Structure and reactivity of diol host-guest compounds

Harvey, Grant Andrew

Structure and reactivity of diol host-guest compounds

Master Thesis

1990

Publisher

University of Cape Town

Department

Department of Chemistry

Faculty

Faculty of Science

Abstract

The crystal structures of trans-9, 10-dihydroxy-9, 10-diphenyl-9, 10- dihydroanthracene with various guest molecules have been determined by X-ray diffraction. The guests were 2-butanone, 4-vinylpyridine, 4-methylpyridine and 2-methylpyridine. The host to guest ratios were determined by microanalysis and density measurements. The change of the overall host lattice structure upon guest release was studied by X-ray powder diffraction. The thermal characteristics of the compounds were studied using thermogravimetric analysis and differential scanning calorimetry. Guest desorption from three of the four compounds occurred in a single step whereupon the host framework collapsed back to the guest-free structure. The compound containing 4-methylpyridine, released the guest molecules in a two-step process. Evidence of a new host phase was identified from the XRD pattern of this intermediate phase. On further guest release, the intermediate phase converted to the guest-free host structure. In an attempt to reconcile thermodynamics with structure, the correlation between hydrogen bond length and guest desorption enthalpy was investigated.