A Highly Porous Metal–Organic Framework: Structural Transformations of a Guest‐Free MOF Depending on Activation Method and Temperature

Abstract

A doubly interpenetrating porous metal-organic framework (SNU-77) has been synthesized from the solvothermal reaction of the extended carboxylic acid tris(4'-carboxybiphenyl)amine (H(3)TCBPA) and Zn(NO(3))(2)⋅6H(2)O in N,N-dimethylacetamide (DMA). SNU-77 undergoes single-crystal-to-single-crystal transformations during various activation processes, such as room-temperature evacuation, supercritical CO(2) drying, and high temperature evacuation, to afford SNU-77R, SNU-77S, and SNU-77H, respectively. These guest-free MOFs exhibited different fine structures with different window shapes and different effective window sizes at room temperature. Variable-temperature synchrotron single-crystal X-ray analyses reveal that the guest-free structure is also affected by changes in temperature. Despite the different fine structures, SNU-77R, SNU-77S, and SNU-77H show similar gas sorption properties due to the nonbreathing nature of the framework and an additional structural change upon cooling to cryogenic gas sorption temperature. SNU-77H exhibits a large surface area (BET, 3670 m(2) g(-1)), a large pore volume (1.52 cm(3) g(-1)), and exceptionally high uptake capacities for N(2), H(2), O(2), CO(2), and CH(4) gases.

Comparison of Gas Sorption Properties of Neutral and Anionic Metal–Organic Frameworks Prepared from the Same Building Blocks but in Different Solvent Systems

“…ing Information), similarly to the case of SNU-77 S. [21] The powder X-ray diffraction patterns indicate that the framework structure of SNU-150' is similar to that of SNU-150 ( Figure 3).…”

“…It is quite well recognized that charged frameworks show superior gas sorption properties to neutral ones. [18,[28][29][30] When the gas adsorption properties of SNU-150' are compared with those of SNU-77 S, [21] which also has PdF 2 topology, it is found that SNU-150' adsorbs much smaller amounts of N 2 and H 2 gases at 77 K and 1 atm, as well as a smaller amount of CO 2 gas at 195 K and 1 atm. This must be attributed to the significantly smaller surface area (1852 m 2 g À1 ) of SNU-150' than that (3670 m 2 g À1 ) of SNU-77 S. When the gas adsorption properties of SNU-151' are compared with those of SNU-100', which has an anionic framework with diethA C H T U N G T R E N N U N G yl-A C H T U N G T R E N N U N G ammonium cations, it is observed that SNU-151' is superior to SNU-100'.…”

Activation‐Dependent Breathing in a Flexible Metal–Organic Framework and the Effects of Repeated Sorption/Desorption Cycling

“…[5] Large variations in the resulting sorption capacity were observed for these three methods.I naseparate study Park and co-workers investigated the effect of activation methods on the fine structure of SNU-77, also at hree-dimensional Zn carboxylate. [6] Yang et al were also able to optimise the sorption capacity of Cu-BTC by solvent exchange with various solvents prior to activation. [7] In general, however,d etailed structural investigations of the effect of solvent-mediated activation are limited.…”

Path integral Monte Carlo simulations of H2 adsorbed to lithium-doped benzene: A model for hydrogen storage materials

“…Our best estimate of the 0 K H 2 adsorption enthalpy, ∆H bind (0 K), was −12.4 kJ.mol −1 , 20 within 2 kJ.mol −1 of the experimentally measured ∆H ads of H 2 to bare metal sites. 21 In this paper we extend our 0 K calculations to finite temperature; in the long term, room temperature H 2 storage is required if H 2 is to become a viable alternative to fossil fuels in vehicles. Moreover, the experimental characterisation of putative H 2 storage materials typically takes place between 77 and 98 K. 22 Although quantum effects become less important as temperature increases, H 2 is known to exhibit quantum behaviour at ambient temperature, 17,19 and thus a quantum rather than classical formalism is required.…”