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Perovskite solar cells (PSCs) continue to be the "front runner" technology among emerging photovoltaic devices in terms of power conversion efficiency and versatility of applications. However, improving stability and understanding their relationship with their ionic–electronic transport mechanisms continue to be challenging. In this work, a case study of NiOx-based inverted PSCs and the effect of different interface passivating treatments on device performance is presented. Impedance spectroscopy (IS) measurements in short-circuit conditions were performed under different illumination intensities, as well as bias-stress operational stability tests under constant illumination intensity. Surface treatments that involved bulky Lewis bases resulted in better and more stable performance. In contrast, acidic anion donors could induce both an initial performance decrease with a characteristic three-arcs impedance Nyquist plot and a subsequent instability during light exposure. Drift–diffusion simulations suggest strong modifications of surface recombination at the interface with the hole transport material, and for the ion concentration and mobilities in the perovskite. Importantly, capacitance and resistance are shown to peak maximum and minimum values, respectively, around mobile ion concentration (Nion) of 1016 and 1017 cm−3. These features relate to the transition from a drift-, for low Nion below a threshold value, to a diffusion-dominated transport in the bulk of the perovskite, for high Nion beyond the threshold value. Our results introduce a general route for characterization of instability paths in PSCs via IS performed under short-circuit conditions. [ABSTRACT FROM AUTHOR]

In this Frontier Article, the work carried out within our research group in Bologna in the field of surface decorated metal carbonyl clusters will be outlined and put in a more general context. After a short Introduction, clusters composed of a metal carbonyl core decorated on the surface by metal–ligand fragments will be analyzed. Both metal–ligand fragments behaving as Lewis acids and Lewis bases will be considered. Then, the focus will be moved to clusters composed of a naked metal core decorated and stabilized on the surface by metal-carbonyl fragments. The structure and bonding (where theoretical studies are available) of such surface decorated metal carbonyl clusters will be presented, and compared to atomically precise ligated nanoclusters. [ABSTRACT FROM AUTHOR]

Aluminum-doped polycyclic aromatic hydrocarbons (PAHs) are underexplored despite the broad applications of boron-containing PAHs in areas such as catalysis and optoelectronics. We disclose the donor-free, sterically unprotected 9-methyl-9-aluminafluorene (Me-AlFlu; 2), synthesized by heating a 9,9-dimethyl-9-stannafluorene and AlMe3 in hexanes. The compound is a dimer, (2)2, with trans-positioned AlMe substituents in the solid state. In solution, (2)2 shows a dynamic cis/trans-interconversion rather than a monomer-dimer equilibrium (Tol-d8, RT). Lewis bases L cleave (2)2 into monomeric adducts 2·L (L = OEt2, thf, pyridine). Lewis acidic AlBr3 transforms (2)2 into a 2,2′-(Br2Al)2-1,1′-biphenyl (3), crystallographically characterized as dimeric (3)2. (3)2 is a synthetic equivalent for the elusive free Br-AlFlu: Treatment with donor molecules furnishes Br-AlFlu·L adducts (L = OEt2, pyridine); the three-coordinate, monomeric aluminafluorene Mes*-AlFlu was prepared from (3)2, Mes*Li, and a 2,2′-dilithio-1,1′-biphenyl in quantitative yield (Mes* = 2,4,6-(tBu)3C6H2). [ABSTRACT FROM AUTHOR]

Compared with rare-earth (RE)...heteroatom interaction, RE...π interaction, frequently used in facilitating regio- and stereoselectivity of olefin polymerizations, is seldomly used to trigger catalytic C − H functionalization. Here, we describe a direct anti-Markovnikov hydroallylation reaction of styrene derivatives with 1-aryl-2-alkyl alkenes and α-alkenes by use of RE...π interaction. This protocol provides a straightforward and atom-efficient route for the synthesis of valuable chain elongated internal alkenes (65 examples, up to 99% yield, > 19:1 E/Z ratio). The reaction proceeds via an allylic Csp3‒H activation pathway initiated by site-selective deprotonation with the assistance of cationic imidazolin-2-iminato scandium alkyl species followed by alkene insertion into the resulting scandium-allyl bond. A catalytic amount of Lewis base additives, such as amine and tetrahydrofuran (THF) show significant effects on the reactivity and E/Z selectivity. The reaction mechanism is elucidated by experimental studies and theoretical calculations. The hydroallylation of alkenes represents a straightforward method for the construction of chain elongated alkenes. Here the authors report a scandium-catalyzed anti-Markovnikov hydroallylation reaction of styrene derivatives with 1-aryl-2-alkyl alkenes and α-alkenes for the synthesis of chain elongated internal alkenes. [ABSTRACT FROM AUTHOR]

To investigate the characteristics and mechanism of fillers' influence on the interfacial adhesion properties between asphalt mastic and granite aggregate, four kinds of active fillers were selected to replace limestone mineral powder (LMP) in four proportions. Firstly, composite asphalt mastic (CAM) was prepared, and the adhesion property of the interface between different asphalt mastic and granite aggregate was evaluated based on the surface free energy (SFE). The optimum replacement rates were recommended by immersion Marshall tests and freeze–thaw splitting tests, and the water-temperature durability performance of granite asphalt mixtures under different treatment measures was verified by Hamburg rutting tests. Microproperty tests were carried out to analyze the effect of fillers on interfacial adhesion properties and mechanisms. The results showed that the alkaline minerals in the active fillers increased the Lewis base fraction of the asphalt mastic, which enhanced the SFE of the mastic. The maximum increase of the energy ratio (ER) with calcium carbide slag powder (CCSP) was 17%, and its enhancement of interfacial adhesion performance exceeded that of the other three active fillers. In addition, at the 60% replacement rate, CCSP improved MS0 and freeze-thaw split test strength ratio (TSR) by 9% and 15%, respectively, which exceeded the improvements from using OPC (7% and 14%, respectively). Comprehensive analysis indicated the optimal replacement rates of the four active fillers [steel slag powder (SSP), CCSP, slag powder (SP), and OPC] were 30%, 60%, 15%, and 60%, respectively. The results of microscopic tests revealed that the surface morphology and oxide mineral content of active fillers were more complex than those of LMP, which supported their ability to effectively absorb light oils from the asphalt on the granite aggregate surface and displace low-valent cations on the granite surface, thereby improving the state of the asphalt mastic–granite interface. [ABSTRACT FROM AUTHOR]

We present experimental probes of contact ion-pair (CIP) SN2 reactions for simplest prototype systems by 19F-NMR spectroscopy. This study provides crucial evidences for the reactions of CIP metal salts facilitated by Lewis base phase transfer catalysts (PTCs) [2,2,2]-cryptand, 18-crown-6, pentaethylene glycols (pentaEGs) and BINOL–based pentaEG. The 19F-NMR spectra of MF (M = K, Cs) ion-pairs in various solvents are used as fingerprinting tools to identify the CIP CsF/PTC/substrate complexes in SN2 reactions. Examination of the prototype reactions demonstrates that the novel CIP mechanism, which is in sharp contrast to the conventional perspectives, may account for the observed phenomenal efficiency of the SN2 processes using the alkali metal salts under the influence of various PTCs. In this extremely efficient and selective protocol of wide applicability, the CIP MF is activated by the Lewis base PTCs acting on the counter-cation M+ to drastically mitigate the latter's retarding Coulomb forces on the adjacent nucleophile F-, with or without the participation of hydrogen bonds. The bimolecular substitution reaction, or Sn2 reaction, is a fundamental transformation that is taught in introductory organic chemistry classes, understood using the backside-attack model. Here the authors provide evidence that the traditional understanding may be incomplete, describing SN2 reactions via a contact ion-pair mechanism with 19 F-NMR. [ABSTRACT FROM AUTHOR]

