0̷D Porous Molecular Solids

Categories: “Chemistry

Reference #: 2012-035

OTC Contact: Zeinab Abouissa M.S.
Phone: 202-687-2702
Email: zaa9@georgetown.edu


There is much contemporary interest in the development of new micro/nanoporous materials for gas capture/sequestration, separation, sensing, etc. Efforts have mainly been directed toward molecule-derived materials that exhibit permanent “open” pores (e.g., metal-organic frameworks (MOFs), covalent organic frameworks (COFs), polymers of intrinsic microporosity (PIMs), and even intrinsically porous molecular solids (PoMoSs).

Researchers at Georgetown University’s Department of Chemistry have developed 0D ultra-microporous crystalline cavitand solids that exhibit extreme gas confinement in the solid-state for a variety of guests, which are derived from shape persistent macrocycles, container molecules, hydrogen bonded frameworks, and even some metal-organic frameworks (MOFs).

These compounds exhibit remarkable thermodynamic and kinetic stability as well as remarkable selectivity for sorption of small molecules. For example, the crystalline compounds are capable of highly selective gas capture during crystallization (e.g., ethane vs. propane, chloromethane vs. dimethyl ether, ethylene vs. ethane, propene vs. propane, chloromethane vs. chloroethane, etc.) and confine highly volatile gases at unusually high temperatures. Moreover, while crystals are permeable to certain small molecules without any disruption of their single crystallinity, the kinetics of gas egress are qualitatively slow in comparison to open-pore materials, but are intriguingly highly guest dependent.

Further advantages of these crystalline compounds include:
i) Easy and Low cost of manufacturing
ii) Solution processability
iii) Trivial assembly and/or disassembly, thus are intrinsically incollapsible
iv) Amenable to organic alloying

Figure 1. Various 0D PoMoSs and their gas-occupied (C2H6, Xe N2, respectively) structures.

Moreover, by offering pores that completely encapsulate putative sorbates, they have the potential to optimize thermodynamic
selectivity with respect to gas/guest capture. Additionally, the kinetics of substrate uptake and/or release can vary enormously,
are largely dependent upon molecular and crystalline structure, and can therefore be engineered. Thus these solids possess a wide
range of applications in the capture, sorption, kinetic separations, and/or extreme kinetic confinement of commodity gases and
other small molecules.


U.S. Patent No.10,435,413
U.S. Patent Application No. 16/565,981


Travis Holman Ph.D., Professor
Department of Chemistry