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An anion-responsive boron-containing π-conjugated polymer was synthesized via the Sonogashira coupling polymerization. The 11B NMR, UV/vis absorption, and fluorescence spectra confirmed the formation of an anion complex between the polymer and tetrabutylammonium fluoride (TBAF). Thin films were then prepared either by the pre-addition method, where the thin film was prepared using a solution of the polymer and TBAF, or by the post-addition method, where the polymer thin film was treated with an aqueous TBAF solution. The contact angle measurements revealed an enhancement in wettability with both methods. Consequently, wettability can be controlled via anion-complex formation at the surface. [ABSTRACT FROM AUTHOR]

Alkali metal borohydrides present a rich source of energy dense materials of boron and hydrogen, however their potential in propellants has been hitherto untapped. Potassium borohydride is a promising fuel with high gravimetric energy density and relatively low sensitivity to air and moisture. Problems arise due to the dehydrogenation of the borohydride on heating with minimal energy release. Common methods to extract both boron and hydrogen by means of borane species involve direct reaction of boron trifluoride species with alkali borohydrides. However, these methods face storage and safety issues due to rapid release of diborane on mixing the reactants. We propose a method of diborane release through controlled release of boron trifluoride by means of a tetrafluoroborate based ionic liquid. The trifluoride is released from the ionic liquid at elevated temperatures and enables safe mixture of the reactants at room temperature. It was found that the reaction between borohydride and boron trifluoride proceeds well above room temperature with potassium borohydride releasing diborane and potassium fluoride. The reaction pathway shows a primary reaction releasing diborane and potassium fluoride and a second less energy efficient step leading to the formation of potassium tetrafluoroborate. A 3D printed propellant formulation was also tested. [ABSTRACT FROM AUTHOR]

Boron trifluoride diethyl etherate, commonly referred to as BF3 ⋅ OEt2, plays a crucial role as a potent reagent in various organic transformations, particularly in the synthesis of heterocyclic systems through the establishment of carbon‐carbon & carbon‐heteroatom bonds. Its Lewis acid properties, reactivity, and stability at room temperature make it essential for a wide range of chemical reactions. BF3 ⋅ OEt2 demonstrates remarkable efficacy in processes such as hydroxylation of double bonds, epoxide cleavage, acid esterification, cyanation, coupling, and diverse cyclization reactions, surpassing other Lewis acids in performance. Its significant impact on organic synthesis extends to the formation of natural products, highlighting its profound significance in the realm of chemistry. The unique properties and versatility of boron trifluoride diethyl etherate make it a fundamental tool for a diverse array of chemical transformations. The numerous applications of this reagent in organic synthesis have prompted the development of a comprehensive review, focusing on its various roles and contributions in this field. [ABSTRACT FROM AUTHOR]

The study of the structure and conformational properties of ammonia–boron trifluoride in the cavity of 24 carbon and inorganic nanotubes using the PBE/3ζ DFT approximation showed that the conformational preference of the encapsulated molecule is determined by geometry and chemical composition of the host nanostructure. The combined effect of these factors leads to the predominance of eclipsed conformation of guest molecule for four endoclusters. In other cases, the main minimum on the potential energy surface corresponds to the staggered or pseudo‐staggered forms of BF3←NH3. The guest molecule carries the electric charge and has a shortened B←N bond. These conclusions are confirmed by the results of the virtual reaction of ammonia and boron trifluoride in the cavity of individual nanotubes. [ABSTRACT FROM AUTHOR]

The small, lipophilic tetrafluoroborate anion is ubiquitous in the imidazol(in)ium and iminium precursors to N‐heterocyclic carbenes (NHCs), including cyclic (alkyl)(amino)carbenes (CAACs). Its symmetrical distribution of charge over four highly electronegative fluorine atoms confers high stability, attenuating basicity while shielding the boron center. Here we report that this inertness does not withstand the nucleophilicity of free carbenes, when combined with a polarizing lithium cation. Reaction of CAAC ⋅ HBF4 salts with LiN(SiMe3)2, a protocol widely used to liberate free CAACs, generates zwitterionic CAAC‐BF3 adducts within minutes at 80 °C, or hours at room temperature, even for bulky N‐diisopropylphenyl (DIPP) CAACs. Imidazol(in)ium tetrafluoroborates likewise form NHC‐BF3 adducts in excellent yields. [ABSTRACT FROM AUTHOR]

Fused-ring electronic acceptors (FREAs) have transformed the field of organic solar cells. However, the prevailing syntheses of FREAs suffer from low yield, difficulty in separation, and high cost. Here, we report new and streamlined syntheses with three distinctive key steps. First, a universal approach to fuse neighboring aromatic units via a single carbon atom is demonstrated with ytterbium triflate and boron trifluoride as the catalysts. This approach allows the incorporation of diverse side-chain combinations. Second, nitrogen atom fusing neighboring aromatics is realized by using oxo-molybdenum catalyst, featuring lower reaction temperatures and enhanced yields. Third, an organic catalyst, proline, is identified to catalyze the aldol condensation with high yield to afford the most typical FREAs having acceptor-donor-acceptor (ADA) configurations. Our new chemistries enable easy syntheses of a wide range of FREAs, substantially expanding the scope and availability of these coveted materials at reduced synthetic cost, particularly for organic electronics. [ABSTRACT FROM AUTHOR]

