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The elimination of lactones is a crucial method for preparing corresponding cycloalkane derivatives, but the commonly used catalyst NaI is unstable and non-recyclable. In this work, reusable MgI2@SiO2 was prepared for heterogeneous catalytic lactone elimination. Cyclopropyl methyl ketone was synthesized from 2-acetyl-γ-butyrolactone using MgI2@SiO2 as a catalyst at 180 °C and 1 atm. The yield and selectivity were both over 99%. The activity of MgI2@SiO2 was estimated to be 11 times that of NaI. The high activity of MgI2@SiO2 is attributed to the Lewis hard acidity of Mg2+ and the soft basicity of I−. The high selectivity of Cyclopropyl methyl ketone comes from the faster reaction rate, and its good stability is due to the strong interactions between Mg2+ and I− with the carrier. This work provides a feasible scheme for the efficient and low-cost elimination synthesis of corresponding cycloalkanes from lactones. [ABSTRACT FROM AUTHOR]

Broadening the scope of functionalities that can be covalently bound to single‐walled carbon nanotubes (SWCNTs) is crucial for enhancing the versatility of this promising nanomaterial class in applied settings. Here we report the covalent linkage of triphenylphosphine oxide [Ph3P(O)] to SWCNTs, a hitherto overlooked surface functionality. We detail the synthesis and structural characterization of a new family of phosphine oxide‐functionalized diaryliodonium salts that can facilitate direct Ph3P(O) transfer and afford novel SWCNTs with tunable Ph3P(O) content (SWCNT‐P). The molecularly‐distributed and robust nature of the covalent Ph3P(O) attachment in SWCNT‐P was supported by a combination of characterization methods including Raman, infrared, UV/Vis‐NIR and X‐ray photoelectron spectroscopies coupled with thermogravimetric analysis. Electron microscopy further revealed the effectiveness of the Ph3P(O) moiety for de‐bundling SWCNTs to yield SWCNT‐P with superior dispersibility and processability. Finally, electrochemical studies established that SWCNT‐P is sensitive to the presence of Li+, Na+ and K+ wherein the Gutmann‐Beckett Lewis acidity parameters of the ions were quantitatively transduced by Ph3P(O) to electrochemical responses. This work hence presents a synthetic, structural, spectroscopic and electrochemical foundation for a new phosphorus‐enriched responsive nanomaterial platform featuring the Ph3P(O) functionality. [ABSTRACT FROM AUTHOR]

Thorium, a predominant actinide in the Earth's crust, presents significant environmental and health risks due to its radioactive nature. These risks are particularly pronounced during the mining and processing of monazite for rare earth elements (REEs), which contain substantial thorium concentrations. Current instrumental analysis methods for thorium, offer high accuracy but require laborious sample preparations and expensive instruments, making them unsuitable for on‐site analysis. Herein, we present a class of color‐tunable luminescent lanthanide‐based metal–organic frameworks (Ln‐MOFs) as fluorochromic sensors for Th4+ cations. Utilizing a heterobimetallic Eu3+/Tb3+ doping strategy, the luminescence colors of EuxTb1‐x‐BDC‐OH can be finely tuned from red, to orange, and to green. More intriguingly, the higher Lewis acidity of Th4+ facilitates the transformation of EuxTb1‐x‐BDC‐OH into a UiO‐type Th‐MOF via a dissolution‐recrystallization mechanism. This process results in a gradual reduction of characteristic Ln3+ emissions and the emergence of blue color ligand‐based fluorescence, thereby leading to selective fluorochromic responses with increasing Th4+ concentrations and enabling visible detection of Th4+ cations. Additionally, a custom‐built portable optoelectronic device is fabricated, which directly converts luminescence colors into red‐green‐blue (RGB) values. This device enables easy quantification of Th4+ concentrations without the need for complex instrumentation. [ABSTRACT FROM AUTHOR]

A computational approach to directly estimate the relative acidity of a given Lewis acid is presented. This approach is based on the strength of the π‐conjugation in trans‐crotonaldehyde‐Lewis acid complexes, the species used in the well‐known Childs’ Lewis acidity scale. It is found that the π‐conjugative strength values given by the Energy Decomposition Analysis – Natural Orbital for Chemical Valence method strongly correlate not only with the variation of the bond lengths in the system, which are greatly affected by the nature of the Lewis acid, but also with the downfield shifts experienced by the different nuclei of the conjugated system upon binding to the Lewis acid. These strong correlations indicate that the (easy‐to‐compute) π‐conjugation energies can be used as an alternative Lewis acidity scale. [ABSTRACT FROM AUTHOR]

The synthesis and reactivity of an air and water stable Bicyclic (alkyl)(amino)carbene (BICAAC) stabilized phosphenium cation (1) is reported. Air and water stable phosphenium cation are rare in the literature. Compound 1 is obtained by reaction of BICAAC with Ph2PCl in THF followed by anion exchange with LiOTf. The reduction and oxidation of 1 yielded corresponding α‐radical phosphine species (2) and BICAAC stabilized phosphenium oxide (3) respectively. All compounds are well characterized by single crystal X‐ray diffraction studies. The Lewis acidity of compounds 1 and 3 are determined by conducting fluoride ion affinity experiments using UV‐Vis spectrophotometry and multinuclei NMR spectroscopy. Compounds 1 and 3 exhibited selective binding to fluoride anion but did not interact with other halides (Cl− and Br−). Quantum chemical calculations were performed to understand the structure and nature of bonding interactions in these compounds, as well as to comprehend the specific bonding affinity to fluoride over other halide ions. [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]

Aluminum reagents are widely used as strong Lewis acids for organic transformations and catalysis. In recent years, a variety of Al‐Lewis superacids could be accessed by preparation of aluminum cations paired with weakly‐coordinating anions or by use of perfluorinated substituents at the metal. While the majority of these Al‐Lewis superacids is composed of a tricoordinate Al‐metal atom, examples for dicoordinate Al species are very scarce. In this study, we report the preparation of [(Mes*)Al(H)(OEt2)]+[Al(ORF)4]− (Mes*=2,4,6‐tBu3‐C6H2, RF=C(CF3)3) by reaction of protonated ether [H(OEt2)2]+[Al(ORF)4]− with [Mes*AlH2]2. Structural analysis supported by computed frontier orbitals and atomic charges reveals that the cation is best described as diethylether adduct of dicoordinate [(Mes*)Al(H)]+ and acts as synthon to this low‐coordinate cation. To incorporate the masking of the coordination site by the ether, the enthalpy of dissociation is included in the computed fluoride‐ and hydride ion affinities (XIA) and entropic effects are treated by defining a "free ion affinity" (fXIA), basing on the Gibbs energy change. Hereby, the Lewis acidity of free Lewis acids as well as their solvent adducts can be estimated. [ABSTRACT FROM AUTHOR]

Carbon‐carbon bond forming reactions are powerful synthetic tools for constructing organic molecular frameworks. In this study, strongly Lewis acidic bis(pentafluorophenyl)boron enolates were generated from alkynes through oxygen transfer from 2,6‐dibromopyridine N‐oxide using tris(pentafluorophenyl)borane [B(C6F5)3]. Boron enolates were highly reactive owing to the strong Lewis acidity of the boron centers, and thus immediately coupled with alkynes. N‐Ethynylphthalimide reacted as an alkyne with 2,6‐dibromopyridine N‐oxide and B(C6F5)3 to form a semi‐stable bis(pentafluorophenyl)boron enolate through the coordination of the carbonyl group to the boron center. This enolate underwent coupling with another alkyne. [ABSTRACT FROM AUTHOR]