[Display omitted] • FeO x can optimize the catalyst structure and stabilize the catalyst performance. • FeO x more conducive to the adsorption of nitro and the desorption of the product. • FeO x can effectively mask some acid sites, inhibit the hydrolysis of CHO. • The Cu+ interface carries out the adsorption and desorption of the reactants. • CuFeAl catalyst showes best performance for converting NCH to CHO (yield: > 93 %). Nitrocyclohexane (NCH) hydrogenation to cyclohexanone oxime (CHO) is of great significance in the production of caprolactam. In this work, CuFeAl-Layered Double Hydroxide (CuFeAl-LDH) catalysts with lamellar structure were prepared by co-precipitation method and applied for NCH hydrogenation, and the promoting role of FeO x was discussed. It was found that FeO x species promote the reduction of Cu2+ and control the ratio of Cu+ to Cu0. In situ DRIFT and density-functional theory (DFT) calculation results confirm that the presence of FeO x species can act as lewis base site to reduce the acid sites and facilitate the isomerization of nitrosocyclohexane to CHO, and promotes the adsorption of NCH and the desorption of the formed CHO to prevent its further reaction to form byproducts. CuFe 0.05 Al shows the best catalytic performance of 100 % NCH conversion and 93.35 % selectivity to CHO under mild conditions. This work provides a new idea for the design of non-noble metal-based catalysts with high activity for the selective hydrogenation of nitro compounds. [ABSTRACT FROM AUTHOR]

Suppressing deep-level defects at the perovskite bulk and surface is indispensable for reducing the non-radiative recombination losses and improving efficiency and stability of perovskite solar cells (PSCs). In this study, two Lewis bases based on chalcogen-thiophene (n-Bu4S) and selenophene (n-Bu4Se) having tetra-pyridine as bridge are developed to passivate defects in perovskite film. The uncoordinated Pb2+ and iodine vacancy defects can interact with chalcogen-concave group and pyridine group through the formation of the Lewis acid-base adduct, particularly both the defects can be surrounded by concave molecules, resulting in effective suppression charge recombination. This approach enables a power conversion efficiency (PCE) as high as 25.37% (25.18% certified) for n-i-p PSCs with stable operation at 65 °C and 1-sun illumination for 1300 hours in N2 (ISOS-L-2 protocol), retaining 94% of the initial efficiency. Our work provides insight into the bowl-shaped Lewis base in defects passivation by coordinated strategy for high-performance photovoltaic devices. Suppressing deep-level defects at the perovskite bulk and surface is critical to reduce the non-radiative recombination losses in perovskite solar cells. Here, authors employ concave-shaped chalcogen molecules for defect passivation, achieving certified efficiency of 25.18% for stable n-i-p devices. [ABSTRACT FROM AUTHOR]

Metalation of dimesitylphosphane oxide, Mes2P(O)H (1), with alkali metal reagents (nBuLi, NaH, and A(hmds); A = K, Rb, and Cs) in THF yields the corresponding dimesitylphosphinites of lithium (2-thf), sodium (3-thf), potassium (4-thf), rubidium (5-thf), and caesium (6). Their molecular structures exhibit a broad and fascinating variety. Dinuclear compounds 2-thf, 3-thf, and 5-thf have central four-membered A2O2 rings, whereas the potassium congener crystallises as a tetranuclear complex with an inner A4O4 heterocubane cage. The tetranuclear caesium congener precipitates without thf coligands and exhibits a quite unique structure in its crystalline state. Due to their catalytic activity in hydrophosphorylation reactions, we focus on the solvent–structure relationship of the potassium derivatives. In hydrocarbons, [K4(O-PMes2)4]2 (4) is formed, and bidentate Lewis bases like dme and tmeda are unable to deaggregate this tetranuclear cage compound, but bases with a higher denticity (diglyme, triglyme, and pmdeta) split this cage compound into dinuclear complexes with central K2O2 rings. In addition, very bulky P-bound aryl groups like 2,4,6-triisopropylphenyl in dinuclear 8-thf hinder the formation of tetranuclear cage compounds, whereas 2-methylnaphthyl substituents are not bulky enough and the tetranuclear cage compound 7-thf is stabilised. For the 2,4,6-triisopropylphenyl substituent, the rubidium and caesium congeners 11 and 12 crystallise with two central A2O2 rings interconnected by π-interactions. A heteroleptic potassium complex 9-hmds, containing hmds as well as phosphinite anions, represents a snapshot on the way from the starting K(hmds) to the phosphinite-based heterocubane congener. Finally, heterobimetallic [{(thf)K}2Mg(O-PMes2)4] (10-thf) with tetrahedrally coordinated Mg centres has been isolated. [ABSTRACT FROM AUTHOR]

Single‐junction perovskite solar cells (PSCs) have achieved certified power conversion efficiencies (PCEs) of 26.1%, which approaches their practical performance limit. Multi‐junction tandem solar cells can unlock even higher PCEs, where narrow‐bandgap lead‐tin (Pb‐Sn) perovskites, with a bandgap of 1.21–1.25 eV, are well‐suited as the bottom photo absorber in all‐perovskite tandems. Bulk engineering and surface treatments of Pb‐Sn perovskites using Lewis base molecules have been shown to reduce the defect density within the bulk and at the electron transport layer interface, thereby improving device performance. Nevertheless, the buried interface between Pb‐Sn perovskite and the commonly used hole transport layer PEDOT:PSS remains problematic due to the reactivity of polystyrene sulfonate (PSS) with Sn2+ ions, which negatively impacts device performance. To overcome this issue, a novel carbazole‐based self‐assembled monolayer, BrNH3‐4PACz is synthesized, that provides a suitable dipole moment at the indium‐tin oxide interface for efficient hole extraction and features an ionic ammonium head group that passivates the perovskite at the buried interface. This dual functionality enabled the fabrication of a p‐i‐n architecture Pb‐Sn PSC with a bandgap of 1.24 eV, achieving a champion PCE of 23% and an open‐circuit voltage of 0.88 V, which ranks among the highest reported values in the literature. [ABSTRACT FROM AUTHOR]

In the framework of SMD approach a systematic computational study of structural, electronic and thermodynamic properties of molecular complexes of Cl2, ICl and I2 with series of N‐containing Lewis bases in solvents of different polarity was carried out. Results indicate that molecular complexes of Cl2 with strong and medium‐strong LB undergo spontaneous ionization in the acetonitrile solution. The increase of the solvent polarity can change the nature of interaction in X'XLB systems from molecular X'X ← LB donor‐acceptor complexes to 3‐center 4‐electron bound X'→X+ ← LB in solvents of medium polarity and to the contact ion pairs X'→[XLB]+ in polar solvents. Thus, the controlled generation of cationic [LB∙X]+ species is possible by varying the nature of LB, varying the nature of the solvent, and varying the nature of the halogen X. Molecular Cl2 has the greatest tendency to form ionic species in polar solvents. Spontaneous ionization of molecular nσ complexes of chlorine with strong LB in medium‐polar solvents (starting from OEt2, ε = 4.24) should not be neglected and single point solvation energy computations on gas phase optimized geometries are not reliable for such systems. [ABSTRACT FROM AUTHOR]

