The formation of homogeneous and heterogeneous 2:1 complexes between dialkyl- and diarylammonium ions and α-cyclodextrin and cucurbit[6]uril in aqueous formic acid |
| |
Authors: | Hans-Jü rgen Buschmann, Lucia Mutihac,Eckhard Schollmeyer |
| |
Affiliation: | aDeutsches Textilforschungszentrum Nord-West e.V., Adlerstrasse 1, D-47798 Krefeld, Germany;bUniversity of Bucharest, Department of Analytical Chemistry, 4-12, Regina Elisabeta Blvd., 033018, Bucharest, Romania |
| |
Abstract: | Dialkyl- and diarylammonium ions are able to form complexes with α-cyclodextrin and cucurbit[6]uril. These amines are able to complex two guest molecules simultaneously resulting in the formation of homogeneous or heterogeneous 1:2 (ratio of dialkylammonium to ligand) complexes. The stability constants and reaction enthalpies for the formation of 1:1 complexes have been measured using potentiometric and calorimetric titrations. Differences between the values obtained by these methods can be attributed to solvent composition. Only for the 1:2 complex formation with cucurbit[6]uril, the ligands influenced each other. The polar carbonyl groups at each portal of the cucurbit[6]urils interacted simultaneously with the protonated amino group resulting in an electrostatic repulsion between both molecules. No further interactions between two complexed molecules of α-cyclodextrin or cucurbit[6]uril and α-cyclodextrin were observed. The absence of polar groups in the case of α-cyclodextrin led to unaffected formation of homogeneous and even heterogeneous 1:2 complexes. |
| |
Keywords: | Dialkylamines Cucurbit[6]uril α -Cyclodextrin, Mixed complexes, Calorimetry |
本文献已被 ScienceDirect 等数据库收录! |
|