3D Metal–Organic Frameworks Based on Co(II) and Bithiophendicarboxylate: Synthesis,Crystal Structures,Gas Adsorption,and Magnetic Properties |
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| Authors: | Vadim A Dubskikh Anna A Lysova Denis G Samsonenko Alexander N Lavrov Konstantin A Kovalenko Danil N Dybtsev Vladimir P Fedin |
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| Institution: | Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia; (V.A.D.); (A.A.L.); (D.G.S.); (A.N.L.); (K.A.K.); (V.P.F.) |
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| 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. |
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| Keywords: | cobalt(II) metal– organic framework 2 2′ -bithiophen-5 5′ -dicarboxylic acid gas adsorption adsorption selectivity magnetic measurements |
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