Synthesis Of Novel Tweezers Hydrazone Receptors And The Recognition Properties

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 anion recognition, as an important part of molecular recognition, has been given great attention from many specialists. We have synthesized some novel hydrazone tweezers receptors and studied on their anion recognition properties. The major contents are as follows:Researches in the development of anion recognition were briefly reviewed, Which contain the following topics: (i)the principle of molecular recognition, the significane of anion recognition, the structural characteristics of anions impact on receptor design; (ii) the development of anion recognition properties hydrazone receptors; (iii) the development of anion recognition properties in water-containing media. (â…³) tweezers receptors anion recognition properties.1.Three novel 1,3-benzyldiacyl hydrazone derivatives(4a⁴c) have been designed and synthesized in the paper.The binding properties of the receptors with anions such as F^-, Cl^-, Br^-, I^-, CH₃COO^-, HSO₄^-, H₂PO₄^- and ClO₄^- in DMSO were investigated by UV-Vis and ¹H NMR spectroscopy. As a result, receptor 4a(1,3-benzyldi (4-nitrophey -l-2-furfuraldehyde) methacylhydrazone) can recognize anions through hydrogen binding in DMSO solutions. A clear color chang was observed from yellow to dark yellow and pale red upon addition of F^- and CH₃COO^- . ¹H NMR titrations and salvation effect confirm hydrogen bonding interaction between the receptors and anions. Job curve indicates that a 1:1 stoichiometry complex is formed between the receptors and the two anions. Based on the above results, the recognition binding mode were discussed. The molecular recognition ability is discussed in terms of the size and shape-fit as well as the recognition model between host and guest molecules.2.Three novel artificial tweezer receptors 1, 3-benzyldiacylhydrazone derivatives with symmetrical structure have been synthesized. Receptor 3a for anions (F^-, Cl^-, Br^-, I^-, AcO^-, HSO₄^-, H₂PO₄^-, ClO₄^-) were investigated by UV-vis spectroscopy in DMSO and even in DMSO-H2O binary solutions, respectively. Remarkable color changes from colorless to yellow were observed by the'naked-eye'upon the addition of AcO^-, F^- and H₂PO₄^- to solution of receptor 3a. The ¹H NMR signals indicated that the receptor 3a occur deprotonation after the addition of an excess of fluoride anion. In particular, the anions recognition was successfully applied to inorganic CH3COONa in 15% H₂O-85% DMSO. These findings were expected to be of significance for designing and developing novel color-based anion sensors operated in aqueous.3. Six 1,3-benzyldiacyl hydrazone derivatives(4a⁴f) with symmetrical structure have been designed and synthesized by condensation of 1,3-benzyldiacyl hydrazine from 1,3-phthalic acid with various aromatic aldehydes and were characterized by elemental analysis, IR, and ¹H NMR. by UV-Vis studies about receptors colorimetric sensors for anions are presented. As a result, receptor 4a, 4b and 4c can recognize F^- and CH₃COO^- . the color and absorb solution spectrum have seen tremendous changes that are clearly visible to the naked eye. Preliminary test results showed that the biological activity of the series some of the compounds in different concentrations of plant growth regulator show a certain regularity.