CO2 chemical fixation offers a feasible approach for carbon mitigation and high‐value utilization, but it is still challenging to develop an efficient catalyst for CO2 conversion into cyclic carbonate. Herein, the triethylenediamine‐derived dicationic ionic liquids (DIL‐X, X = Cl, Br, and I) were grafted into UiO‐66 linkers through self‐assembly of Zr4+ ions and the mixed ligands of terephthalic acid and DIL‐bearing dicarboxylic acid, resulting in UiO‐66‐DIL‐Xn, (n designated as molar amount of the feeding DIL‐X). Their catalytic performance was evaluated by the epoxide cycloaddition reaction in the absence of solvent and cocatalyst. Among them, the UiO‐66‐DIL‐Cl0.4 catalyst exhibited outstanding performance, with a chloropropene carbonate yield of 92% and a high selectivity of 99% under 0.1 MPa CO2 at 110 °C for 16 h. Its high activity could be ascribed to the cooperativity among Lewis acidity of MOF nodes, the enhanced CO2 absorption, and the strong nucleophilicity offered by halogen ions of ionic liquid‐modified MOF. Moreover, UiO‐66‐DIL‐Cl0.4 presented excellent recyclability and substrate extension. A potential catalytic mechanism for the epoxide‐CO2 cycloaddition into cyclic carbonate has been proposed. This work will shed light on the rational design of functionalized MOFs‐based catalysts for CO₂ utilization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Preparation of interconnected hollow carbon spheres functionalized with B and Tb single atoms. • B doping increases the Lewis acidity of Tb, promoting the occurrence of rate-determining step of ring-opening reaction. • The prepared TbN 4 B 2 /C can adsorb full band light to achieve efficient photothermal conversion. • The CO 2 cycloaddition reaction with using TbN 4 B 2 /C as catalyst is a photothermal synergistic catalytic mechanism. Nowadays, it is becoming increasingly urgent to lower the escalating carbon dioxide (CO 2) to reduce greenhouse effect. Fortunately, it is an ideal strategy by using the inexhaustible solar energy as the driving force to manipulate the cycloaddition reaction, the atomic efficiency of which is 100 %. This work represents the first attempt on utilization of rare-earth metal Tb with atomic dispersion, and the structure of Tb coordinated with 4 N -atoms and 2B-atoms was constructed on interconnected carbon hollow spheres. The introduction of electron-deficient B reduces the electron density of Tb, thereby boosting Lewis acidity and promoting the occurrence of ring-opening reaction. The mechanism exploration enunciates that TbN 4 B 2 /C is a photothermal synergistic catalyst, the combined action of photogenerated electrons and strong Lewis acidic site of Tb reduces the free energy of the rate-determining step, and then improving the yield of cyclic carbonate up to 739 mmol g-1h−1. [ABSTRACT FROM AUTHOR]

Over the past three decades, triflate salts have emerged as crucial Lewis acid catalysts in organic synthesis, playing a significant role in cyclization, C−H bond functionalization, and various other reactions. Among these, rare‐earth triflates have garnered attention due to their water compatibility, environmental friendliness, noncorrosive nature, and reusability. In particular, scandium(III) triflate [Sc(OTf)3] stands out as a water‐resistant Lewis acid with remarkable catalytic activity in aqueous environments. Unlike typical Lewis acids such as AlCl3, BF3, and SnCl4, which are decomposed or deactivated by water, Sc(OTf)3 remains stable and effective. Its exceptional Lewis acidity, resilience against hydrolysis, and recyclability make it a prominent green catalyst. The unique stability of Sc(OTf)3 in water is attributed to the smaller size of scandium ions (Sc3+), enhancing its catalytic efficiency. Sc(OTf)3 has a longstanding history in organic synthesis, facilitating a wide range of reactions including aldol, Michael, allylation, Friedel‐Crafts acylations, Diels‐Alder, Mannich, cycloadditions (including cyclopropanation), and cascade reactions. The increasing utilization of Sc(OTf)3 over the past decade underscores the necessity for updated insights. This review provides a concise overview of the versatility of Sc(OTf)3 as a catalyst, focusing on developments from 2017 to 2024. [ABSTRACT FROM AUTHOR]

AbstractPoly(δ-valerolactone) (PVL) is a polymer that has garnered significant researcher interest due to its intriguing features and prospective uses across numerous domains, particularly in medicine. This work aimed to assess the influence of the Lewis acidity of the bis(β-diketonate)Zr catalyst complex on the ring-opening polymerization of δ-valerolactone. The ligand in the compound contains an electron-donating group, specifically the methyl group (2a). Furthermore, electron-withdrawing groups employed include phenyl (2b–2c) and trifluoromethyl groups (2d). Characterization data indicate that PVL has been successfully synthesized with a bis(β-diketonate)Zr complex catalyst. The hierarchy of Lewis acid strength for the bis(β-diketonate)Zr complex is 2c > 2b > 2d ≫ 2a. The sequence of PVL DP from highest to lowest is 2b, 2c, 2d and 2a. Nonetheless, the elevated Lewis acidity of complex 2c does not provide PVL with the greatest degree of polymerization. The steric barrier of complex 2c, which contains two phenyl groups, is larger than that in complex 2b. Consequently, the coordination process of the nucleophilic monomer with the electrophilic zirconium central atom becomes increasingly difficult. [ABSTRACT FROM AUTHOR]

Pnictogen pincer complexes are a fascinating class of compounds due to their dynamic molecular and electronic structures, and valuable stoichiometric or catalytic reactivity. As recognition of their unique chemistry has grown, so too has the library of pincer ligands employed and pnictogen centres engaged to prepare them. Here we computationally study how the choice of pincer ligand framework and pnictogen influence the electronic and steric outcomes within the complexes obtained. The most relevant electronic parameter is the pnictogen‐centred electrophilicity, which has been quantified by fluoride ion affinities and LUMO energies, while the most relevant steric parameter is the crowding around the central pnictogen, which has been quantified by the %Vbur values and visualized using steric maps. The resulting trends are analyzed with reference to binding pocket size, acceptor orbital type, electronic delocalization, π‐donor strengths, and heteroatom incorporation. Thus, considering 16 ligand frameworks and 4 heavy pnictogen centres, this study provides a broad‐spectrum view of stereo‐electronic variation in pnictogen pincer complexes, which, together with a recent study on geometric variation in the same family, provides a substantial dataset to guide future molecular design and reactivity studies. [ABSTRACT FROM AUTHOR]

Two homologous series of pnictogen(III) dications, stabilized by 2,6‐bis(benzimidazole‐2‐yl)pyridine ligands have been prepared. Both series contain PnIII‐X moieties (Pn = P, As, Sb, Bi; X = Cl or Ph) and have been fully characterized using spectroscopic methods including X‐ray crystallography. The Lewis acidity of these compounds has also been probed by computational methods; the results suggest that the dictations are strong Lewis acids, with the PnCl2+ compounds being more acidic than the PnPh2+ compounds, and with Lewis acidity increasing from P to Bi, in both series. The PhP2+‐containing compound was also found to be a versatile PIII transfer reagent, leading to new synthetic routes for various PhP‐containing compounds. The redox chemistry of all compounds has also been probed using cyclic voltammetry and chemical reductions. In some cases the resulting PnI moieties could be trapped using diazabutadienes. [ABSTRACT FROM AUTHOR]

