Reversible Single-Crystal-to-Single-Crystal Structural Transformation in a Mixed-Ligand 2D Layered Metal-Organic Framework: Structural Characterization and Sorption Study
Department of Chemistry, Soochow University, Taipei 11102, Taiwan
Instrumentation Center, National Taiwan University, Taipei 10617, Taiwan
National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
Authors to whom correspondence should be addressed.
Academic Editor: George E. Kostakis
Crystals 2017, 7(12), 364; https://doi.org/10.3390/cryst7120364
Received: 20 November 2017 / Revised: 3 December 2017 / Accepted: 5 December 2017 / Published: 7 December 2017
(This article belongs to the Special Issue Structural Design and Properties of Coordination Polymers)
A 3D supramolecular network, [Cd(bipy)(C4O4)(H2O)2]·3H2O (1) (bipy = 4,4′-bipyridine and C4O42− = dianion of H2C4O4), constructed by mixed-ligand two-dimensional (2D) metal-organic frameworks (MOFs) has been reported and structurally determined by the single-crystal X-ray diffraction method and characterized by other physicochemical methods. In 1, the C4O42− and bipy both act as bridging ligands connecting the Cd(II) ions to form a 2D layered MOF, which are then extended to a 3D supramolecular network via the mutually parallel and interpenetrating arrangements among the 2D-layered MOFs. Compound 1 shows a two-step dehydration process with weight losses of 11.0% and 7.3%, corresponding to the weight-loss of three guest and two coordinated water molecules, respectively, and exhibits an interesting reversible single-crystal-to-single-crystal (SCSC) structural transformation upon de-hydration and re-hydration for guest water molecules. The SCSC structural transformation have been demonstrated and monitored by single-crystal and X-ray powder diffraction, and thermogravimetic analysis studies.