Strong Donor Research Articles

Dendritic phytic acid as a proton-conducting crosslinker for improved thermal stability and proton conductivity

There is growing interest in materials that exhibit enhanced proton conductivity at elevated temperatures without the need for humidification. Here, we develop a dendritic proton-conducting dopant for proton exchange membranes based on phytic acid (PhA) salts. PhA, which contains six phosphate groups capable of facilitating proton exchange, interacts with 4-dimethylaminopyridine (DMAP). DMAP serves as a strong electron donor, making it highly reactive with PhA. In this endeavor, cellulose sulfonic acid was selected as the base proton exchange membrane. Notably, the dimethylamino group of DMAP on the surface of DMAP-PhA acts as a basic site, enabling acid-base interactions with the sulfonic acid groups of cellulose sulfonic acid. As a result, DMAP-PhA functions as a proton-conducting crosslinker, significantly improving the thermal stability of the composites and increasing proton conductivity by enhancing the degree of proton dissociation at each interaction site.

N-Heterocyclic Carbenes and N-Heterocycles as Synthetic Reagents and Building Blocks.

N-Heterocyclic carbenes (NHCs) have become important tools in modern synthetic chemistry due to their versatility as organocatalysts and ligands in organometallic complexes. Since their first isolation and characterization, NHCs have demonstrated significant utility in various catalytic processes, offering advantages such as strong σ-electron donation and the ability to stabilize reactive intermediates. However, beyond their well-documented roles in catalysis, the potential of NHCs as stoichiometric reagents and synthetic building blocks remains an underexplored yet promising area. This Mini-review aims to shed light on these lesser-known applications of NHCs and their N-heterocyclic precursors or derivatives in organic synthesis. Furthermore, we discuss how the unique electronic and steric properties of NHCs can be harnessed to develop new synthetic methodologies or construct interesting organic frameworks. By highlighting these emerging uses, we hope to encourage further research into the non-catalytic applications of NHCs, broadening their scope and impact in synthetic chemistry.

Stabilization of [(N5)2BX]2- and [(N5)2B2X2]2- (X = H, F, Cl, Br) by Conjugation and Hyperconjugation Effects.

The isolation of nucleophilic boron bases has led to a paradigm shift in boron chemistry. Previous studies of the bis(carbene) borylene complexes revealed that these compounds possess strong donor abilities, and their reaction inertness is due to the large steric hindrance between boron reagents and reactant. In the present study, we have theoretically studied the [(N5)2BX]2- and [(N5)2B2X2]2- compounds (X = H, F, Cl, Br). Their electronic structures and properties are discussed by using the NBO, LOL, and ELF methods. We found that both π-conjugation and hyperconjugation effects can effectively stabilize the substituted nucleophilic anionic boron compounds [(N5)2BX]2- and [(N5)2B2X2]2-. Substituents, especially X = H, stabilize the boron center through highly delocalized π-bonding, involving the formally "empty" in-plane p orbitals of the boron atom. While the halogen substituents have high electron withdrawal ability, leading to systems being less stable, we suggest the borinium anions [(N5)2BH]2- and [(N5)2B2H2]2- as possible synthetic targets of novel environmentally friendly catalysts.

Potential Push-Pull Carbon Superbases Based on Methyl Substitution of Rare Tautomers of Imines

Push-pull imines with strong electron donor group(s) display exceptional basicity in the gas phase. Most of them do not exhibit prototropic tautomerism, and gas-phase acid-base equilibria have been already well described and reviewed. Some questions remain for tautomeric systems, particularly for their uncommon forms. As shown by quantum-chemical calculations, some often-neglected tautomers display higher basicity than the thermodynamically favored forms. However, their participation in tautomeric mixtures being in equilibrium is negligible, and their basicity can be impossible to measure in the gas phase by the equilibrium method. During this work, we examined the gas-phase proton basicity for some acyclic and cyclic push-pull organic bases containing the tautomeric amidine or guanidine group. By quantum-chemical calculations, we confirmed the existence of very low amounts of rare tautomeric forms, in particular, those bearing a methylidene (=CH2) group. We also demonstrated that the alkyl derivatives of rare tautomers, being free of prototropy, can be good candidates as very strong push-pull C bases, i.e., bases protonated on the =CH2 group.

