Clathrates with mixed guests

Abstract

The inclusion ability of two host compounds H1, 9-(1-naphthyl)-9H-xanthen-9-ol, and H2, 9-(1-naphthyl)-9H-thioxanthen-9-ol was studied. We have previously shown that H1 successfully forms inclusion compounds with 1,4-dioxane[1] and acetone [2]. Here we report on the structures of H1•DMF and H1•DMA where DMF = N,Ndimethylformamide and DMA = N,N-dimethylacetamide. Numerous attempts at forming inclusion compounds between H2 and selected small organic guests including DMF and DMA were unsuccessful and yielded powders of the host alone. Both H1•DMF and H1•DMA successfully solved in P(-1), the host: guest ratios were 1:1 and their structures were stabilized by hydrogen bonding of the typeSulphur is less electronegative than oxygen and is less likely to be involved in hydrogen bonding. Interestingly even though the hydrogen bonding in the inclusion compounds of H1 does not involve the ether oxygen of the host, still no inclusion is found for H2. The kinetics of desolvation for H1•DMF and H1•DMA were analysed as well as competition experiments. MS18 P02 Clathrates with Mixed Guests Keywords: clathrates, molecular recognition, crystal structuresInvestigation of the selectivities of two diol organic hosts for pairs of small organic guests gave very interesting results which could be correlated with the crystal structures of the inclusion compounds containing mixtures of the two guests. This study comprises two separate investigations and in the first investigation the selectivity of the host 9,9'-(biphenyl-4,4'-diyl)difluoren-9-ol (H1) for a pair of guests with very similar chemical compositions but significantly different boiling points was examined. The second investigation involved a pair of guests with very similar boiling points and which form inclusion compounds with a particular host which have different host:guest ratios when crystallised at different temperatures. We thus investigated the selectivity of the host 9,9'-(ethyne-1,2-diyl)difluoren-9-ol (H2) for these guests and carried out the competition experiments at two different temperatures in order to see whether the selectivity would change with changing temperature.Clathrate compounds are an important aspect of supramolecular chemistry and this study displays some novel results showing interesting selectivity profiles, and more importantly giving new insight into clathrates with mixed guests through crystal structure analysis, which in each case could be correlated with the selectivity profiles. -(1,4)-linked D-glucopyranosyl residues have a hydrophobic, relatively rigid cavity able to host a plethora of molecules. Being chiral compounds, CDs can, in principle, discriminate between enantiomers (guests) forming preferentially with one of the two a more stable inclusion complex [1,2]. X-ray crystallography can provide details of the factors that lead to chiral recognition. Structures of CD inclusion complexes with each enantiomer separately suggest that not only the cavity, which undergoes "induced fit" by the presence of the guest, but the guest's H-bondin...

Engineering Crystal Properties through Solid Solutions

“…Recrystallization from a mixture of those solvents produces a solid solution in which both solvents are included as guests (Figure 7). 109 In the analogue 9,9′-(ethyne-1,2-diyl)bisIJfluoren-9-ol) host, selectivity toward butanol and propanol guests varies with crystallization temperature. 110 Petit and co-workers describe the chiral discrimination of modified cyclodextrin toward the enantiomers of p-bromophenylethanol.…”

Inclusion Compounds of Dehydrocholic Acid with Solvents

“…These solutions, as well as the mother liquors, were analysed by gas chromatography. The results are shown in Figure 4A-C , in which X represents the mole fraction of a given guest in the liquid mixture and Z that of same guest entrapped in the crystals [ 12 ]. The diagonal line represent zero selectivity.…”

Cocrystals Help Break the “Rules” of Isostructurality: Solid Solutions and Polymorphism in the Malic/Tartaric Acid System

“…32 Perhaps earlier examples of this type of materials are represented by enantiomeric systems 33,34 and inclusion compounds. 35 More recently, pharmaceutical 28,32,34 and porous 36 cocrystal solid solutions have also been reported.…”