Design And Synthesis Of Novel Sensors For Cyanide Recognition Properties

Sensors are widely used in environmental, biological and many other fields due to its rapid identification, simple synthesis process, their high sensitivity and good selectivity. In recent several years, it has become a hot research topic. Among the sensors, reaction-based sensors are designed according to the special chemical reaction between the sensor and object, with specific selectivity and higher sensitivity, are widely applied in detection of various kinds of ions and toxic chemical substances. In this paper, based on the mechanism of ICT, we synthesized two novel sensors for the detection of cyanide using nucleophilic addition reaction of the C=C and C=N. The main contents are as follows:1.A new dual-channel sensor for the detection of cyanide was developed based on the conjugated of naphthalene and malononitrile. Upon the addition of CN", the sensor displayed very large blue-shift in both fluorescence (80 nm) and absorption (120 nm) spectra. The sensor of cyanide was performed via the nucleophilic attack of cyanide anion to vinylic groups of the sensor with a 1:1 binding stoichiometry and the color changed of the sensor is mainly due to the intramolecular charge transfer process improvement. The intramolecular charge transfer progress was blocked with color changed and fluorescence blue-shift. The mechanism of sensor reaction with CN" ion was studied using 1H NMR and mass spectrometry.2. A "donor-two-acceptor" cyanide sensor L2based on 3-ethyl-2-methyl-1,3-benzothiazol-3-ium iodide and 5-nitrosalicylaldehyde has been designed and prepared. This structurally simple sensor displays rapid response for cyanide over other common anions (F-, Cl-, Br-, I-, AcO-, H2PO4-, HSO4-, ClCS2-, N3- and SCN") in aqueous solution. A large blue shift (87 nm) was also observed in the absorption spectra in response to CN". The bleaching of the color could be clearly observed by the naked eye. By the nucleophilic attacking of CN- to the benzothiazol C-2 atom of the sensor, the intramolecular charge transfer progress was blocked with color changed and fluorescence quenched. The mechanism of the reaction of the sensor with the cyanide ion was established by using 1H NMR and mass spectrometry.