An Anionic Mesoionic Carbene (anMIC) and its Transformation to Metallo MIC-Boranes: Synthesis and Properties.

Neutral mesoionic carbenes (MICs) based on a 1,2,3-triazole core have had a strong impact on various branches of chemistry such as homogeneous catalysis, electrocatalysis, and photochemistry/photophysics. We present here the first general synthesis of anionic mesoionic carbenes (anMICs) based on a 1,2,3-triazole core and a borate backbone. The free anMIC is stable in solution under an inert atmosphere at low temperatures, and can be stored for several weeks. Analysis of donor properties shows that these anMICs are extremely strong σ-donors, bypassing the donor properties of strong donors such as MICs, NHCs, anionic NHCs and N-heterocyclic olefins. The room temperature conversion of the free anMICs leads to three equally interesting compound classes: an amide-coordinated borane based on a MIC-borane backbone, a polymeric triazolide and an amide-coordinated metallo-MIC-borane. The metallo-MIC-borane is an interesting precursor for the synthesis of further amide-coordinated MIC-borane compounds. Quantum chemical calculations have been used to elucidate the mechanism of transformation of the anMICs. Gold(I) complexes of the anMIC ligands are potent catalysts for the hydroamination of alkynes without the need for any additional reagents. We thus introduce three new categories of mesoionic compounds here with potential for different branches of chemistry and beyond.

Low Temperature Emissive Cyclometalated Cobalt(III) Complexes.

A series of CoIII complexes [Co(RImP)2][PF6], with HMeImP = 1,1'-(1,3-phenylene)bis(3-methyl-1-imidazole-2-ylidene)) and R = Me, Et, iPr, nBu, is presented in this work. The influence of the strong donor ligand on the ground and excited-state photophysical properties was investigated in the context of different alkyl substituents at the imidazole nitrogen. X-ray diffraction revealed no significant alterations of the structures and all differences in the series emerge from the electronic structures. These were probed via cyclic voltammetry and UV-vis spectroscopy, detailing the influence of the different alkyl substituents on the ground-state properties. All complexes are emissive at 77 K from a 3MC state, which exhibits lifetimes in the range of 1-5 ns at room temperature, depending on the alkyl substituent. Therefore, it is clearly shown that even small differences in the electronic structure have a large impact on the details of the excited state landscape. The observed behavior was rationalized by a detailed DFT analysis, which shows that the minimum-energy crossing point to the ground-state is located only slightly above the MC energy: Consequently, nonradiative decay to the ground state at room temperature is enabled, while at 77 K this path is prohibited, leading to low-temperature 3MC emission.

Physicochemical Characterization of Gallstone Surfaces to Predict Their Interaction with Salmonella Typhi.

Salmonella Typhi can adhere to and build biofilms on the surface of gallstones causing abnormal gallbladder mucosa, which could lead to carcinogenesis. The surface physicochemical properties of microbial cells and materials have been shown to play a crucial role in adhesion. Therefore, the purpose of this study was to investigate, for the first time, the surface properties of nine gallstones and to evaluate the influence of these parameters on the theoretical adhesion of S. Typhi to gallstone surfaces. The physicochemical properties were determined by SEM-EDX and contact angle measurements (CAM) while the predictive adhesion of S. Typhi on gallstones was estimated using the XDLVO approach. SEM-EDX analysis revealed that cholesterol is the principal component on the surface of all gallstones, with carbon and oxygen as the main elements. Aluminum was detected as a trace element in only three gallstones: GS2, GS4, and GS5. S. Typhi CIP5535 has a hydrophilic character (ΔGiwi = 33.54mJm-2), as well as strong electron donor (γ- = 55,80mJ m-2) and weak electron acceptor properties (γ+ = 1,95mJ m-2). Regarding gallstones, it was found that they have a hydrophobic character (ΔGiwi between -29,9mJm-2 and -75,2mJ m-2), while their electron donor/acceptor characters change according to each gallstone. Predictive adhesion showed that all gallstones could be colonized by S. Typhi except GS1, GS5, and GS6 . Understanding the interfacial phenomena implicated in the process of bacterial adhesion makes it possible to limit or even inhibit the adhesion of S. Typhi on gallstone surfaces.

