Spotlights on Recent JACS Publications

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Spotlights Cite This: J. Am. Chem. Soc. 2017, 139, 14335-14335

pubs.acs.org/JACS

Spotlights on Recent JACS Publications

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SELF-ASSEMBLY OF NON-SOLID, YET FUNCTIONAL, SUB-MICROMETER ARCHITECTURES Researchers interested in functional materials have begun looking to non-solid supramolecular assemblies for potential applications in novel device concepts. A popular source of such materials is π-conjugated moleculesknown as π-gelators that undergo sol−gel transitions to form soft materials with unique optoelectronic properties. Despite numerous reports of gel materials created from π-gelators, major hurdles remain before these materials can be integrated into real technological devices. Now, researchers led by Emanuele Orgiu and Paolo Samori ̀ report the in situ supramolecular self-assembly of a π-gelator to create a sub-micrometer electrodic cavity (DOI: 10.1021/ jacs.7b04347). The resulting cavity exhibits the properties of a memristor, which is an electrical component that regulates and remembersthe amount of electrical current flowing through a circuit. The sol−gel transition of the gel-based memristor is both reversible and controllable via heating and DC biasa voltage applied to control a circuit. This work may help lay the foundation for the development of a new generation of non-solid, stimuli-responsive devices and extend the frontier of solid-state electronics. Christine Herman, Ph.D.

MODEL COMPLEX AFFORDS INSIGHTS INTO ELUSIVE C−H HYDROXYLATION MECHANISM The selective hydroxylation of C−H bonds is a key step in numerous biochemical transformations as well as the preparation of chemicals and pharmaceuticals. This hydroxylation is carried out in nature by the large cytochrome P450 family of enzymes, although far fewer synthetic catalysts are capable of effecting the same transformation. A detailed understanding of the mechanism could aid in the design of improved synthetic catalysts. However, observation of the crucial “rebound” step, involving transfer of a hydroxyl radical from a transient iron porphyrin hydroxide, has been precluded by the lack of a stable synthetic complex with the same oxidation level. David Goldberg and co-workers have now succeeded in the direct observation and study of the rebound step by using a model iron complex (DOI: 10.1021/jacs.7b07979). The researchers replace porphyrin with a bulky corrole ligand to afford enhanced electronic and steric stabilization of the iron hydroxide complex. Mechanistic studies importantly provide evidence that the rebound occurs in a concerted, rather than stepwise, fashion. The insights afforded from this study will be of great value to chemists and biologists targeting new catalysts and optimized enzyme function for C−H hydroxylation. Katie Meihaus, Ph.D. SELF-REPLICATING MOLECULES HELP MAKE MORE OF THEIR OWN It is one of those questions that can keep a person awake at night: How did life get started? One way chemists have tried to get a handle on it is by developing and studying systems of selfreplicating molecules. In most cases, these replicators have either been designed and synthesized by researchers, or emerged spontaneously from a set of chemical building blocks, but they have not been formed from replicating parent molecules in a manner we associate with the evolution of life. Now Sijbren Otto and colleagues describe a new system in which an existing replicator helps catalyze the production of a new one (DOI: 10.1021/jacs.7b07346). By screening a library of macrocyclic disulfide replicators containing different amino acid functional groups, the team shows that an octameric macrocycle containing eight serines stimulates the production of a hexameric replicator with six threonines through crosscatalysis. The discovery brings synthetic replicating systems into a more life-like realm and creates new opportunities to examine evolutionary history as a control on the proliferation of life. Deirdre Lockwood, Ph.D.

RECORD METHANE STORAGE IN A TOPOLOGICALLY DIVERSE METAL−ORGANIC FRAMEWORK The high natural abundance of methane (CH4) and its low carbon dioxide emissions from combustion render it a promising alternative to conventional fossil fuels in motor vehicles. However, energy-intensive compression or liquefaction is necessary to store enough CH4 on-board for reasonable driving ranges. A more promising CH4 storage strategy may be to utilize metal−organic frameworks (MOFs), which are porous, three-dimensional structures with high surface areas capable of adsorbing large volumes of gas. Still, many challenges must be faced in the use of MOFs for such an application, one of the most important being the need for substantial increases in framework CH4 storage capacities. Yue-Biao Zhang and colleagues report a family of mixedlinker MOFs for CH4 storage that are constructed from zinc clusters and both di- and tritopic ligands, allowing assorted topologies to be achieved within a single network (DOI: 10.1021/jacs.7b08347). The framework displays the greatest diversity of pore sizes and shapes and sets an impressive record for CH4 storage, which far exceeds the capacities of previous benchmark materials. These results suggest that engineering diverse pore structures within individual MOFs may be an important strategy to target materials suitable for transportation applications. Katie Meihaus, Ph.D. © 2017 American Chemical Society

Published: October 18, 2017 14335

DOI: 10.1021/jacs.7b10766 J. Am. Chem. Soc. 2017, 139, 14335−14335