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Interest in the field of hybrid double perovskite halides has grown rapidly over the last few years, with important developments in 3D, 2D and 1D systems. Their chemical scope has also expanded from an initial focus on materials containing post-transition metals, which are of potential utility for photovoltaic applications, to recent work that covers transition metals and rare earths with very interesting magnetic and optical properties. This reflection article traces the development of this important area from our 2016 communication in Materials Horizons(F. Wei, Z. Deng, S. Sun, F. Xie, G. Kieslich, D. M. Evans, M. A. Carpenter, P. D Bristowe and A. K. Cheetham, Mater. Horiz., 2016, 3, 328–332, https://doi.org/10.1039/C6MH00053C).

Long-duration storage of hydrogen is necessary for coupling renewable H2with stationary fuel cell power applications. In this work, aluminum formate (ALF), which adopts the ReO3-type structure, is shown to have remarkable H2storage performance at non-cryogenic (>120 K) temperatures and low pressures. The most promising performance of ALF is found between 120 K and 160 K and at 10 bar to 20 bar. The study illustrates H2adsorption performance of ALF over the 77 K to 296 K temperature range using gas isotherms, in situ neutron powder diffraction, and DFT calculations, as well as technoeconomic analysis (TEA), illustrating ALF’s competitive performance for long-duration storage versus compressed hydrogen and leading metal–organic frameworks. In the TEA, it is shown that ALF’s storage capacity, when combined with a temperature/pressure swing process, has advantages versus compressed H2at a fraction of the pressure (15 bar versus 350 bar). Given ALF’s performance in the 10 bar to 20 bar regime under moderate cooling, it is particularly promising for use in safe storage systems serving fuel cells.

We report hybrid and all-inorganic, vacancy-ordered double perovskites of d2W4+with the formula A2WCl6(A = CH3NH3+, Rb+, and Cs+). These compounds, which are reddish in color, can be distinguished from structurally similar compounds obtained by hydrothermal methods on the basis of structure, spectroscopic, and magnetic properties. The latter are green and incorporate oxygen, with the actual formula Cs2WOxCl6–xand distinct optical absorption and emission behavior. The local-moment magnetism of the pure-red d2compounds reported here does not correspond to the appropriate Kotani model, suggesting as-yet undiscovered physics in these systems.

Separating oxygen from air to create oxygen-enriched gas streams is a process that is significant in both industrial and medical fields. However, the prominent technologies for creating oxygen-enriched gas streams are both energy and infrastructure intensive as they use cryogenic temperatures or materials that adsorb N2from air. The latter method is less efficient than the methods that adsorb O2directly. Herein, we show, via a combination of gas adsorption isotherms, gas breakthrough experiments, neutron and synchrotron X-ray powder diffraction, Raman spectroscopy, and computational studies, that the metal–organic framework, Al(HCOO)3(ALF), which is easily prepared at low cost from commodity chemicals, exhibits substantial O2adsorption and excellent time-dependent O2/N2selectivity in a range of 50–125 near dry ice/solvent (≈190 K) temperatures. The effective O2adsorption with ALF at ≈190 K and ≈0.21 bar (the partial pressure of O2in air) is ≈1.7 mmol/g, and at ice/salt temperatures (≈250 K), it is ≈0.3 mmol/g. Though the kinetics for full adsorption of O2near 190 K are slower than at temperatures nearer 250 K, the kinetics for initial O2adsorption are fast, suggesting that O2separation using ALF with rapid temperature swings at ambient pressures is a potentially viable choice for low-cost air separation applications. We also present synthetic strategies for improving the kinetics of this family of compounds, namely, via Al/Fe solid solutions. To the best of our knowledge, ALF has the highest O2/N2sorption selectivity among MOF adsorbents without open metal sites as verified by co-adsorption experiments..

Hybrid layered double perovskite (HLDP) halides comprise hexacoordinated 1+ and 3+ metals in the octahedral sites within a perovskite layer and organic amine cations between the layers. Progress on such materials has hitherto been limited to compounds containing main group 3+ ions isoelectronic with PbII(such as SbIIIand BiIII). Here, we report eight HLDP halides from the A2MIMIIIX8family, where A= para-phenylenediammonium (PPDA), 1,4-butanediammonium (1,4-BDA), or 1,3-propanediammonium (1,3-PDA); MI= Cu or Ag; MIII= Ru or Mo; X = Cl or Br. The optical band gaps, which lie in the range 1.55 to 2.05 eV, are tunable according to the layer composition, but are largely independent of the spacer. Magnetic measurements carried out for (PPDA)2AgIRuIIICl8and (PPDA)2AgIMoIIICl8show no obvious evidence of a magnetic ordering transition. While the t2g3MoIIIcompound displays Curie–Weiss behavior for a spin-only d3ion, the t2g5RuIIIcompound displays marked deviations from the Kotani theory.

