Three Redox States of Nitrosyl: NO+, NO., and NO−/HNO Interconvert Reversibly on the Same Pentacyanoferrate(II) Platform

Not so elusive : [Fe^II(CN)₅(HNO)]^3? has been characterized spectroscopically after the two‐electron reduction of nitroprusside (see scheme). The complex is stable at pH 6, slowly decomposing to [Fe(CN)₆]^4? and N₂O. It is deprotonated at increasing pH value with oxidation of bound NO^? to [Fe^II(CN)₅(NO)]^3?. [Fe^II(CN)₅(HNO)]^3? is the first non‐heme iron–nitroxyl complex prepared in aqueous solution that is reversibly redox‐active under biologically relevant conditions.

     

Water‐Stable Zirconium‐Based Metal–Organic Framework Material with High‐Surface Area and Gas‐Storage Capacities

We designed, synthesized, and characterized a new Zr‐based metal–organic framework material, NU‐1100 , with a pore volume of 1.53 ccg^?1 and Brunauer–Emmett–Teller (BET) surface area of 4020 m²g^?1; to our knowledge, currently the highest published for Zr‐based MOFs. CH₄/CO₂/H₂ adsorption isotherms were obtained over a broad range of pressures and temperatures and are in excellent agreement with the computational predictions. The total hydrogen adsorption at 65 bar and 77 K is 0.092 g g^?1, which corresponds to 43 g L^?1. The volumetric and gravimetric methane‐storage capacities at 65 bar and 298 K are approximately 180 v_STP/v and 0.27 g g^?1, respectively.     

Progress,highlights and perspectives on NiO in perovskite photovoltaics

The power conversion efficiency (PCE) of NiO based perovskite solar cells has recently hit a record 22.1% with a hybrid organic–inorganic perovskite composition and a PCE above 15% in a fully inorganic configuration was achieved. Moreover, NiO processing is a mature technology, with different industrially attractive processes demonstrated in the last few years. These considerations, along with the excellent stabilities reported, clearly point towards NiO as the most efficient inorganic hole selective layer for lead halide perovskite photovoltaics, which is the topic of this review. NiO optoelectronics is discussed by analysing the different doping mechanisms, with a focus on the case of alkaline and transition metal cation dopants. Doping allows tuning the conductivity and the energy levels of NiO, improving the overall performance and adapting the material to a variety of perovskite compositions. Furthermore, we summarise the main investigations on the NiO/perovskite interface stability. In fact, the surface of NiO is commonly oxidised and reactive with perovskite, also under the effect of light, thermal and electrical stress. Interface engineering strategies should be considered aiming at long term stability and the highest efficiency. Finally, we present the main achievements in flexible, fully printed and lead-free perovskite photovoltaics which employ NiO as a layer and provide our perspective to accelerate the improvement of these technologies. Overall, we show that adequately doped and passivated NiO might be an ideal hole selective layer in every possible application of perovskite solar cells.

The power conversion efficiency of NiO based perovskite solar cells has recently hit a record 22.1%. Here, the main advances are reviewed and the role of NiO in the next breakthroughs is discussed.     

Impregnated ruthenium on magnetite as a recyclable catalyst for the N-alkylation of amines, sulfonamides, sulfinamides, and nitroarenes using alcohols as electrophiles by a hydrogen autotransfer process

Various impregnated metallic salts on magnetite have been prepared, including cobalt, nickel, copper, ruthenium, and palladium salts, as well as a bimetallic palladium-copper derivative. Impregnated ruthenium catalyst is a versatile, inexpensive, and simple system for the selective N-monoalkylation of amino derivatives with poor nucleophilic character, such as aromatic and heteroaromatic amines, sulfonamides, sulfinamides, and nitroarenes, using in all cases alcohols as the initial source of the electrophile, through a hydrogen autotransfer process. In the case of sulfinamides, this is the first time that these amino compounds have been alkylated following this strategy, allowing the use of chiral sulfinamides and secondary alcohols to give the alkylated compound with a diastereomeric ratio of 92:8. In these cases, after alkylation, a simple acid deprotection gave the expected primary amines in good yields. The ruthenium catalyst is quite sensitive, and small modifications of the reaction medium can change the final product. The alkylation of amines using potassium hydroxide renders the N-monoalkylated amines, and the same protocol using sodium hydroxide yields the related imines. The catalyst can be easily removed by a simple magnet and can be reused up to ten times, showing the same activity.     

Li8Si8, Li10Si9, and Li12Si10: Assemblies of Lithium-Silicon Aromatic Units

We report the global minima structures of Li₈Si₈, Li₁₀Si₉, and Li₁₂Si₁₀ systems, in which silicon moieties maintain structural and chemical bonding characteristics similar to those of their building blocks: the aromatic clusters T_d−Li₄Si₄ and C_2v−Li₆Si₅. Electron counting rules, chemical bonding analysis, and magnetic response properties verify the silicon unit‘s aromaticity persistence. This study demonstrates the feasibility of assembling silicon-based nanostructures from aromatics clusters as building blocks.     