The quest for sustainable synthesis of carboxylic acids has led to the exploration of innovative routes and catalysts for the oxidative cleavage of carbon−carbon double bonds, prevalent in bio‐derived molecules. This process involves multiple steps including epoxidation, hydrolysis and vicinal diol cleavage, often catalysed by unsustainable homogeneous or noble‐metal catalysts. In this study, we present the utilization of Fe‐ZSM‐5 as a versatile bifunctional catalyst capable of catalysing both hydrolysis and vicinal diol cleavage steps, utilizing propylene oxide as model compound and H2O2 as oxidizing agent. The prepared Fe‐ZSM‐5 features the zeolite intrinsic Lewis and Brønsted acidity functions, essential for the hydrolysis step, as well as high fractions of monomeric FeOx species, crucial for the subsequent vicinal diol cleavage, leading to streamlined carboxylic acids formation in a one‐pot, two‐step process. Moreover, by combining Fe‐ZSM‐5 with TS‐1, renowned for its epoxidation activity, we demonstrate the complete cascade reaction in one pot, under mild conditions, starting from ethylene. Our study expands the utility of cost‐effective zeolite‐based catalysts enriched with abundant Fe metal for the one‐pot oxidative cleavage of C=C double bonds, offering a promising pathway towards sustainable carboxylic acid synthesis. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Herein, we describe a direct route for the synthesis of 3‐gem‐difluorovinyl lactams through Zn‐mediated reductive hydrodehalogenation. Importantly, by using inexpensive deuterium oxide (D2O), the high value‐added vicinal dideuterated gem‐difluoroalkenes with excellent deuterium (D) incorporation were prepared. Mechanism studies indicated a successive single electron transfer process: the reaction initially undergoes hydrodechlorination to give the intermediate α‐trifluoromethylidene lactams, which are then activated by the in‐situ generated zinc cations and reduced to the desired product via hydrodefluorination. [ABSTRACT FROM AUTHOR]

Aiming at intramolecular frustrated Lewis pairs (FLPs) based on soft Lewis acidic bismuth centers, a phosphine function was combined with a dichloridobismuthane unit on a phenylene backbone utilizing a scrambling approach. The reaction between two equivalents of BiCl3 and (o‐(Ph2P)C6H4)3Bi yielded (o‐(Ph2P)C6H4)BiCl2(THF), the structure of which indicated Bi...P interactions and thus a pronounced Lewis acidity at the bismuth center that was confirmed by the Gutmann‐Beckett method. However, the system turned out to be insufficient to be utilized for FLP reactivity. Hence, the chloride ligands were exchanged by iodide and C2F5 substituents, respectively. Despite a lower electronegativity the iodide compound exhibits a shorter Bi...P contact, while the C2F5 substituents led to a further decrease of the Lewis acidity, despite their high group electronegativity. DFT calculations rationalized this by a quenching of the Lewis acidity inherent to the σ*(Bi−C) orbital by negative hyperconjugation from occupied p‐orbitals at the F atoms. Furthermore, it turned out that the strength of the covalent Bi−X σ‐bond is a more important factor than the charge at Bi in determining the energetic accessibility and thus Lewis acidity of the antibonding σ*(Bi−C) orbital. [ABSTRACT FROM AUTHOR]

The reduction of CO and CO 2 by hydrogen to form formaldehyde and methanoic acid is a common way for renewable resources. In the recent decade, Frustrated Lewis Pairs provides a synergetic reaction based on the cooperative Lewis acidity and Lewis basicity to capture small molecules, such as H 2 , CO and CO 2. Generally, the energy barrier is used as the only way to evaluate the performance of different catalyst, lacking a common rule to connect the structure of catalyst and the corresponding properties. However, CO/CO 2 is polarized as the Lewis pairs by Frustrated Lewis Pairs in the activation, the degradation can be viewed as the hydrogenation of activated CO/CO 2. Herein, we learn three classic Frustrated Lewis Pairs composed by Pier's acid and different N-heterocyclic groups to understand the Lewis acidy and basicity in capture of CO and CO 2. By comparing the hydrogenation ability of pristine Frustrated Lewis Pairs and activated CO/CO 2 , the hydrogenation model based on the Lewis acidity or basicity, including the pristine Frustrated Lewis Pairs and the activated CO/CO 2 , can be a common rule to clarify the performances of the degradation of CO/CO 2. [Display omitted] • Establish the hydrogenation model to evaluate the CO/CO 2 degradation efficiency. • CO/CO 2 absorption can be improved by enhanced basicity/acidity of Lewis pairs. • Strong acidity of Lewis pairs catalyst benefits the degradation of CO. • Hydrogenation of CO 2 is determined by stability and basicity of absorbed CO 2. [ABSTRACT FROM AUTHOR]

Transition metal catalysis plays a pivotal role in chemical synthesis. Noble metals often grab significant attention in organometallic catalysis due to their high reactivity. However, the serious issues associated with these metals such as low abundance, toxicity, geopolitical limitations, and volatile prices are driving the scientific community to discover sustainable alternatives. In this context, iron appears to be the first choice as an alternative metal due to its unique properties, including a range of stable oxidation states, Lewis acidity, high abundance in the earth's crust, and low toxicity. Over the past two decades, substantial progress has been made in iron catalysis. This overview examines the recent developments in iron‐catalyzed industrially relevant transformations such as hydroformylation, olefin isomerization, hydrosilylation, hydrophosphination, carbonylation, Wacker‐type oxidation, and plastic depolymerization. As witnessed throughout this review, the performance of iron can be significantly altered by suitable ligand selection and by tailoring the electronic and steric properties of the iron center. While noble metals remain the industry work‐horse, iron is inching closer and with extensive scientific understanding, it may replace noble metals in the near future. [ABSTRACT FROM AUTHOR]

Establishing unprecedented types of bonding interactions is one of the fundamental challenges in synthetic chemistry, paving the way to new (electronic) structures, physicochemical properties, and reactivity. In this context, unsupported element‐element interactions are particularly noteworthy since they offer pristine scientific information about the newly identified structural motif. Here we report the synthesis, isolation, and full characterization of the heterobimetallic Bi/Pt compound [Pt(PCy3)2(BiMe2)(SbF6)] (1), bearing the first unsupported transition metal→bismuth donor/acceptor interaction as its key structural motif. 1 is surprisingly robust, its electronic spectra are interpreted in a fully relativistic approach, and it reveals an unprecedented reactivity towards H2. [ABSTRACT FROM AUTHOR]