Polyanion-based electrode materials are important for rechargeable sodium(Na)-ion batteries owing to their structural stability and their high redox voltage. The redox voltages and gravimetric capacities of polyanion electrodes can be tuned by the choice of transition metal and/or polyanion groups. In this work we explore the effect of changing polyanion groups on the redox voltages and the gravimetric capacities of polyanion electrodes. Using first-principles calculations, we examine the influence of polyanionic substitutions on the stability and electrochemical behavior of the Na3V2(PO4)3electrode material, which adopts the prototype structure of the natrium superionic conductor (NaSICON). Starting from the Na3V2(PO4)3structure, we explore the partial or total substitution of PO43–groups by SiO44–or SO42–moieties, unveiling the uncharted multicomponent Na–V–P–(Si/S)–O phase diagram. We show that small amounts of SiO44–can activate the VV/IVredox couple, which is not experimentally accessible in the PO43–NaSICON analogue, thereby increasing the average Na intercalation voltage. In the case of SO42–substitution, we observe an increase in voltage of each V redox couple (i.e., VIII/II, VIV/III, and VV/IV) but at the expense of the maximum amount of Na+intercalated. We show that exploiting the varying inductive effects of different polyanion groups can be effective for tuning the energy density of NaSICON electrode materials.

Thin films with effective ion sieving ability are highly desired in energy storage and conversion devices, including batteries and fuel cells. However, it remains challenging to design and fabricate cost-effective and easy-to-process ultrathin films for this purpose. Here, we report a 300 nm-thick functional layer based on porous organic cages (POCs), a new class of porous molecular materials, for fast and selective ion transport. This solution processable material allows for the design of thin films with controllable thickness and tunable porosity by tailoring cage chemistry for selective ion separation. In the prototype, the functional layer assembled by CC3 can selectively sieve Li+ions and efficiently suppress undesired polysulfides with minimal sacrifice for the system’s total energy density. Separators modified with POC thin films enable batteries with good cycle performance and rate capability and offer an attractive path toward the development of future high-energy-density energy storage devices.

Hybrid organic–inorganic perovskite (HOIP) ferroelectrics are attracting considerable interest because of their high performance, ease of synthesis, and lightweight. However, the intrinsic thermodynamic origins of their ferroelectric transitions remain insufficiently understood. Here, we identify the nature of the ferroelectric phase transitions in displacive [(CH3)2NH2][Mn(N3)3] and order–disorder type [(CH3)2NH2][Mn(HCOO)3] via spatially resolved structural analysis and ab initiolattice dynamics calculations. Our results demonstrate that the vibrational entropy change of the extended perovskite lattice drives the ferroelectric transition in the former and also contributes importantly to that of the latter along with the rotational entropy change of the A-site. This finding not only reveals the delicate atomic dynamics in ferroelectric HOIPs but also highlights that both the local and extended fluctuation of the hybrid perovskite lattice can be manipulated for creating ferroelectricity by taking advantages of their abundant atomic, electronic, and phononic degrees of freedom.

The evolution of metal–organic frameworks (MOFs) has been one of the most exciting aspects of materials chemistry over the last 20 years. In this Account, we discuss the development during this period in our understanding of the factors that control the crystallization of MOFs from solution. Both classical porous MOFs and dense MOF phases are considered. This is an opportune time at which to examine this complex area because the experimental tools now available to interrogate crystallization processes have matured significantly in the last 5 years, particularly with the use of in situ synchrotron X-ray diffraction. There have also been impressive developments in the use of density functional theory (DFT) to treat not only the energies of very complex structures but also their entropies. This is particularly important in MOF frameworks because of their much greater flexibility compared with inorganic structures such as zeolites.