This article explores the synthesis of methyl-substituted psoralen derivatives and their potential for DNA photocrosslinking. Psoralen is a natural compound used in skin disease treatment, but it can have toxic and mutagenic effects. The researchers aimed to enhance the reactivity of psoralen and control crosslinked product formation by adding methyl substituents at specific positions. They developed a synthetic method for creating psoralen derivatives and tested their photocrosslinking abilities with DNA. The results showed that the presence of methyl substituents reduced the formation of harmful diadducts. The article suggests further research to explore different psoralen derivatives and investigate their photocrosslinking properties. [Extracted from the article]

The single-center convergent close-coupling (CCC) method is applied to calculate positron scattering from boron. A model potential approach is utilized to extract the positronium formation, direct ionization, and values between the positronium formation and ionization thresholds. We present results for total, electron loss, elastic, momentum transfer, total bound state excitation, positronium formation, direct ionization, stopping power, and mean excitation energy from 10 − 5 eV to 5000 eV. For boron, there is only one other set of theoretical positron calculations for elastic and momentum transfer above 500 eV, which is in excellent agreement with the current CCC results. Using the current results for boron atoms and previous CCC calculations for hydrogen and fluorine atoms, positron scattering from BF, BF 2 , BF 3 , and BH molecules is calculated for energies between 0.1 eV and 5000 eV with a modified independent atom approach. [ABSTRACT FROM AUTHOR]

The construction of novel complexes can lead to the manifestation of unexpected structures and properties, thereby making chemical exploration in experiments a potential source for novel discoveries. In this study, by reacting 6,6'-dihydrazineyl-2,2'-bipyridine with acyl chlorides and subsequently coordinating with boron trifluoride, two different boron-tetradentate ligand complexes were simultaneously generated. One of these complexes exhibited a unique structure in which tetra-BF2 moieties coordinated to all four coordination sites of the ligand molecule, forming a flag-hinged structure around the bipyridine part. The second complex featured a helical structure formed by the hybridization of two BF2 and one B-O-B moieties, representing a highly unusual form of the complex. The structures of these two boron complexes were consistently observed when various substituted acyl chlorides were employed. Furthermore, it was found that enhancing electron-donor properties could induce a redshift in emissions. Utilizing the dimethylamino group as the proton receptor promoted a yellow-to-blue fluorescence switch in the tetra-BF2 complex and an OFF/ON fluorescence in the B-O-B bridged complex upon protonation. The helical chirality observed in the latter complex resulted in stable (P)/(M)-enantiomers after optical resolution. This complex exhibited circular dichroism with a |gabs| of up to 1.2 × 10-2 and circularly polarized luminescence with a |glum| on the order of 10-3 in solution and polymer film. [ABSTRACT FROM AUTHOR]

This study investigated the effect of fluoride and boron compound additives on the synthesis and hydration process of calcium aluminate (CA2). The analysis showed that the temperature of the full synthesis of CA2 without mineralizing additives was 1500 °C. However, the addition of fluorine and boron compounds at 1% and 3% significantly reduced the synthesis temperature to a range of 1100–1300 °C. The addition of fluoride compounds did not result in the formation of fluoride compounds from CaO and Al2O3, except for the calcium borate phase (Ca3(BO3)2) under certain conditions. In addition, the cellular parameters of the synthesized calcium aluminate phases were not affected by the use of these additives. Hydration studies showed that fluoride additives accelerate the hydration process, potentially improving mechanical properties, while boron additives slow down the reaction with water. These results highlight the relevance of fluoride and boron additives to the synthesis process and hydration kinetics of calcium aluminate, suggesting the need for further research to optimize their application in practice. TG studies confirmed the presence of convergence with respect to X-ray determinations made. SEM, EDS and elemental concentration maps confirmed the presence of a higher Al/Ca ratio in the samples and also showed the presence of hexagonal and regular hydration products. [ABSTRACT FROM AUTHOR]

Organoboron compounds demonstrate diverse applications in the fields of organic synthesis, materials science, and medicinal chemistry. Compared to the conventional hydroboration reaction, radical hydroboration serves as an alternative approach for the synthesis of organoborons via different mechanisms. In radical hydroboration, a boryl radical is initially generated from homolytic cleavage of a B–H or a B–B bond, which is then added to an unsaturated double bond to deliver a carbon radical. Subsequent hydrogen atom transfer or reduction of the carbon radical to form a carbanion followed by protonation gave the final product. Over the past few years, numerous efforts have been made for efficient synthesis of boryl radicals and the expansion of substrate scope of the radical hydroboration reaction. Here, we discuss the recent advancement of radical hydroboration and its associated mechanisms. Numerous radical hydroboration strategies employing N-heterocyclic carbene borane, bis(pinacolato)diboron and pinacolborane as the boron source were illustrated. Thermochemical, photochemical and electrochemical strategies for the generation of boryl radicals were also discussed in detail. [ABSTRACT FROM AUTHOR]