Although the adduct of aluminum trichloride with thionyl chloride has been reported, no thionyl chloride adduct of a main group element Lewis acid or organometallic compound has been structurally characterized. In this communication we present the synthesis and reactivity of the structurally ascertained adduct of thionyl chloride with tris(pentafluoroethyl)gallane as a representative of a main group element Lewis acid. Gallium and indium compounds with electron withdrawing groups, e.g. the pentafluoroethyl ligand, display versatile properties. While gallates and indates, [MR4]−, behave as weakly coordinating anions, neutral gallanes and indanes, MR3, are strong Lewis acids. Salts with the tetrakis(pentafluoroethyl)gallate and ‐indate, [M(C2F5)4]− (M=Ga, In), have recently been studied in detail. In contrast to this, work on the syntheses of the free Lewis superacids M(C2F5)3 (M=Ga, In) is scarce and underdeveloped. The hydrates [M(C2F5)3(OH2)2] proved to be suitable starting materials, particularly due to their thermal stability. Herein we report on synthesis and characterization of reactive adducts, [M(C2F5)3D], with the weak donor molecules (D) SOCl2 and Me3SiF. The effective Lewis acidities of Ga(C2F5)3 and In(C2F5)3 were experimentally determined by the (modified) Gutmann‐Beckett method and their catalytic potential is showcased. [ABSTRACT FROM AUTHOR]

Establishing unprecedented types of bonding interactions is one of the fundamental challenges in synthetic chemistry, paving the way to new (electronic) structures, physicochemical properties, and reactivity. In this context, unsupported element‐element interactions are particularly noteworthy since they offer pristine scientific information about the newly identified structural motif. Here we report the synthesis, isolation, and full characterization of the heterobimetallic Bi/Pt compound [Pt(PCy3)2(BiMe2)(SbF6)] (1), bearing the first unsupported transition metal→bismuth donor/acceptor interaction as its key structural motif. 1 is surprisingly robust, its electronic spectra are interpreted in a fully relativistic approach, and it reveals an unprecedented reactivity towards H2. [ABSTRACT FROM AUTHOR]

Establishing unprecedented types of bonding interactions is one of the fundamental challenges in synthetic chemistry, paving the way to new (electronic) structures, physicochemical properties, and reactivity. In this context, unsupported element‐element interactions are particularly noteworthy since they offer pristine scientific information about the newly identified structural motif. Here we report the synthesis, isolation, and full characterization of the heterobimetallic Bi/Pt compound [Pt(PCy3)2(BiMe2)(SbF6)] (1), bearing the first unsupported transition metal→bismuth donor/acceptor interaction as its key structural motif. 1 is surprisingly robust, its electronic spectra are interpreted in a fully relativistic approach, and it reveals an unprecedented reactivity towards H2. [ABSTRACT FROM AUTHOR]

Establishing unprecedented types of bonding interactions is one of the fundamental challenges in synthetic chemistry, paving the way to new (electronic) structures, physicochemical properties, and reactivity. In this context, unsupported element‐element interactions are particularly noteworthy since they offer pristine scientific information about the newly identified structural motif. Here we report the synthesis, isolation, and full characterization of the heterobimetallic Bi/Pt compound [Pt(PCy3)2(BiMe2)(SbF6)] (1), bearing the first unsupported transition metal→bismuth donor/acceptor interaction as its key structural motif. 1 is surprisingly robust, its electronic spectra are interpreted in a fully relativistic approach, and it reveals an unprecedented reactivity towards H2. [ABSTRACT FROM AUTHOR]

Boron-doped acenes have attracted attention due to their unique structures and intriguing luminescent properties. However, the hitherto known boron-doped acenes have only one or two boron atoms, limiting the chemical space of this unique family of compounds and the capability to tune their optical properties. Herein, we report the synthesis of quadruply boron-doped acenes, including pentacene, heptacene, and nonacene. The importance of the boron doping level on the luminescent properties of acenes is demonstrated. The title compounds manifest enhanced Lewis acidity as compared with dihydrodiboraacenes, leading to Lewis-base-responsive emission in the solid state. Moreover, quadruply boron-doped nonacene displays mechanochromic luminescence in addition to Lewis-base-responsive properties, realizing high-contrast solid-state multicolor emission. This work greatly expands the chemistry of boron-doped acenes and offers opportunities for developing boron-based luminescent materials. Boron-doped acenes have attracted attention due to their unique structures and luminescent properties but the hitherto known boron-doped acenes have only one or two boron atoms, limiting the chemical space of this family of compounds. Here, the authors demonstrate the synthesis of quadruply boron-doped acenes, including pentacene, heptacene, and nonacene. [ABSTRACT FROM AUTHOR]

The recycling of polyethylene terephthalate (PET) waste plastics has garnered global attention as an essential area of research to address. Chemical upcycling methods, such as glycolysis, offers a visible solution by directly converting PET wastes into high-valued monomers, enabling their reintegration into the plastic life cycle. However, the recovery of metal salt catalyst and the thermal stability of organic catalyst pose challenges in PET glycolysis. Zeolites with strong Brønsted acid are widely used in the degradation of polyolefins, but in PET glycolysis, they face the problems of acid site mismatch and difficult contact with PET. In this work, nanosized FAU-type zeolite catalysts (100-FAU) were employed to carry out PET glycolysis, which were green synthesized at low temperature without organic template. In comparison to commercial FAU-type catalysts, 100-FAU exhibits enhanced Lewis acidity and basicity along with increased accessibility to active sites. The 100% degradation of PET was achieved within 1 h, resulting in a BHET yield of 64.2%. Prolonging the reaction time to 1.5 h led to an enhanced BHET yield of 72.1%. The quality of the primary product bis(2-hydroxyethyl) terephthalate (BHET) was verified through IR, DSC, and NMR characterizations. Furthermore, as a solid catalyst with high thermal stability, zeolite can be easily recovered via filtration and demonstrated stable performance over at least 5 cycles, and proved effective for glycolysis of commercially waste PET plastics. The acid–base dual-functional catalytic mechanism of Na-form FAU in PET glycolysis was proposed. Under its guidance, the promoting effect of other Na-form nanosized zeolites on PET degradation was verified. [ABSTRACT FROM AUTHOR]

[Display omitted] Li metal batteries (LMBs) are among the most promising options for next-generation secondary batteries under the rapidly growing demand for high-energy–density electrochemical energy storage. However, the implementation of LMBs are hindered by major obstacles such as dentritic Li deposition and low cycling Coulombic efficiency. A practical functional separator is developed in this study, which consists of a Lewis acidic mixed oxide of ZrO 2 -SiO 2 -Al 2 O 3 as a functional coating with anion anchoring ability to modulate ion transport in the vicinity of the Li metal anode, delivering a high Li+ transference number of 0.88 in carbonate electrolytes that suppresses dendrite formation. The strong Lewis acid sites in ZrO 2 -SiO 2 -Al 2 O 3 originate from coordinatively unsaturated Zr4+ ions, which immobilize anions and reduce their decomposition rate. This significantly improves the chemical stability of the electrolyte and induces a more stable solid electrolyte interphase layer. The modified separator enables an anode-free cell containing a high-loading LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode to present stable charge and discharge cycling for 150 cycles at 0.5C. By effectively suppressing Li dendrite growth and supporting the long-term operation of anode-free LMBs, this study offers a novel approach to rationally design mixed oxides with high Lewis acidity for functional separators. [ABSTRACT FROM AUTHOR]