The discovery of new crystalline inorganic compounds─novel compositions of matter within known structure types, or even compounds with completely new crystal structures─constitutes an important goal of solid-state and materials chemistry. Some fractions of new compounds can eventually lead to new structural and functional materials that enhance the efficiency of existing technologies or even enable completely new technologies. Materials researchers eagerly welcome new approaches to the discovery of new compounds, especially those that offer the promise of accelerated success. The recent report from a group of scientists at Google who employ a combination of existing data sets, high-throughput density functional theory calculations of structural stability, and the tools of artificial intelligence and machine learning (AI/ML) to propose new compounds is an exciting advance. We examine the claims of this work here, unfortunately finding scant evidence for compounds that fulfill the trifecta of novelty, credibility, and utility. While the methods adopted in this work appear to hold promise, there is clearly a great need to incorporate domain expertise in materials synthesis and crystallography.

Advances in telecommunications require electronics that operate at ever-increasing frequencies, exemplified by 5G or fifth-generation technologies that operate in the GHz regime. At high frequencies, electrical circuits are plagued by so-called RCdelays, arising from the time constant τ = RCfor electrical signals which is the product of the resistance Rand the capacitance C, respectively, of conductors and their insulating substrates. Besides using high quality, low-Relectrical conductors such as high-purity Cu with low surface roughness, small RCdelays are achieved by lowering the dielectric constant κ of the materials used in printed circuit board substrates. These largely comprise particles of an inorganic material, notably functionalized SiO2, embedded in a polymer-based matrix. The value of κ of the composite is primarily dictated by κ of the inorganic material. The properties of the inorganic component also impact other relevant parameters such as the quality factor, mechanical strength, and thermal expansion of the substrate. Here, we ask whether there are inorganic compounds with dielectric constants (measured at 10 GHz) that are lower than that of SiO2and potentially replace it in electronics. We describe the key characteristics for low-κ materials and develop a framework for screening such compounds by employing some guiding principles, followed by using a combination of empirical estimates and density functional perturbation theory-based calculations. We then report experimental results on two promising aluminum-based low-κ compounds for high-frequency applications. The first is the cristobalite form of AlPO4. The second is the simplest 3D metal–organic framework, aluminum formate Al(HCOO)3. The measured values of κ at 10 GHz, which are 4.0 for AlPO4and 3.8 for Al(HCOO)3, compare well with what is measured on SiO2particles.

Materials with near-infrared (near-IR) luminescence are desirable for applications in communications and sensing, as well as biomedical diagnostics and imaging. The most used inorganic near-IR emitters rely on precise doping of host crystal structures with select rare-earth or transition metal ions. Recently, another class of materials with intrinsic near-IR emission has been reported. The compositions of these materials were initially described as vacancy-ordered halide double perovskites Cs2MoCl6and Cs2WCl6, but further investigation by some of us on the compound reported as Cs2WCl6revealed an oxyhalide instead, with a composition Cs2WOxCl6–x, where 1 < x< 2. Here we demonstrate that the Mo compounds similarly possess the composition Cs2MoOxCl6–xor Cs2MoOxBr6–xwhere 1 < x< 2. Preparing the pure halide appears harder for Mo than for W, and we have not succeeded in doing so. The distinctly different composition requires the coordination environment and oxidation state for the Mo and W centers to be reconsidered from what was assumed for the pure halides. In this work, we examine the mechanism for near-IR emission in these materials given their true structures and compositions. We demonstrate that the luminescence is due to the specific d-orbital splitting caused by the presence of oxygen in the distorted [MOX5]2–octahedra (X is Cl or Br). The fine structure in the emission spectra at low temperatures has been resolved and is attributed to vibronic coupling to the Mo–O and W–O bond stretches. Understanding the true structure and composition of these interesting materials, besides explaining the near-IR luminescence, suggests how this desirable emission can be realized and manipulated.

Lithium-ion batteries are essential for portable technology and are now poised to disrupt a century of combustion-based transportation. The electrification revolution could eliminate our reliance on fossil fuels and enable a clean energy future; advanced batteries would facilitate this transition. However, owing to the demanding performance, cost, and safety requirements, it is challenging to translate new materials from laboratory prototypes to industrial-scale products. This Perspective describes that journey for a new lithium-ion battery anode material, TiNb2O7(TNO). TNO is intended as an alternative to graphite or Li4Ti5O12with better rate and safety characteristics than the former and higher energy density than the latter. The high capacity of TNO stems from the multielectron redox of Nb5+to Nb3+, its operating voltage window well above the Li+/Li reduction potential prevents lithium dendrite formation, and its open crystal structure leads to high-power performance. Nevertheless, the creation of a practical TNO anode was nonlinear and nontrivial. Its history is built on 30 years of fundamental science that preceded its application as a battery anode, and its battery development included a nearly 30-year gap. The insights and lessons contained in this Perspective, many of them acquired firsthand, serve two purposes: (i) to unite the disparate studies of TiNb2O7into a coherent modern understanding relevant to its application as a battery material and (ii) to highlight briefly some of the challenges faced when scaling up a new material that affect TiNb2O7as well as new electrode candidates more generally.