We demonstrate herein a reported syntheses pathway for form unsubstituted boron subnaphthalocyanines (BsubNcs) since their discovery in 1995 and to avoid random bay-position halogenation. This was achieved through the use of triphenyl borates as the macrocyclic templating reagent avoiding the formation of random bay-position halogenated BsubNc by-products. We also outline a method to screen boron templating reagents by computing their Lewis acidity using the fluoride ion affinity method as well as the screening of the macrocyclic precursor by determining its Lewis basicity using a boron trifluoride affinity scale of various organic macrocyclic precursors in order to balance these parameters to enable macrocycle formation. We find that a balancing of these parameters enabled multiple methods for the synthesis of unsubstituted BsubNc. For this study, we isolated the axially fluorinated and axially pentafluorophenoxylated BsubNcs and characterize their photophysical and electrochemical properties as there was no random bay-position substitutions. For this study, we also demonstrated as a 'part 2' the versatility in the synthetic methods developed through the synthesis of boron subphthalocyanines (BsubPcs), other BsubNcs and a hybrid materials of BsubPc + BsubNc called Bsub(Pc3-p + Ncp). We also explored an industrially relevant synthesis method of triphenyl borates and found it to be successful in the processes outlined herein providing a potential route to improving the sustainability of this class of triphenyl borate materials. [ABSTRACT FROM AUTHOR]

The paper presents the estimate of hydrodynamic parameters of the gas phase motion at low-temperature fractionation of boron trifluoride in a packed column. The following parameters are detected: density and viscosity for reacting phases in the operational temperature range, gas velocity at the phase inversion point, Reynolds number, and retention capacity for the investigated types of packed beds. Using the Logos software, numerical simulation of gas velocity and pressure distribution in the packed bed is performed for fractionation of boron trifluoride. [ABSTRACT FROM AUTHOR]

There is a continuous interest in cannabinoids like Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD). Previous experimental research has described the conversion of CBD to either Δ8-THC or Δ9-THC, depending on the acid catalyst applied. The use of para-toluene sulfonic acid (pTSA) has led to the formation of Δ8-THC, while boron trifluoride etherate (BF3·Et2O) has mainly yielded Δ9-THC. The enormous difference in product selectivity between these two catalysts was investigated with Molecular Modeling, applying quantum chemical density functional theory. It was found that pTSA leads to fast isomerization of Δ9-CBD to Δ8-CBD and subsequent ring closure to Δ8-THC. BF3·Et2O catalysis leads to the formation of tertiary carbenium ions in the transition states, which yield Δ9-THC and some iso THC. Under dry conditions in refluxing toluene, it was found that pTSA is predominantly present as a dimer, and only a small fraction is available as monomeric catalyst. Applying the computationally derived activation barriers in transition state theory yielded reaction rates that predicted the amounts of cannabinoids that are in close agreement with the experimental findings from the previous literature. [ABSTRACT FROM AUTHOR]

In order to replace the expensive metal/ligand catalysts and classic toxic and volatile solvents, commonly used for the hydration of alkynes, the hydration reaction of alkynes was studied in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIm-BF4) adding boron trifluoride diethyl etherate (BF3·Et2O) as catalyst. Different ionic liquids were used, varying the cation or the anion, in order to identify the best one, in terms of both efficiency and reduced costs. The developed method was efficaciously applied to different alkynes, achieving the desired hydration products with good yields. The results obtained using a conventional approach (i.e., adding BF3·Et2O) were compared with those achieved using BF3 electrogenerated in BMIm-BF4, demonstrating the possibility of obtaining the products of alkyne hydration with analogous or improved yields, using less hazardous precursors to generate the reactive species in situ. In particular, for terminal arylalkynes, the electrochemical route proved to be advantageous, yielding preferentially the hydration products vs the aldol condensation products. Importantly, the ability to recycle the ionic liquid in subsequent reactions was successfully demonstrated.

Synthesis of alkyl, aryl, and vinyl boronic esters carrying various chiral and achiral diol‐protecting groups were synthesized starting from the corresponding alkyl, aryl, and vinyl lithium or Grignard reagents. Good to excellent yields were obtained for a large range of substrates. The reaction can be conducted in a gram scale to obtain the product over 80 % yield. This approach provides direct access to neopentyl, pinene, and other boronic esters that are difficult to achieve. Using trimethoxyborane or 2‐isopropoxy pinacolboronic ester. Detailed mechanistic studies have been conducted to understand the mechanism behind the formation of boronic ester starting from organometallic reagents. [ABSTRACT FROM AUTHOR]

Boron-based multiple-resonance (MR) emitters exhibit the advantages of narrowband emission, high absolute photoluminescence quantum yield, thermally activated delayed fluorescence (TADF), and sufficient stability during the operation of organic light-emitting diodes (OLEDs). Thus, such MR emitters have been widely applied as blue emitters in triplet–triplet-annihilation-driven fluorescent devices used in smartphones and televisions. Moreover, they hold great promise as TADF or terminal emitters in TADF-assisted fluorescence or phosphor-sensitised fluorescent OLEDs. Herein we comprehensively review organoboron-based MR emitters based on their synthetic strategies, clarify structure–photophysical property correlations, and provide design guidelines and future development prospects. [ABSTRACT FROM AUTHOR]

