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Discovery of metastability in the active phase of perovskite solar cells

November 01, 2019

Cesium lead iodide (CsPbI₃) has long been a promising light absorbing material for perovskite solar cells. Researchers from the Navrotsky lab, in a recently published study (J. Am. Chem. Soc. 2019, 141, 14501) conducted calorimetric studies on cubic(α) and orthorhombic(δ) CsPbI₃ polymorphs, obtaining their enthalpies of formation from binary iodides, and discussing the relative stabilities. Cubic phase CsPbI₃, the desirable phase for light absorbing material, is confirmed to be metastable under ambient conditions.

New insights into hydrogenase active site biosynthesis

October 14, 2019

[FeFe]-hydrogenases catalyze H₂ evolution at extraordinary rates at low overpotential using base metal (not platinum). In the field of renewable energy, the biosynthesis of these enzymes’ active sites, the H-cluster, is of intense interest. Among its many cofactors, the azadithiolate is unique, and its biosynthesis remains enigmatic. Three Fe–S proteins, HydE, HydF, and HydG, are essential for the H-cluster bioassembly. This paper describes an in vitro assembly approach where a synthetic [Fe(cysteine)(CO)₂(CN)] complex, “syn-B,” allows HydG- free biosynthesis of the active enzyme.

A radical enzyme intermediate trapped using non-native substrates

October 01, 2019

In a recent publication "Trapping and Electron Paramagnetic Resonance Characterization of the 5′dAdo• Radical in a Radical S-Adenosyl Methionine Enzyme Reaction with a Non-Native Substrate", Rick Sayler and coworkers in R. David Britt's Lab at UC Davis used non-natural substrates in the HydG radical SAM enzyme to trap and characterize the hot 5'deoxyadenosyl radical for the first time in such an enzyme reaction.

More information at https://pubs.acs.org/doi/10.1021/acscentsci.9b00706

A new Zintl phase for direct thermal to electrical energy conversion

September 27, 2019

Thermoelectric materials have shown promise as a clean energy alternative to fossil fuels that can convert waste heat into electrical power.  The Kauzlarich lab (He et al., Chem. Mater., 2019), in collaboration with Prof. Donadio and NASA-JPL, have been able to elucidate the structural and physical properties of a new material, Yb₂₁Mn₄Sb₁₈, showing large thermoelectric efficiency in the mid-to-high temperature regime.  The favorable properties of Yb₂₁Mn₄Sb₁₈ come intrinsically from its unique crystal structure, highlighted below. 

CO₂ reduction promoted by metal-promoted Mo₆S₈ clusters

September 05, 2019

In a recent publication (Perryman and coworkers, Materials Horizons, 2019) the Velázquez Lab describes for the first time experimental evidence of CO₂ reduction (CO₂R) activity over the compositionally modular Chevrel-Phase chalcogenide framework. In this unique framework, “promotion” of Mo₆S₈ units by a ternary metal species allows for electronic tuning of CO₂R-active sites, and further acts to stabilize anionic domains of key reaction intermediates, thereby providing an avenue toward controllable catalytic selectivity.

A Closer Look at Time Tested Reactions

May 29, 2019

In a recent publication (Zhu, Li, Tsui and coworkers, J. Am. Chem. Soc. 2019, 141, 6247-6253), the Tantillo and Kurth labs reinvestigated the mechanism of the Davis–Beirut reaction and Cadogan cyclization for 2H-indazole synthesis. At last, the elusive 2H-indazole N-oxide has been isolated, characterized, and modelled. This work highlights the amount of mechanistic insights gained when synthetic chemistry is coupled with computational support!

Metals influence C-peptide, a hormone related to insulin

May 20, 2019

A recently accepted publication by Heffern and coworkers in ChemBioChem details how metals like zinc, copper, and chromium affect a peptide hormone known as C-peptide. C-peptide is made during insulin production in the pancreas and may help with sugar transport, kidney disease, and nerve damage in patients with diabetes. Their findings show that copper and chromium stop C-peptide from being taken up by cells but zinc does not.

DMT Microdosing Produces Antidepressant and Anxiolytic Effects

March 04, 2019

In a recent publication (Cameron and coworkers, ACS Chemical Neuroscience, 2019), the Olson Lab demonstrates for the first time that psychedelic microdosing—the practice of administering subhallucinogenic doses on a chronic, intermittent schedule—may reduce depression and ease anxiety.  This work suggests that the hallucinogenic properties of psychedelic compounds like DMT might not be necessary for their therapeutic effects.

Thermodynamics of H₂O and CO₂ Absorption and Guest-induced Phase Transitions in Zeolite RHO

February 09, 2019
Scientific Achievement

The zeolite RHO structure is unusually flexible in response to guest molecule occupancy. Gas absorption calorimetry determined the energetics of H₂O and CO₂ interaction with the framework as a function of loading from near zero coverage to saturation for several cation exchanged zeolite RHO materials. Framework flexibility and an associated “gate opening” phase transition from the dehydrated acentric form to the hydrated centric form during water absorption are clearly detected and quantified. The interactions with CO₂ are weaker than with H₂O.

Solid state synthesis from KH and thermoelectric properties of K₈E₈Ge₃₈ (E = Al, Ga, In)

February 07, 2019

The Kauzlarich lab (Perez and coworkers, Inorganic Chemistry) has recently reported the synthesis, low-temperature thermoelectric properties, structures, and composition of the type-I Clathrates K₈E₈Ge₃₈ (E = Al, Ga, In) using KH, E, and Ge. K₈E₈Ge₃₈ shows significant thermoelectric (zT) improvement over the Si analog (K₈AI₈Si₃₈) due to a reduced electrical resistivity. This work points towards more sustainable cost-effective materials for optimal thermoelectric performance.

A Bump-Hole Approach for Directed RNA Editing

January 30, 2019

In a recent publication in Cell Chemical Biology (Monteleone and coworkers, A Bump-Hole Approach for Directed RNA Editing, 2018) the Beal and Fisher labs describe a site directed-RNA editing system with reduced off-target activity.  A variety of systems have been developed to direct reactions that change nucleic acid sequences, either in DNA (genome editing) or in RNA (transcriptome editing) and these systems are trans

Designing Reactions with Post-Transition-State Bifurcations

December 19, 2018

Deep understanding of the factors controlling reactivity and selectivity for chemical reactions empowers chemists to control product distributions and design reactions with desired outcomes. The work described here provides a recipe for designing reactions with post-transition-state bifurcations (PTSBs)—reactions in which a single transition state leads directly to two (or more) products.

Student researchers having fun with Chemistry