LAUSR

Four xanthenyl-derived host compounds, namely trans-N,N′ -bis(9-phenyl-9-xanthenyl)cyclohexane-1,4-diamine (1,4-DAX), trans-N,N′ -bis(9-phenyl-9-thioxanthenyl)cyclohexane-1,4-diamine (1,4-DAT), N , N ′-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine (OED) and N,N ′-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine (SED) were assessed for their selectivity behaviour in the presence of both the saturated and unsaturated heterocyclic six-membered ring guest solvents morpholine (MOR), piperidine (PIP), dioxane (DIO) and pyridine (PYR). Related compounds OED and SED behaved similarly when each was recrystallized from mixtures of these guests, both selecting for MOR and discriminating against PYR, while, surprisingly, the performance of structurally-similar 1,4-DAX and 1,4-DAT in equivalent conditions, on the other hand, was entirely contrasting: only 1,4-DAX formed complexes from such guest mixtures and 1,4-DAT failed to do so in each instance. Furthermore, 1,4-DAX preferred PYR, an observation distinct from that of OED and SED. Single crystal diffraction (SCXRD) experiments were carried out on suitable crystals formed by 1,4-DAX with these guests, and it was revealed that the preference for PYR may be attributed to both host–guest π–π interactions and a shorter H-bond between molecules of the host and PYR compared with other complexes. SCXRD experiments were not possible for OED, SED and 1,4-DAT owing to either the inability of the host compound to complex with these guests or poor crystal quality of the resultant complexes.