Formation of molecular complexes and subsequent heterolytic halogen‐halogen bond splitting upon reactions of molecular Cl2 with nitrogen‐containing Lewis bases (LB) are computationally studied at M06‐2X/def2‐TZVPD and for selected compounds at CCSD(T)/aug‐cc‐pvtz//CCSD/aug‐cc‐pvtz levels of theory. Obtained results are compared with data for ICl and I2 molecules. Reaction pathways indicate, that in case of Cl2∙LB complexes the activation energies for the heterolytic Cl‐Cl bond splitting are lower than the activation energies of the homolytic splitting of Cl2 molecule into chlorine radicals. The heterolytic halogen splitting of molecular complexes of X2∙Py with formation of [XPy2]+...X3− contact ion pairs in the gas phase is slightly endothermic in case of Cl2 and I2, but slightly exothermic in the case of ICl. Formation of {[ClPy2]+...Cl3−}2 dimers makes the overall process exothermic. Taking into account that polar solvents favor ionic species, generation of donor‐stabilized Cl+ in the presence of the Lewis bases is expected to be favorable. Thus, in polar solvents the oxidation pathway via donor‐stabilized Cl+ species is viable alternative to the homolytic Cl‐Cl bond breaking. [ABSTRACT FROM AUTHOR]

Formation of molecular complexes and subsequent heterolytic halogen‐halogen bond splitting upon reactions of molecular Cl2 with nitrogen‐containing Lewis bases (LB) are computationally studied at M06‐2X/def2‐TZVPD and for selected compounds at CCSD(T)/aug‐cc‐pvtz//CCSD/aug‐cc‐pvtz levels of theory. Obtained results are compared with data for ICl and I2 molecules. Reaction pathways indicate, that in case of Cl2∙LB complexes the activation energies for the heterolytic Cl‐Cl bond splitting are lower than the activation energies of the homolytic splitting of Cl2 molecule into chlorine radicals. The heterolytic halogen splitting of molecular complexes of X2∙Py with formation of [XPy2]+...X3− contact ion pairs in the gas phase is slightly endothermic in case of Cl2 and I2, but slightly exothermic in the case of ICl. Formation of {[ClPy2]+...Cl3−}2 dimers makes the overall process exothermic. Taking into account that polar solvents favor ionic species, generation of donor‐stabilized Cl+ in the presence of the Lewis bases is expected to be favorable. Thus, in polar solvents the oxidation pathway via donor‐stabilized Cl+ species is viable alternative to the homolytic Cl‐Cl bond breaking. [ABSTRACT FROM AUTHOR]

The main categories of transition metal–mercury heterometallic compounds are briefly summarized. The attention is focused on complexes and clusters where the {Hg-Y} fragment, where Y represents a halide atom, interacts with transition metals. Most of the structurally characterized derivatives are organometallic compounds where the transition metals belong to the Groups 6, 8, 9 and 10. More than one {Hg-Y} group can be present in the same compound, interacting with the same or with different transition metals. The main synthetic strategies are discussed, and structural data of representative compounds are reported. According to the isolobality with hydrogen, {Hg-Y} can form from one to three M-{Hg-Y} bonds, but further interactions can be present, such as mercurophilic and Hg···halide contacts. The formal oxidation state of mercury is sometimes ambiguous and thus {Hg-Y} can be considered as a Lewis acid or base on varying the transition metal fragment. Density functional theory calculations on selected Group 6 and Group 9 model compounds are provided in order to shed light on this aspect. [ABSTRACT FROM AUTHOR]

A computational study of X-H···Y binary hydrogen-bonded complexes was undertaken to examine the red- and blue-shifting behavior of three model X-H proton donors interacting with a series of Lewis bases: Y = NH3, NCLi, NCH, NCF, C2H2, BF, CO, N2 and Ne. Two of these proton donors, FArH and F3CH, have blue-shifting tendencies, while the third, FH, has red-shifting tendencies. A perturbation theory model for frequency shifts that was derived many years ago was employed to partition the predicted frequency shift into the sum of two components, one dependent on the second derivative of the interaction energy with respect to X-H displacement and the other dependent on the X-H bond length change in the binary complex. The predicted shifts were found to be in good agreement with standard ab initio computations, but they were obtained at much lower computational cost. The change in the infrared intensity of the X-H stretching frequency, expressed as a ratio of complex to monomer intensities, was also investigated, along with its relation to the X-H permanent dipole moment derivative and total induced dipole moment derivative with respect to X-H displacement, and used to rationalize the observed infrared intensity changes in the red- and blue-shifted X-H···Y complexes. [ABSTRACT FROM AUTHOR]

A novel 3D magnesium‐based metal organic framework (Mg‐MOF) has been solvothermally synthesized using 5‐(pyridin‐4‐yl)isophthalic acid. The ligand has demonstrated to preserve two types of coordination modes depending on the connection mode of the pyridine group. The uncoordinated pyridine groups provide Lewis base sites (LBSs), whereas the coordinated ones promote to form a rarely reported eight‐connected tetranuclear Mg clusters. Benefiting from the multinuclearity with high number of connections, the framework keeps good performance of high thermal stability until 500°C. Furthermore, the framework exhibits potential open metal sites (OMSs) benefiting from the terminal coordinated water groups of the metal clusters. Owing to the abundant active sites, the Mg‐MOF exhibits good sensitivity to nitrofuran antibiotics and Cr2O72−, with high KSV (at 104 M−1 level) and low limit of detection (LOD) values (∼10−6 M). Density functional theory (DFT) investigation reveals that the interchange of the HOMO–LUMO energy levels of the framework and antibiotics is responsible for the sensing activity. In addition, the Mg‐MOF is greatly recyclable in five cycles while maintaining the structural rigidity and sensing activity, making it a promising luminescence probe material. [ABSTRACT FROM AUTHOR]

Constructing structurally robust and catalytically active metal nanoclusters for catalyzing multi‐component reactions is an interesting while challenging task. Inspired by Lewis acid and Lewis base catalysis, we realized the combination of both Lewis acid and Lewis base sites on the surface of a stable gold nanocluster Au35Cd2. The catalytic potential of Au35Cd2 in four‐component Ugi reaction was explored, demonstrating high activity and exceptional recyclability. In‐depth mechanism studies indicate that the catalytic synergy of the Lewis acid/base pair is crucial for the high efficiency of Au35Cd2‐catalyzed Ugi reaction. Bearing the stable structure, multiple activation sites and hierarchical chirality, Au35Cd2 is expected to display further interesting catalytic performance such as asymmetric catalysis. [ABSTRACT FROM AUTHOR]

A detailed mechanistic investigation of the Zn (II)‐catalyzed Csp–Csp2 (Sonogashira‐type) cross‐coupling reaction is reported herein, using the Density Functional Theory method. The present study unveiled an unconventional non‐redox mechanism for Zn‐catalyzed cross‐coupling reaction, where the oxidation state of Zn remains intact throughout the catalytic cycle. Our study further revealed the significant role of the base in controlling the feasibility of cross‐coupling reactions that are catalyzed by electron‐deficient metal centers. Our study indicates that K3PO4 acts as an ancillary ligand (Lewis base) for the electron‐deficient Zn (II) catalytic center rather than as a proton abstractor for the nucleophilic coupling partner (phenylacetylene) in this reaction. The active catalyst was identified to be a four‐coordinate bis‐DMEDA Zn (II) complex. The mechanism proceeds via the initial activation of the nucleophilic coupling partner (phenylacetylene), followed by the electrophilic coupling partner (organic halide) activation liberating the cross‐coupled product by a concerted nucleophilic substitution pathway. The turn‐over limiting step was identified to be the activation of the electrophilic coupling partner. The activation barrier obtained for the reaction, 31.0 kcal/mol concords well with experimental temperature requirements (125°C). The coordination by base is found to stabilize the rate‐determining intermediates and transition states involved in the reaction. The mechanistic insights gained from this study could aid in the rational design and development of sustainable cross‐coupling reactions using zinc as the catalyst. [ABSTRACT FROM AUTHOR]