Chemical transformations of 3‐amino‐2‐quinolones

In order to find new antimalarial drugs, an exploration about the chemical properties of the starting compounds 3‐amino‐6‐chloro‐4‐phenyl‐1H‐quinolin‐2‐one ( 1 ) and 3‐amino‐4‐methyl‐1H‐quinolin‐2‐one ( 2 ) was developed. Acylation with acyl chloride, sulfonyl chloride and acetic anhydride were carried out. Despite a previous report [2], when acetyl chloride or acetic anhydride were assayed on 1 , only the diacetyl derivative 7 was obtained. When this compound was heated at reflux temperature in a mixture of acetic acid and acetic anhydride, it was transformed in the oxazoloquinoline 8 . Further reactions of the acyl derivatives with diazomethane afforded 1‐methylated compounds. Compound 2 gave the imine 16 by condensation with 4‐nitrobenzaldehyde.     

Synthesis, solid-state structure, and bonding analysis of the beryllocenes [Be(C5Me4H)2], [Be(C5Me5)2], and [Be(C5Me5)(C5Me4H)

The beryllocenes [Be(C(5)Me(4)H)(2)] (1), [Be(C(5)Me(5))(2)] (2), and [Be(C(5)Me(5))(C(5)Me(4)H)] (3) have been prepared from BeCl(2) and the appropriate KCp' reagent in toluene/diethyl ether solvent mixtures. The synthesis of 1 is facile (20 degrees C, overnight), but generation of decamethylberyllocene 2 demands high temperatures (ca. 115 degrees C) and extended reaction times (3-4 days). The mixed-ring beryllocene 3 is obtained when the known [(eta(5)-C(5)Me(5))BeCl] is allowed to react with K[C(5)Me(4)H], once more under somewhat forcing conditions (115 degrees C, 36 h). The structures of the three metallocenes have been determined by low-temperature X-ray studies. Both 1 and 3 present eta5/eta1 geometries of the slip-sandwich type, whereas 2 exhibits an almost regular, ferrocene-like, sandwich structure. In the mixed-ring compound 3, C(5)Me(5) is centrally bound to beryllium and the eta(1)-C(5)Me(4)H ring bonds to the metal through the unique CH carbon atom. This is also the binding mode of the eta(1)-ring of 1. To analyze the nature of the bonding in these molecules, theoretical calculations at different levels of theory have been performed on compounds 2 and 3, and a comparison with the bonding in [Be(C(5)H(5))(2)] has been made. As for the latter molecule, energy differences between the eta5/eta5 and the eta5/eta1 structures of 2 are very small, being of the order of a few kcal mol(-1). Constrained space orbital variations (CSOV) calculations show that the covalent character in the bonding is larger for [Be(C(5)Me(5))(2)] than for [Be(C(5)H(5))(2)] due to larger charge delocalization and to increased polarizability of the C(5)Me(5) fragment.     

A metal-complex-tolerant CuAAC 'click' protocol exemplified through the preparation of homo- and mixed-metal-coordinated [2]rotaxanes

A series of mono- and bis-metallated [2]rotaxanes has been prepared using a CuAAC 'click' protocol that is compatible with metal-coordinated building blocks and ligands; the methodology provides a general means for appending a metal ion or complex to an organic scaffold via Cu(I)-catalysed 'click' chemistry, even when the molecule contains redox-active or kinetically labile metals or vacant ligand sites.     

Interfacial energy exchange and reaction dynamics in collisions of gases on model organic surfaces

Molecular beam scattering experiments and molecular dynamics simulations have been combined to develop an atomic-level understanding of energy transfer, accommodation, and reactions during collisions between gases and model organic surfaces. The work highlighted in this progress report has been motivated by the scientific importance of understanding fundamental interfacial chemical reactions and the relevance of reactions on organic surfaces to many areas of environmental chemistry. The experimental investigations have been accomplished by molecular beam scattering from ω-functionalized self-assembled monolayers (SAMs) on gold. Molecular beams provide a source of reactant molecules with precisely characterized collision energy and flux; SAMs afford control over the order, structure, and chemical nature of the surface. The details of molecular motion that affect energy exchange and scattering have been elucidated through classical-trajectory simulations of the experimental data using potential energy surfaces derived from ab initio calculations. Our investigations began by employing rare-gas scattering to explore how alkanethiol chain length and packing density, terminal group relative mass, orientation, and chemical functionality influence energy transfer and accommodation at organic surfaces. Subsequent studies of small molecule scattering dynamics provided insight into the influence of internal energy, molecular orientation, and gas–surface attractive forces in interfacial energy exchange. Building on the understanding of scattering dynamics in non-reactive systems, our work has recently explored the reaction probabilities and mechanisms for O₃ and atomic fluorine in collisions with a variety of functionalized SAM surfaces. Together, this body of work has helped construct a more comprehensive understanding of reaction dynamics at organic surfaces.