Synthesis And Anion Recognition Properties Of Receptors Bearing Phenolic Hydroxy Groups

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 anion sensors bearing phenolic hydroxy groups 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 development of anion recognition properties of receptors bearing hydroxy groups were summarized including (i) receptors bearing alcoholic hydroxy groups (ii) receptors bearing phenolic hydroxy groups (iii) receptors bearing Azo-phenolic hydroxy groups.2. Novel receptors based on Schiff base bearing phenolic hydroxy groups have been synthesized and characterized. The UV-vis date indicated that a 1:1 stoichiometry complex was formed between receptors and F. ¹H NMR titrations and solvation effect confirmed hydrogen interaction between the receptors and anion. The results indicated that the affinity is related to the number of hydrogen bond. Hence, the receptors 1, 2 and 3 can act as fluoride ion sensors even in the presence of other hahide ions.3. Novel azine based receptors bearing phenolic hydroxyl groups have been synthesized and characterized. A remarkable color change was observed from ¹H NMR and UV-vis titrations upon addition of fluoride ions to the solution of receptors in DMSO. The addition of chloride, bromide and iodide to the receptors did not induce any change. The UV-vis date indicated that a 1:1 stoichiometry complex was formed between receptors and F. ¹H NMR titrations and solvation effect confirmed hydrogen interaction between the receptors and anion. Hence, the receptors bearing phenolic hydroxyl groups can act as fluoride ion sensors even in the presence of other hahide ions.4. Azo-salicylaldehyde Schiff containing an acidic H-bond donor moiety have been synthesized and characterized. The UV-vis date indicated that the receptors can act as selective colorimetric sensors either for basic anions or for acidic species hydrogen sulfate in water-containing medium. The experiment of Br0nsted acid-base reaction by adding the sodium hydroxide or perchloric acid revealed that deprotonation/protonation of the OH fragment by different anions and that the deprotonation/protonation process is fully reversible. The deprotonation/protonation of the receptors is responsible for the dramatic color change.5. A new series of crowned sulfonylhydrazone derivatives 3a³h have been synthesized by condensation of aromatic aldehydes with (benzo-15-crown-5)-4'-sulfohydrazide (2) and characterized by elemental analysis, IR, ¹H NMR, ¹³C NMR and mass spectra. The compound 2 was synthesized from benzo-15-crown-5 via sulphonation and hydrazinolysis. The UV-vis data indicated that the receptors 3d, 3e and 3h bearing phenolic hydroxy groups can act as selective sensors for basic anions.