Syntheses And Binding Properties Of Novel (Bis) Calix[4]arene With Amide And Thiourea Units

Calixarene are the third generation of the host molecules, as a building block to construct the novel host molecules with good recognition abilities towards the guests. Recently, people have paid much attention to N, S-bridged calixarenes. Because calixarene derivatives containing amide,thiourea and urea units, through have good recognition abilities towards the guests. Therefore, studies on their derivation and recognition properties are in the ascendant. In this paper, calix[4]arene is used as a building block, and a series of calix[4]arene derivatives containing amide,thiourea and urea units are designed and synthesized, and their binding properties towards metal cations and anion are studied.Firstly, we synthesized a calix[4]arene derivative with the structure of open-chain containing two amide units and four thiourea units. Metal cation extraction experiments demonstrate that calix[4]arene derivative containing amide and thiourea units shows much better extraction property towards transition metal ions than that of calixarene derivative only containing amide groups, and it exhibits a good extraction selectivity towards Co²⁺, Cs⁺.Secondly, a novel N-calix[4]arene aza-crown ether derivative is synthesized. Metal cation extraction experiments demonstrate that calix[4]arene derivative containing amide and thiourea units shows good extraction property towards soft metal ions.Thirdly, dumbbell-biscalix[4]arenes aza-crown ether are synthesized. Metal cation extraction experiments demonstrate that the novel compounds show excellent extraction property towards transition metal ions and poor extraction property towards alkali metal, and they exhibit a good extraction selectivity towards Pb²⁺, Ag⁺ and Ni²⁺. The compound 3a exhibits a good extraction selectivity towards Co²⁺. It is found that the extraction percentage of these new calix[4]arene derivatives for soft cations are higher than that of calixarene derivative only containing amide gronps.The anion binding extraction experiments suggest that these derivatives exhibit excellent recognition towards anion. UV-vis is used to study the binding property of novel compounds towards ^-OOC(CH₂)4_COO^- anions, and their binding constants are calculated. The results show that it possesses good complexation abilities towards ^-OOC(CH₂)₄COO^-, and 1:1 complex compound is formed between host and guest molecules.