Preparation and Spectroscopic Study of Different Stoichiometric Solid Supramolecular Inclusion Complexes of β-Cyclodextrin with Short Chain Aliphatic Amines

The solid Supramolecular complexes of β-cyclodextrin (β-CD) with ethylenediamine 1, diethylenetriamine 2 and triethylamine 3 were obtained and characterized using elemental analysis, powder X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, and 1H nuclear magnetic resonance spectroscopy. Based on the results of elemental analysis and 1H NMR, the guest-host stoichiometries of the three solid complexes were determined to be 5:2 for 1-β-CD, 1:1 for 2-β-CD, and 1:3 for 3-β-CD. The yields were relative to the molar volume ratio of guest toβ-CD cavity, and increased in the order: 1-β-CD<2-β-CD<3-β-CD. X-ray diffraction patterns of the inclusion complexes gave very good exhibitions not only in location of diffraction peaks but also in shape and diffraction intensity of the peaks due to the intermolecular complexations betweenβ-CD and the guests. The formation of host-guest inclusion complexes exhibited obviously enhanced phase change temperatures of the complexed guests such as 1 and 3. The H-5 protons located at the narrower rim inside the CD cavity experienced a higher shift upon inclusion while all other protons experienced lower shifts.