Author:
Barton Benita,Vorgers Jarryd A.,Hosten Eric C.
Abstract
Abstract1,4-Phenylene-bis(di-p-tolylmethanol) (H), a host compound with the wheel-and-axle design, formed complexes with organic guest solvents pyridine (PYR) and 2-, 3- and 4-methylpyridine (2MP, 3MP and 4MP). The host: guest (H: G) ratios were 1:3, 1:2, 1:2 and 1:1, respectively. Host crystallization experiments from mixed guests demonstrated H to prefer both PYR and 4MP; however, it was established that these difficult-to-separate (by fractional distillations) guest mixtures cannot be purified/separated by means of H through supramolecular chemistry strategies owing to these selectivities for PYR and 4MP being less than optimal. Single crystal X-ray diffraction experiments showed that each guest compound was held in its complex by means of a classical hydrogen bond with H, and that one of the preferred guests, PYR, experienced a significantly shorter contact of this type than the other guests. Hirshfeld surface analyses demonstrated that PYR was also involved in a greater percentage of (guest)N···H(host) interactions compared with the other guest molecules. Thermal analyses, on the other hand, revealed that 4MP (also a favoured guest species) formed the most stable complex of the four in this investigation. These results with H were compared to those obtained when employing a closely related host compound from a previous report, 1,4-bis(diphenylhydroxymethyl)benzene: while both host species preferred the same guests (PYR and 4MP), the extent of the selectivity of that host compound compared with H in the present work was significantly more enhanced. Thus, minor modifications may deleteriously affect the selectivity behaviour of closely related host compounds.
Funder
Nelson Mandela University
Publisher
Springer Science and Business Media LLC