Unveiling the influence of oxidation state and heavy atom effects in chalcogen group on boron centered D(X)BNA core: a computational study on RTP versus TADF

The effects of heavy atoms and oxidation states in chalcogen groups on D(X)BNA cores, combined with substitutions of weak and strong donors, led to the identification of potential TADF and RTP molecules among the 14 molecules.

A Trithia‐Bridged N‐Heterotriangulene: The Hitherto Missing Electron Donor

AbstractThe very first representative of trithia‐bridged N‐heterotriangulene, a triphenylamine with sulfur atoms bridging the ortho‐positions, was synthesized by a sequence of regioselective sulfenylation with phthalimidesulfenyl chloride followed by Lewis acid‐catalyzed electrophilic cyclization. X‐ray crystallography revealed a saddle‐shaped geometry of the polycyclic scaffold. UV/Vis absorption spectroscopy and cyclic voltammetry were used to characterize the optoelectronic properties. The title compound is a particularly strong electron donor forming a perfectly stable radical cation, which was analyzed by electron paramagnetic resonance spectroscopy and X‐ray crystallography. The electron donor properties were further highlighted by the formation of crystalline donor‐acceptor complexes with strong cyano‐based acceptors.

A Trithia-Bridged N-Heterotriangulene: The Hitherto Missing Electron Donor.

The very first representative of trithia-bridged N-heterotriangulene, a triphenylamine with sulfur atoms bridging the ortho-positions, was synthesized by a sequence of regioselective sulfenylation with phthalimidesulfenyl chloride followed by Lewis acid-catalyzed electrophilic cyclization. X-ray crystallography revealed a saddle-shaped geometry of the polycyclic scaffold. UV/Vis absorption spectroscopy and cyclic voltammetry were used to characterize the optoelectronic properties. The title compound is a particularly strong electron donor forming a perfectly stable radical cation, which was analyzed by electron paramagnetic resonance spectroscopy and X-ray crystallography. The electron donor properties were further highlighted by the formation of crystalline donor-acceptor complexes with strong cyano-based acceptors.

Spatial Conformation Engineering of Aromatic Ketones for Highly Efficient and Stable Perovskite Solar Cells.

Carbonyl-containing materials employed in state-of-the-art hybrid lead halide perovskite solar cells (PSCs) exhibit a strong structure-dependent electron donor effect that predominates in defect passivation. However, the impact of the molecular spatial conformation on the efficacy of carbonyl-containing passivators remains ambiguous, hindering the advancement of molecular design for passivating materials. Herein, we show that altering the spatial torsion angle of aromatic ketones from twisted to planar configurations, as seen in benzophenone (BP, 27.2°), anthrone (AR, 15.3°), and 9-fluorenone (FO, 0°), leads to a notable increment of the electron cloud density around the carbonyl group, thus improving the passivation ability for lead-based defects. Consequently, the PSC performance also relies on the torsion angle of the aromatic ketones, with the coplanar FO-based PSC achieving a highest power conversion efficiency (PCE) of 25.13% and retaining 92% of its initial efficiency after 1000 h of operation at the maximum power point under continuous 1-sun illumination (ISOS-L-1I). Moreover, a perovskite mini-module (14.0 cm2) containing FO exhibits a PCE of 20.19%. Our findings highlight the influence of molecular conformation on the passivation effect of the carbonyl group, offering deeper insight into the design and development of aromatic ketones as passivators for highly efficient and stable PSCs.

