硫杂冠醚对Ag(I)和Tl(I)的萃取

基于冠醚的配位化学及软硬酸碱理论，设计并合成了五种硫杂冠醚，系统研究了其对Ag(I)和Tl(I)两种软酸离子的络合能力。模拟计算结果表明，五种冠醚与Ag(I)和Tl(I)络合后构型均发生了转变，且结构优化后的五种冠醚与Ag(I)络合过程的ΔG和ΔU均较负，表现出了一定的配位能力，而与Tl(I)络合过程的ΔG和ΔU均接近于0，配位能力相对较差。五种冠醚对Ag(I)和Tl(I)的萃取实验结果表明，五种冠醚对Ag(I)的络合常数分别为3.97, 6.58, 20.61, 9.76, 13.40，对Tl(I)的络合常数分别为4.24, 4.65, 5.80, 4.77, 4.33；在复杂体系中，冠醚2, 3, 4, 5对Ag(I)均具有较高的萃取率及选择性识别能力，而冠醚1对Ag(I)表现出较差的选择性识别能力。五种冠醚对Tl(I)几乎不具有选择性萃取能力。

Extraction of Ag(I) and Tl(I) by thiacrown ether

Based on the coordination chemistry of crown ether and soft and hard acid-base theory (HSAB) of crown ether, five kinds of thiacrown ethers were designed and synthesized. And their complexation abilities to two soft acid ions-Ag(I) and Tl(I) were systematically investigated. Firstly, the five crown ethers and their complexes with Ag(I) and Tl(I) complexes were optimized by Gaussian 16 software. On this basis, the Gibbs free energy change (ΔG), enthalpy change (ΔH), internal energy change (ΔU) and other thermodynamic parameters of the complexation process of five sulfur crown ethers with Ag(I) and Tl(I) at 298.15 K were calculated. The simulation results showed that the five thiacrown ethers had changed after being complexed with Ag(I) and Tl(I), and the ΔG and ΔU of the five crown ethers after structural optimization were negative in the complexation process with Ag(I), showing a certain coordination ability. However, during the complexation with Tl(I), ΔG and ΔU were close to 0, and the coordination ability was relatively poor. On the basis of simulation calculation, the extraction ability of five crown ethers on Ag(I) and Tl(I) was investigated by solvent extraction. The experimental results showed that the complex constants of five thiacrown ethers for Ag(I) were 3.97, 6.58, 20.61, 9.76, 13.40, respectively in the single system. In the multi-system, thiacrown ethers 2, 3, 4, and 5 had higher extraction rate and selective recognition ability for Ag(I), while thiacrown ether 1 exhibited poor selective recognition ability for Ag(I), this may be due to the small cavity of thiacrown ether 1. However, the five thiacrown ethers had almost no selectivity for Tl(I), this may be related to the coordination properties of Tl(I). Finally, combined with the simulation results and extraction experiments, the extraction mechanism of five crown ethers on Ag(I) and Tl(I) was analyzed in detail.