Breathing Effect in a Cobalt Phosphonate upon Dehydration/Rehydration: A Single‐Crystal‐to‐Single‐Crystal Study

Abstract

Two cobalt phosphonates, [Co2(2,2′-bpy)2(H2O)(pbtcH)] (1) and [Co2(H2O)(pbtcH)(phen)2] (2; pbtcH5=5-phosphonatophenyl-1,2,4-tricarboxylic acid, 2,2′-bpy=2,2′-bipyridine, phen=1,10-phenanthroline), with layer structures are reported. Compound 1 contains O-C-O and O-P-O bridged tetramers of Co4, which are further connected by pbtcH(4-) units to form a layer. In compound 2, the cobalt tetramers made up of water-bridged Co2 dimers and O-P-O linkages are connected into a layer by pbtcH(4-) units. Upon dehydration, compounds 1 and 2 experience single-crystal-to-single-crystal (SC-SC) structural transformations to form [Co2(2,2′-bpy)2(pbtcH)] (1 a) and [Co2(pbtcH)(phen)2] (2 a), respectively. The process is reversible in each case. Notably, a breathing effect is observed for 1, accompanied by pore opening and closing due to the reorientation of the coordinated 2,2′-bpy molecules. The transformation was also monitored by in situ IR measurements. Magnetic studies reveal that antiferromagnetic interactions are mediated between the magnetic centers in compounds 1 and 1 a, whereas ferromagnetic interactions are dominant in compound 2.

Structural and spectroscopic characterization of two new layered uranyl(VI) p-xylenediphosphonate compounds synthesized via ionothermal method

“…During the last several decades, the field of metal phosphonates has received increasing attention owing to their potential applications in catalysis [1,2], proton conductivity [3][4][5], gas absorption and separation [6][7][8], magnetism [8][9][10][11], and optics [12]. The crystal chemistry of actinide phosphonates is an important subfield of metal phosphonates, where major attention was paid to uranium [13][14][15][16][17][18][19] and thorium [20][21][22], with only a few neptunium [22][23][24], plutonium [25][26][27][28], and americium [28] complexes.…”

Syntheses, structures and properties of group 12 element (Zn, Cd, Hg) coordination polymers with a mixed-functional phosphonate-biphenyl-carboxylate linker

“…30 Metal organophosphonates are stable in water or aqueous environment 31 and can be reversibly hydrated and dehydrated. 27,[32][33][34][35][36] The use of metal phosphonates in catalysis, luminescence, 37 ion or proton exchange or conductivity 38,39 and in separation is discussed and investigated. 40 Cobalt and iron organophosphonates exhibit magnetic properties.…”

Modulating the microporosity of cobalt phosphonates via positional isomerism of co-linkers

“…12 More recently, we employed 5-phosphonatophenyl-1,2,4tricarboxylic acid (pbtcH 5 , Scheme 1) to react with cobalt salts in the presence of rigid 2,2'-bipyridine or 1,10-phenanthroline co-ligands. 13,14 Microporous product was achieved successfully through a post-synthetic thermal treatment of the nonporous precursor of Co 2 (pbtcH)(2,2'-bpy) 2 (H 2 O). 13 It is noted that metal phosphonates incorporating flexible N-donor co-linkers have rarely been described.…”

“…13,14 Microporous product was achieved successfully through a post-synthetic thermal treatment of the nonporous precursor of Co 2 (pbtcH)(2,2'-bpy) 2 (H 2 O). 13 It is noted that metal phosphonates incorporating flexible N-donor co-linkers have rarely been described. 15 In particular, the influence of the positional isomerism of co-linkers on the microporosity of these materials has never been documented.…”