Design and structural regularities of zigzag-like supramolecular 1D assemblies of polyhalogenated 2,6-, 2,4-diaminopyridines and 18-crown-6

Co-crystallization of polyhalogenated 2,6-, 2,4-diaminopyridines and 18-crown-6 yields associates (host–guest complexes) with the stoichiometry 1:1. According to the X-ray crystal data, molecules of the components are alternately coordinated by means of the hydrogen bond between the oxygen atoms of the crown ether and the hydrogen atoms of the pyridine amino groups forming thus the 1D assembly (the infinite rod); both components are arranged in a zigzag line along the rod axis. This supramolecular configuration is identical to the configuration of co-crystals of 18-crown-6 and polyfluorinated meta-arylenediamines. The results obtained demonstrate that a mutual arrangement of amino groups in a rigid aromatic ring serves as a design tool for supramolecular architecture in this type of co-crystals. Using the DSC analysis, melting heats of the co-crystals were determined. A linear inverse correlation between the supramolecular structural unit (the rod unit length) and the specific melting heat was revealed.