Studies On Design, Synthesis And Properties Of Thiacalix[4]arene

Thiacalixarenes are of great significance in both supramolecular chemistry and materials science fields, as well as practical domain of advanced techniques such as ion transport, molecular switch, molecular devices and chemical sensors. In particular, thiacalix[4]arene-based crown ethers display more remarkable functions in selective recognition due to the combination of the advantages derived from the polyether chain and three-dimensional thiacalix[4]arene cavity. The design and synthesis of diverse optical and redox active receptors is a challenging topic in supramolecular chemistry. However, there is a paucity of using thiacalixarene as scaffold to construct fluorogenic and electrochemical receptors. This dissertation is an account of the design, synthesis, and supramolecular properties of novel thiacalix[4]arene-based crown ether receptors.The main results are as follows:1. The recent research progress of thiacalix[4]arene-based crown ethers, including molecular design, chemical preparation and their applications in supramolecular recognition and sensing, was briefly reviewed.2. A total of four new thiacalix[4]arene derivatives were successfully synthesized. Their structures were fully characterized by IR, 1^H NMR, 13^C NMR, MS and elemental analysis, as well as the structures of two compounds being determined by X-ray diffraction techniques.3. The first examples of thiacalix[4]arene crown ether receptors possessing an optical- and redox-active anthraquinone probe, as well as 1,2,3-triazole linkers were synthesized via the CuAAC reaction. The recognition and sensing properties of these novel receptors were investigated via fluorescence, UV-Vis, and 1^H NMR titrations, theoretical calculations and cyclic voltammetry techniques. It was found that receptor R1 shows a good selectivity for fluorescent sensing of Pb²⁺, while R2 displays a highly selectivity fluorescent sensing of Zn²⁺, Cd²⁺, Pb²⁺, La³⁺, Eu³⁺, and Tb³⁺. R3 reveals an remarkable selectivity for fluorescent sensing of Zn²⁺, Co²⁺, and Ni2+ at pH = 7.4, but a diverse selectivity for fluorescent sensing of La³⁺, Eu³⁺, and Tb³⁺ at pH = 4.0.