism of the probe p-TNS to CN^- and N₂H₄ was proposed reasonably through spectral characterizations and theoretical calculations. Combined with theoretical calculations, it was speculated that the solvent dependence may be caused by the ICT effect in the molecule. The probe p-TNS could be prepared into test strips for the detection of cyanide and hydrazine. In addition, the probe molecule can also be used to detect trace amounts of cyanide in agricultural products, and respond to gaseous hydrazine by direct contact, indicating that the probe p-TNS has good practical application prospects. Therefore, this molecular framework provides a new way of thinking about detecting multiple target substances.

Keywords: Chemosensor; Cyanide; Hydrazine; ICT; RAHB.