In recent years, perovskite solar cells (PSCs) have been attracting more and more attention. Although perovskite materials have high defect tolerance, defects remain the main factor that seriously affects the efficiency and stability of PSCs. Herein, the ionic liquid of 1-butyl, 3-methylimidazolium acetate ([BMIM][ACO]) was introduced into the SnO2/perovskite interface for the first time. Thanks to the dipoles formed by ILs spontaneously, the work function of SnO2 was reduced and the transport ability of carriers was improved as well. Moreover, the Lewis acidity and lone pair electrons of [BMIM][ACO] contribute to the passivation of I– defects, Pb2+ defects, or Pb-I anti site defects. In addition, the presence of dipoles will repel the approach of photogenerated holes and the reverse transport of electrons, reducing the recombination of defect sites through field-effect passivation. The solar cell with efficiency of 19.43% was obtained under such a dual passivation effect, and the best device maintained 75.21% of the initial efficiency after 80 h of continuous illumination. [ABSTRACT FROM AUTHOR]

Nitroxides find application in various areas of chemistry, and a more in‐depth understanding of factors controlling their reactivity with metal complexes is warranted to promote further developments. Here, we report on the effect of the metal centre Lewis acidity on both the distribution of the O‐ and N‐centered spin density in 2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO) and turning TEMPO from the O‐ to N‐radical mode scavenger in metal‐TEMPO systems. We use Et(Cl)Zn/TEMPO model reaction system with tuneable reactivity in the solid state and solution. Among various products, a unique Lewis acid‐base adduct of Cl2Zn with the N‐ethylated TEMPO was isolated and structurally characterised, and the so‐called solid‐state ′slow chemistry′ reaction led to a higher yield of the N‐alkylated product. The revealed structure‐activity/selectivity correlations are exceptional yet are entirely rationalised by the mechanistic underpinning supported by theoretical calculations of studied model systems. This work lays a foundation and mechanistic blueprint for future metal/nitroxide systems exploration. [ABSTRACT FROM AUTHOR]

Inspired by the previous machine‐learning study that the number of hydrogen‐bonding acceptor (NHBA) is important index for the hole mobility of organic semiconductors, seven dithienobenzothiazole (DBT) derivatives 1 a–g (NHBA=5) were designed and synthesized by one‐step functionalization from a common precursor. X‐ray single‐crystal structural analyses confirmed that the molecular arrangements of 1b (the diethyl and ethylthienyl derivative) and 1c (the di(n‐propyl) and n‐propylthienyl derivative) in the crystal are classified into brickwork structures with multidirectional intermolecular charge‐transfer integrals, as a result of incorporation of multiple hydrogen‐bond acceptors. The solution‐processed top‐gate bottom‐contact devices of 1b and 1c had hole mobilities of 0.16 and 0.029 cm2 V−1s−1, respectively. [ABSTRACT FROM AUTHOR]

Extremely limited research exploring the photocatalytic potential of main group metals, such as aluminum, gallium, and tin, has been undertaken due to their weak light harvesting properties. This study reports the efficient transformation of sugars to 5‐hydroxymethylfurfural (HMF) with high yield employing an original heterogeneous photocatalyst comprising a gallium(III) complex immobilized on an alumina support. Under visible light irradiation, the reaction rate of HMF formation is ~143 times higher than the equivalent thermal reaction performed in the absence of light. The turnover number (TON) of the heterogeneous gallium(III) photocatalyst was as high as 1500, which was ca. two orders of magnitude higher than the TON of the homogeneous gallium(III) system. It is proposed that photoirradiation significantly enhances the Lewis acidity of the catalyst by forming a semi‐coordination state between gallium(III) and N‐donor ligands, enabling the increased interaction of reactant sugar molecules with gallium(III) active sites. Consistent with this, the photoresponsive coordination of the gallium(III) complex and the abstraction of the hydroxy group by the metal under irradiation with visible light is observed by NMR spectroscopy for the first time. These findings demonstrate that efficient photocatalysts derived from the main group elements can facilitate biomass conversion using visible light. [ABSTRACT FROM AUTHOR]

Lithium/carbon fluoride (Li/CFx) batteries have garnered significant attention due to their exceptional theoretical energy density (2180 Wh kg−1) in the battery field. However, its inadequate rate capability and limited adaptability at low‐temperature are major bottlenecks to its practical application due to the low conductivity of CFx materials and electrochemical inertness of discharge products LiF. Herein, an efficient and novel functional electrolyte formula is disclosed with tin trifluoromethanesulfonate (Sn(OTf)2) as an additive to solve these challenges. It is shown that Sn(OTf)2 possessing reasonable Lewis acidity can effectively facilitate the dissolution of LiF during the discharging process. Thereafter, the CFx electrode materials exhibit excellent rate performance with 1145 Wh kg−1 at 15 000 mA g−1 (or 15 A g−1, 30 °C) and high capacity retention of 95.8% at a low temperature of −50 °C compared with the operating temperature of 30 °C. Moreover, the Sn2+ dissolved from Sn(OTf)2 promotes the formation of Li‐Sn alloy on the lithium metal anode, effectively protecting the lithium metal anode, and Li/CFx battery can be well stored for over 1 000 h at 60 °C with negligible self‐discharge behavior. This work presents a novel electrolyte exploring strategy that can effectively guide the development of next‐generation electrolytes operating under extreme conditions. [ABSTRACT FROM AUTHOR]

Nano bimetallic oxides as nanoproteases have the great advantages in the heterogeneous hydrolysis of proteins. Here, we report that bimetallic delafossite CuFeO2 submicron particles (CuFeO2 SMPs) display a high protease activity towards selective cleavage of peptide bond involving hydrophobic residue at 25 °C. CuFeO2 SMPs have excellent regeneration performance with high structural stability. The strong Lewis acidity of Fe3+ and the strong nucleophilicity of Cu+ bound hydroxyl groups are both necessary for the high protease activity of CuFeO2 SMPs. Low‐valent metal ion has a great advantage in that low‐valent Cu+ bound hydroxyl has strong nucleophilicity, resulting in promotion of protein hydrolysis via high‐efficient bimetallic catalysis. This study provides evidence that the protease activity of CuFeO2 SMPs depends on metal ion‐bound hydroxyls on their surface. Our findings highlight that the valence of metal ions in artificial protease and their surface hydroxyls are two important factors that determine their catalytic efficiency. [ABSTRACT FROM AUTHOR]

The n-butyltin(IV) trichloride (nBuSnCl3) initiator was successfully utilized in the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) under solvent-free conditions. Its reactivity was investigated by the non-isothermal differential scanning calorimetry (DSC). Effect of nBuSnCl3 concentration on the ROP of ε-CL was investigated by the Kissinger and model fitting methods. The obtained activation energy (Ea) values for the ROP of ε-CL with 1.0 mol% of nBuSnCl3 were higher than 2.0, and 4.0 mol%, respectively. Furthermore, the degree of aggregation (m) of nBuSnCl3 in the ROP of ε-CL was determined by the DSC technique. From the obtained m values at 120 and 140 °C, nBuSnCl3 presented in a non-aggregated state in the non-isothermal ROP of ε-CL. The performance of nBuSnCl3 was also compared with the di-n-butyltin(IV) dichloride (nBu2SnCl2) and tri-n-butytlin(IV) chloride (nBu3SnCl). The number of chloride and n-butyl groups adjacent to the Sn active center significantly affected the solvent-free ROP of ε-CL. From the non-isothermal DSC measurement, the polymerization exotherms for the ROP of ε-CL with nBuSnCl3 occurred and were completed at a lower temperature range than nBu2SnCl2, and nBu3SnCl, respectively. The Ea value for the ROP of ε-CL initiated by nBu3SnCl was higher than nBu2SnCl2, and nBuSnCl3, respectively. The values of pre-exponential factor (lnA) for the ROP of ε-CL initiated by nBu3SnCl, nBu2SnCl2, and nBuSnCl3 were determined from the first order reaction model fitting (f(α) = 1−α) and compensation effect. The kinetics data demonstrated that the reactivity of nBuSnCl3 was higher than nBu2SnCl2, and nBu3SnCl due to the lowest steric hindrance and the highest Lewis acidity of nBuSnCl3. Larger-scale (250 g) polymerization of ε-CL was preliminarily investigated by using the highly reactive nBuSnCl3 initiator. nBuSnCl3 could effectively produce PCL with weight average molecular weight (Mw) of 7.1 × 104 g/mol and 82% yield at 150 °C for 24 h. The probable mechanism of the ROP of ε-CL with nBu3SnCl was proposed via the coordination-insertion mechanism. [ABSTRACT FROM AUTHOR]

