Gas Storage in Porous Molecular Materials

Abstract

Molecules with permanent porosity in the solid state have been studied for decades. Porosity in these systems is governed by intrinsic pore space, as in cages or macrocycles, and extrinsic void space, created through loose, intermolecular solid‐state packing. The development of permanently porous molecular materials, especially cages with organic or metal–organic composition, has seen increased interest over the past decade, and as such, incredibly high surface areas have been reported for these solids. Despite this, examples of these materials being explored for gas storage applications are relatively limited. This minireview outlines existing molecular systems that have been investigated for gas storage and highlights strategies that have been used to understand adsorption mechanisms in porous molecular materials.

Broadband Dielectric Spectroscopic Detection of Ethanol: A Side-by-Side Comparison of ZnO and HKUST-1 MOFs as Sensing Media

“…The behavior of the doped material is also consistent with guest-induced electronic and vibrational structure changes of the SURMOF films [ [26], [74]]. Furthermore, the temperature dependence of the impedance in the SURMOF suggests that either nitrogen adsorption at the open metal sites is gated by thermal-induced conformational changes in the MOF cage to allow access to the open metal sites [75,76], or the DUT has temperature drifts below 50 °C [77]. Irrespective of the reason for the S21 saturation above 50 °C, all subsequent experiments were conducted at 65° C or higher temperatures to avoid the S21 drift.…”

Stabilizing Porosity in Organic Cages through Coordination Chemistry

“…NMR spectra ( 1 H, 13 C, and DOSY) were collected at room temperature (25 °C) on Bruker 400 MHz spectrometers. 1 H and 13 C chemical shifts are reported in ppm, relative to tetramethylsilane using residual resonances from solvents as internal standards. X-ray photoelectron spectra were collected using a Thermo Fisher K-Alpha XPS instrument at the University of Delaware's Surface Analysis Facility.…”

“…Both POCs and PCCs have proven to be highly tunable materials, where diverse organic functionality can be incorporated at the periphery of the cages both prior to cage assembly and post-synthetically. − Although very high surface POCs are more common, the incorporation of transition metal-based nodes in PCCs provides another handle for tuning the properties of these structures and allows them to access greater structural diversity . Furthermore, open transition metal cation sites are known to play a critical role in many potential applications of these materials, including in gas storage, gas separations, and catalysis. , …”

“…12 Furthermore, open transition metal cation sites are known to play a critical role in many potential applications of these materials, including in gas storage, gas separations, and catalysis. 13,14 Many permanently porous organic cages are synthesized via reversible Schiff base chemistry to generate structures whose permanent porosity is reliant upon the structural rigidity of the generated imine linkages. Structures of this type were first reported by Skowronek and Gawronski from the [4 + 6] Schiff base condensation of triformyl benzene with diaminocyclohexane.…”

Metal-Free Pyrene-Based Conjugated Microporous Polymer Catalyst Bearing N- and S-Sites for Photoelectrochemical Oxygen Evolution Reaction

“…From the last few decades, porous nanomaterials have attracted huge attention in addressing some of the major commercial/household problems. Their surface-active porous architecture makes them promising material within a certain domain of applications such as gas storage (Deegan et al, 2021), sensing (Ramírez-González et al, 2020), and separation (Hiraide et al, 2020), as well as in biomedical research. Additionally, the ease of fabrication of organic functional groups at the pore surface and high specific surface area make them desirable materials for various energy harvesting applications.…”