Studies On Synthesis And Properties Of Several Novel Thiacalix"4"arene Receptors

Thiacalixarenes are one of the hot research topics in supramolecular chemistry and materials science, and have shown wide applications in some advanced techniques such as selective ion transport, molecular devices, chemical sensors and molecular switch. Investigation on optical- and redox-active receptors is a field of increasing interest. So, on the base of the recent research progress of thiacalix[4]arene-based optical- and redox- active receptors including the molecular design, synthesis and their applications in supramolecular recognition, a study on synthesis, characterization and properties of new thiacalix[4]arene receptors attaching the optical and electrochemical probes in the upper rim was carried out. The main results are as follows:In the first part, a 1,3-dialkylation derivative of thiacalix[4]arene was obtained by the selective O-alkylation reaction, and used as the key intermediate in the following synthesis. Seven novel thiacalix[4]arene derivatives, alternately attaching two same groups at the upper rim and two different pair units at the lower rim, were successfully synthesized via the selective electrophilic substitution at the upper rim directed by the hydroxy and alkoxy groups. Their structures were fully characterized by IR, 1H NMR, 13C NMR and elemental analysis, as well as the structures of five molecules being determined by X-ray diffraction techniques.In the second part, the first examples of thiacalix[4]arene receptors R1 and R2, in which two ferrocenyl or two quinolinyl units were alternately attached in the upper rim as responding probes by 1,2,3-triazole linkers, respectively, were synthesized via click reaction. Their recognizing and sensing properties for some metal ions were evaluated using fluorescence, UV-Vis and cyclic voltammetry techniques. It was found that R1 shows a good selectivity for fluorescent sensing of Zn²⁺, Cd²⁺and Cu²⁺ ions, while R2 gives a high selectivity for fluorescent sensing of Ag+ and Ni2+.In the last part, a 1,3-alternate thiacalix[4]arene acyclic crown ether receptor R3, containing four ferrocenyl probes in the terminus of four ether chains was synthesized via the CuAAC reaction. Its recognition and sensing properties was examined via fluorescence, UV-Vis and cyclic voltammetry methods. It was found that R3 can selectively sense Cu²⁺ and H₃O⁺.