A Flexible Dihydrogen-Bonded Organic Framework with SelectiveGas Adsorption Properties

Abstract

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 $C_2$H_2$ and $C_3$H_4$ while excluding other light hydrocarbons and CO2 under ambient conditions, resulting in high adsorption uptake ratios of $C_2$H_2$/$CH_4$ (24.9), $C_2$H_2$/$C_2$H_4$ (8.1), $C_2$H_2$/$CO_2$ (2.3), and $C_3$H_4$/$C_3$H_6$ (19.7) at 1 bar. The different $CO_2$, $C_2$H_2$, and $C_3$H_4$ adsorption affinities were further investigated by GCMC and DFT modeling. The calculated binding energy trend is consistent with the uptake trend observed in experiments.