Synthesis And Properties Of Chalcone Derivatives As Chemosensors For Cyanide Anions

Cyanide has formidable toxicity and threatens the safety of human and animal life. However, cyanide plays an important role in many industrial production. Therefore, the investigation on cyanide anion chemosensors aroused the interest of many scholars. In this thesis, sixteen chemosensors for cyanide anions were designed and synthesized. They are divided into two categories including chalcone derivatives and coumarin chalcone derivatives. Their photophysical properties and cyanide ion recognition properties were investigated systematically. The molecular structures of the compounds are shown in the following:(1) Chalcone compounds 1-8(2) Coumarin chalcone compounds 9-16In this thesis, sixteen compounds were synthesized, among which, the crystal structure of three compounds(compound 1, 9 and 13) were obtained. The crystal structure of the three compounds were analysized systematically. The results indicates that compounds 1 and 9 possess high planarity. The planarity of compound 13 is bad, which induces the poor fluorescence of compound 13.Among chalcone compounds 1-8, nitro substituted chalcone compounds 1 and 2 can recognize cyanide ions in aqueous solution. The detection limits of the compounds for CN- in CH3CN-H2O(1:1, v/v) with UV-vis absorption as detected signal are 0.2 ?M(1) and 0.19 ?M(2). The color and fluorescence changes of diethylamine nitro subsitituted chalcone compound 3 can be employed to recognize cyanide anions by naked eye. Bonding mechanism analysis indicates that to compounds 1, 2, 4, 5 and 7, Michael addition reaction occurs and cyanide ions are bonded to C=C double bond of conjugated bridge. between the compounds and cyanide anions. For chalcone compounds 3 and 8 based on diethylaminecoumarin group, Michael addition reaction also occurs, but cyanide ions are bonded to 4-position of coumarin group. By comparing the situ 1H NMR and job's plots of compounds 6 and 7 for cyanide anions, the response mechanism of compound 6 for cyanide is not Michael addition reaction and is interaction between hydrogen in amine and hydroxyl group and cyanide ions.In the coumarin chalcone compounds system, the eight compounds 9-16 can not only recognize CN-, but also can recognize Cu2+. In addition, the color of this kind of compounds are very deep and the color change of compounds are more obvious after adding CN- or Cu2+. And then cyanide anions can be by recognized nacked eyes. Specially, compounds 13-16 with pyrrol ring were got accidentally during the process of synthesizing compounds 9-12. And the structure of the four compounds is very novel. Besides, the mechanism investigation indicates that cyanide group is bonded to C=C double bond in conjugated bridge(9-12) or 4-position of coumarin group(14 and 16)). The bonding mechanism between the compounds and copper ions is complexation.