Synthesis Of Novel Schiff Base Receptors And The Ions Recognition Properties

This paper includes four chapters:Chapter1: The first chapter is about the research of cation recognition in recentyears, which contain the following part:（i） the research status and the principle ofmolecular recognition, the significance of cations recognition;（ii） the impact ofcations structural characteristics on receptor design;（iii） the latest research status ofanions and ions recognition;Chapter2: The second chapter is about one simple mercapto thiadiazole-basedreceptor was synthesized by a convenient method. A simple and sensitive mercaptothiadiazole Schiff-base colorimetric chemosensor2was synthesized. It exhibits goodselectivity and sensitivity for the mercury cation over other metal cations such as Zn²⁺,Pb²⁺, Cd²⁺, Ni²⁺, Co²⁺, Ag+, Ca²⁺, Mg²⁺and Cr³⁺both in aqueous solution and onpaper-made test kits. The change in color is very easily observed by the naked eye inthe presence of Hg²⁺cation, whereas other metal cations do not induce such a change.The chemosensor2showed remarkably anti-interference ability towards other metalcations and the detection limit toward Hg²⁺was1.5×10^-5M.Chapter3. The third chapter is about a novel and sensitive anion receptor3, bearingSchiff base structure, nitrophenyl azobenzol and carboxyl groups, was developed andcharacterized as a single chemosensor for the recognition of HSO₄^-anion. Thedifferent responses of UV–Vis spectra and color changes of3could be applied to therecognition for HSO₄^-over other anions such as F^-, CI^-, Br^-, I^-, AcO^-, H₂PO₄^-andCIO4-by the naked eye. Furthermore, the anion binding interaction of receptor–anionwas also studied using UV–Vis and1H NMR titration which revealed that3displayeda remarkable binding ability for the HSO₄^-with an association constant K_a=6.59×10⁴M^-1. And the detection limitation of HSO₄^-with the receptor3was2.0×10^-6mol L^-1 in aqueous solution. Most importantly, the qualitative detection of HSO₄^-using receptor3was attempted with test kit which was made from receptor3.