The CrB and MnB doped graphdiyne (CrB@GDY and MnB@GDY) electrocatalysts were screened out from 27 candidates with low thermodynamic energy barriers and high selectivity for urea synthesis based on a new four-step screening strategy. [Display omitted] • Thermodynamic stability, hydrogenation and C N coupling process are used to screen double-atom catalysts for urea synthesis. • CrB@GDY and MnB@GDY exhibited low thermodynamic energy barriers of 0.41 eV and 0.66 eV for urea synthesis, respectively. • Established a catalytic activity relationship between the d-band center of the double-atom catalysts and urea performance. • CrB@GDY and MnB@GDY can suppress the side reactions (CO 2 RR, NRR). Electrocatalytic C N coupling using nitrogen (N 2) and carbon dioxide (CO 2) as precursors offers a promising alternative for urea production under mild conditions, compared to traditional synthesis approaches. However, the design and screening of extremely efficient electrocatalysts remains a significant challenge in this field. Hence, we propose a systematic approach to screen efficient double-atom catalysts (DACs) with both metal and boron active sites, employing density functional theory (DFT). A comprehensive evaluation of 27 potential catalysts were performed, taking into account their stability, co-adsorption of N 2 and CO 2 , as well as the potential-determining step (PDS) involved urea formation. The calculated results show that co-doped graphdiyne with CrB and MnB double atoms (CrB@GDY and MnB@GDY) emerge as potential electrocatalysts for urea production, displaying thermodynamic energy barriers of 0.41 eV and 0.66 eV, respectively. More importantly, these two DACs can significantly suppress the ammonia (NH 3) and C 1 products formation. Furthermore, a catalytic activity relationship between the d -band centers of the DACs and urea production performance were established. This study not only forecasts two promising DACs for subsequent experimental work but also establishes a theoretical framework for the evaluation of DACs in electrocatalytic urea synthesis. [ABSTRACT FROM AUTHOR]

During the synthetic studies toward 5,6,7,3′,4′-monomethoxytetrahydroxyflavones, a concise pedalitin synthesis procedure was achieved. As previously reported, 6-hydroxy-2,3,4-trimethoxyacetophenone was prepared by Friedel–Crafts acylation of 1,4-dihydroxy-2,6-dimethoxybenzene with boron trifluoride diethyl etherate in acetic acid. When aldol condensation of 6-hydroxy-2,3,4-trimethoxyacetophenone 2b with vanillin was performed in basic conditions, it produced 2′-hydroxychalcone 3b, and, surprisingly, along with 3-hydroxyflavone 4 in a considerable amount. We propose that this oxidative cyclization is presumably due to the contribution of a quinone methide, likely to be subjected to aerobic oxidation. The chalcone was then subjected to oxidative cyclization with iodine in dimethyl sulfoxide to afford flavone 5 in good yield. To our delight, serial demethylation of the three methoxy groups at the 5-, 6-, and 3′-positions of 5 proceeded smoothly to produce pedalitin 1, under hydrogen bromide solution (30% in acetic acid). The crystal structures of 3-hydroxyflavone 4 and pedalitin tetraacetate 6 were unambiguously determined by X-ray crystallography. [ABSTRACT FROM AUTHOR]

A new strategy to access α‐functionalized alicyclic amines via their corresponding imine‐BF3 complexes is reported. Isolable imine‐BF3 complexes, readily prepared via dehydrohalogenation of N‐bromoamines in a base‐promoted/18‐crown‐6 catalyzed process followed by addition of boron trifluoride etherate, undergo reactions with a wide range of organometallic nucleophiles to afford α‐functionalized azacycles. Organozinc and organomagnesium nucleophiles add at ambient temperatures, obviating the need for cryogenic conditions. In situ preparation of imine‐BF3 complexes provides access to α‐functionalized morpholines and piperazines directly from their parent amines in a single operation. α‐Functionalized morpholines can be elaborated further, for instance by installing a second substituent in the α′‐position. [ABSTRACT FROM AUTHOR]

