Building up 3-D framework structure from interlinking layered cobalt phosphates and organic pillars

Abstract

A new cobalt phosphates (trans-1,4-dach) 0.5Co 3(H 2O)(OH)(PO 4)(HPO 4)·(3+ x)H 2O ( 1), has been synthesized under a hydrothermal condition and structurally characterized by single-crystal X-ray diffraction. It consists of cobalt phosphates layers and coordinated bis-N-donor ligands, trans-1,4-diaminocyclohexane, which are interlinked to form a 3-D framework structure with 1-D tunnel occupied by water molecules. When its channel water is fully removed at a relatively low temperature, the pillars fold up, and no porosity can be detected by sorption. However, the structural integrity of the compound is retained, and the pillar can still rise to its original upright position after contact with water vapor. This implies that some channel water molecules play a wedge function to control the up and down positions of the organic bis-N-donor ligands. When 1 is partially dehydrated, it revealed adsorption of various linear organic molecules, although the fully dehydrated one did not adsorb any organic molecules. Magnetic susceptibility measurements showed that 1 is an antiferromagnet with a canted interaction at a transition temperature of about 10 K. Crystal data: monoclinic, C2/ c, a=28.653(10) Å, b=12.874(4) Å, c=8.266(3) Å, β=97.257(7), V=3025(2) Å3, Z=8.