Thermodynamic study of complex formation of benzo-18-crown-6 with K+, Tl+, and Pb2+ in water |
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Authors: | Yasuyuki Takeda |
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Institution: | (1) Department of Chemistry, Faculty of Science, Chiba University, 260 Yayoi-cho, Chiba, Japan |
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Abstract: | H
0 and S
0 values of the complex formation in water of benzo-18-crown-6 (B18C6) with K+, Tl+, and Pb2+ were determined and compared with those of 18-crown-6. The H0 values of B18C6 are negative. The stability in water of the B18C6-metal ion complex at 25°C is governed largely by the magnitude of the H
0 value. The B18C6-metal ion complex is less stable in water than the corresponding 18C6-metal ion complex. This is due largely to a less favorable enthalpic contribution of the B18C6-metal ion complex compared with the corresponding 18C6-metal ion complex. The two aromatic ether oxygen atoms of B18C6 are responsible for the larger H
0 value of the B18C6-metal ion complex compared with the corresponding 18C6-metal ion complex. |
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Keywords: | Benzo-18-crown-6 metal ions complexation water thermodynamics |
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