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

Abstract

By incorporating co-ligands 1,2-bis(imidazol-1-ylmethyl)-benzene (1,2-bix), 1,3-bis(imidazol-1-ylmethyl)benzene (1,3-bix) and 1,4-bis(imidazol-1-ylmethyl)benzene (1,4-bix), three isomeric cobalt phosphonates Co5(1,2-bix)2(pbtc)2(H2O)4·8H2O (1), Co5(1,3-bix)2(pbtc)2(H2O)4·7.5H2O (2), and Co5(1,4-bix)2(pbtc)2(H2O)4·6H2O (3) (pbtcH5 = 5-phosphonatophenyl-1,2,4tricarboxylic acid) have been isolated successfully. Compound 1 shows a layer structure in which chains containing alternatively arranged Co3O2 trimers and Co2 dimers are connected by pbtc 5ligands. The 1,2-bix co-ligand adopts a cismode, and coordinates to the cobalt atoms from the same chain. Upon dehydration, compound 1 experiences a single crystal-to-single crystal (SC-SC) structural transformation forming a new crystal phase Co5(1,2-bix)2(pbtc)2(H2O)4 (1a). The process is reversible on re-hydration, showing a breathing effect. In compounds 2 and 3, similar layers composed of cobalt phosphonate chains and pbtc 5linkages are also found, which are further cross-linked by 1,3-bix or 1,4-bix into 3D framework structures. The three compounds show different microporosities, as confirmed by the different N2 gas adsorption behaviors.

Robust Multifunctional Yttrium-Based Metal–Organic Frameworks with Breathing Effect

“…[1,1′-Biphenyl-3,3′,5,5′-tetrayltetrakis­(phosphonic acid) (H 8 btp) was prepared by a three-step reaction sequence according to published procedures with small modifications (Scheme ). , …”

“…[1,1′-Biphenyl-3,3′,5,5′-tetrayltetrakis-(phosphonic acid) (H 8 btp) was prepared by a three-step reaction sequence according to published procedures with small modifications (Scheme 1). 28,29 A solution of [{(phen)Cu(μ-OH)} 2 C•3H 2 O (cat-1, 0.0231 g, 0.0358 mmol) and 3,5-dibromophenylboronic acid (0.500 g, 0.179 mmol) in propan-2-ol (5 mL) was stirred at ambient temperature overnight in air. The resulting gray mixture was monitored by TLC (nhexane), and once the reaction was complete, the mixture was concentrated in vacuo.…”

Coordination Behavior of Bis-Imidazole and Various Carboxylate Ligands towards Zn(II) and Cd(II) Ions: Synthesis, Structure, and Photoluminescence Study

“…Previous studies showed that carboxylate auxiliary ligands can provide cooperative coordination together with the N-containing ligands to meet the requirements of the coordination geometries of the metal ions in the assembly process. Although many bis-imidazol ligands and different poly-acids have been widely used to synthesize new coordination polymers [19][20][21][22][23][24][25], there are relatively rare in exploring the effect of the introduction of substituents and different carboxylic acid positions on the structure.…”

Multiple-Step Humidity-Induced Single-Crystal to Single-Crystal Transformations of a Cobalt Phosphonate: Structural and Proton Conductivity Studies

“…Metal phosphonates, as an important class of organic–inorganic hybrid materials, have received increasing attention recently due to their significance in the fields of catalysis, ion exchange, magnetism, and proton conductivity. , Although solid-state phase transitions have been reported in metal phosphonate systems together with drastic changes in their physical and chemical properties, those showing SC-SC transformations are extremely rare. − Albrecht-Schmitt and co-workers reported a few nanotubular uranyl phosphonates which can exchange ions in a SC-SC manner in solution . Reversible SC-SC transformations were also observed in the cobalt phosphonates Co 2 (pbtcH)­(2,2′-bpy) 2 (H 2 O) and Co 2 (pbtcH) (phen) 2 (H 2 O) (pbtcH 5 = 5-phosphonatophenyl-1,2,4-tricarboxylic acid) upon dehydration and rehydration, which involve the breakage and reconstruction of covalent bonds .…”