Different germline variants in the XPA gene are associated with severe, intermediate, or mild neurodegeneration in xeroderma pigmentosum patients.

Xeroderma pigmentosum (XP) is a rare autosomal recessive disease caused by pathogenic variants in seven nucleotide excision repair genes (XPA to XPG) and POLH involved in translesion synthesis. XP patients have a >1000-fold increased risk for sunlight-induced skin cancers. Many Japanese XP-A patients have severe neurological symptoms due to a founder variant in intron 3 of the XPA gene. However, in the United States we found XP-A patients with milder clinical features. We developed a simple scoring scale to assess XP-A patients of varying neurological disease severity. We report 18 XP-A patients examined between 1973 and 2023 under an IRB approved natural history study. Using our scale, we classified our XP-A cohort into severe (n = 8), intermediate (n = 5), and mild (n = 5) disease groups at age 10 years. DNA repair tests demonstrated greatest reduction of DNA repair in cells from severe patients as compared to cells from mild patients. Nucleotide sequencing identified 18 germline pathogenic variants in the 273 amino acid, 6 exon-containing XPA gene. Based on patient clinical features, we associated these XPA variants to severe (n = 8), intermediate (n = 6), and mild (n = 4) clinical phenotypes in the patients. Protein structural analysis showed that nonsense and frameshift premature stop codon pathogenic variants located in exons 3 and 5 correlated with severe disease. Intermediate disease correlated with a splice variant at the last base in exon 4. Mild disease correlated with a frameshift variant in exon 1 with a predicted re-initiation in exon 2; a splice variant that created a new strong donor site in intron 4; and a large genomic deletion spanning exon 6. Our findings revealed correlations between disease severity, DNA repair capacity, and XPA variant type and location. In addition, both XPA alleles contributed to the phenotypic differences in XP-A patients.

Antenna effect on Zn(II) porphyrin-based molecular ensembles for the detection of 2,4-dinitrophenol through energy and electron transfer process.

Twomodular systems were synthesizedcomposed of triphenylamine (ZnTPAP) and pyrene (ZnPyP) covalently linked at meso position of the Zn(II) porphyrins. Both compounds behaved as energy transfer antenna and orthogonal units to enhance the electron donating ability of Zn(II) porphyrins. Detailed photophysical and aggregation studies reveal that an appreciable electronic interaction exists between peripheral units to the porphyrin π-system so that they behave like strong donor materials. The electrochemical and computational studies demonstrate delocalization of the frontier highest occupied molecular orbital (-5.08eV) over the triphenylamine entities (ZnTPAP) in addition to the porphyrin macrocycle. Fluorescence experiments withZnTPAP and ZnPyP in the presence ofdifferent nitro analytes at various concentrations show turn-off fluorescence behaviour and exhibit superior selectivity towards 2,4-dinitrophenol (DNP) with limit of detection (LOD) of ~ 2.3 and 9.2ppm for ZnTPAP and ZnPyP. Photoinduced electron transfer process is involvedin the static and dynamicfluorescence quenching process. A Stern-Volmer quenching association constant (Ksv) determination revealed that ZnTPAP is more sensitive than the ZnPyP. This is attributed to thestrong donating behaviour of TPA unitscaused by intermolecular interaction through metal center and strong π-π interactions with nitro analytes. The present study provides new insights into the ability to tune the affinity and selectivity of porphyrin-based sensors utilising electronic factors associated with the central Zn(II) ion. Furthermore, a smartphone-interfaced portable fluorimetric method by recognising colour variations in RGB and the luminance (L) values facilitate sensitive and real-time sensing at low concentration levels will have a significant impact on development of a new class of chemosensors.

Study on the formation mechanism and effective manipulation of polymorphs and solvates in Osimertinib-Caffeic acid multi-component crystal with distinct properties.