This work developed an efficient route to produce fuel bioadditive alkyl levulinates. Special attention was paid to butyl levulinate, which is a bioadditive with an adequate carbon chain size to be blended with liquid fuels such as diesel or gasoline. In this process, levulinic acid was esterified with butyl alcohol using cheap and commercially affordable metal nitrates as catalysts, producing bioadditives at more competitive costs. Iron (III) nitrate was the most active and selective catalyst toward butyl levulinate among the salts evaluated. In solvent-free conditions, with a low molar ratio and catalyst load (1:6 acid to alcohol, 3 mol% of Fe (NO3)3), conversion and selectivity greater than 90% after an 8 h reaction was achieved. A comparison of the iron (III) nitrate with other metal salts demonstrated that its superior performance can be assigned to the highest Lewis acidity of Fe3+ cations. Measurements of pH allow the conclusion that a cation with high Lewis acidity led to a greater H+ release, which results in a higher conversion. Butyl levulinate and pseudobuty levulinate were always the primary and secondary products, respectively. The consecutive character of reactions between butyl alcohol and levulinic acid (formation of the pseudobutyl levulinate and its conversion to butyl levulinate) was verified by assessing the reactions at different temperatures and conversion rates. A variation in Fe(NO3)3 catalyst load impacted the conversion much more than reaction selectivity. The same effect was verified when the reactions were carried out at different temperatures. The reactivity of alcohols with different structures depended more on steric hindrance on the hydroxyl group than the size of the carbon chain. A positive aspect of this work is the use of a commercial iron nitrate salt as the catalyst, which has advantages over traditional mineral acids such as sulfuric and hydrochloric acids. This solid catalyst is not corrosive and avoids neutralization steps after reactions, minimizing the generation of residues and effluents. [ABSTRACT FROM AUTHOR]

Our interest in the design of heavy pnictogen‐based Lewis acids for anion trafficking across biological membrane mimics has led us to investigate trivalent bismuthenium cations as chloride anion transporters. Here, we describe two chlorodiarylbismuthines, elaborated on a peri‐substituted naphthalene backbone and stabilized by an adjacent thio‐ or seleno‐ether functionality that engages the bismuth center in a Ch→Bi interaction (Ch=chalcogen). These new derivatives are stable in aqueous environment and readiliy transport chloride anions across the membrane of phospholipid‐based vesicles loaded with KCl. In addition to establishing the use of such motifs in anion transport, this investigation shows that the Lewis acidity, lipophilicity, and thus chloride transport properties depend on the nature of the chalcogen. [ABSTRACT FROM AUTHOR]

Iodosilarene derivatives (PhIO, PhI(OAc)2) constitute an important class of oxygen atom transfer reagents in organic synthesis and are often used together with iron-based catalysts. Since the factors controlling the ability of iron centers to catalyze alkane hydroxylation are not yet fully understood, the aim of this report is to develop bioinspired non-heme iron catalysts in combination with PhI(OAc)2, which are suitable for performing C-H activation. Overall, this study provides insight into the iron-based ([FeII(PBI)3(CF3SO3)2] (1), where PBI = 2-(2-pyridyl)benzimidazole) catalytic and stoichiometric hydroxylation of triphenylmethane using PhI(OAc)2, highlighting the importance of reaction conditions including the effect of the co-ligands (para-substituted pyridines) and oxidants (para-substituted iodosylbenzene diacetates) on product yields and reaction kinetics. A number of mechanistic studies have been carried out on the mechanism of triphenylmethane hydroxylation, including C-H activation, supporting the reactive intermediate, and investigating the effects of equatorial co-ligands and coordinated oxidants. Strong evidence for the electrophilic nature of the reaction was observed based on competitive experiments, which included a Hammett correlation between the relative reaction rate (logkrel) and the σp (4R-Py and 4R'-PhI(OAc)2) parameters in both stoichiometric (ρ = +0.87 and +0.92) and catalytic (ρ = +0.97 and +0.77) reactions. The presence of [(PBI)2(4R-Py)FeIIIOIPh-4R']3+ intermediates, as well as the effect of co-ligands and coordinated oxidants, was supported by their spectral (UV–visible) and redox properties. It has been proven that the electrophilic nature of iron(III)-iodozilarene complexes is crucial in the oxidation reaction of triphenylmethane. The hydroxylation rates showed a linear correlation with the FeIII/FeII redox potentials (in the range of −350 mV and −524 mV), which suggests that the Lewis acidity and redox properties of the metal centers greatly influence the reactivity of the reactive intermediates. [ABSTRACT FROM AUTHOR]

With the objective of gaining insight into the modulation of the reduction potential of the Ni(II / I) couple, we have synthesized two mononuclear nickel(II) complexes, NiLen (H2Len = N,N′-bis(3-methoxysalicylidene)-1,2-diamino-2-methylpropane) and NiLpn (H2Lpn = N,N′-bis(3-methoxysalicylidene)-1,3-diamino-2,2-dimethylpropane) of two N2O4 donor ligands and recorded their cyclic voltammograms. Both the nickel complexes show reversible reduction processes for the Ni(II / I) couple in acetonitrile solution but the reduction potential of NiLpn (E1/2 = −1.883 V) is 188 mV more positive than that of NiLen (E1/2 = −2.071 V). In the presence of redox inactive metal ions (Li+, Na+, K+, Mg2+, Ca2+ and Ba2+), the reduction potentials are shifted by 49–331 mV and 99–435 mV towards positive values compared to NiLen and NiLpn, respectively. The shift increases with the decrease of the pKa of the respective aqua-complexes of the metal ion but is poorly co-linear; however, better linearity is found when the shift of the mono- and bi-positive metal ion aqua complexes is plotted separately. Spectrophotometric titrations of these two nickel complexes with the guest metal ions in acetonitrile showed a well-anchored isosbestic point in all cases, confirming the adduct formation of NiLen and NiLpn with the metal ions. Structural analysis of single crystals, [(NiLen)Li(H2O)2]·ClO4 (1), [(NiLpn)Li(H2O)]·ClO4 (2), [(NiLpn)2Na]·BF4 (3) and [(NiLpn)2Ba(H2O)(ClO4)]·ClO4 (4), also corroborates the heterometallic adduct formation. The orbital energies of the optimised heterometallic adducts from which electron transfers originated were calculated in order to explain the observed reduction process. A strong linear connection between the calculated orbital energies and the experimental E1/2 values was observed. According to MEP and 2D vector field plots, the largest shift for divalent metal ions is most likely caused by the local electric field that they impose in addition to Lewis acidity. [ABSTRACT FROM AUTHOR]

