Ayesha Jacobs

Complexation with diol host compounds. Part 33. Inclusion and separation of pyridines by a diol host compound

The host 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol includes pyridine and the picolines. The structures of these inclusion compounds and their lattice energies have been determined. The selectivity of the host for a particular guest has been measured by competition experiments and the results are rationalised in terms of the structural features of the host-guest 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¯.

Salts of (+)-deoxycholic acid with amines: structure and chiral resolution

P\bar 1.

A comparison of the inclusion ability of two related hosts

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 with Mixed Guests : Structure and Selectivity

(+)-deoxycholic acid (DCA) is a bile acid involved in the solubilization of fats in the gastrointestinal tract. The bile acids contain hydroxyl groups directed below the plane and methyl groups pointing above the plane, thus providing both a hydrophilic side and a hydrophobic side. The inclusion compounds of the bile acids have attracted much interest and Giglio[1] has reviewed the inclusion compounds of DCA. Miyata et.al. [2,3] related the inclusion ability of different bile acids and their derivatives with various organic guests. The bile acids are also chiral, enabling their application in chiral studies. Thus the use of DCA as a chiral resolving agent has been explored. [4,5,6] In this study we focus on the salts formed between DCA and the chiral amines sec-butylamine and 3-methyl-2-butylamine. The salts were characterized using thermal analysis and single crystal X-ray diffraction. In the structures we observed proton transfer from the carboxylic acid moiety of DCA to the nitrogen of the amine guest. The chiral discrimination of DCA for racemic mixtures of sec-butylamine and 3-methyl-2-butylamine yielded interesting results. A mixture of DCA and racemic secbutylamine yielded exclusively crystals of the (R)-2-butylammonium deoxycholate. A similar experiment with DCA and racemic 3-methyl-2butylamine resulted in only crystals of the (S)-3methyl-2-butylammonium deoxycholate.

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