Storage and sorption properties of acetylene in jungle-gym-like open frameworks

The acetylene-sorption properties of six porous coordination polymers (PCPs), [M-2(L)(2)(dabco)](n) (dabco = 1,4-diazabicyclo[2.2.2]octane, M = Cu2+ (1), Zn2+ (2), L = 1,4-benzenedicarboxylate (bdc; 1a, 2a), 1,4-naphthalenedicarboxylate (ndc; 1b, 2b), 9,10-anthracenedicarboxylate (adc; 1c, 2c)), were investigated. The acetylene sorption isotherms of 1 and 2 measured at 195 K are of type I and show a steep increase at low relative pressures. The sorption properties of carbon dioxide at 195 K were also investigated. Compounds 1 and 2 showed a large difference in onset pressure between acetylene sorption isotherms, although the difference between the carbon dioxide sorption isotherms is not so significant. In particular, 2c displayed a remarkable affinity for acetylene. The acetylene sorption isotherm at 298 K showed that the adsorption amounts for 2c and 2b at 298 K, 1 atm (101 and 106 mL g(-1), respectively) were higher than those of other conventional porous materials. Notably, of the compounds 1 and 2, the porous crystals 2c had the highest affinity for acetylene.