Complexes of host compound (−)-(2R,3R)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT) with guests anisole and the methyl-substituted anisoles: host selectivity, thermal and single crystal diffraction considerations
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(−)-(2R,3R)-2,3-Dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT) was determined to be a highly efficient host compound for anisole and the methyl-substituted anisoles (MA), clathrating each of these organic solvents with 2:1 host:guest ratios. Furthermore, this host displayed selectivity when presented with mixed guests, and guest–guest competition studies involving the methylanisoles revealed a host selectivity order of p-MA > m-MA > o-MA, whilst the addition of unsubstituted anisole to these experiments showed this guest to now be the preferred one (anisole > p-MA > m-MA > o-MA). Single crystal diffraction analyses indicated the absence of hydrogen bonding between host and guest molecules, and that guests were retained within the host crystal only by means of CH–π, π–π stacking and other short interaction types. The latter involved host aromatic carbon or hydrogen atoms and guest methoxyl or methyl hydrogens and aromatic carbons, as well as host and guest methoxyl hydrogens. Results from thermal analyses provided the reason for the observed selectivity order, with complexes comprising preferred guests anisole and p-MA displaying enhanced thermal stabilities relative to those with o- and m-MA.
KeywordsHost–guest chemistry Supramolecular chemistry DMT Anisole Methylanisole
Financial support is acknowledged from the Nelson Mandela University and the National Research Foundation (NRF). L. Bolo and K. Ngobo are thanked for thermal analyses.
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