Investigating the formation mechanism and effective manipulation of multi-component crystal polymorphs is crucial for facilitating industrial drug development. Herein, five novel Osimertinib-caffeic acid forms were first strategically tailored by varying solvent selection. Theoretical analysis demonstrated this polymorphism is correlated with multiple hydrogen bond donors-acceptors within multi-component system, which provides manipulation space for reconfiguration of intermolecular interactions and structural competition, while solvent further induced or involved in hydrogen-bonded rearrangements. Molecular dynamics simulation and solvent characterization revealed strong solute-solvent interaction and hydrogen bond donor propensity promoted the generation of hydrate. Small molecular size or large cavity of crystal facilitated solvent entry, resulting in the generation of channel-type solvates. Higher solvation free energy implied faster reaction rate and poorer solvent removal ability for solvates. Thermal analysis confirmed removal of the solvent occupying crystal channels for precursor solvates led to polymorph formation while maintaining the structure. Properties assessments revealed multi-component crystals significantly enhanced the physicochemical properties of Osimertinib. Polymorphs and hydrate exhibited remarkable distinctions in solubility, dissolution rate and physical stability. Nanoindentation and tableting tests confirmed distinct mechanical properties of different forms. Overall, this exploration has the potential to reshape the landscape of multi-component crystal polymorph development, paving the way for manipulating intermolecular interactions.

Controlling Hydrogen Evolution and CO2 Reduction at Transition Metal Hydrides.

ConspectusFuel-forming reactions such as the hydrogen evolution reaction (HER) and CO2 reduction (CO2R) are vital to transitioning to a carbon-neutral economy. The equivalent oxidation reactions are also important for efficient utilization in fuel cells. Metal hydride intermediates are common in these catalytic and electrocatalytic processes. Guiding metal hydride reactivity is important for achieving selective, kinetically fast, and low overpotential redox reactions. Our work has focused on understanding kinetic and thermodynamic aspects for controlling these reactive hydride species in an effort to design more selective electrocatalysts that operate at low overpotentials. Key to our research approach is understanding the free energy changes and rate of discrete steps of catalysis through the synthesis of proposed intermediates to independently investigate catalytic steps. Hydricity, the free energy of hydride dissociation, and how these values change with metal and ligand environment have informed catalyst design in the past few decades. We describe here how we have advanced upon these earlier studies.In our early studies we sought to understand solvent-dependent changes in hydricity for transition metal hydrides and how they impact the free energy for reduction of CO2 to formate (HCO2-). Additionally, we described how hydricity values can be applied to optimize HER and CO2R catalysis. This framework provides general guidelines for achieving selective CO2 reduction to formate without concomitant generation of H2. Kinetic information on steps in the proposed catalytic cycle of HER and CO2R catalysts were evaluated to identify potential rate-determining steps. As a second approach to achieve selective reduction for CO2, we explored two catalyst design strategies to kinetically inhibit HER using electrostatic (charged) and steric interactions. Hydricity values and other considerations for minimizing the free energy of proposed catalytic steps were also used to design an electrocatalyst for the interconversion between CO2 and HCO2- at low overpotentials. Further, we discuss our efforts to translate the CO2 hydrogenation activity of homogeneous catalysts to electrocatalysis.All of these catalytic systems operate with classical metal hydrides, where the electrons and proton are colocated on the metal center. However, classical metal hydrides all require very reducing potentials to generate sufficiently strong hydride donors for CO2 reduction. An analysis of metal hydride hydricity and reduction potentials shows that the strong correlation between reduction potential and hydricity is a general trend because the former is also highly correlated to pKa. However, formate dehydrogenase (FDH) generates a competent hydride donor at more mild potentials through bidirectional hydride transfer, where the proton and electrons of the hydride are not colocated. This bioinspired approach points to a promising new strategy for generating strong hydride donors at milder potentials and will surely open new avenues for using hydricity as a guide for addressing new and existing problems in catalysis.