In this work, reed canary grass and activated carbons developed from this biomass were used as novel adsorbents to remove sulfamethoxazole (SMX) from water. Raw biomass adsorbent with the lowest surface area demonstrated the lowest SMX adoption capacity of 20.2 ± 1.6 mg/g and the activated carbon adsorbent with the highest surface area showed the highest adsorption capacity of 160.5 ± 4.2 mg/g. π-π, hydrogen bonding, Lewis acid base, and hydrophobic interactions are the possible mechanisms that could be responsible for adsorption of SMX on the adsorbents. Methanol, hydrochloric acid solution, sodium hydroxide solution, and deionized water were used to desorb SMX from the adsorbent. The results of using 20 mL of solvent at 35 °C showed that methanol could desorb loaded SMX with a higher desorption efficiency (80.1 ± 2%) than the aqueous solvents (9.5-46.5%). Decreasing the temperature to 25 °C decreased the desorption efficiency of methanol to 58.5 ± 1%. By decreasing the methanol volume to 5 mL, SMX desorption efficiency could remain comparable (59.1 ± 1.2%). Reusing the adsorbent in 4 adsorption desorption cycles showed that SMX adsorption capacity reduced from 124.9 ± 3.8 mg/g in the first adsorption cycle to 82.1 ± 2.2 mg/g in the second adsorption cycle and was stable in the third and fourth cycles. [ABSTRACT FROM AUTHOR]

The heavier group 15 elements As, Sb, and Bi are more restricted in their biochemistry than the nearly ubiquitous lighter congeners N and P, but organisms do encounter compounds of these elements as environmental toxins, starting materials for secondary metabolite biosynthesis, substrates for primary metabolism, or exogenously applied medicines. Under many physiological conditions, these compounds are transformed into pnictogen(III) species, the soft Lewis acidic character of which leads them to interact strongly with biologically relevant soft Lewis bases such as small-molecule thiols or cysteine residues of proteins and peptides. The archetypal complexes As(Cys)3, Sb(Cys)3, and Bi(Cys)3 have been studied in the past but a lack of detailed information about their molecular structures has hampered the analysis of protein structures featuring As(III), Sb(III), and Bi(III) bound to cysteine thiolate residues. In many cases, the formation of such protein adducts is proposed to play a key role in the mechanism of action of inorganic drugs that feature these elements. Here, we refine synthetic strategies to access As(Cys)3, Sb(Cys)3, and Bi(Cys)3, describe their crystal structures, analyze structural trends across the series and across Pn(SR)3 compounds deposited in the Cambridge Structural Database, and compare their features to the structures of proteins with these centers bound to Cys3 motifs. Significant differences were noted for many of the protein structures. [ABSTRACT FROM AUTHOR]

Alcoholysis of Cp′3Ln (Ln = La, Ce; Cp′ = C5H4SiMe3) generate high-yielding (72–97%) bimetallic LnIII complexes of [Cp′2Ln(μ-OR)]2 [R = Et, iPr, or C6H4-4-tBu]. Single-crystal X-ray diffraction of these complexes reveal unexpected decreases in Ln⋯Ln distances, increasing Cpcent–Ln–Cpcent angles, and increasing intermolecular C⋯C contacts with bulkier bridging alkoxides, in line with structural control driven by significant dispersion forces. 1H NMR spectroscopy of [Cp′2Ce(μ-OEt)]2 and [Cp′2Ce(μ-OiPr)]2 revealed significantly upfield resonances assigned as methylene and methine moieties of −43.74 and −70.85 ppm, respectively. 2D 1H DOSY NMR experiments of [Cp′2Ce(μ-OiPr)]2 in C6D6 supported a dimeric structure in solution, including in the presence of a Lewis base (i.e., THF). Reduction of [Cp′2La(μ-OiPr)]2 using KC8 in the presence of 2.2.2-cryptand at −78 °C generated a purple solution and X-band EPR spectroscopy revealed an eight-line hyperfine pattern indicative of a LaII species. [ABSTRACT FROM AUTHOR]

Four new coordination polymers based on 5‐(((1H‐imidazol‐2‐yl)methyl)amino) isophthalic acid (H3L) and auxiliary ligands (1,10‐phenanthroline, 2,2′‐bipyridine, and 4,4′‐bipyridine), namely, {[Zn(HL)(phen)(H2O)] ⋅ 2H2O}n (CP 1), {[Ni(HL)(phen)(H2O)]}n (CP 2), {[Ni(HL)(2,2′‐bpy)(H2O)] ⋅ 2H2O}n (CP 3) and {[Cd(HL)(4,4′‐bpy)0.5(H2O)] ⋅ 2H2O}n (CP 4) were rationally assembled. Furthermore, these four CPs were screened as heterogeneous catalysts for CO2 cycloaddition and cyanosilylation reactions under mild conditions. The catalytic experiments showed that CP 1 had the better catalytic performance, excellent substrate tolerance and recyclability for the above two reactions. It is speculated that the excellent activity of CP 1 may be due to the open Lewis base site and the Lewis acidic characteristics of the zinc (II) center. After five cycles, the catalytic activities of CP 1 did not significantly decrease, and the structures remained unchanged. Therefore, the CP 1 was considered efficient and stable heterogeneous catalysts for above the two reactions. [ABSTRACT FROM AUTHOR]

The discriminative detection of volatile primary aliphatic diamines (VPADs) is a relevant and timely issue. This paper explores the distinctive optical features of H-type and J-type aggregates on paper-based (PB) films, namely H-PB and J-PB films, respectively, of a Lewis acidic Zn(salen)-type complex upon chemisorption of vapors of ditopic VPADs versus those of monotopic volatile amines. While volatile monotopic Lewis bases upon chemisorption give rise to mono-adducts accompanied by enhancement of the fluorescence, in contrast, VPADs act as ditopic bases forming di-adducts with distinct optical properties, leading to fluorescence quenching. This behavior enables the sensitive and discriminative detection of VPAD vapors from those of volatile monoamines. For example, for ethylenediamine (EDA), using J-PB films, sensitive detection is achieved with a LOD down to 6.6 ppm, lower than the OSHA permissible exposure limit of 10 ppm for EDA, and a linear dynamic range up to 100 ppm. Instead, H-PB films enable the detection of EDA vapors at higher ppm concentrations (up to 3000 ppm) with a linearity of up to 1000 ppm. Thus, the combination of both H-PB and J-PB films of the Zn(salen)-type complex represents a unique example of the sensitive and discriminative detection of EDA vapors in such a wide concentration range. [ABSTRACT FROM AUTHOR]

Currently, all‐perovskite tandem solar cells have achieved power conversion efficiencies exceeding 29%. The further improvement is limited by mixed Sn–Pb narrow‐bandgap perovskite subcells. The facile oxidation of Sn2+ to Sn4+ poses an inherent challenge that limits the efficiency and stability of Sn–Pb perovskite solar cells. In this study, a multi‐dentate chelating additive, 3‐amino‐2‐chloroisonicotinamide (ACPC), is developed. Its amino group could anchor I− of the perovskite lattice by hydrogen bonds, thereby preventing I− migration and oxidation. On the other hand, the carbonyl group of ACPC as a Lewis base group could coordinate with Sn2+, effectively protecting Sn2+ from oxidation. Ultimately, the multi‐dentate chelating effect of ACPC helps to suppress the oxidation of Sn–Pb perovskite and its related nonradiative recombination. The resulting Sn–Pb perovskite solar cells obtain a top power‐conversion efficiency (PCE) of 23.09% and a high open‐circuit voltage (VOC) of 0.902 V while the control values only reach 19.11% and 0.825 V. As a result of the improved performance of the Sn–Pb perovskite solar cells, the corresponding all‐perovskite tandem solar cells achieve a PCE of 27.60%, retaining 85.7% of initial PCE after 500 h continuous 1 sun illumination. [ABSTRACT FROM AUTHOR]

