Quantum sieving effect of three-dimensional Cu-based organic framework for H2 and D2

The crystal structure of [Cu(4,4'-bipyridine)(2)(CF3SO3)(2)](n) metal-organic framework (CuBOTf) of one-dimensional pore networks after pre-evacuation at 383 K was determined with synchrotron X-ray powder diffraction measurement. Effective nanoporosity of the pre-evacuated CuBOTf was determined with N-2 adsorption at 77 K. The experimental H-2 and D-2 adsorption isotherms of CuBOTf at 40 and 77 K were measured and then compared with GCMC-simulated isotherms using the effective nanoporosity. The quantum-simulated H-2 and D-2 isotherms at 77 K using the Feynman-Hibbs effective potential coincided with the experimental ones, giving a direct evidence on the quantum molecular sieving effect for adsorption of H-2 and D-2 on CuBOTf. However, the selectivity for the 1:1 mixed gas of H-2 and D-2 was 1.2. On the contrary, experimental H-2 and D-2 isotherms at 40 K had an explicit adsorption hysteresis, originating from the marked pore blocking effect on measuring the adsorption branch. The blocking effect for quantum H-2 is more prominent than that for quantum D-2; the selectivity for D-2 over H-2 at 40 K was in the range of 2.6 to 5.8. The possibility of the quantum molecular sieving effect for H-2 and D-2 adsorption on [Cu-3(benzene-1,3,5-tricarboxylate)(2)(H2O)(3)](n) of three-dimensional pore networks was also shown at 77 K.