Context: The mesophase pitch prepared by acid catalytic method typically had the advantages of low softening point and high solubility. To fully understand the mechanism of acid-catalyzed reactions and gain a deeper understanding of the microstructure of mesophase pitch, this article studied the mechanism of hydrofluoride/boron trifluoride (HF/BF3)–catalyzed anthracene using molecular simulation methods. The results showed that there might be two types of carbocations present in the system: classical and non-classical carbocations, and five reactions might occur, protonation reaction, chain elongation reaction, intramolecular cyclization reaction, deprotonation reaction, and dehydrogenation reaction. Classical carbocations acted as reactive intermediates in the chain elongation reaction and intramolecular cyclization reaction. When anthracene occurred chain elongation reactions with carbocations to form polymers, the generation of the tetramer required lager energy barriers than that of the dimer and trimer. The stiffness and flatness of molecules could be increased via intramolecular cyclization reactions. The polymers of anthracene might also occurred dehydrogenation reactions when the non-classical carbocations played the role of reactive intermediates. The dehydrogenation reactions required large energy barriers, which might be the reason for the product having a high aliphatic hydrogen content. Method: The Materials Studio (MS) 2020 software was used to complete the simulation. The atomic charge distribution calculation and the structure optimization of molecules were carried out using the B3LYP functional and DNP basis. The DFT-D (TS) dispersion corrections were added to calculate the dispersion interaction between aromatic molecules. The complete LST/QST method was used to search the transition states and calculate the reaction energy barrier. [ABSTRACT FROM AUTHOR]

Boron trifluoride (BF3) is a highly corrosive gas widely used in industry. Confining BF3 in porous materials ensures safe and convenient handling and prevents its degradation. Hence, it is highly desired to develop porous materials with high adsorption capacity, high stability, and resistance to BF3 corrosion. Herein, we designed and synthesized a Lewis basic single‐crystalline hydrogen‐bond crosslinked organic framework (HCOF‐50) for BF3 storage and its application in catalysis. Specifically, we introduced self‐complementary ortho‐alkoxy‐benzamide hydrogen‐bonding moieties to direct the formation of highly organized hydrogen‐bonded networks, which were subsequently photo‐crosslinked to generate HCOFs. The HCOF‐50 features Lewis basic thioether linkages and electron‐rich pore surfaces for BF3 uptake. As a result, HCOF‐50 shows a record‐high 14.2 mmol/g BF3 uptake capacity. The BF3 uptake in HCOF‐50 is reversible, leading to the slow release of BF3. We leveraged this property to reduce the undesirable chain transfer and termination in the cationic polymerization of vinyl ethers. Polymers with higher molecular weights and lower polydispersity were generated compared to those synthesized using BF3 ⋅ Et2O. The elucidation of the structure–property relationship, as provided by the single‐crystal X‐ray structures, combined with the high BF3 uptake capacity and controlled sorption, highlights the molecular understanding of framework‐guest interactions in addressing contemporary challenges. [ABSTRACT FROM AUTHOR]

There is a need for the replacement of toxic lead with nontoxic materials in radiation shielding applications. Instead of pure lead, lead mixed compounds/mixtures/alloys are considered to be less toxic and hence preferred for radiation shielding purposes. The compounds with magnesium are said to be having good magnetic and mechanical properties. Meanwhile, the boron element avoids secondary radiation and absorbs neutrons. The compound which is a mixture of lead, magnesium and boron is expected to be a good shielding material for radiation for X-rays/gamma rays. Hence in the present study, we have synthesised the lead–magnesium–boron (LMB) nanocomposites (NCs) using the green synthesis approach for the first time. LMB is synthesised by solution combustion method using Aloe vera as a reducing agent. The synthesised NCs are characterised using well-known characterisation techniques. Powder X-ray diffraction confirmed the formation of multi-phase LMB NCs, and average crystal size is found to be 13–15 nm. Surface morphology and chemical composition are affirmed by SEM and EDX. The optical energy gap is found to be 1.87 eV. FTIR confirmed the functional groups. X-rays/gamma rays, neutrons and bremsstrahlung radiation shielding efficiency are measured by experimental and theoretical, compared with conventional shielding materials. LMB NCs have proved to be efficient. Hence, LMB NCs proved to be potential in X-rays/gamma rays, neutrons and bremsstrahlung radiation shielding. [ABSTRACT FROM AUTHOR]

This article describes the synthesis of 5-Methoxy-2-acetyl-1-naphthol, a compound that can be used to create the quinone moiety found in daunomycinone. The authors sought an alternative procedure for the synthesis of this compound that would use readily available starting materials and improve yields. They developed a method that involved converting 5-methoxy-1-tetralone to 5-methoxy-1-naphthol, acetylating it to obtain 5-methoxy-1-naphthyl acetate, and then subjecting it to a Fries rearrangement to produce 5-Methoxy-2-acetyl-1-naphthol. The authors achieved an overall yield of 50% using this method. [Extracted from the article]

The potency of heteroatom-doping in reshaping optoelectronic properties arises from the distinct electronegativity variations between heteroatoms and carbon atoms. By incorporating two heteroatoms with differing electronegativities (e.g., B = N), not only is the architectural coherence of π-conjugated systems retained, but also dipolar traits are introduced, accompanied by unique intermolecular interactions absent in their all-carbon analogs. Another burgeoning doping strategy, featuring the heteroatom–boron–heteroatom motif (X–B–X, where X = N, O), has captured growing attention. This configuration's coexistence of the boron-heteroatom unit and an isolated heteroatom stimulates mutual modulation in the dipole of the boron-heteroatom unit and the heteroatom's electronegativity. In this Feature article, we present an encompassing survey of XBX-doped π-conjugated systems, elucidating how the integration of the X–B–X unit induces transformative structural and property changes within π-conjugated systems. [ABSTRACT FROM AUTHOR]