Frustrated Lewis Pairs (FLP) have found exciting access in catalysis and small molecule activation. Here, we describe the potential of two vanadium(V) oxido complexes with monoanionic bidentate N,O donors, [VOCl(LCF3)2] (1 a), [VOCl(LH)2] (1 b) as bases in FLPs. Upon reaction of 1 a with the Lewis acid B(C6F5)3 the FLP [VOCl(LCF3)2]/B(C6F5)3 (1 a/B(C6F5)3) was observed. Addition of Ph3SiH led to the reduction of VV to VIV under formation of the adduct [V{OB(C6F5)3}(LCF3)2] (2 a) while FLP reactivity was not observed. Dissolving 2 a in CH3CN leads to the VIV oxido complex, [VO(LCF3)2] (3 a). In contrast, when 1 b was reacted with B(C6F5)3, a VIV oxido complex [VO(LH)2] (3 b) was obtained. Upon addition of B(C6F5)3 to 3 b no reaction leading to the expected adduct such as 2 a could be observed. Only few crystals deriving from a disproportion reaction could be identified as an adduct dimer [V{OB(C6F5)3}LH(μ‐O)]2. While FLP reactivity could not be found yet with the described systems, the redox labile nature and versatility of the metal complexes are demonstrated. [ABSTRACT FROM AUTHOR]

The first Lewis acid base adducts of MoF6 and an organic base have been synthesized, i. e., MoF6(NC5H5) and MoF6(NC5H5)2. These adducts are structurally characterized with X‐ray crystallography, showing that both adducts adopt capped trigonal prismatic structures. The MoF6(NC5H5) and MoF6(NC5H5)2 adducts are fluxional on the NMR time scale at room temperature. Two different fluorine environments could be resolved by 19F NMR spectroscopy at −80 °C for the 1 : 2 adduct, MoF6(NC5H5)2, whereas MoF6(NC5H5) remains fluxional at that temperature. Density functional theory (DFT) calculations aide the assignment of the infrared and Raman spectra. Natural Bond Order and Molecular Electrostatic Potential analyses elucidate the structures and properties of the MoF6 pyridine adducts. Regions of significantly higher molecular electrostatic potential, i. e., σ‐holes, in trigonal prismatic compared to octahedral MoF6 rationalize the capped trigonal prismatic geometry of the adducts. Whereas MoF6(NC5H5) is stable at room temperature under exclusion of moisture, MoF6(NC5H5)2 decomposes at 60 °C in pyridine solvent, and the solid slowly decomposes at room temperature after 24 h. [ABSTRACT FROM AUTHOR]

The first Lewis acid base adducts of MoF6 and an organic base have been synthesized, i. e., MoF6(NC5H5) and MoF6(NC5H5)2. These adducts are structurally characterized with X‐ray crystallography, showing that both adducts adopt capped trigonal prismatic structures. The MoF6(NC5H5) and MoF6(NC5H5)2 adducts are fluxional on the NMR time scale at room temperature. Two different fluorine environments could be resolved by 19F NMR spectroscopy at −80 °C for the 1 : 2 adduct, MoF6(NC5H5)2, whereas MoF6(NC5H5) remains fluxional at that temperature. Density functional theory (DFT) calculations aide the assignment of the infrared and Raman spectra. Natural Bond Order and Molecular Electrostatic Potential analyses elucidate the structures and properties of the MoF6 pyridine adducts. Regions of significantly higher molecular electrostatic potential, i. e., σ‐holes, in trigonal prismatic compared to octahedral MoF6 rationalize the capped trigonal prismatic geometry of the adducts. Whereas MoF6(NC5H5) is stable at room temperature under exclusion of moisture, MoF6(NC5H5)2 decomposes at 60 °C in pyridine solvent, and the solid slowly decomposes at room temperature after 24 h. [ABSTRACT FROM AUTHOR]

Gas-phase heterogeneous catalytic CO2 hydrogenation to commodity chemicals and fuels via surface frustrated Lewis pairs is a growing focus of scientific and technological interest. Traditional gas-phase heterogeneous surface frustrated Lewis pair catalysts primarily involve metal oxide-hydroxides (MOH•••M). An avenue to improve the process performance metrics lies in replacing the Lewis base MOH with a stronger alternative; an intriguing example being the amine MNH2 in metal nitrides. This study establishes a proof-of-concept that an amine-type photoactive surface frustrated Lewis pair (MNH2•••M) can be constructed in titanium nitride (TiNxOy) when integrated with a nanoscale platinum spillover co-catalyst. This surface frustrated Lewis pair, comprising Ti-NH2 as the Lewis base and low-valent Ti as the Lewis acid, facilitates the gas-phase light-assisted heterogeneous reverse water-gas shift reaction. The reaction proceeds via a surface-active carbamate intermediate, Ti-(H2N-COO)-Ti, whereby the synergism of Lewis acidic and Lewis basic sites endows it with superior performance indicators compared to TiNxOy alone, as well as conventional platinum supported metal oxides. Heterogeneous surface frustrated Lewis pairs catalysis have been predominantly focused on metal oxide hydroxides. This study instead explores a different chemical composition space by shifting from metal oxides to metal nitrides for CO2 photoreduction. [ABSTRACT FROM AUTHOR]

Chalcogen bonds (ChBs) involving selenium have attracted substantial scholarly interest in past years owing to their fundamental roles in various chemical and biological fields. However, the effect of the valency state of the electron-deficient selenium atom on the characteristics of such ChBs remains unexplored. Herein, we comparatively studied the σ-hole-type Se∙∙∙O ChBs between SeF2/SeF4 and a series of oxygen-bearing Lewis bases, including water, methanol, dimethyl ether, ethylene oxide, formaldehyde, acetaldehyde, acetone, and formic acid, using ab initio computations. The interaction energies of these chalcogen-bonded heterodimers vary from −5.25 to −11.16 kcal/mol. SeF2 participates in a shorter and stronger ChB than SeF4 for all the examined heterodimers. Such Se∙∙∙O ChBs are closed-shell interactions, exhibiting some covalent character for all the examined heterodimers, except for SeF4∙∙∙water. Most of these chalcogen-bonded heterodimers are predominantly stabilized through orbital interactions between the lone pair of the O atom in Lewis bases and the σ*(Se–F) antibonding orbitals of Lewis acids. The back-transfer of charge from the lone pair of selenium into the σ* or π* antibonding orbitals of Lewis bases is also observed for all systems. Energy decomposition analysis reveals that the electrostatic component significantly stabilizes the targeted heterodimers, while the induction and dispersion contributions cannot be ignored. [ABSTRACT FROM AUTHOR]

Helicobacter pylori affects about half of the population around the world. Therefore, timely and reliable diagnosis of the disease is required. Non-invasive detection of H. pylori is the technique of choice for infection control. Sample collection from saliva is non-invasive, but the bacteria load in human saliva is lower than in samples collected from the stomach, blood or stool. Hence, a detection method of high specificity and sensitivity is required. The purpose of this study was to evaluate the applicability of the Surface Plasmon Resonance (SPR) biosensor, based on the binding of Lewis b (Leb) blood group antigen to the specific adhesin BabA, for H.pylori detection in saliva. Our studies on saliva artificially contaminated with H. pylori, demonstrated that the BabA - Leb binding reaction had high specificity. The results obtained indicated that there are two mechanisms that inhibit the viability of H. pylori. The first involves the direct interaction between H. pylori and the oral antagonistic bacteria, and the second involves the bactericidal effect of certain proteins produced by the oral background bacterial flora. Although the sensitivity of detection of the proposed method needs to be increased, the results obtained proved its applicability and feasibility for H. pylori detection in saliva and the good prospects it offers for both clinical application and as a rapid point-of-care test. [ABSTRACT FROM AUTHOR]

