Hexagonal nanoporous host structures based on 2,4,6-tris-4-(halo-phenoxy)-1,3,5-triazines (halo=chloro, bromo)

Abstract

Based on our earlier observation that para-halogenated phenoxy triazines self-assemble as hexagonal nanoporous frameworks, this study deals with the inclusion of structurally related guest species in the one-dimensional channels of the title host compounds. A systematic analysis of six isomorphous, X-ray crystal structures (space group P6₃/m) provides valuable information of wide-ranging implications in host-guest chemistry: (1) construction of a host lattice with weak intermolecular interactions; (2) correlation of guest-size and host-channel area with order/disorder in the host; (3) role of molecular symmetry and multi-point hydrogen bond recognition for ordered guest species; (4) unusual structural behaviour and properties of guests constrained in a narrow channel. Lastly, a ternary adduct crystal shows an intricate hydrogen bonding network in the polar space group R3c with a super-cell of c=63.67 Å.