Preparation of Microporous Molecular Crystals Having Hydrogen-Bonded Networks and Their Application to Functional Organic Materials

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An anthracene bisresorcinol derivative 1 has been shown to form molecular sheets composed of hydrogen-bonded polyresorcinol chains together with large cavities roofed and floored by the anthracene rings. The cavities selectively incorporate a variety of guest molecules.(1) Diels-Alder Reaction As Catalyzed by Microporous Crystal 1As confirmed before, crystal 1 incorporates two molecules of ethyl acetate and benzene in each cavity. When the guest molecules are changed respectively into acrolein (dienophile) and 1.3-cyclohexadiene, a facile and catalytic Diels-Alder reaction takes place in a highly stereoselective (endo-selective) manner, where the roles of 1 as a microporous catalyst are (a) to assemble two reactants in the cavity, (2) to activate the dienophile via acid-catalysis through host-guest hydrogen-bonding, (3) to exert steric constraint in a 3D cavity, and (4) to exchange reactants and products in the cavity.(2) Functional Self-Assembly of 1D ChainsAnthracene monoresorcinol compound 2 forms similar but 1D hydrogen-bonded network. The chains are held together via intercalation of the orthogonal anthracene substituents ; in the cavities are included guest molecules in a 1 : 1 host-guest stoichiometry. The cavities are much less thick as compared with those in the 2D network of host 1 and show a novel thickness selectivity in the guest-binding, where a remarkable preference for linear alkyl groups to brached ones is observed. Closely packed anthracene-guest alternate columns can be constructed in this way.