The tin-containing Lewis acid group (C2F5)3Sn was combined with a phosphonium ylide as base function in one molecule: o-[(C2F5)3Sn]-C6H4(Ph)2PCMe2. It was prepared by reacting the ortho-lithiated triphenylphosphoniumdimethylmethylide (o-Li-C6H4)(Ph)2PCMe2 with the stannyl chloride (C2F5)3SnCl to afford o-[(C2F5)3Sn]-C6H4(Ph)2PCMe2 in 86 % yield. It forms a ring structure with a bond between tin and the ylidic carbon atom both in solution and in the solid state and can thus be considered as a hidden frustrated Lewis pair. The title compound is unreactive towards H2, CO2, CS2, PhNCO and decomposes in the presence of SO2 or NH3. However, it is active in the catalytic reduction of CO2 with pinacolborane, H–BPin. The title compound reacts slowly with H–BPin in an unselective reaction from which a reduction product with cleaved C2F5 group, the phosphonium stannate (II) o-[(C2F5)2Sn]-C6H4(Ph)2PCHMe2, could be obtained in small amounts. [ABSTRACT FROM AUTHOR]

Efficiency reduction in perovskite solar cells (PSCs) during the magnification procedure significantly hampers commercialization. Vacuum‐flash (VF) has emerged as a promising method to fabricate PSCs with consistent efficiency across scales. However, the slower solvent removal rate of VF compared to the anti‐solvent method leads to perovskite films with buried defects. Thus, this work employs low‐toxic Lewis base ligand solvent N‐ethyl‐2‐pyrrolidone (NEP) to improve the nucleation process of perovskite films. NEP, with a mechanism similar to that of N‐methyl‐2‐pyrrolidone in FA‐based perovskite formation, enhances the solvent removal speed owing to its lower coordination ability. Based on this strategy, p–i–n PSCs with an optimized interface attain a power conversion efficiency (PCE) of 24.19% on an area of 0.08 cm2. The same nucleation process enables perovskite solar modules (PSMs) to achieve a certified PCE of 23.28% on an aperture area of 22.96 cm2, with a high geometric fill factor of 97%, ensuring nearly identical active area PCE (24%) in PSMs as in PSCs. This strategy highlights the potential of NEP as a ligand solvent choice for the commercialization of PSCs. [ABSTRACT FROM AUTHOR]

The literature on aluminum coordination networks so far contains data on COO-bridged derivatives exclusively. This paper addresses the question whether or not aluminum complexes, especially carbamate-bridged {Al3(μ 3−O)}7+ units, can also form networks via the neutral ligand positions. Our findings show that a highly unexpected polymerization of the aluminum carbamates can occur during the isolation of the initially targeted compound. Although bidentate ligands bind to the neutral ligand coordination sites as expected, they do not act as linker molecules but cause an uncontrolled networking via the carbamate ligands. One- and two-dimensional solution and solid-state NMR experiments were primarily used to investigate the coordination behavior of the ligands and to elucidate the actual obtained product. [ABSTRACT FROM AUTHOR]

A novel [4+2] annulation reaction between o‐acylamino‐aryl MBH carbonates and isatylidene malononitriles has been successfully developed. This methodology exhibits excellent substrate tolerance, affording a series of spiro[indolin‐3,2′‐quinoline] framework compounds with yields up to 98%. The scalability of the reaction is also noteworthy, as evidenced by the 95% yield of the final product upon a 50‐fold scale‐up. [ABSTRACT FROM AUTHOR]

A novel (Z)-10-(bromoiodomethylene)phenanthren-9(10H)-one crystal structure is reported herein. Its synthetic formation arising from the phenyl shift during the electrophilic iodination of the alkynol of fluorenone provides proof of the early proposed mechanism of the McNelis rearrangement. The implication of the Z-geometry in the mechanism is discussed. Single crystal X-ray diffraction studies on the title compound show the β-vinyl bromine and the β-iodine atoms trans and syn, respectively, to the C = O in the molecule establishing the configuration of the dihaloenone about the alkenyl motif as Z-geometry. The intermolecular interactions primarily involve the iodine and oxygen atoms with a C-I...O = C distance of 3.110 (1) Ả, which describes an I...O halogen bond since the I···O distance is less than the sums of the respective van der Waals radii, 3.50 Å. In this interaction, the iodine acts as a Lewis acid, and the carbonyl oxygen serves as the Lewis base electron donor moiety. Consistent with the strong directional polarization of halogen bonds, the C-I···O angle = 167°. There is an additional intramolecular C-I ∙∙∙O = C distance of 3.147 (1) Å and I∙∙∙I distance of 3.956 (1) Å along the c-axis. These interactions form a one-dimensional, non-planar infinite network along the c-axis. [ABSTRACT FROM AUTHOR]

Diverse transformations of allenoates catalyzed by Lewis bases have emerged as a powerful platform for generating new chemical entities in organic synthesis. Herein, an N‐heterocyclic carbene (NHC) catalyzed [3+3] cyclization of 2‐(acetoxymethyl)buta‐2,3‐dienoates with 1 C,3O‐bisnucleophiles has been developed. This approach provides a facile method to synthesize highly functionalized 4H‐pyran derivatives with a broad substrate scope (31 examples, up to 83 % yield). [ABSTRACT FROM AUTHOR]

Electrolysis of seawater using anion exchange membrane water electrolyzers (AEMWEs) under neutral conditions, is an attractive method for hydrogen production. Unfortunately, competitive anodic chlorine evolution reaction together with sluggish oxygen evolution reaction (OER) kinetics caused by insufficient OH−, significantly limit the system's current density and operational stability. Herein, Lewis base phosphate (PO43−) is used as a proton acceptor to accelerate the cleavage of OH−H bonds, which facilitates the accumulation of *OH. NiFeP nanosheets grown on pretreated nickel foam (NiS‐A) are used as the free‐standing electrode. During the OER process, the pre‐catalyst NiFeP spontaneously transforms into Lewis base‐PO43− decorated Ni(Fe)OOH. Experimental studies and density functional theory calculations reveal that Ni(Fe)OOH active phases adsorb H2O intermediates and synergize with the protophilic Lewis base PO43− to favor the dissociation of water molecules (*H2O→*OH+H++e−), ensuring the timely supply of *OH in neutral media. Meanwhile, PO43− also exhibits excellent ability to repel chloride ions in seawater splitting, achieving ≈98.2% oxygen Faradaic efficiency. The optimized NiFeP/NiS‐A delivers a low overpotential (280 mV at 10 mA cm−2) and long‐term OER durability (over 400 h at 500 mA cm−2). Integrating NiFeP/NiS‐A in a seawater‐based AEMWE can achieve an industrially required current density of 1.0 A cm−2 (60 °C) at 1.8 V and an operation stability over 220 h. [ABSTRACT FROM AUTHOR]

The Lewis superacid Ga(OTeF5)3 has been synthesized and characterized, revealing a monomeric structure in solution and a dimeric structure in the solid state. Isolated adducts of Ga(OTeF5)3 with strong and weak Lewis bases have been characterized spectroscopically as well as by single‐crystal X‐ray diffractometry. The Lewis acidity of this new species has been evaluated by means of different experimental and theoretical methods, which has allowed to classify it as one of only a few examples of a gallium‐based Lewis superacid. The high Lewis acidity of Ga(OTeF5)3 was used to amplify the strength of the Brønsted acid HOTeF5, leading to the protonation of diethyl ether. Furthermore, Ga(OTeF5)3 was utilized to access the strong oxidizing system Ga(OTeF5)3/Xe(OTeF5)2 in SO2ClF, which was successfully employed in the synthesis of the dimethyl chloronium salt [Cl(CH3)2][Ga(OTeF5)4], a strong electrophilic methylation reagent. [ABSTRACT FROM AUTHOR]