Objective: The present contribution describes a novel approach for obtaining steroid derivatives of the iso-type from sapogenins for drug discovery. Methodology: Diastereomeric 23-acetyl-spirostanols were prepared by acetolysis of smilagenin (4) (25R) using boron trifluoride diethyl etherate in acetic anhydride followed by treatment of the epimeric epoxycholestene obtained (6 or 9) under basic hydrolysis. Higher regioselectivity was attained in the presence of ZnCl2 in acetic anhydride. Results: Acetolysis of smilagenin (4) (25R) using boron trifluoride diethyl etherate in acetic anhydride afforded 20-α-methyl epoxycholestene 6 as the major product, two furostene derivatives (7 and 8), as well as the new 20-β-methyl epoxycholestene 9. Increased regioselectivity for the acetolysis of smilagenin (4) was observed using ZnCl2 in acetic anhydride affording 6 in 90% yield. Subsequent treatment of the epimeric epoxycholestene (6 or 9) under basic hydrolysis afforded two new diastereomeric 23-acetyl-spirostanols 14 and 15. The structures of all compounds were established using 1D and 2D NMR techniques. Conclusions: Formation of the two diastereomeric 23-acetyl-spirostanols (14 and 15) from epimeric epoxycholestenes 6 and 9 with KOH/EtOH proceeds with high stereospecificity. The configuration at C-20, C-22, C-23, and C-25 for the new iso-type 23-acetyl-spirostanol 15 was established by X-ray crystal analysis as 20R, 22R, 23S, and 25R. In addition to the above, the X-ray of 15 was analyzed and compared with the crystallographic data of sarsasapogenin acetate (16), smilagenin (4) and 23-acetyl-sarsasapogenin (17). [ABSTRACT FROM AUTHOR]

1-Fluorine-substituted spiroboracarbocycles were first synthesized by cycloboration of monoterpenes ((–)-β-pinene, (–)-camphene, and l(–)-menthol methylene derivative) with boron trifluoride (BF3·THF) in the presence of two-component catalytic system Cp2TiCl2/Mg in tetrahydrofuran. [ABSTRACT FROM AUTHOR]

• B-containing coatings have been formed on Mg alloy in one stage. • The macroscopic cross section of the interaction of neutrons with samples was determined. • B increases the macroscopic cross section of the interaction of samples with neutrons. The work provides the results of the one-step formation of boron-containing coatings on an Mg–Mn–Ce alloy by plasma electrolytic oxidation. The results of studies of the composition, structure and morphology of heteroxide coatings are presented. It was established that the boron is contained in the coating mainly in the form of B or B 2 O 3. The introduction of B changes the color of coatings, and also helps to increase their porosity. The method of determining the full cross section of the interaction of thermal neutron absorption efficiency by samples material using the installation of neutron-activation analysis based on 252Cf was developed. It was shown that the introduction of boron into the formed coatings allows to increase the macroscopic cross-section of the interaction of samples with thermal neutrons by 3.8 times. This effect opens the potential for the use of synthesized material in the field of nuclear technologies and aerospace industry. [ABSTRACT FROM AUTHOR]

The reaction of alicyclic oximes and dioximes with epichlorohydrin in the presence of a BF3O(C2H5)2 catalyst to obtain chlorohydrin ethers of the corresponding dioximes was studied. A probable mechanism for the reaction is proposed. Epoxy ethers of dioximes were synthesized by dehydrochlorination of chlorohydrin ethers with alkali. The physico-chemical parameters of the synthesized compounds were determined. The composition and structure of chlorohydrin and epoxy ethers were proven by ¹H, 13C NMR, IR-spectroscopy and the hydroxyl, chlorine and epoxy numbers of the synthesized compounds were determined. The synthesized epoxy compounds can be used as synthetic fibers in the textile industry. [ABSTRACT FROM AUTHOR]

The copper borate of CuB2O4 in tetragonal form was successfully synthesized as a single-phase by using a solid-state method without using any modifying agent. For the designed experimental procedure, the optimized reaction conditions were estimated as a reaction temperature of 950 °C, reaction time of 240 min, argon atmosphere and Cu:B ratio of 1:5. The possible reaction mechanism estimated for both boron sources of boric acid and boron oxide. In both sets, the lower ratios of Cu:B supported CuB2O4 formation. In the use of boric acid as a boron source, higher reaction yield percentages (98 %) and lower particle sizes were determined. The micron-scale rounded particles were observed in morphological analyses and the particles were shaped in homogeneity in the use of boron oxide as a boron source. The specific FT-IR peaks were observed at the band values of 1190, 1035, 988, 945, 890, 695, 631, 540 and 479 cm−1. The experimental results highlighted the probable use of solid-state in the copper borate synthesis. [ABSTRACT FROM AUTHOR]

