Structure solution from powder diffraction of copper 1,4- benzenedicarboxylate

In the synthesis of the microporous metal-organic framework copper 1,4-benzenedicarboxylate [Cu(BDC)], solvent exchange with methanol prior to recrystallization lowers the desolvation temperature to 160 C and produces more crystalline Cu(BDC). The solution to the crystal structure of Cu(BDC) has been determined by using ab initio quantum molecular calculations and refinement with synchrotron X-ray powder diffraction data. This solution is in the P$\bar {1}$ space group with a = 5.25 Å, b = 9.67 Å, c = 10.77 Å, α = 90.29, β = 91.06, γ = 92.413, and V = 546.04 ų. The Brunauer-Emmett-Teller (BET) surface area was 903 m²g^-1 with 777 m²g^-1 of micropore surface area. The uptake of CO₂ and CH₄ up to 20 bar were 5.2 and 2.7 mmolg^-1, respectively. These values are compared to those of 1,3,5-benzenetricarboxylate [Cu₃(BTC) ₂, HKUST-1] and used to show that the elevated metal-site density per unit volume is responsible for a proportionally higher uptake on the basis of relative surface areas. The platelike particles with perpendicular pores are promising candidates for mixed-matrix membranes.