Inclusion behaviour of related organic host compounds

Abstract

The inclusion behaviour of the two host compounds, 9-(4-methoxyphenyl)-9Hxanthen- 9-o1 (A1)• and 9-(4-methylphenyl)-9H-xanthen-9-o1 (A10) were investigated. These host compounds are large, bulky, rigid and they contain functionalities that allow them to selectively interact with other molecules, such as the guests in this work. The host molecules form inclusion complexes with small organic guest molecules. The host•••guest interactions are the interesting focus of this study.

The host A1 included the guests: cyclohexane, 1,4-dioxane and N,N-dimethylformamide. Kinetics of desolvation were studied for the 1,4-dioxane and N,N-dimethylformamide compounds. Guest-exchange reactions were performed. The hostA1 was also used in the separation of 1, 4-dioxane and benzene.

The host A10 included the guests; benzene, 1,4-dioxane, cyclohexane, cyclohexanone, N,N-dimethylacetamide and N,N-dimethylformamide. Kinetics of desolvation were studied for the benzene and cyclohexane compounds. The host A10 was used in the separation of the following pairs of guests: benzene and 1,4-dioxane; N,N-dimethylformamide and N,Ndimethylacetamide.

The structures of the compounds were elucidated using single crystal X-ray diffraction. Thermal analysis was performed in order to determine the thermal stabilities of the complexes, including techniques such as thermogravimetry, differential scanning calorimetry and melting point measurement. The reactions in the guest exchange experiments were monitored using differential scanning calorimetry.

Competition experiments were performed to determine the selectivity of a host for a series of related guests. These experiments were conducted between pairs of guests.