Hybrid materials are increasingly demonstrating their utility across several optical, electrical, and magnetic applications. Cu(I) halide-based hybrids have attracted attention due to their strong luminescence in the absence of rare-earths. Here, we report three Cu(I) and Ag(I) hybrid iodides with 1,5-naphthyridine and additional triphenylphosphine (Ph3P) ligands. The compounds are built on (Cu/Ag)-I staircase chains or on a rhomboid Cu2I2dimer and display intense and tunable luminescence. Replacing Cu with Ag, and adding the second kind of organic ligand (Ph3P) tunes the emission color from red to yellow and results in significantly enhanced quantum yield. Density functional theory-based electronic structure calculations reveal the separate effects of the inorganic module and organic ligand on the electronic structure, confirming that bandgap, optical absorption, and emission properties of these phosphors can be systemically and deliberately tuned by metal substitution and organic ligands cooperation. The emerging understanding of composition-structure–property relations in this family provides powerful design tools toward new compounds for general lighting applications.

The replacement of the presently used liquid electrolytes by a nonflammable solid electrolytes is an important avenue to create safer batteries. The natrium superionic CONductor (NaSiCON) Na1+xZr2SixP3–xO12(0 ≤ x≤ 3) that displays high bulk ionic conductivity and good stability toward other NaSiCON-based electrodes is a good solid electrolyte in NaSiCON-based batteries. Despite the sizeable share of research on Na1+xZr2SixP3–xO12, the structural and thermodynamic properties of NaSiCON require better understanding for more efficient synthesis and optimization as a solid electrolyte, which often follows chemical intuition. Here, we analyze the thermodynamic properties of the rhombohedral NaSiCON electrolyte by constructing the Na1+xZr2SixP3–xO12phase diagram, based on density functional theory calculations, a cluster expansion framework, and Monte Carlo simulations. Specifically, we build the phase diagram as a function of temperature and composition (0 ≤ x≤ 3) for the high-temperature rhombohedral structure, which has been also observed in several positive electrode materials, such as Na3Ti2(PO4)3, Na3V2(PO4)3, Na3Cr2(PO4)3, and Na3Fe2(PO4)3. Through the phase diagram, we identify the concentration domains providing the highest Na+-ion conductivity and previously unreported phase-separation behavior across three different single-phase regions. Furthermore, we note the similarities in the phase behavior between Na1+xZr2SixP3–xO12and other NaSiCON-based monotransition metal electrodes and discuss the potential competition between thermodynamics and kinetics in experimentally observed phase separation. Our work is an important addition in understanding the thermodynamics of NaSiCON-based materials and in the development of inexpensive Na-ion batteries. From our results, we propose that the addition of SiO44–moieties to single-transition metal NaSiCON-phosphate-based electrodes will significantly slow the kinetics toward phase separation.

Hybrid manganese halides have attracted widespread attention because of their highly emissive optical properties. To understand the underlying structural factors that dictate the photoluminescence quantum yield (PLQY) of these materials, we report five new hybrid manganese bromides with the general formula AmMnBr4[m= 1 or 2, A= dimethylammonium (DMA), 3-methylpiperidinium (3MP), 3-aminomethylpiperidinium (3AMP), heptamethylenimine (HEP), and trimethylphenylammonium (TMPEA)]. By studying the crystal structures and optical properties of these materials and combining our results with the findings from previously reported analogs, we have found a direct correlation between Mn···Mn distance and the PLQY, where high PLQYs are associated with long Mn···Mn distances. This effect can be viewed as a manifestation of the concentration-quenching effect, except these are in stoichiometric compounds with precise interatomic distances rather than random alloys. To gain better separation of the Mn centers and prevent energy transfer, a bulky singly protonated cation that avoids H-bonding is ideal. We have demonstrated this principle in one of our newly reported material, (TMPEA)2MnBr4, where a PLQY of 70.8% for a powder sample and 98% for a large single crystal sample is achieved. Our study reveals a generalized method for improving PLQYs in hybrid manganese bromides and is readily extended to designing all varieties of highly emissive hybrid materials.

