Since 1990, natural gas as an alternative to petroleum-based fuels has been on the rise for over 30 years. This trend is projected to continue through at least 2050. The difficulty in utilizing methane, the main component of natural gas, as opposed to gasoline as a transportation fuel is that methane is a gas with a density of just 6.56 x 10-4 g/cm3 at S.T.P. whereas gasoline is a liquid with a density of 0.77 g/cm3. This difference in density corresponds to needing large pipelines for the transport of methane as opposed to a tanker truck for gasoline. In regions where pipelines cannot be laid the methane is transported as liquefied natural gas (LNG) or compressed natural gas (CNG). The processes to produce LNG or CNG from natural gas are energy intensive and require cryogenic temperatures and/or high pressure. Similarly, the utilization of natural gas as a transportation fuel necessitates the use of expensive and energy intensive techniques. Alternative storage methods for methane gas have been achieved by utilizing metal-organic frameworks for adsorptive storage. Here, the best material (taking cost, stability, scalability, deliverable capacity, and processability into consideration) is likely HKUST-1 with a volumetric uptake of 250 cm3/cm3. However, the U.S. Department of Energy (DOE) target for methane storage by adsorbent materials is 350 cm3/cm3. Framework materials are maxing out at 100 cm3/cm3 less than the DOE goal and therefore better adsorbent materials need to be synthesized to reach this target. Particularly when the high packing losses for these materials result in real volumetric storage capacities that are significantly lower. Porous cages are a group of materials which utilize metal paddlewheels and organic linkers to synthesize discrete molecules. Utilizing carbazole as the base ligand a series of porous cages have been synthesized with various metals. Functionalization of the carbazole moiety in the N-position has been probed utilizing substrates such as alkyl chains and aromatic ring systems. Functionalization of the carbazole moiety has led to the synthesis of highly crystalline and thermally stable cages. Functionalization allows for modulation of both intrinsic and extrinsic porosity of the cages, changing their gas uptake properties.

Tuning the stability and porosity of carbazole-based coordination cages through ligand functionalization

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.