Structure of a Porous Cu2(pzdc)2(bpp) (pzdc: Pyrazine-2,3-dicarboxylate, bpp: 1,3-Bis(4-pyridyl)propane) Coordination Polymer and Flexibility upon Concomitant Hysteretic CO2 Adsorption

A porous coordination polymer was prepared using pyrazine-2,3-dicarboxylate (pzdc) and a dipyridyl ligand that contains −CH2CH2CH2– as a spacer, namely, 1,3-bis(4-pyridyl)propane (bpp). The material was thoroughly tested for determination of textural and adsorption properties in an attempt to elucidate structural flexibility in the absence of a gate opening pressure phenomenon. The periodic framework (monoclinic, P21/c, a = 13.300(3), b = 13.112(7), c = 10.808(5) A, β = 101.28(4)°) composition is Cu2(pzdc)2(bpp))·4H2O, with an overall structural arrangement similar to those present in other two-dimensional copper + pzdc based coordination polymers, but showcasing a heavily distorted, parallelogram-shaped gallery along c. The structure appears stable up to 510 K based on thermogravimetric analysis and in situ high temperature X-ray diffraction data; complete elimination of water takes place at 373 K. Upon activation, the material effective surface area and pore volume are much smaller than those of other C...