Infrared spectroscopic study of the role of water in crown ethers and their molecular complexes with 3- and 4-nitrophenol
Infrared spectroscopic study of the role of water in crown ethers and their molecular complexes with 3- and 4-nitrophenol
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DOI：
10.1023/a:1007918700343
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发表时间：
1997-07-01
期刊：
影响因子：
--
通讯作者：
Derwish, GAW
中科院分区：
文献类型：
--
作者：
ElEswed, BI;Zughul, MB;Derwish, GAW
研究了3-硝基苯酚和4-硝基苯酚冠醚晶体配合物18-冠-6 （18C6）、苯并-18-冠-6 （B18C6）、二苯并-18-冠-6 （DB 18C6）、双环己烯-18-冠-6 （DC18C6）和二苯并-24-冠-8 （DB24C8）的红外光谱。未络合冠醚的光谱显示出吸水带，表明存在两种类型的结合水分子，即被强醚腔场包围的空泡水和外层氢键水分子。在与3-和4-硝基酚络合后，由空泡水引起的带消失，留下外层水作为宿主冠醚和客体酚之间的桥梁。结果进一步表明，冠醚和酚类化合物中，B18C6和DC18C6与3-硝基酚的相互作用最强。酚类化合物的行为可以用配合物中感应σ矩比共振矩的贡献增加来解释。
The IR spectra of the crystalline complexes of 3- and 4-nitrophenol with crown ethers were studied, viz., 18-crown-6 (18C6), benzo-18-crown-6 (B18C6), dibenzo-18-crown-6 (DB 18C6), dicyclohexano-18-crown-6 (DC18C6) and dibenzo-24-crown-8 (DB24C8). The spectra of uncomplexed crown ethers showed water absorption bands which indicate the presence of two types of bound water molecules, viz., cavitant water enclosed by the strong ether-cavity field and outer-layer hydrogen-bonded water molecules. Upon complexation with 3- and 4-nitrophenol, the bands attributed to cavitant water disappeared, leaving the outer layer water to act as a bridge between the host crown ether and the guest phenols. The results further showed that of the crown ethers and of the phenols, B18C6 and DC18C6 and 3-nitrophenol, have the strongest interaction. The behaviour of the phenols was explained by the increased contribution of the inductive sigma-moment over the resonance pi-moment in the complexes.