The Lewis superacid Ga(OTeF5)3 has been synthesized and characterized, revealing a monomeric structure in solution and a dimeric structure in the solid state. Isolated adducts of Ga(OTeF5)3 with strong and weak Lewis bases have been characterized spectroscopically as well as by single‐crystal X‐ray diffractometry. The Lewis acidity of this new species has been evaluated by means of different experimental and theoretical methods, which has allowed to classify it as one of only a few examples of a gallium‐based Lewis superacid. The high Lewis acidity of Ga(OTeF5)3 was used to amplify the strength of the Brønsted acid HOTeF5, leading to the protonation of diethyl ether. Furthermore, Ga(OTeF5)3 was utilized to access the strong oxidizing system Ga(OTeF5)3/Xe(OTeF5)2 in SO2ClF, which was successfully employed in the synthesis of the dimethyl chloronium salt [Cl(CH3)2][Ga(OTeF5)4], a strong electrophilic methylation reagent. [ABSTRACT FROM AUTHOR]

Terphenylgermanium Ar*Ge [Ar*=C6H3(2,6‐Trip)2, Trip=2,4,6‐C6H2iPr3] was found to act as a novel μ2‐Ge‐bis(hexahapto‐Trip) bridging ligand. Deprotonated terphenyl germanium trihydride [Li(thf)3][Ar*GeH2] (1) undergoes reductive elimination and transfer of hydrogen in reaction with dimeric [(COD)RhCl]2 to yield the dinuclear complex [Ar*GeRh(COE)RhCl(COD)] (2). Subsequent chloride abstraction from compound 2 using Na[BArF4] or Li[Al(OtBuF)4] results in the cationic complexes [Ar*GeRh(COE)Rh(COD)][WCA] (3) {WCA: [BArF4]− (ArF=C6H3–3,5‐(CF3)2), [Al(OtBuF)4]−}. Ligand exchange of olefin for CO yields the carbonyl complex [Ar*Ge(Rh(CO))2][BArF4] (4). In an alternative approach to the synthesis of carbonyl complex 4, [Li(thf)3][Ar*GeH2] (1) was treated with [Rh(CO)2Cl]2 leading to the isolation of a hexanuclear rhodium cluster [(μ3‐Ar*Ge)2{Rh(CO)2}6(μ3‐H)2] (5) in reasonable yield. In reactions with [Rh(CO)2Cl]2 or [Ph3PAuCl] complex 4 abstracts the chloride ligand and forms tetranuclear complexes featuring a GeRh3‐ or GeRh2Au‐rectangle, [Ar*GeCl(Rh3(CO)4)][BArF4] (6), or [Ar*GeCl{Rh2(CO)2}(AuPPh3)][BArF4] (7). [ABSTRACT FROM AUTHOR]

Compared to the outstanding development in the synthesis of Si−B single bonded species, borylsilanes and their application to organic synthesis, the chemistry of Si=B double bonded species, borasilenes and boratasilenes have only made little progress, first of all, due to the difficulties in accessing such double bonds. Herein we report the synthesis of the first Si=B analogue of a vinyl halide, a bromoboratasilene, via formal borylene insertion to the coordination sphere of a monoatomic Si(0) complex, using a dihaloborane as the borylene source. The treatment of bromoboratasilene toward neutral or anionic Lewis bases gives access to new boratasilenes, all of which were proved to possess significant Si=B double bond character by XRD analysis and DFT calculations. These results demonstrate exciting strategies to synthesize new types of Si=B double bonded species which should further progress the chemistry of boron, silicon‐containing molecules. [ABSTRACT FROM AUTHOR]

Vicinal stereogenic centers represent prevalent structural motifs in organic synthetic chemistry, and their construction poses a longstanding challenge. Transition-metal-catalyzed asymmetric allylic substitution has become a well-established enantioselective C–C bond-forming reaction. When these reactions involve a prochiral nucleophile and an allylic electrophile with a terminal substituent, the creation of vicinal stereogenic centers becomes feasible. However, despite remarkable achievements having been accomplished, realizing this transformation with precise control over both the enantio- and diastereoselectivity remains a significant challenge. To address the stereoselective challenges, the introduction of a second catalyst to the transition-metal-catalyzed asymmetric allylic alkylation to control the diastereoselectivity during C–C bond formation has proven particularly fruitful. In this short review, we aim to highlight recent advances in dual catalysis that enable diastereo- and enantioselective allylic substitutions. 1 Introduction 2 Construction of Vicinal Stereogenic Centers by Organo and Metal Dual Catalysis 2.1 Chiral Phase-Transfer Catalysis and Transition-Metal Dual Catalysis 2.2 Chiral Amine and Transition-Metal Dual Catalysis 2.3 NHC and Transition-Metal Dual Catalysis 2.4 Chiral Aldehyde and Transition-Metal Dual Catalysis 2.5 Chiral Lewis Base and Transition-Metal Dual Catalysis 3 Construction of Vicinal Stereogenic Centers by Metal and Metal Dual Catalysis 3.1 Lewis Acidic Metal and Iridium Dual Catalysis 3.2 Lewis Acidic Metal and Palladium Dual Catalysis 3.3 Palladium and Ruthenium Dual Catalysis 3.4 Other Advancements in the Construction of Vicinal Stereogenic Centers through Synergistic Bimetallic Catalysis Enabling Asymmetric Allylic Alkylation 4 Conclusions and Future Outlook [ABSTRACT FROM AUTHOR]

We investigate here the ability of N-iodophthalimide (NIPht) to act as a halogen bond (HaB) donor, in comparison with well-known HaB donors N-iodosuccinimide (NISucc) and N-iodosaccharin (NISacc). The structure of NIPht itself is reported, together with those of neutral adducts with 4-dimethylaminopyridine (DMAP), 4,4′-bipyridine and 2,2′-bipyridine derivatives. Comparison with analogous adducts involving NISucc and NISacc shows that NIPht behaves essentially like NISucc as a HaB donor, both forming weaker adducts than NISacc with a given Lewis base. A symmetric anionic complex [NPht–I–NPht]− is isolated in the presence of [K(18-crown-6)]+. It exhibits N–I distances very close to those observed in the known [NSucc–I–NSucc]− and [NSacc–I–NSacc]− species (2.24–2.26 Å), confirming the 3-center–4-electron (3c–4e) character of the bonding in these species. This similarity confirms the peculiar character of the only other reported salt of [NPht–I–NPht]−, namely [Me4N][NPht–I–NPht], where the longer N–I distances (2.29 Å) are a consequence of a specific solid-state arrangement and C–H⋯O hydrogen bonds. [ABSTRACT FROM AUTHOR]

N‐Methyl‐2‐pyrrolidone (NMP) has become one of the mainstream Lewis base ligand solvents for the fabrication of high‐quality FA‐based perovskite films. However, the NMP‐based perovskite films with small grain sizes always own a mirror surface which will increase the reflection of light and limit the current of perovskite solar cells (PSCs). In this work, 2‐pyrrolidone (NP) with a higher boiling point and stronger binding to precursor components is introduced into the precursor solution to improve the crystallization and morphology of perovskite. Finally, a rougher perovskite film with a larger grain size can be fabricated via an optimized NP and NMP mixed ligand solvent. Based on this strategy, the champion device achieved a power conversion efficiency (PCE) of 24.20% (certified PCE of 23.81%) and 22.13% on an aperture area of 0.0875 and 22.96 cm2, respectively. In addition, the introduction of NP enhances the humidity and light stability of the film, and the device retained 94.1% of its initial efficiency after 120 h. [ABSTRACT FROM AUTHOR]