The operational stability of polymer solar cells is a critical concern with respect to the thermodynamic relaxation of acceptor‐donor‐acceptor (A‐D‐A) or A‐DA'D‐A structured small‐molecule acceptors (SMAs) within their blends with polymer donors. Giant molecule acceptors (GMAs) bearing SMAs as subunits offer a solution to this issue, while their classical synthesis via the Stille coupling suffers from low reaction efficiency and difficulty in obtaining mono‐brominated SMA, rendering the approach impractical for their large‐scale and low‐cost preparation. In this study, we present a simple and cost‐effective solution to this challenge through Lewis acid‐catalyzed Knoevenagel condensation with boron trifluoride etherate (BF3 ⋅ OEt2) as catalyst. We demonstrated that the coupling of the monoaldehyde‐terminated A‐D‐CHO unit and the methylene‐based A‐link‐A (or its silyl enol ether counterpart) substrates can be quantitatively achieved within 30 minutes in the presence of acetic anhydride, affording a variety of GMAs connected via the flexible and conjugated linkers. The photophysical properties was fully studied, yielding a high device efficiency of over 18 %. Our findings offer a promising alternative for the modular synthesis of GMAs with high yields, easier work up, and the widespread application of such methodology will undoubtedly accelerate the progress of stable polymer solar cells. [ABSTRACT FROM AUTHOR]

Fluoroborane-type molecules (R1R2B–F) are of interest in synthetic chemistry, but to date, apart from a handful of small species (such as H2BF, HBF2, and BF3), little is known concerning the effect of substituents in governing the strength of the B–F bonds of such species toward homolytic dissociation in the gas phase. In this study, we have calculated the bond dissociation enthalpies (BDEs) of thirty unique B–F bonds at the CCSD(T)/CBS level using the high-level W1w thermochemical protocol. The B–F bonds in all species considered are very strong, ranging from 545.9 kJ mol−1 in (H2B)2B–F to 729.2 kJ mol−1 HBF2. Nevertheless, these BDEs still vary over a wide range of 183.3 kJ mol−1. The structural properties that affect the BDEs are examined in detail, and the homolytic BDEs are rationalized based on molecule stabilization enthalpies and radical stabilization enthalpies. Since polar B–F bonds may represent a challenging test case for density functional theory (DFT) methods, we proceed to examine the performance of a wide range of DFT methods across the rungs of Jacob′s Ladder for their ability to compute B–F BDEs. We find that only a handful of DFT methods can reproduce the CCSD(T)/CBS BDEs with mean absolute deviations (MADs) below the threshold of chemical accuracy (i.e., with average deviations below 4.2 kJ mol−1). The only functionals capable of achieving this feat were (MADs given in parentheses): ωB97M-V (4.0), BMK (3.5), DSD-BLYP (3.8), and DSD-PBEB95 (1.8 kJ mol−1). [ABSTRACT FROM AUTHOR]

We disclose a novel boron trifluoride induced C–H activation and difluoroboronation at room temperature, thus providing a straightforward gateway to a series of N,O-bidentate organic BF2 complexes. The scope of the method is demonstrated with 24 examples. All the synthesized compounds exhibit fluorescence and some of them have large Stokes shifts. [ABSTRACT FROM AUTHOR]

When tetraketone, in which two dibenzoylmethanate groups are connected by a disulfide bridge through central (α) carbon atoms, was treated with a mixture of boron trifluoride ether and tributyl borate, a binuclear complex containing bordibenzoylmethanate fragments was obtained. Like aromatic disulfides, this compound is cleaved by the action of sulfuryl chloride and bromine to form sulfenyl chloride or sulfenyl bromide derivatives. These compounds enter into substitution and addition reactions common for sulfenyl halides, making it possible to obtain bordibenzoylmethanate complexes containing various functional groups linked to the chelate cycle through the central carbon atom. Based on studying the UV spectra of the obtained compounds, an assumption was made about the nature of the interaction of α and β substituents with the chelate ring. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Acenes with linearly fused benzene rings have attracted much attention due to their intriguing optical and electronic properties. Nevertheless, the poor ambient stability of longer acenes has hampered the investigation of their physicochemical properties and potential applications. The incorporation of main group elements into the acene backbones provides a viable strategy to enhance the stability, and meanwhile, generates a new family of heteroatom‐doped acenes (namely heteroacenes) with modified properties and functions. In particular, boron‐containing acenes represent an attractive class of heteroacenes owing to the existence of vacant p orbital of boron, which endows the π‐conjugated systems with appealing features, such as Lewis acidity, electron‐accepting capability, stimuli‐responsivity, and adjustable photophysical properties. During the past decade, significant progress has been achieved in the synthesis and applications of boron‐containing acenes, but a focused review on this topic has been elusive. Here, we summarize the recent advances in the studies on boron‐containing acenes, covering their synthesis, intriguing properties, and various applications in electroluminescence and electronic devices, as well as in biosensors, etc. We hope that this timely review will stimulate new research interest in this unique family of materials and promote their optoelectronic applications. [ABSTRACT FROM AUTHOR]

A preparation of t-butyl esters of Nα-protected amino acid is described that Nα-P proceeds from protected amino acids and t-butanol using anhydrous magnesium sulfate and an excess of boron trifluoride diethyl etherate as additional reagents. The method affords t-butyl esters in good yields and a variety of amino acid side chains and substituents tolerate the reaction conditions. [ABSTRACT FROM AUTHOR]

