Synthesis And Anion Recognition Properties Of Thiosemicarbazone And Sulfahydrazone Derivates

Molecular recognition is the process that host molecular form binding with guest molecular selectively and produce some special function, which is an important research area in supramolecular chemistry. The development of anion coordination chemistry is delayed compared with neutral moleculars and cations. It is therefore necessary to construct novel anion receptors. In this thesis, we have synthesized some novel thiosemicarbazone and sulfahydrazone derivative receptors and studied on their anion recognition properties. The major contents are as follows:1. Researches in the development of anion recognition were briefly reviewed. The coordination chemistry of anions has received little attention over the last 30 years when compared to that devoted to coordination chemistry of cations. Therefore a number of anion recognition systems have been reported. The content of this chapter includes: (1) Molecular recognition. (2) Structural characters of anions. (3) Noncovalent interactions existed in anion coordination. (4) The development of anion recognition researchers of thiosemicarbazone derivative receptors. (5) the former research work on synthesis and recognition property of crown ether2. Three N-arylthiosemicarbazone receptors of 4'-acetylbenzo-15-crown-5 have been prepared and characterized. The binding properties of the receptors 3a, 3b, 3c with anions such as F^-, Cl^-, Br^-, I^-, CH₃COO^-, HSO₄^- and NO₃^- in acetonitrile were examined by UV-Vis spectroscopy method. The results showed that the three receptors had a better selectivity for F^- and CH₃COO^-, but no evident binding with Cl^-, Br^-, I^-, ClO₄^- and NO₃^-. The UV-Vis data confirmed that a 1:1 stoichiometry complex was formed between compound 3a, 3b, or 3c and anions. Moreover, from the investigation of their bioactivity, they showed good plant growth regulative property.3. Six N-arylsulfahydrazone receptors of 4'-acetylbenzo-15-crown-5 have been prepared and characterized. The binding properties of the receptors with anions such as F^-, Cl^-, Br^-, I^-, CH₃COO^-, H₂PO₄^-, HSO₄^- and NO₃^- in DMSO were examed by UV-Vis. The results showed that the six receptors had a better selectivity for F^-, CH₃COO^- and H₂PO₄^-, but no evident binding with Cl^-, Br^-, I^-, ClO₄^- and NO₃^-, and the compounds with hydroxyl showed better recognizable function than others. Futhermore, they showed good plant growth regulative property from the investigation of their bioactivity.4. A new series of p-aryldiformaldehyde bisarylthiosemicarbazone receptors (3a, 3b, 3c) have been synthesized by simple steps in good yields. Their anion recognition properties were studied by UV-vis. The result showed that receptors 3a, 3b, 3c had no evident binding with Cl^-, Br^-, I^-, NO₃^- and HSO₄^- but a better selectivity for F^-, CH₃COO^- and H₂PO₄^-. Upon addition of the three anions to the receptors in DMSO, the solution acquired a color change from colorless to dark yellow that can be detected by the naked-eyes, thus the receptors can act as fluoride ion sensors even in the presence of other halide ions.