Synthesis And Anion Recognition Properties Of Novel Schiff Base Receptors Based On Azophenol And Mercapto Thiadiazole

There are three chapters for this thesis:Molecular recognition is the process that host molecular binds with guestmolecular selectively and result in some special functions, which is an important fieldof researching in supramolecular chemistry. It include the recognition for anions,cations and neutral moleculars, in which the development of anions coordinationchemistry is slower than that of neutral moleculars and cations. It is thereforenecessary to design novel anion receptors. The anion recognition chemistry, as animportant part of molecular recognition, has been given considerable attention fromlots of specialists both home and abroad. The key is to synthesize artificial hosts withhigh selectivity for particular ions so as to sense special ions selectively incompetive media such as water. A series of novel selective colorimetric acetate hostscontaining Schiff Base, azophenol and mercapto thiadiazole had been designed andsynthesized and their ions recognition were studied. The anions recognition of manyother phenolic hydroxyl host were also studied.The major contents are as follows:1. Literature review:Researches in the development of anions recognition were briefly reviewed,Which contain the following topics:①the principle of molecular recognition, thesignificane of anion recognition, the structural characteristics of anions impacting onhost design, host characteristics of schiff base;②the development of anionsrecognition properties of thiourea hosts and thiourea hosts bearing schiff base;③thedevelopment of anions recognition properties about complex of schiff base hosts;④the development of anions recognition properties of azophenol;⑤the development ofanion recognition properties of Schiff base bearing phenolic hydroxyl hosts;⑥thedevelopment of anion recognition properties of Schiff base without phenolic hydroxylhosts;⑦the development of anion recognition properties of phenolic hydroxyl hosts;⑧the development of anion recognition properties in water-containing media.2.The studies of anion host3bearing Schiff base, azophenol and mercaptothiadiazole: A novel acetate selective anion host3based on azophenol and mercaptothiadiazole had been designed and synthesized. host3behaves a single selectivity andsensitivity in the recognition for AcO-anion over other anions such as F^-, Cl^-, Br^-, I^-,H₂PO₄^-, HSO₄^-and ClO₄^-by naked-eyes and UV-vis spectra changes in aqueoussolution （H₂O/DMSO,5:5, v/v）. The color of the solution containing host3had anobvious change from colorless to orange only after the addition of AcO-in aqueoussolution while other anions did not cause obvious color change.1H NMR titrationresults revealed that the binding process includes two steps:（i） hydrogen bondinginteractions （for small quantities of acetate） and （ii） proton transfer between the host3and the coordinated anion （for high quantities of acetate）. The association constant Kawas7.35×10³M^-1. The detection limitation of AcO-with the host3was1.0×10^-6mol·L1. The cations recognition properties of a novel acetate selective anion host3based on azophenol and mercapto thiadiazole were also carried out in DMSO andDMSO-H₂O with UV-vis spectra separately. The results showed that host3could notselectively recognize cations which were used.3.The studies of anion recognition properties phenolic hydroxyl hosts inwater-containing media:The development of anion recognition properties of5-nitro salicylic aldehydehost（M4） as well as a series of colorimetric phenolic hydroxyl hosts4-nitrophenol（M1）,2-nitrophenol（M2） and2,4-dinitrophenol（M3） were studied inboth single media and water-containing media.