A Flexible Coordination Polymer Crystal Providing Reversible Structural and Magnetic Conversions

Abstract

Structural flexibility is a remarkable characteristic of coordination polymers and significant for the attainment of environmental responsivity. We have prepared a 2D cyanide-bridged MnIICrIII coordination polymer, [Mn(NNdmenH)(H2O)][Cr(CN)6].H2O (1; NNdmen = N,N-dimethylethylenediamine), with sophisticatedly arranged removable water coligands. The compound clearly showed a reversible single-crystal-to-single-crystal transformation between the 2D sheet and a 3D pillared-sheet framework of dehydrated [Mn(NNdmenH)][Cr(CN)6] (1a). The structural change was reversible and accompanied with generation/cleavage of CN-Mn bonds between 2D sheets by dehydration/hydration. Compounds 1 and 1a also exhibited a ferrimagnetic ordering at 35.2 and 60.4 K, respectively, and the magnetic characteristics were reversibly converted by guest adsorption/desorption. In addition, the dehydrated 1a demonstrated a size-selective solvent adsorption linking chemi- and physisorption processes and shrinkage/expansion of its framework. The flexible magnetic framework incorporating removable coligands delivered multifunctions with chemical response.

Bis[4-(4-pyridyl)pyridinium] (4-carboxypyridine-2,6-dicarboxylato-κ3O2,N,O6)(pyridine-2,4,6-tricarboxylato-κ3O2,N,O6)ferrate(III) trihydrate

“…Great interest has been focused on the rapidly expanding field of supramolecular chemistry and crystal engineering of the coordination polymers in reacent years because of their intriguing network topoloies as well as their potential application as functional materials in many areas such as separations and catalysis, gas storage, and magnetism (Kaneko et al, 2007;Li et al, 2008;Lin et al, 2009). Pyridine-2,4,6-tricarboxylic acid (H 3 ptc) is a good building block for constructing supramolecular complex, which can link 3 d, 4f and 3 d-4f metal ions.…”

“…For the design and synthesis of coordination polymer complexes and their potential applications, see: Kaneko et al (2007); Li et al (2008); Lin et al (2009). For the H 3 ptc ligand, see: Ghosh & Bharadwaj (2006); Lin et al (2007); Syper et al (1980).…”

Microporous magnets

“…6). 74,75 The hydrated form of the compound is built up from the connection of four cyanide groups in the equatorial position of [Cr(CN) 6 ] 3À to adjacent Mn II centers, forming a 2-D corrugated sheet structure in the ab plane. A protonated ligand and a water molecule are bound at the axial positions of the octahedral Mn II center.…”

Recent advance in porous coordination polymers from the viewpoint of crystalline-state transformation

“…Adjacent layers contact to each other in a certain packing model to further build the 3D structure and the layer usually possesses various structure features. Because weak interaction such as hydrogen bond or π-π interaction contributes to the slipping or distortion of the layer, 2D PCPs are good candidates for the research of dynamic structure transformation [65].…”