Bismuth trihalides, BiX3(X = F, Cl, Br, and I), have been thrust into prominence recently because of their close chemical relationship to the halide perovskites of lead, which exhibit remarkable performance as active layers in photovoltaic cells and other optoelectronic devices. In the present work, we have used calculations based on density functional theory to explore the energetics and electronic properties of BiX3in a variety of known and hypothetical structure types. The results for BiX3are compared with those obtained for the halides of the later rare earths, represented by YX3and LuX3. The relative thermodynamic stabilities of the known and hypothetical structures are calculated, along with their band gaps. For the BiX3systems, we have explored the role of lone-pair effects associated with bismuth(III), and for BiI3, we have compared the predicted structural behavior as a function of pressure with the available experimental data. We have also attempted to synthesize LuF3in the perovskite-related ReO3-type structure, which is predicted to be only ∼7.7 kJ mol–1above the convex hull. This attempt was unsuccessful but led to the discovery of a new hydrated phase, (H3O)Lu3F10H2O, which is isomorphous with the known ytterbium analogue.

Hybrid halide double perovskites are a class of compounds attracting growing interest because of their richness of structure and property. Two-dimensional (2D) derivatives of hybrid double perovskites are formed by the incorporation of organic spacer cations into three-dimensional (3D) double perovskites. Here, we report a series of seven new layered double perovskite halides with propylammonium (PA), octylammonium (OCA), and 1,4-butyldiammonium (BDA) cations. The general formulas of the compounds are AmMIMIIIX8(single-layered Ruddlesden–Popper type with m= 4 and A= PA or OCA, and single-layered Dion–Jacobson type with m= 2 and A= BDA, MI= Ag, MIII= In or Bi, X = Cl or Br) and PA2CsMIMIIIBr7(bilayered, with MI= Ag, MIII= In or Bi). These families of compounds demonstrate great versatility, with tunable layer thickness, the ability to vary the interlayer spacing, and the ability to selectively tune the band gap by varying the MIand MIIIcations along with the halide anions. The band gap of the single-layered materials varies from 2.41 eV for PA4AgBiBr8to 3.96 eV for PA4AgInCl8. Photoluminescent emission spectra of the layered double perovskites at low-temperature (100 K) are reported, and density functional theory electronic structure calculations are presented to understand the nature of the band gap evolution. The development of new structural and compositions in layered double perovskite halides enhances the understanding of structure–property relations in this important family.

Recent advances in the metal–organic framework (MOF)-related catalysts for electrochemical ammonia synthesis protocols under ambient reaction conditions are summarized and discussed.The design and fabrication of efficient electrocatalysts from MOF for the reduction of N2and NO3−are systematically analyzed.Based on the current advances, the ongoing challenges and promising perspectives are highlighted.

To investigate local electron transfer in metal-organic frameworks (MOFs), we synthesized a new MOF structure composed of zinc cations and 1,4-naphthalenedicarboxylate (14ndc) linker anions. The crystal structure was determined by single crystal X-ray diffractometry and the optical properties were investigated by measurements of luminescence and excitation spectra. [Zn4(ndc)3(OH)2](C2H5OH)(1.4H2O) crystallizes in space group $P\bar{1}$and contains ZnO4and ZnO6coordination spheres linked by the naphthalenedicarboxylate (ndc, C12H6O42-) units. Under UV irradiation, the MOF shows violet luminescence, which is probably due to energy transfer involving two different systems in the structure. The MOF shows good stability in a water/ethanol mixed solvent (approximately 3:5 ratio by volume that is consistent with the solvent used for sample preparation).We synthesized a new MOF structure composed of zinc cations and 1,4-naphthalenedicarboxylate linker anions. Under UV irradiation, the MOF shows violet luminescence peaked at 395 nm, which is probably due to energy transfer involving two different systems in the structure.

