The ZIF system zinc(II) 4,5-dichoroimidazolate: theoretical and experimental investigations of the polymorphism and crystallization mechanisms

In this report, we summarize our theoretical and experimental investigations on the zeolitic imidazolate framework (ZIF) system [Zn(dcim)2] (dcim=4,5-dichloroimidazolate) that have been published recently. These comprise: (1) a theoretical study on hypothetical conformational [Zn(dcm)2]-SOD polymorphs with the same underlying sodalite (SOD) topology but distinct dcim linker orientations, (2) a synthetic work that resulted in the experimental realization of the most stable predicted (trigonal) SOD-type framework conformer and improved synthetic protocols for a previously discovered cubic SOD-type material, (3) a detailed structural analysis of the trigonal and cubic SOD-type materials, (4) a comparative characterization of the SOD-type materials by gas physisorption measurements, (5) a synthetic work that resulted in the discovery of a complete series of intermediate frameworks with the trigonal and cubic SOD-type materials as the end members, and (6) time-resolved in-situ light and stopped-flow synchrotron small-angle and wide-angle X-ray scattering experiments on the rapid crystallization of the RHO-type polymorph (ZIF-71). In addition, we report as yet unpublished work, concerning time-resolved in-situ angular-dispersive synchrotron X-ray diffraction experiments on RHO-/SOD-type phase selection via the coordination modulation approach during competitive formation of the RHO-type and SOD-type materials.