Orthogonal and antenna effects on the chemosensing behaviour of porphyrins towards 2,4,6-trinitrophenol: Colour recognition and portable photodiode device

In this work, we have developed two modular freebase porphyrins containing triphenylamine (H2TPAP) and pyrene (H2PyP) units at meso position to understand the role of antenna and orthogonal effects on photophysical and chemosensing behaviour with different nitroaromatic compounds (NACs). The fluorescence studies demonstrate that H2TPAP exhibit strong electronic coupling over H2PyP to induce energy transfer process from peripheral units to porphyrin π-system and behave like strong donor materials. The sequential energy and electron transfer process upon addition of different NACs reveals that H2TPAP show unprecedented selectivity towards the detection of 2,4,6-Trinitrophenol (TNP) with a limit of detection (LODs) of ∼2.3 and ∼6.8 ppm for H2PyP. The mechanistic investigations through NMR and other spectroscopic methods evident that the strong donor-acceptor interactions, protonation at the central core of H2TPAP show both colorimetric and fluorimetric changes with the order of quenching efficiency as TNP>4-NP>2,4-DNP > DUN>4-NBA. A handheld portable photodetector was developed to monitor the dynamic change in photocurrent response. Further, a smartphone interfaced portable fluorimetric method was developed by recognizing colour variations in terms of RGB and the luminance (L) values facilitate sensitive and real-time sensing at low concentrations levels will have a significant impact on the development of new handheld chemosensor devices for real time detection of explosive compounds.

Platinum-Catalyzed Regio- and Enantioselective Diboration of Unactivated Alkenes with (pin)B-B(dan).

Asymmetric diboration of terminal alkenes is well established, and subsequent selective functionalization of the less hindered primary boronic ester is commonly achieved. Conversely, selective functionalization of the sterically less accessible secondary boronic ester remains challenging. An alternative way to control chemoselective functionalization of bis(boron) compounds is by engendering different Lewis acidity to the two boryl moieties, since reactivity would then be dictated by Lewis acidity instead of sterics. We report herein the regio- and enantioselective Pt-catalyzed diboration of unactivated alkenes with (pin)B-B(dan). A broad range of terminal and cyclic alkenes undergo diboration to furnish the differentiable 1,2-bis(boron) compounds with high levels of regio- and enantiocontrol, giving access to a wide variety of novel building blocks from a common intermediate. The reaction places the less Lewis acidic B(dan) group at the less hindered position and the resulting 1,2-bisboryl alkanes undergo selective transformations of the B(pin) group located at the more hindered position. The regioselectivity of the diboration has been studied by DFT calculations and is believed to originate from the trans influence, which lowers the activation barrier for formation of the regioisomer that places the weaker electron donor [B(pin) vs B(dan)] opposite the strong electron donor (alkyl group) in the platinum complex.

Engineering π‐Electron Bridge Enables Low‐Potential 2D Redox Polymer Anodes for High‐Voltage Aqueous All‐Organic Batteries

AbstractAqueous all‐organic batteries (AAOBs) have emerged as a hot topic but their development was plagued by limited choices of anode materials, generally facing an intractable trade‐off between low potential and high stability. Here, we propose a novel π‐electron bridge engineering strategy to explore a class of 2D dioxin‐bridged redox covalent organic polymer (RCOP) as trade‐off‐breaking anodes for high‐voltage AAOBs. By establishing a tunable RCOP platform, we perform theoretical study to scrutinize how bridge units between active sites affect the electrode potential and redox activity for the first time. We discover that compared to common pyrazine bridge, the weakened conjugation and strong electron donor character of the proposed dioxin bridge can induce elevated LUMO level and enriched π‐electron populations in active sites, heralding a low electrode potential and enhanced redox activity. Besides, the nonaromaticity‐induced molecular flexibility of dioxin bridge mitigates intermolecular stacking for sufficient active sites exposure. To experimentally corroborate this, a new dioxin‐bridged 2D RCOP (D‐HATN) and its pyrazine‐bridged analogue (P‐HATN) are synthesized for proof‐of‐concept demonstration. D‐HATN displays excellent compatibility with Na+/Zn2+/NH4+/H3O+ and obviously lower redox potentials in various dilute electrolytes compared to P‐HATN and most reported organic anodes, while featuring rapid Grotthuss‐type proton conduction and unprecedented durability in acid – 91.8 % capacity retention after 20000 cycles. Thus, the D‐HATN‐involved all‐organic proton battery delivers an average output voltage of 0.75 V, which can be further elevated to 1.63 V with alkaline‐acidic hybrid electrolyte design, affording markedly‐increased specific energy.