Pure metal–organic framework (MOF) layers deposited on porous supports are important candidates for molecular sieving membranes, but their performance usually deviates from theoretical estimations. Here, we combine step-wise scanning electron microscopy imaging, time-resolved synchrotron X-ray scattering, terahertz infrared spectroscopy, and density functional theory calculation to investigate the ZIF-8 membrane formation on two types (polydopamine and TiO2) of functionalized porous supports. Though molecular sieving of ZIF-8 membranes for smaller gases (He, H2, and CO2) can be achieved with both types of functionalized supports, we unravel that the strong interaction between MOF and polydopamine can disrupt the formation of “perfect” MOF crystals at the interface, leading to a “contracted” MOF structure with partially uncoordinated imidazolate ligands. This further affects the low-frequency dynamical parameters of the framework and inhibits the effective seeded growth. Eventually, it leads to an unexpected loss of selectivity for the bulkier gases (N2and CH4) for ZIF-8 on polydopamine-functionalized supports. This work links the dynamical aspects of MOFs with their gas transport behavior and highlights the importance of regulating the interfacial weak forces to preserve the ideal molecular sieving efficiency of MOF membranes, which also provides guidance for defect engineering of MOF film fabrication for sensing and electronic devices beyond membranes.

We describe the solid-state structural evolution in four hybrid hexaiodoplatinate(IV) compounds, demonstrating the increasingly important role that extended hydrogen bonding plays in directing the structure across the series. The compounds are A2PtI6, where A is one of the following amines: ammonium, NH4+; methylammonium, CH3NH3+; formamidinium, CH(NH2)2+; guanidinium, C(NH2)3+. These are closely related in structure and properties to the hybrid halide perovskites of lead(II) that have recently established their prowess in optoelectronics. The first three of these compounds crystallize in the vacancy-ordered double perovskite A2Pt□I6(□ indicates a vacant site) structure in the K2PtCl6archetype, despite the relatively large perovskite tolerance factors involved. The last compound, (GUA)2PtI6, crystallizes in a vacancy-ordered variant of the hexagonal CsNiCl3structure: the K2MnF6structure. A combination of solid-state 195Pt and 1H NMR spectroscopy and detailed density functional theory calculations helps to reveal structural trends and establish the hydrogen-bonding tendencies. The calculations and measured optical properties support the surprising observation in these iodosalt compounds that, for smaller A cations, the conduction bands are considerably disperse, despite lacking extended I–Pt–I connectivity.

Two-dimensional (2D) transition-metal (groups IV, V, VI) carbides (MXenes) with formulas M3C2have been investigated as CO2conversion catalysts with well-resolved density functional theory calculations. While MXenes from the group IV to VI series have demonstrated an active behavior for the capture of CO2, the Cr3C2and Mo3C2MXenes exhibit the most promising CO2to CH4selective conversion capabilities. Our results predicted the formation of OCHO•and HOCO•radical species in the early hydrogenation steps through spontaneous reactions. This provides atomic level insights into the computer-aided screening for high-performance catalysts and the understanding of electrochemical mechanisms for CO2reduction to energy-rich hydrocarbon fuels, which is of fundamental significance to elucidate the elementary steps for CO2fixation.

We report high-throughput computational screening of 137 953 hypothetical metal–organic frameworks (hMOFs) and 4764 computation-ready experimental MOFs (CoRE-MOFs) for the capture of thiols (methanethiol and ethanethiol) from air. To minimize the competitive adsorption of moisture, 31 816 hydrophobic MOFs are first identified on the basis of a threshold criterion in the Henry constant of water, and then used to assess the adsorption capacity of thiol (NSH) and the selectivity of thiol over air (SSH/Air). The highest NSHand SSH/Airare predicted to be 70.86 mg/g and 2.6 × 107, respectively. Most of the high-performance MOFs are found to be hMOFs. The structure–property relationships are derived for NSHand SSH/Airwith MOF descriptors (including the isosteric heat, the largest cavity diameter, surface area, and void fraction). While the relationship with isosteric heat tends to be monotonic, there exist optimal ranges in the other relationships. Principal component analysis is applied to assess the interrelationships among the four descriptors; then multiple linear regression is used to quantitatively determine the respective effects of descriptors on NSHand SSH/Air. It is revealed that the isosteric heat is a key descriptor governing thiol capture. Moreover, decision tree modeling is employed to define a clear effective path to screen high-performance MOFs. Finally, the best MOFs are identified. The microscopic insights obtained from our bottom-up approach are useful toward the development of MOFs and other nanoporous materials for thiol capture from air or in a variety of environmental and industrial situations.

