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The First “Organic Zeolite” with Isomerizing Building Blocks:  Single-Crystal-to-Single-Crystal Desolvation and Structure of the Empty Matrix

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journal contribution
posted on 23.07.2002, 00:00 by D. V. Soldatov, E. V. Grachev, J. A. Ripmeester
The microporous β polymorph of the title compound has been prepared as a crystalline product by slow removal of the guest from the inclusion compound with methylene chloride, [CuL2]*2/3(CH2Cl2) (L is 1,1,1-trifluoro-5,5-dimethyl-5-methoxyacetylacetonate, {CF3COCHCOC(CH3)2OCH3}-). Collapse of the crystals of the β polymorph into the thermodynamically stable α form has been studied by visual observation and DSC calorimetry, the product exhibiting much higher kinetic stability than the polycrystalline samples prepared so far. The crystal structure of the β polymorph was determined by single-crystal XRD methods both at 293 and 173 K. The β polymorph retains the same 3D polymeric coordination framework as found previously in inclusion compounds of the complex. The structures of the β and α polymorphs are compared and the variation of the β matrix in a series of compounds was analyzed. The β framework described in this work seems to be the most flexible of all coordination polymers known so far, preserving its microporous structure upon guest exchange or removal; the complete range of change in molar volume observed for the matrix is 8.6%.