de Namor Angela F Danil, Jumaa Ahmad, Al Hakawati Nawal
Laboratory of Thermochemistry, School of Chemistry & Chemical Engineering, University of Surrey, Guildford, Surrey GU2 7XH, UK.
Department of Biological Sciences, Faculty of Science, Beirut Arab University, Tripoli P.O. Box 11-5020, Lebanon.
Int J Mol Sci. 2025 Aug 20;26(16):8043. doi: 10.3390/ijms26168043.
The state of the art in the thermodynamics of calix[4]resorcinarene derivatives and its metal ion complexes is briefly discussed in the introduction. This is followed by the synthesis and characterization of a recyclable calix[4]resorcinarene amide derivative (L). The 1H NMR analyses in CD3CN and CD3OD showed solvent-dependent conformational changes with a notable downfield chemical shift in the aromatic proton (H-2) in moving from deuterated methanol to acetonitrile, indicating an interaction of the solvent within the ligand cavity as suggested by molecular dynamic simulations. 1H NMR complexation in acetonitrile revealed that L forms relatively strong 1:1 complexes with cations, with selectivity for Ca(II) and, to lesser extent, with Pb(II) over other metal cations. The composition of the complexes is corroborated by conductance measurements. The thermodynamics of these systems indicate that the complexation process is predominantly enthalpy controlled in acetonitrile, while it is entropy controlled in methanol. A remarkable outcome of fundamental studies is found in its application as new material for the removal of Ca(II) from water. The capacity of to remove Ca(II) from water is 24 mmol/g which exceeds by far the capacity of cation exchange resins.
引言部分简要讨论了杯[4]间苯二酚芳烃衍生物及其金属离子配合物的热力学研究现状。接下来是一种可回收杯[4]间苯二酚芳烃酰胺衍生物（L）的合成与表征。在CD3CN和CD3OD中的1H NMR分析表明，随着从氘代甲醇转移到乙腈，芳族质子（H-2）出现显著的低场化学位移，溶剂依赖性构象发生变化，这表明如分子动力学模拟所表明的，溶剂在配体腔内发生了相互作用。在乙腈中的1H NMR络合表明，L与阳离子形成相对较强的1:1络合物，对Ca(II)具有选择性，在较小程度上对Pb(II)的选择性高于其他金属阳离子。络合物的组成通过电导率测量得到证实。这些体系的热力学表明，络合过程在乙腈中主要受焓控制，而在甲醇中受熵控制。在其作为从水中去除Ca(II)的新材料的应用中发现了基础研究的一个显著成果。从水中去除Ca(II)的容量为24 mmol/g，远远超过阳离子交换树脂的容量。