BICAAC (bicyclic (alkyl)(amino)carbene) as ambiphilic carbene has been utilized to prepare stable neutral tetrahydrodiborane [BICAAC→ ${\to }$ (H2)B−B(H2)← ${\leftarrow }$ BICAAC] and dihydrodiborene [BICAAC→(H)B=B(H) ← ${\leftarrow }$ BICAAC] compounds. The Lewis base stabilized dihydrodiborene is isoelectronic and isolobal to conventional olefins and therefore offers the possibility to explore the formation of π‐complexes with transition metals. Reaction of the diborene with coinage metal salts (CuCl, AgBr and CuI) leads to the formation of π‐diborene metal complexes via η2 side‐on coordination. These are first examples of dihydrodiborene coinage metal complexes. Interestingly, coordination of two CuCl units to the diborene has been observed for the first time with a considerable lengthening of >B=B< and B- ${-}$ CBICAAC bonds manifesting the key role of the BICAAC combined with small steric requirements of hydride substituents in stabilizing these complexes. The energy decomposition analysis (EDA) calculations reveal the interaction between the diborene and Cu(I)/Ag(I) is mainly electrostatic in nature. [ABSTRACT FROM AUTHOR]

Interest is growing in transition metal‐free compounds for small molecule activation and catalysis. We discuss the opportunities arising from synthesizing sodium‐doped amorphous silicon‐boron‐nitride (Na‐doped a‐SiBN). Na+ cations and 3‐fold coordinated BIII moieties were incorporated into an amorphous silicon nitride network via chemical modification of a polysilazane followed by pyrolysis in ammonia (NH3) at 1000 °C. Emphasis is placed on the mechanisms of hydrogen (H2) activation within Na‐doped a‐SiBN structure. This material design approach allows the homogeneous distribution of Na+ and BIII moieties surrounded by SiN4 units contributing to the transformation of the BIII moieties into 4‐fold coordinated geometry upon encountering H2, potentially serving as frustrated Lewis acid (FLA) sites. Exposure to H2 induced formation of frustrated Lewis base (FLB) N−= sites with Na+ as a charge‐compensating cation, resulting in the in situ formation of a frustrated Lewis pair (FLP) motif (≡BFLA⋅⋅⋅Hδ−⋅⋅⋅Hδ+⋅⋅⋅:N−(Na+)=). Reversible H2 adsorption‐desorption behavior with high activation energy for H2 desorption (124 kJ mol−1) suggested the H2 chemisorption on Na‐doped a‐SiBN. These findings highlight a future landscape full of possibilities within our reach, where we anticipate main‐group‐mediated small molecule activation will have an important impact on the design of more efficient catalytic processes and the discovery of new catalytic transformations. [ABSTRACT FROM AUTHOR]

Catalyst‐controlled switchable (4+3) and (4+2) annulation reactions of Morita–Baylis–Hillman carbonates with benzofuran‐derived azadienes have been established. Employing PCy3 as the catalyst, the reaction could provide a variety of synthetically useful benzofuro[3,2‐b]azepines in good yields (80–92%) with excellent chemo‐ and regioselectivities via (4+3) cycloaddition reactions. Whereas changing the catalyst from PCy3 to DMAP, the chemo‐ and regioselectivities were switched to construct highly substituted spirotetrahydroquinoline scaffolds with three sequential stereocenters containing all‐carbon spiro‐quaternary stereocenters in excellent efficiency and diastereoselectivities (92–96% yields with all cases>25:1 dr) via (4+2) annulations. In addition, the synthetic utility of this method was further showcased by gram‐scale reactions and synthetic transformations of the product. [ABSTRACT FROM AUTHOR]

Metal‐containing liquid crystals such as Ln(III) complexes possess unique structural, liquid‐crystalline (LC), optical, and magnetic properties and represent modern cutting‐edge multifunctional materials. Application of mesogenic Ln(III) complexes is hindered by their nontrivial structure–property relationships. These relationships, in turn, depend on various factors, including insufficiently studied physicochemical processes. Although a proper Ln(III) element and the respective ligand environment are selected prior to synthesis of such complexes, the structural features of the coordination polyhedra, especially upon photoexcitation, are not uniquely defined. Therefore, this work focuses on the development of theoretical approaches to creating multifunctional materials represented by highly luminescent mesogenic Eu(III) complexes with β‐diketones and Lewis bases. The relationships between their structure, the parameters of Voronoi–Dirichlet polyhedra, the luminescence efficiency, and the LC properties were considered. The calculated excited states and intramolecular energy transfer rates were used to determine intramolecular energy transfer channels. The LC behavior of the studied materials was shown to mainly depend on the ligand environment, whereas their optical properties were found to be mostly governed by the coordination polyhedra. [ABSTRACT FROM AUTHOR]

Hydride abstraction from the borane adduct, (BICAAC) ⋅ BH3 afforded the hydride bridged dinuclear borenium ion equivalent complexes 1 and 2 that have been characterized by various spectroscopic and spectrometric techniques followed by the assessment of Lewis acidity using the Gutmann‐Beckett method. The single crystal X‐ray structure of complex 2 revealed the presence of discrete ions in the solid state. The complex (BICAAC) ⋅ BH2(OTf) (3), obtained from the reaction of (BICAAC) ⋅ BH3 with MeOTf, formed the corresponding boronium cations [(BICAAC) ⋅ BH2(L)]+(OTf)− on reaction with Lewis bases (L= pyridine (4) and DMAP (5)). Complexes 1 and 2 demonstrated notable catalytic activity in the hydrosilylation of a diverse array of carbonyls using 1.0 mol % catalyst loading (achieving the highest turnover frequency (TOFmax) of up to 1200 h−1 with benzaldehyde. A broad substrate scope has been presented for aldehydes and ketones decorated with various electron‐donating and withdrawing substituents along with this the hydrosilylation of a few para‐quinone methides has also been presented. [ABSTRACT FROM AUTHOR]

Two tri‐ and two hexadentate poly‐Lewis acids (PLAs) with calyx‐like structures of C3 symmetry containing aluminum‐ and boron‐containing Lewis acidic functions were prepared by tin‐metal exchange reactions. The triply hydrosilylated [12]annulene served as basic framework. It forms a calyx‐like structure by the stereo‐ and regioselective attachment of three SiMeCl2 groups to the planar [12]annulene. The PLA precursors were generated by attaching three or six trimethylstannylethynyl groups to the silicon atoms. Lewis acid functions were introduced using the reagents bis‐(bis(trimethylsilyl)methyl)aluminium hydride (HAl[CH(SiMe3)2]2) and catecholatochloroborane (ClBCat). The complexation behavior of the PLAs towards different Lewis bases was investigated by NMR. Bases included pyridine, polydentate nitrogen‐ and phosphorus‐containing bases. Additionally, three molecules of a bidentate phosphorus‐containing base were captured with hexadentate PLAs. Diffusion NMR experiments provided insight into the aggregation processes: some of the adducts had a significantly larger volume than expected, indicating the formation of larger adducts than the expected 1 : 1 adduct, including larger 2 : 2 adduct cages. The distances between the Lewis acid units and the steric requirement of the attached substituents determine the complexation behavior of the PLAs. Thus, the weak Lewis acidic BCat units show no (tridentate case) or a strong (hexadentate case) interaction with PMe2‐containing bases, if they can act cooperatively. [ABSTRACT FROM AUTHOR]