3D Metal–Organic Frameworks Based on Co(II) and Bithiophendicarboxylate: Synthesis, Crystal Structures, Gas Adsorption, and Magnetic Properties

Abstract

Three new 3D metal-organic porous frameworks based on Co(II) and 2,2′-bithiophen-5,5′-dicarboxylate (btdc2−) [Co3(btdc)3(bpy)2]·4DMF, 1; [Co3(btdc)3(pz)(dmf)2]·4DMF·1.5H2O, 2; [Co3(btdc)3(dmf)4]∙2DMF∙2H2O, 3 (bpy = 2,2′-bipyridyl, pz = pyrazine, dmf = N,N-dimethylformamide) were synthesized and structurally characterized. All compounds share the same trinuclear carboxylate building units {Co3(RCOO)6}, connected either by btdc2– ligands (1, 3) or by both btdc2– and pz bridging ligands (2). The permanent porosity of 1 was confirmed by N2, O2, CO, CO2, CH4 adsorption measurements at various temperatures (77 K, 273 K, 298 K), resulted in BET surface area 667 m2⋅g−1 and promising gas separation performance with selectivity factors up to 35.7 for CO2/N2, 45.4 for CO2/O2, 20.8 for CO2/CO, and 4.8 for CO2/CH4. The molar magnetic susceptibilities χp(T) were measured for 1 and 2 in the temperature range 1.77–330 K at magnetic fields up to 10 kOe. The room-temperature values of the effective magnetic moments for compounds 1 and 2 are μeff (300 K) ≈ 4.93 μB. The obtained results confirm the mainly paramagnetic nature of both compounds with some antiferromagnetic interactions at low-temperatures T < 20 K in 2 between the Co(II) cations separated by short pz linkers. Similar conclusions were also derived from the field-depending magnetization data of 1 and 2.

Water-Driven Structural Transformation in Cobalt Trimesate Metal-Organic Frameworks

“…Nevertheless, among the most intriguing applications for Co-MOFs, there is the low-dimensional magnetism. Divalent cobalt centers in MOFs offer the opportunity to realize low dimensional magnetism studies [17,18]. In fact, the different arrangements that cobalt ions can have in the MOFs metal nodes (chains [19], single atoms [20], paddle wheel [21]) allows one to obtain materials with very peculiar magnetic properties.…”

Advances of typical mesoporous materials and the application in drug delivery

“…It is worth noting that the coordination bond between metal ions and organic ligands ensures the degradability of MOFs, avoiding toxic side effects caused by the accumulation of drug carriers. Meanwhile, due to the presence of metal ions, photosensitivity and/or magnetic targeting can be utilized to achieve the goal of targeted diagnosis and synergistic therapy [42,43]. For example, zeolite imidazole framework (ZIF) materials, formed by imidazole or its derivatives as organic ligands linked with Zn 2+ , can rapidly decompose in acidic solutions.…”

Structural Diversity and Carbon Dioxide Sorption Selectivity of Zinc(II) Metal-Organic Frameworks Based on Bis(1,2,4-triazol-1-yl)methane and Terephthalic Acid

“…as other important components [ 2 ]. Thus, to achieve economically feasible CO 2 capture, highly selective adsorbents are required, and currently a lot of effort is being put into the search for metal–organic frameworks with a highly selective adsorption ability toward CO 2 with high capacity for further storage [ 3 , 4 , 5 ] or transformation into valuable chemical products [ 6 , 7 ].…”