Engineering π-Electron Bridge Enables Low-Potential 2D Redox Polymer Anodes for High-Voltage Aqueous All-Organic Batteries.

Aqueous all-organic batteries (AAOBs) have emerged as a hot topic but their development was plagued by limited choices of anode materials, generally facing an intractable trade-off between low potential and high stability. Here, we propose a novel π-electron bridge engineering strategy to explore a class of 2D dioxin-bridged redox covalent organic polymer (RCOP) as trade-off-breaking anodes for high-voltage AAOBs. By establishing a tunable RCOP platform, we perform theoretical study to scrutinize how bridge units between active sites affect the electrode potential and redox activity for the first time. We discover that compared to common pyrazine bridge, the weakened conjugation and strong electron donor character of the proposed dioxin bridge can induce elevated LUMO level and enriched π-electron populations in active sites, heralding a low electrode potential and enhanced redox activity. Besides, the nonaromaticity-induced molecular flexibility of dioxin bridge mitigates intermolecular stacking for sufficient active sites exposure. To experimentally corroborate this, a new dioxin-bridged 2D RCOP (D-HATN) and its pyrazine-bridged analogue (P-HATN) are synthesized for proof-of-concept demonstration. D-HATN displays excellent compatibility with Na+/Zn2+/NH4 +/H3O+ and obviously lower redox potentials in various dilute electrolytes compared to P-HATN and most reported organic anodes, while featuring rapid Grotthuss-type proton conduction and unprecedented durability in acid - 91.8 % capacity retention after 20000 cycles. Thus, the D-HATN-involved all-organic proton battery delivers an average output voltage of 0.75 V, which can be further elevated to 1.63 V with alkaline-acidic hybrid electrolyte design, affording markedly-increased specific energy.

Platinum‐Catalyzed Regio‐ and Enantioselective Diboration of Unactivated Alkenes with (pin)B−B(dan)

AbstractAsymmetric diboration of terminal alkenes is well established, and subsequent selective functionalization of the less hindered primary boronic ester is commonly achieved. Conversely, selective functionalization of the sterically less accessible secondary boronic ester remains challenging. An alternative way to control chemoselective functionalization of bis(boron) compounds is by engendering different Lewis acidity to the two boryl moieties, since reactivity would then be dictated by Lewis acidity instead of sterics. We report herein the regio‐ and enantioselective Pt‐catalyzed diboration of unactivated alkenes with (pin)B−B(dan). A broad range of terminal and cyclic alkenes undergo diboration to furnish the differentiable 1,2‐bis(boron) compounds with high levels of regio‐ and enantiocontrol, giving access to a wide variety of novel building blocks from a common intermediate. The reaction places the less Lewis acidic B(dan) group at the less hindered position and the resulting 1,2‐bisboryl alkanes undergo selective transformations of the B(pin) group located at the more hindered position. The regioselectivity of the diboration has been studied by DFT calculations and is believed to originate from the trans influence, which lowers the activation barrier for formation of the regioisomer that places the weaker electron donor [B(pin) vs B(dan)] opposite the strong electron donor (alkyl group) in the platinum complex.