The physicochemical properties of the potassium neptunate K2NpO4have been investigated in this work using X-ray diffraction, X-ray absorption near edge structure (XANES) spectroscopy at the Np-L3edge, and low-temperature heat capacity measurements. A Rietveld refinement of the crystal structure is reported for the first time. The Np(VI) valence state has been confirmed by the XANES data, and the absorption edge threshold of the XANES spectrum has been correlated to the Mössbauer isomer shift value reported in the literature. The standard entropy and heat capacity of K2NpO4have been derived at 298.15 K from the low-temperature heat capacity data. The latter suggest the existence of a magnetic ordering transition around 25.9 K, most probably of the ferromagnetic type.

Metal-organic frameworks are a novel family of chemically diverse materials, which are of interest across engineering, physics, chemistry, biology and medicine-based disciplines. Since the development of the field in its current form more than two decades ago, priority has been placed on the synthesis of new structures. However, more recently, a clear trend has emerged in shifting the emphasis from material design to exploring the chemical and physical properties of structures already known. In particular, although such nanoporous materials were traditionally seen as rigid crystalline structures, there is growing evidence that large-scale flexibility, the presence of defects and long-range disorder are not the exception in metal-organic frameworks, but the rule. Here we offer some perspective into how these concepts are perhaps inescapably intertwined, highlight recent advances in our understanding and discuss how a consideration of the interfaces between them may lead to enhancements of the materials' functionalities.

Based on a new “one for two” strategy, a single two-dimensional (2D) metal–organic framework (MOF) precursor has been transformed into both electrodes (i.e., a Co3O4cathode and a N-doped carbon anode) for a flexible asymmetric supercapacitor. The device demonstrated not only highly robust mechanical flexibility but also outstanding electrochemical performance. The “one for two” concept can significantly ease the fabrication process and has great potential to be extended to other functional materials for different applications.

Reactions inside the pores of metal–organic frameworks (MOFs) offer potential for controlling polymer structures with regularity to sub-nanometre scales. We report a wet-chemistry route to poly-3,4-ethylenedioxythiophene (PEDOT)–MOF composites. After a two-step removal of the MOF template we obtain unique and stable macroscale structures of this conductive polymer with some nanoscale regularity.

Exclusive capture of carbon dioxide (CO2) from hydrocarbons via adsorptive separation is an important technology in the petrochemical industry, especially for acetylene (C2H2) production. However, the physicochemical similarities between CO2and C2H2hamper the development of CO2-preferential sorbents, and CO2is mainly discerned via C recognition with low efficiency. Here, we report that the ultramicroporous material Al(HCOO)3, ALF, can exclusively capture CO2from hydrocarbon mixtures, including those containing C2H2and CH4. ALF shows a remarkable CO2capacity of 86.2 cm3g–1and record-high CO2/C2H2and CO2/CH4uptake ratios. The inverse CO2/C2H2separation and exclusive CO2capture performance from hydrocarbons are validated via adsorption isotherms and dynamic breakthrough experiments. Notably, the hydrogen-confined pore cavities with appropriate dimensional size provide an ideal pore chemistry to specifically match CO2via a hydrogen bonding mechanism, with all hydrocarbons rejected. This molecular recognition mechanism is unveiled by in situ Fourier-transform infrared spectroscopy, X-ray diffraction studies, and molecular simulations.

Hybrid halide perovskites AMIIX3(A = ammonium cation, MII= divalent cation, X = Cl, Br, I) have been extensively studied but have only previously been reported for the divalent carbon group elements Ge, Sn, and Pb. While they have displayed an impressive range of optoelectronic properties, the instability of GeIIand SnIIand the toxicity of Pb have stimulated significant interest in finding alternatives to these carbon group-based perovskites. Here, we describe the low-temperature solid-state synthesis of five new hybrid iodide perovskites centered around divalent alkaline earth and lanthanide elements, with the general formula AMIII3(A = methylammonium, MA; MII= Sr, Sm, Eu, and A = formamidinium, FA; MII= Sr, Eu). Structural, calorimetric, optical, photoluminescence, and magnetic properties of these materials are reported.

In a search for lead-free materials that could be used as alternatives to the hybrid perovskites, (MA)PbX3, in photovoltaic applications, we have discovered a hybrid double perovskite, (MA)2KBiCl6, which shows strong similarities to the lead analogues. Spectroscopic measurements and nanoindentation studies are combined with density functional calculations to reveal the properties of this interesting system.

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Bad, naughty Brits. We've been arraigned on charges of land grab for attempting to secure exclusive territorial rights within the member states of the European Union. The most difficult arguments [...]