Jana H. Taljaard

Inclusion of pyridine and acetone by a diol host: structure, thermal stability and kinetics of desolvation

The host compound, 1,4-di-(5H-dibenzo[a,d]cyclohepten-5-ol)-buta-1,3-diyne, H, forms inclusion compounds with pyridine(H·2PYR) and acetone(H·2ACE). Their crystal structures, thermal behaviour and kinetics of desolvation have been determined. In addition the effect of particle size on the onset of guest release has also been studied.

Inclusion compounds of isomeric xanthenol hosts with aniline

Two isomeric xanthenol host compounds have been found to form inclusion compounds with aniline (ANI). These hosts are H1 = 9-(4-methoxyphenyl)-9H-xanthen-9-ol and H2 = 9-(3-methoxyphenyl)-9H-xanthen-9-ol. We have elucidated the structures of the inclusion compounds and determined their kinetics of desolvation. H1·½ANI crystallises in the triclinic space group P with the host in general positions and the aniline guest on a centre of symmetry. H2·ANI was solved successfully in the monoclinic space group P21/c with both the host and guest molecules in general positions. For H1·½ANI there is (Host)–OH⋯O–(Host) hydrogen bonding whereas in H2·ANI (Host)–OH⋯N–(Guest) hydrogen bonding occurs. We have correlated the structures with the thermal stabilities of these compounds.

Solvent manipulation of N-methylacetamide inclusion compounds with a xanthenol host

Abstract Three crystal structures of N-methylacetamide (NMA) with the xanthenol host 9-(4-methoxyphenyl)-9H-xanthen-9-ol (H) are reported. The crystal structures were obtained by using different solvent compositions. The host compound was dissolved in equimolar mixtures of N-methylacetamide/N,N-dimethylacetamide, N-methylacetamide/1,4-dioxane and N-methylacetamide/aniline which yielded H·NMA, H·2NMA and 2H·2NMA, respectively; H·NMA and 2H·2NMA are polymorphs. Thus, compounds with 1:1 and 1:2 host:guest ratios were obtained. H·NMA solved in the monoclinic space group P21/n whereas both H·2NMA and 2H·2NMA were solved in the triclinic space group P1¯.

A comparison of the inclusion ability of two related hosts

P\bar 1.

Inclusion with Mixed Guests : Structure and Selectivity

For all structures each host molecule is hydrogen bonded to one NMA molecule via (Host)-OH···O-(NMA) linkages. The NMA guests occupy channels and are connected via N–H···O hydrogen bonds forming chains. The thermal stabilities of the compounds were determined using thermogravimetry and differential scanning calorimetry which indicated that 2H·2NMA was the least stable with H·2NMA being the most stable.

Inclusion by a Xanthenol Host: Relating Structure to the Kinetics of Desolvation and Guest Exchange

24 European Crystallographic Meeting, ECM24, Marrakech, 2007 Page s192 Acta Cryst. (2007). A63, s192 MS18 P01 A Comparison of the Inclusion Ability of Two Related Hosts Ayesha Jacobs, Kanyisa L. Nohako, Luigi R. Nassimbeni, Jana H. Taljaard, Department of Chemistry, Cape Peninsula University of Technology, Cape Town, South Africa, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa. E-mail: jacobsa@cput.ac.za