Pore Design of Two-Dimensional Coordination Polymers toward Selective Adsorption

Abstract

We have synthesized four porous coordination polymers (PCPs) using Zn(2+), 4,4'-sulfonyldibenzoate (sdb), and four types of dinitrogen linker ligands, 1,4-diazabicyclo[2,2,2]octane (dabco), 1,4-bis(4-pyridyl)benzene (bpb), 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine (bpt), and 4,4'-bipyridyl (bpy). The bent sdb ligands form a rhombic space connected by zinc paddle-wheel units to form a one-dimensional double chain, and each dinitrogen ligand linked the one-dimensional double chains. There are different assembled structures of two-dimensional sheets with the same connectivities between Zn(2+) and the organic ligands. [Zn2(sdb)2(dabco)]n (1) has a noninterpenetrated and noninterdigitated structure, [Zn2(sdb)2(bpb)]n (2) and [Zn2(sdb)2(bpt)]n (3) have interdigitated structures, and [Zn2(sdb)2(bpy)]n (4) has an interpenetrated structure. The length of the dinitrogen ligands dominated their assembled structures and flexibility, which influence the adsorption properties. The flexible frameworks of 2 and 3 provide different stepwise adsorption behaviors for CO2, CH4, C2H6, and C2H4 affected by their pore diameters and the properties of the gases. Their different adsorption properties were revealed by IR spectroscopy and X-ray analysis under a gas atmosphere. The framework of 4 possesses less flexibility and a smaller void space than the others and a negligible amount of CH4 was adsorbed; however, 4 can adsorb either C2H6 or C2H4 through the gate-opening phenomenon. Measurement of the solid-state (2)H NMR was also carried out to investigate the relationship between the framework structure and the dynamics of bpy with regard to the lower flexibility of 4. We have demonstrated a strategy to control the pore size and assembled structures toward selective adsorption properties of PCPs.

A Family of Nitrogen-Enriched Metal Organic Frameworks with CCS Potential

“…Crystals obtained from this solvent matrix cell lose their crystallinity on removal of the mother-liquor, indicated by the fact that they cease to show extinction under polarized light. Single crystals of Zn-pytz(hydro), were produced by autoclave synthesis, the procedure used was adapted from those of Hijikata et al [31] and Hulvey et al [32]. 0.3 mmol Zn(NO 3 ) 2¨6 H 2 O, 0.9 mmol (NH 4 ) 2 SiF 6 and 0.6 mmol pytz in a 15 mL of 1 part dimethylformamide to 4 parts H 2 O was heated at 383 K for 18 h, before cooling to 293 K at 5 K/min.…”

Studies on oligomeric metal complexes derived from 2,5-bis((1H-1,2,4-triazol-3-yl)carbamoyl)terephthalic acid

“…The final light yellow precipitates were filtered, washed with dry THF followed by ethanol, and purified by column chromatography using ethyl acetate: hexane (1:1) solvent system and dried at room temperature. 1 …”

“…[1][2][3][4] Numerous polymer-metal complexes have been reported not only because of their intriguing variety of architectures and topologies [5][6][7] but also for their properties of high porosity and enormous internal surface areas. [8,9] These properties have potential applications in clean energy, such as storage media for methane, hydrogen, and acetylene [10,11] or as absorbents or membrane fillers in separation and purifications of chemicals.…”

Effect of three bis-pyridyl-bis-amide ligands with various spacers on the structural diversity of new multifunctional cobalt(II) coordination polymers

“…Even small structural changes of the organic ligands such as the symmetry, length, and flexibility or functional groups can produce obvious differences in the final coordination frameworks and topological networks [9][10][11]. Therefore, much efforts have been devoted to constructing new MOCPs with diverse structures and properties through reasonably design and selection of organic bridging ligands [12][13][14].…”