ACS Central Science最新文献

Pulverizing together a Cr^II perovskite, (BA)₂Cr^IICl₄, and a Cr^III doubleperovskite,(BA)₄Ag^ICr^IIICl₈, at roomtemperature affords a new layered perovskite alloy incorporating threedifferent metal ions in each layer: (BA)₈(Ag^ICr^III)Cr^II₂Cl₁₆ (BA = n-butylammonium). The magnetic ground state of this alloyis a spin glass (freezing temperature ∼ 3 K), which we proposearises from intrinsic disorder of superexchange interactions and apropensity to form ferromagnetic clusters. To explore the compositionspace beyond this example, we model the geometrical and topologicalproperties of these complex alloys by representing the [MCl₆]ⁿ⁻ tiling as effectively hard-rhombuspackings on a square lattice. The structures provided by our computationallyefficient model provide insight into magnetic exchange, ordering acrossvarious length scales, and the role of the in-plane Jahn–Tellerdistortion of the Cr^II centers in dictating the packingwithin the inorganic layer. By quantifying local compositional fluctuations,we identify alloy compositions at which the mixing characteristicsare appreciably different from those observed in random square-latticemixtures of three different metals. These results demonstrate a general,mechanochemical route to two-dimensional spin glasses and providedesign principles and computational tools for expanding the phasespace of complex layered halide perovskites with nontrivial magneticground states.

Access to noncanonicalamino acids is increasingly important innatural products synthesis and drug discovery. Enzymatic synthesishas emerged as an efficient strategy for simplifying approaches towardthese molecules. Pyridoxal-5′-phosphate (PLP)-dependent enzymeshave been extensively studied for the biocatalytic functionalizationof α-amino acids. However, the high substrate specificity ofthese enzymes has limited the substrate scope of PLP-mediated biocatalysis.Efforts to identify generalist catalysts may be enabled by catalyticpromiscuity, a property well-known in the PLP-dependent enzyme family.In pursuit of PLP-catalyzed C–C bond formation, we leveragea cofactor-centric approach with PLP-dependent enzymes not previouslyknown to mediate C–C bond formation to access key nucleophilicintermediates. In this work, we show that aminotransferases Aro8 andTyrB can mediate C–C bond formation, the first such activityreported for aminotransferases. Further, this non-native functioncan be improved by the addition of a sacrificial ketoacid. Interestingly,Aro8 and TyrB exhibit distinct conformational dynamics that impactthe diastereoselectivity of the reaction. These results indicate thataminotransferases are an untapped resource for the discovery of newbiocatalysts for C–C bond formation and demonstrate the valueof cofactor-guided reaction discovery.

Leading up to the 2025 Nobel Prize in Chemistry, thefield of metal–organicframeworks (MOFs) shifted the material design paradigm by allowingfor discrete molecular building blocks to be extended into predesignedporous functional materials. Outside of developing an expansive libraryof crystal structures and fundamentals of structure–propertyrelationships, application-driven MOF research has led to commercializationof MOF-based materials for direct air capture of CO₂, atmosphericwater harvesting, and protection of first responders. Today, the MOFfield addresses urgent global challenges related to clean water scarcity,sustainable energy, disease treatment, and advanced technology. ThisOutlook highlights some of the future MOF research avenues that coulddefine the post-Nobel Prize era of framework chemistry, beginningwith the implementation of controlled chemical heterogeneity in well-definedstructures to unlock heterogeneous tandem catalysts or materials forgradient drug release. Upcoming studies of adaptive and/or magneticframeworks will bring MOFs to the forefront of quantum materials research.Finally, this Outlook surveys some of the key challenges to addressto expand MOF commercialization. The early years of reticular chemistryhave provided the conceptual “blocks” to build a newgeneration of frameworks that will reshape the materials landscape,from innovative synthetic strategies to quantum computing and beyond.

Doping a luminescenttris(2,4,6-trichlorophenyl)methyl diradical m (TTM)₂ into a hostcrystal of its diamagnetic precursor m (HTTM)₂ creates a molecular color center with enhancedoptical-spin interface properties important for quantum sensing. Opticalpolarization of the |T₀⟩ sublevel of the diradicaltriplet ground state is achieved by spin-selective intersystem crossingfrom the |T₊⟩ and |T_–⟩sublevels of the triplet excited state at ambient and cryogenic temperatures.Coherent spin control of m (TTM)₂ doped into m (HTTM)₂ using pulsed optically detected magneticresonance (ODMR) spectroscopy results in a 10-fold improvement inODMR contrast over that observed for randomly oriented m (TTM)₂ using continuous-waveODMR. The diradical doped crystal powders achieve spin coherence timesof 2.8, 3.4, and 7.4 μs at 294, 85, and 5 K, respectively. Thediradical photoluminescence is sensitive to weak applied magneticfields independent of temperature, excitation wavelength, and dopantconcentration, providing a promising pathway toward robust quantumsensing of anisotropic magnetic fields under ambient conditions.

Polylactide (PLA)is the world’s top synthetic biopolymerand a major contributor to the circular plastic economy by virtueof its biodegradation and full biomineralization into benign end products.Nevertheless, efficient and complete degradation of PLA at its endof use remains constrained by the need for engineered industrial compostingenvironments that operate at elevated temperatures and high humiditylevels. In this work, PLA samples containing low levels of phthalicor 2-sulfobenzoic acid anhydride additives were prepared using industriallyviable melt-processing. These blends retained mechanical propertiesnearly identical to that of neat PLA while exhibiting significantlyaccelerated hydrolytic degradation, achieving appreciable mass losseswithin one month at 50 °C in artificial seawater. Remarkably,even trace (0.01 wt %, 100 ppm) incorporation of 2-sulfobenzoic acidcyclic anhydride proved highly effective in promoting PLA hydrolysiseven at temperatures below the glass transition temperature of theparent material. Furthermore, incorporation of 2-sulfobenzoic acidcyclic anhydride (0.1 wt %) enabled rapid biodegradation under compostingconditions at 58 °C, achieving 90% within 11 days, surpassingthat of neat PLA. Using anhydrides as strong acid-generating additivesenables acceleration of PLA hydrolysis and biodegradation withoutcompromising its other attractive properties, thereby opening a viablepathway toward realizing the full potential of PLA in a larger arrayof applications.

A long-standing goal in computational chemistry and materialssciencehas been the development of general-purpose interatomic force fieldsthat define the energy and forces associated with arbitrary sets ofatoms. This task can be accomplished with density functional theory(DFT) and other levels of computational quantum chemistry, but thecomputational cost of these methods strongly constrains the physicalproblems that can be explored. Rapid advances in machine-learned interatomicpotentials (MLIPs) mean that calculations at DFT levels of accuracywill soon be accelerated by factors of up to a million, a situationthat will dramatically change the landscape of computational chemistry.In this Outlook, we examine the implications and limitations of MLIPsand describe a research agenda for taking full advantage of theseremarkable tools.