A Flexible Dihydrogen-Bonded Organic Framework with Selective Gas Adsorption Properties

An unprecedented porous organic framework, BSF-11, was prepared by the self-assembly of closo-dodecaborate [B12H12]2- and cationic 2,6-diaminopurine-Cu(II) complexes via multiple proton-hydride dihydrogen bonds. Single crystal structure analysis indicated that BSF-11 displays a 1D channel with a narrow bottleneck (2.79 Å) and a large cavity (7.12 Å). The intrinsic porosity was preserved after thermal activation in vacuum; BSF-11 showed pore opening adsorption of C2H2 and C3H4 while excluding other light hydrocarbons and CO2 under ambient conditions, resulting in high adsorption uptake ratios of C2H2/CH4 (24.9), C2H2/C2H4 (8.1), C2H2/CO2 (2.3), and C3H4/C3H6 (19.7) at 1 bar. The different CO2, C2H2, and C3H4 adsorption affinities were further investigated by GCMC and DFT modeling. The calculated binding energy trend is consistent with the uptake trend observed in experiments.