Behavior of the Wheel-and-Axle Host Compound 1,4-Bis(diphenylhydroxymethyl)benzene in Mixed Pyridyl Guest Solvents

The host ability of the wheel-and-axle compound, 1,4-bis(diphenylhydroxymethyl)benzene H, was extensively investigated in pure pyridine (PYR), 2-methylpyridine(2MP), 3-methylpyridine (3MP), and 4-methylpyridine (4MP) guest pyridines;each one was enclathrated with 1:2 H/G ratios. H wasthen presented with mixed guest solvents, both equimolar and binarynon-equimolar solutions, and it was observed that this host compoundpossesses the ability to separate or purify a great number of thesevarious mixtures. The selectivity of H was demonstratedto be significantly in favor of PYR and 4MP dependent on the typeand amount of each guest present in the solution. The crystal structuresof the four single-solvent complexes were obtained by employing SCXRDanalyses, which also assisted in understanding the host selectivitybehavior in these mixed solvents. Hirshfeld surface investigationsdemonstrated that the preferred guest species, PYR and 4MP, experienceda greater percentage of (guest)N & BULL;& BULL;& BULL;H-O(host)interactions than was observed for the guests less preferred (2MPand 3MP). Finally, data from thermal analyses concurred with some,but not all, of the observations made from the mixed guest solventcompetition experiments. Thehost compound 1,4-bis(diphenylhydroxymethyl)benzenedisplayed selectivity for PYR (and 4MP) owing to shorter and morelinear (host)O-H & BULL;& BULL;& BULL;N(guest) hydrogen bondinginteractions (yellow line) in mixed pyridine and methylpyridine guestsolvents (a stereoview).

Automated summary

The host compound 1,4-bis(diphenylhydroxymethyl)benzene H showed the ability to separate or purify various mixtures of pyridine solvents. The selectivity of the host compound was significantly in favor of pyridine and 4-methylpyridine, depending on the type and amount of guest present. The crystal structures and thermal analyses provided further insights into the host selectivity behavior.