We have reported in the last years the strong effect that Be‐ and Mg‐containing Lewis acids have on the intrinsic properties of typical bases, which become acids upon complexation. In an effort to investigate these changes when the Be and Mg derivatives form clusters of increasing size, we have examined the behavior of the (MX2)n (M = Be, Mg; X = H, F; n = 1, 2, 3) clusters when they interact with ammonia, methanimine, hydrogen cyanide and pyridine, and with their corresponding deprotonated forms. The complexes obtained at the M06‐2X/aug‐cc‐pVTZ level were analyzed using the MBIE energy decomposition formalism, in parallel with QTAIM, ELF, NCIPLOT and AdNDP analyses of their electron density. For n = 1 the interaction enthalpy for the different families of monomers, Be (Mg) hydrides and Be (Mg) fluorides, follows the same trend as the intrinsic basicity of the base that interacts with them. This interaction is greatly reinforced after the deprotonation of the base, resulting in a significant enhancement of the intrinsic acidity of the corresponding MX2–Base complex. For (MX2)2 clusters a further reinforcement of the interaction with the base is observed, this reinforcement being again larger for the deprotonated complexes. However, the concomitant increase of their intrinsic acidity is one order of magnitude larger for hydrides than for fluorides. Unexpectedly, the cyclic conformers (MX2)3, which are more unstable than the linear ones, become the global minima after association with the base and the same is true for the deprotonated complex. Accordingly, a further increase of the intrinsic acidity of the (MX2)3–Base complexes with respect to the (MX2)2–Base ones is observed. This effect is maximum for (MgF2)3 clusters, to the point that the (MgF2)3–Base complexes become more acidic than nitric acid, the extreme case being the cluster (MgF2)3–NCH, whose acidity is higher than that of perchloric acid. [ABSTRACT FROM AUTHOR]

The reactions of the frustrated Lewis pair (F5C2)2SbCH2P(tBu)2 with oxygen, sulphur, selenium and tellurium led to the mono-oxidation products (F5C2)2SbCH2P(E)(tBu)2 (E = O, S, Se, Te). Further oxidation of these chalcogen adducts with tetrachloro-ortho-benzoquinone (o-chloranil) gave (F5C2)2Sb(CH2)(μ-E)P(tBu)2·CatCl (CatCl = o-O2C6Cl4) with a central four-membered ring heterocycle for E = O, S, and Se. For E = Te the elimination of elemental tellurium led to an oxidation product with two equivalents of o-chloranil, (F5C2)2SbCH2P(tBu)2·2CatCl, which is also accessible by reaction of (F5C2)2SbCH2P(tBu)2 with o-chloranil. The synthesised compounds were characterised by NMR spectroscopy and X-ray structure analyses, and the structural properties were analysed in the light of the altered Lewis acidity due to the oxidation of the antimony atoms. [ABSTRACT FROM AUTHOR]

Flexible poly-Lewis acids (PLA) based on the tribenzotriquinacene (TBTQ) scaffold have been synthesised. Hydrosilylation of 4b,8b,12b-triallyltribenzotriquinacene and subsequent exchange of the chlorine substituents with weaker coordinating triflate groups afforded a novel triple silyl-functionalised PLA. By regioselective hydroboration of triallyl–TBTQ with various organoboranes, PLAs with different Lewis acidities were obtained. The synthesised PLAs were combined with neutral bases in host–guest experiments. DOSY NMR spectroscopy was performed to elucidate the complexation process in solution. These experiments revealed a highly dynamic interaction between the boron-functionalised PLA and triazine. However, the addition of one equivalent of tris(dimethylphosphino(methyl))phenylsilane led to the formation of a 1 : 1 adduct, which was confirmed by diffusion experiments. [ABSTRACT FROM AUTHOR]

Numerous strategies for enhancing the reactivity and properties of p-block elements have been devised in the past decades. This Account discusses our approaches by distinct ligand control on p-block elements in their normal (group) oxidation states. Catecholato ligands on silicon, germanium, or phosphorus produce a range of rewarding properties. Substantial electron withdrawal paired with structural constraint effects (influence of deformation energy) impart Lewis superacidity to these abundant elements. The ease of synthesis of such species facilitates screening in catalysis, promising a range of applications by powerful bond activation. Low-barrier Si–O/Si–O bond metathesis provides the most abundant bond in our Earth's crust, with adaptive features under mild conditions, and establishes a new branch of constitutional dynamic chemistry. The redox-active character of catecholates grants access to novel compounds with tunable open-shell features. Overall, p-block catecholates offer unique opportunities due to their versatile features that will enrich the chemistry of the main-group elements. 1 Introduction 2 Halogenated Catecholates at Silicon Cause Substantial Lewis Acidity 3 Constitutional Dynamics Cause a Structural Mystery 4 Strong Silicon Lewis Acids Allow the Exploration of Uncharted Structures, Bond Activations, and Catalysis 5 The Catechol Approach on Other Elements: Germanium and Phosphorus 6 Catechols Are Redox Active: Also at Silicon 7 Conclusion [ABSTRACT FROM AUTHOR]

In enzymatic catalysis, the redox site and Lewis acid are the two main roles played by metal to assist amino acids. However, the reported enzyme mimics only focus on the redox-active metal as redox site, while the redox-inert metal as Lewis acid has, to the best of our knowledge, not been studied, presenting a bottleneck of enzyme mimics construction. Based on this, a series of highly efficient MxV2O5·nH2O peroxidase mimics with vanadium as redox site and alkaline-earth metal ion (M2+) as Lewis acid are reported. Experimental results and theoretical calculations indicate the peroxidase-mimicking activity of MxV2O5·nH2O show a periodic change with the Lewis acidity (ion potential) of M2+, revealing the mechanism of redox-inert M2+ regulating electron transfer of V-O through non-covalent polarization and thus promoting H2O2 adsorbate dissociation. The biomimetic synergetic effect of redox site and Lewis acid is expected to provide an inspiration for design of enzyme mimics. The so far reported enzyme mimics focus on the redox-active metal as a redox site, while the redox-inert metal as Lewis acid has so far not been reported. Here, the authors report efficient MxV2O5·nH2O peroxidase mimics with vanadium as redox site and alkaline-earth metal ion (M2+) as Lewis acid, where the peroxidase-mimicking activity shows a periodic change with the Lewis acidity of the metal. [ABSTRACT FROM AUTHOR]

Elevated concentrations of CO2 in the atmosphere pose significant challenges, notably contributing to the greenhouse effect. CO2 as an abundant C1 resource converting into high-value oxazolidinones is a promising avenue for effective carbon fixation. Herein, a highly stable binuclear cerium–organic framework, [Ce2(DCTP)2(DMA)2(OAc)2]n (1), has been successfully designed and synthesized, which maintains the intact three-dimensional framework after immersing in solutions with pH ranging from 1 to 12 and various common solvents for 24 hours, respectively. Explorations on CO2 conversion indicate that compound 1 exhibits remarkable catalytic efficiency in the cycloaddition reaction of CO2 with aziridines to form oxazolidinones under relatively low CO2 pressure. 1 can be easily regenerated five times without a significant decrease in yield. Mechanistic experiments show that the high catalytic activity of 1 is attributed to the stable three-dimensional framework, high Lewis acidity, and ample cerium active sites. Notably, 1 is a rare lanthanide metal–organic framework-based (Ln-MOF-based) catalyst for the cycloaddition of CO2 with aziridines under mild pressure. [ABSTRACT FROM AUTHOR]

