Sorption behaviour in a unique 3,12-connected zinc–organic framework with 2.4 nm cages† Jinjie Qian, ab Feilong Jiang, a Kongzhao Su, ab Jie Pan, ab Linjie Zhang, ab Xingjun Li, a Daqiang Yuan a and Maochun Hong * a A polyhedral metal–organic framework (FJI-2) has been synthesized based on rare hexanuclear zinc clusters, which comprises 2.4 nm double-walled octahedral cages topologically featuring a new 3,12- connected structure. FJI-2 has a good H 2 uptake capacity of 149.7 cm 3 g 1 (1.34 wt %) at 77 K and 1.0 bar, and the IAST calculation predicts highly selective adsorption of CO 2 over N 2 and CH 4 . Metal–organic frameworks (MOFs) are a novel class of highly porous solid-phase materials with tunable pore size and shape and high internal surface area. Over the past decade, MOF materials have been intensively studied for their promising applications in on-board hydrogen storage 1 and carbon dioxide capture 2 for a clean environment. Compared to other solid physisorbents, including porous zeolites and carbon materials, these metal–organic hybrid materials generally incorporate both metal centers and polyfunctional organic ligands with extraordinary permanent porosity and large pore volume for gas storage. 3 More recently, various strategies have been developed to enhance the interactions between the adsorbed gas mole- cules and the framework, and gas storage capacity by ligand extension 4 and/or creation of open-metal sites. 5 However, decreased stability and reduced porosity of the targeted framework unavoidably occur for interpenetration and extremely active exposed metal sites. 6 On the other hand, higher structural stability and porosity can be simultaneously achieved in polyhedron-based MOF materials as the limited size of the open windows of the poly- hedra largely increases the rigidness of the framework. Theo- retically and experimentally speaking, these polyhedra can be connected together to form three-dimensional MOF materials through either coordination bonds or covalent bonds. 7 Most recently, a highly porous 3,24-connected framework NOTT-122 has been reported by Schr¨ oder's group, which was achieved by connecting the 24 edges of a cuboctahedron with a C 3 - symmetric angularly connected isophthalate linker containing 1,2,3-triazole rings. 8 Polyhedron-based MOF materials are attracting more attention and are of great importance in the eld of solid porous MOF materials for practical applications. Our group is particularly interested in the design and production of new solid porous metal–organic materials. 9 Previously, we utilized the steric hindrance effect of the axial N- donor ligand coordinated with the paddle-wheel zinc clusters, and successfully obtained a highly porous MOF material ([Zn 6 (BTB) 4 (4,4 0 -bpy) 3 ]solv, named as FJI-1;H 3 BTB ¼ 1,3,5- tris(4-carboxyphenyl)benzene; 4,4 0 -bpy ¼ 4,4 0 -bipyridine). 9c FJI-1 exhibits high gas uptake capacity aer supercritical carbon dioxide (SCD) processing with an excess hydrogen storage capacity of 6.52 wt% at 37 bar and the total adsorption capacity of 9.08 wt% at 62 bar. Herein, we report the synthesis, single crystal structure and gas adsorption behavior of a zinc–organic framework [Zn 9 (BTB) 4 (odabco) 3 (m 3 -O) 3 (m 2 -H 2 O) 6 ]$16DEF (FJI-2) (odabco ¼ N-oxide-1,4-diazabicyclo[2.2.2]-octane; DEF ¼ N,N- diethylformamide) where odabco is the product of in situ mono- oxidation of the dabco ligand. FJI-2 structurally consists of 2.4 nm double-walled octahedral cages and topologically features a new binodal network. Crystals of FJI-2 were obtained under solvothermal condi- tions by heating the mixture of Zn(NO 3 ) 3 $6H 2 O, H 3 BTB and dabco in a 2 : 1 : 2 molar ratio in DEF/HBF 4 (5 : 0.1, v/v; DEF ¼ N,N 0 -diethylformamide; HBF 4 ¼ tetrauoroboric acid, 40% in water) at 85  C for 4 days. Powder X-ray diffraction (PXRD) analysis conrms the phase purity of the bulk product (Fig. 4 a Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, State Key Laboratory of Structure Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China. E-mail: hmc@irsm.ac.cn; Fax: +86-591-83794946; Tel: +86-591-83792460 b Graduate School of the Chinese Academy of Sciences, Beijing, 100049, China † Electronic supplementary information (ESI) available: Crystal data for FJI-2: C 11 H 5 N 0.5 O 3 Zn 0.75 , M r ¼ 241.20, cubic, Im  3 (SG no. ¼ 204), a ¼ b ¼ c ¼ 27.3685(2) ˚ A, V ¼ 20500.2(3) ˚ A 3 , T ¼ 173(2) K, Z ¼ 48, D c ¼ 0.9377 g cm 3 , l ¼ 0.71073 ˚ A, 2q max ¼ 67.4  , F(000) ¼ 5808, GOF ¼ 1.092, R 1 and wR 2 are 0.0799 and 0.2527, respectively. The structure was solved by direct methods and rened on F 2 by full-matrix least-squares methods using the SHELXL-97 program package. The topology of the network is analyzed by the program package TOPOS. 15 CCDC 943717. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3ta12391j Cite this: J. Mater. Chem. A, 2013, 1, 10631 Received 20th June 2013 Accepted 19th July 2013 DOI: 10.1039/c3ta12391j www.rsc.org/MaterialsA This journal is ª The Royal Society of Chemistry 2013 J. Mater. Chem. A, 2013, 1, 10631–10634 | 10631 Journal of Materials Chemistry A COMMUNICATION Published on 22 July 2013. Downloaded by Fujian Institute of Research on the Structure of Matter, CAS on 30/08/2013 02:38:47. View Article Online View Journal | View Issue