In the present era, the fixation of atmospheric CO2 is of significant importance and plays a crucial role in maintaining the balance of carbon and energy flow within ecosystems. Generally, CO2 fixation is carried out by autotrophic organisms; however, the scientific community has paid substantial attention to execute this process in laboratory. In this report, we synthesized two carbonato-bridged trinuclear copper(II) complexes, [Cu3(L1)3(μ3-CO3)](ClO4)3 (1) and [Cu3(L2)3(μ3-CO3)](ClO4)3 (2) via atmospheric fixation of CO2 starting with Cu(ClO4)2·6H2O and easily accessible pyridine/pyrazine-based N4 donor Schiff base ligands L1 and L2, respectively. Under very similar reaction conditions, the ligand framework embedded with the phenolate moiety (HL3) fails to do so because of the reduction of the Lewis acidity of the metal center, inhibiting the formation of a reactive hydroxide bound copper(II) species, which is required for the fixation of atmospheric CO2. X-ray crystal structures display that carbonate-oxygen atoms bridge three copper(II) centers in μ3syn–anti disposition in 1 and 2, whereas [Cu(HL3)(ClO4)] (3) is a mononuclear complex. Interestingly, we also isolated an important intermediate of atmospheric CO2 fixation and structurally characterized it as an anti–anti μ2 carbonato-bridged dinuclear copper(II) complex, [Cu2(L2)2(μ2-CO3)](ClO4)2·MeOH (2-I), providing an in-depth understanding of CO2 fixation in these systems. Variable temperature magnetic susceptibility measurement suggests ferromagnetic interactions between the metal centers in both 1 and 2, and the results have been further supported by DFT calculations. The catalytic efficiency of our synthesized complexes 1–3 was checked by means of catechol oxidase and phenoxazinone synthase-like activities. While complexes 1 and 2 showed oxidase-like activity for aerobic oxidation of o-aminophenol and 3,5-di-tert-butylcatechol, complex 3 was found to be feebly active. ESI mass spectrometry revealed that the oxidation reaction proceeds through the formation of complex–substrate intermediations and was further substantiated by DFT calculations. Moreover, active catalysts 1 and 2 were effectively utilized for the base-free oxidation of benzylic alcohols in the presence of air as a green and sustainable oxidant and catalytic amount of TEMPO in acetonitrile. Various substituted benzylic alcohols smoothly converted to their corresponding aldehydes under very mild conditions and ambient temperature. The present catalytic protocol showcases its environmental sustainability by producing minimal waste. [ABSTRACT FROM AUTHOR]

The reaction solvent and catalyst play essential roles in the Prins reaction for the synthesis of 3-methyl-3-buten-1-ol (MBO) from formaldehyde and isobutene. The reactivity of the solid base-catalyzed Prins condensation reaction by formaldehyde and isobutene in supercritical CO2 was investigated using CsH2PO4-modified HZSM-5. We found that the alkaline sites of the alkali-loaded catalyst could extract the α-H on isobutene to generate olefin carbon-negative ions, while the supercritical CO2 with weak Lewis acidity could activate formaldehyde to carbon-positive ions, which can combine more easily with carbon-negative isobutene to react, thus improving the reactivity of the reaction system. [ABSTRACT FROM AUTHOR]

Lewis acidic boron compounds are ubiquitous in chemistry due to their numerous applications, yet tuning and optimizing their properties towards different purposes is still a challenging field of research. In this work, the boron‐based Lewis acid B[OTeF3(C6F5)2]3 was synthesized by reaction of the teflate derivative HOTeF3(C6F5)2 with BCl3 or BCl3 ⋅ SMe2. This new compound presents a remarkably high thermal stability up to 300 °C, as well as one of the most sterically encumbered boron centres known in the literature. Theoretical and experimental methods revealed that B[OTeF3(C6F5)2]3 exhibits a comparable Lewis acidity to that of the well‐known B(C6F5)3. The affinity of B[OTeF3(C6F5)2]3 towards pyridine was accessed by Isothermal Titration Calorimetry (ITC) and compared to that of B(OTeF5)3 and B(C6F5)3. The ligand‐transfer reactivity of this new boron compound towards different fluorides was demonstrated by the formation of an anionic Au(III) complex and a hypervalent iodine(III) species. [ABSTRACT FROM AUTHOR]

Vinylidene rearrangement of alkynes is a well-established and powerful method for alkyne transformations, while use of borylalkynes has remained largely unexplored. This paper describes vinylidene rearrangements of internal borylalkynes using a cationic ruthenium complex. This rearrangement is applicable to alkynes with both tri-(B(pin), B(dan)) and tetracoordinate (B(mida)) boryl groups, and the reaction rate is dramatically affected by the Lewis acidity of the boryl group. Mechanistic study revealed that the rearrangement proceeds via 1,2-boryl migration regardless of the coordination number of the boron center. The migration mode was elucidated by theoretical calculations to indicate that the migration of the tricoordinate boryl groups is an electrophilic process in contrast to the previous vinylidene rearrangements of internal alkynes with two carbon substituents. [ABSTRACT FROM AUTHOR]

A series of substituted ferrocenyl boron derivatives was synthesized. The oxidation of the ferrocenyl unit resulted in a significant increase of the boron‐centered Lewis acidity. The neutral and cationic Lewis acids were characterized by NMR spectroscopy, crystal structure analysis and by computational methods. The new Lewis acids were then applied in the Meinwald rearrangement of epoxides, predominantly furnishing aldehydes as the kinetic products. [ABSTRACT FROM AUTHOR]

Although it is well‐known that the Lewis acidity of Metal‐Organic Frameworks (MOFs) can effectively enhance their catalytic activity in organic transformations, access to these Lewis‐acidic sites remains a key hurdle to widespread applications of Lewis‐acidic catalysis by MOFs. Easy accessibility of strong Lewis acidic sites onto 2D MOFs by using proper activation methods can be a cornerstone in attaining desired catalytic performance. Herein, we report a new 2D chemically stable MOF, IITKGP‐60, which displayed excellent framework robustness over a wide pH range (2–12). Benefiting from the abundant open metal sites (OMSs) and framework robustness, the catalytic activity of the developed material was explored in one‐pot three‐component Strecker reaction and Knoevenagel condensation reaction. Moreover, the developed catalyst is superior in catalyzing the reactions involving sterically hindered substrate (1‐naphthaldehyde) with high turnover number. A comparative catalytic study was conducted using different activation methods (chloroform and methanol exchanged activated samples), highlighting the significant effect of activation methods on its catalytic performances. The sustainable synthetic pathway under solvent‐free conditions for a broad scope of substrates using low catalyst loading and excellent recyclability made the developed pH‐stable framework a promising heterogeneous catalyst. [ABSTRACT FROM AUTHOR]