This review is an attempt to bring together the data from the literature on the synthesis and properties of icosahedral carborane derivatives, in which exo-polyhedral three- and four-coordinated boron substituents are attached directly to the carborane cage through boron–carbon or boron–boron bonds. Various classes of compounds are considered, including carboranyl aryl boranes, boronic acids and their derivatives, boroles, diazaboroles, etc. Particular attention is paid to carborane-fused heterocycles containing boron atoms. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Acenes with linearly fused benzene rings have attracted much attention due to their intriguing optical and electronic properties. Nevertheless, the poor ambient stability of longer acenes has hampered the investigation of their physicochemical properties and potential applications. The incorporation of main group elements into the acene backbones provides a viable strategy to enhance the stability, and meanwhile, generates a new family of heteroatom‐doped acenes (namely heteroacenes) with modified properties and functions. In particular, boron‐containing acenes represent an attractive class of heteroacenes owing to the existence of vacant p orbital of boron, which endows the π‐conjugated systems with appealing features, such as Lewis acidity, electron‐accepting capability, stimuli‐responsivity, and adjustable photophysical properties. During the past decade, significant progress has been achieved in the synthesis and applications of boron‐containing acenes, but a focused review on this topic has been elusive. Here, we summarize the recent advances in the studies on boron‐containing acenes, covering their synthesis, intriguing properties, and various applications in electroluminescence and electronic devices, as well as in biosensors, etc. We hope that this timely review will stimulate new research interest in this unique family of materials and promote their optoelectronic applications. [ABSTRACT FROM AUTHOR]

A novel synthetic method for the formation of thiazolo[4,5‐b]indol‐2‐amines from α‐diazoimidamides and mono‐substituted thioureas in the presence of a catalytic amount of boron trifluoride etherate and camphorsulfonic acid under mild conditions was demonstrated. This methodology has a wide‐ranging scope of α‐diazoimidamides and mono‐substituted thioureas, amenable for upscaling experiments and further transformation. [ABSTRACT FROM AUTHOR]

A facile one-step synthetic approach to dihydrofuro-[3,2- c ]chromenones and furo[3,2- c ]chromenones by the reaction of methyl enol ethers with 4-hydroxycoumarins under metal-free conditions is presented. Dihydrofuro[3,2- c ]chromenones and furo[3,2- c ]-chromenones were selectively obtained by controlling the stoichiometry of boron trifluoride diethyl etherate. An unexpected aryl-group migration followed by aromatization of the furan moiety, leading to a variety of furo[3,2- c ]chromenone derivatives in good yields, is reported. [ABSTRACT FROM AUTHOR]

Polyborylated-alkenes are valuable polymetalloid reagents in modern organic synthesis, providing access to a wide array of transformations, including the construction of multiple C–C and C–heteroatom bonds. However, because they contain similar boryl groups, many times their transformation faces the main challenge in controlling the chemo-, regio- and stereoselectivity. One way to overcome these limitations is by installing different boron groups that can provide an opportunity to tune their reactivity toward better chemo-, regio- and stereoselectivity. Yet, the preparation of polyborylated-alkenes containing different boryl groups has been rare. Herein we report concise, highly site-selective, and stereoselective boron-masking strategies of polyborylated alkenes. This is achieved by designed stereoselective trifluorination and MIDA-ation reactions of readily available starting polyborylated alkenes. Additionally, the trifluoroborylated-alkenes undergo a stereospecific interconversion to Bdan-alkenes. These transition-metal free reactions provide a general and efficient method for the conversion of polyborylated alkenes to access 1,1-di-, 1,2-di-, 1,1,2-tris-(borylated) alkenes containing BF3M, Bdan, and BMIDA, a family of compounds that currently lack efficient synthetic access. Moreover, tetraborylethene undergoes the metal-free MIDA-ation reaction to provide the mono BMIDA tetraboryl alkene selectively. The mixed polyborylalkenes are then demonstrated to be useful in selective C–C and C–heteroatom bond-forming reactions. Given its simplicity and versatility, these stereoselective boron-masking approaches hold great promise for organoboron synthesis and will result in more transformations. Polyborylated-containing alkenes, hold promise as polymetalated building blocks for a wide variety of organic motifs, biologically-active compounds, and natural product synthesis, though strategies for their stereoselective synthesis are lacking. Here, the authors report concise, highly site-selective, and stereoselective boron-masking strategies for polyborylated alkenes. [ABSTRACT FROM AUTHOR]

Branched allylic sulfones are scaffolds widely distributed in bioactive molecules and organic functional materials. The synthesis of allylic sulfones has been developed, e.g., using the Tsuji-Prost reaction, hydrosulfonylation and radical addition reactions, yet the hydrosulfonylation of unactive 1,3-diene without transition metals has been rarely explored. Here we synthesized branched allylic sulfones by boron-catalysed highly regioselective hydrosulfonylation of 1,3-diene with sulfinic acid, without transition metal catalysts. Compared with the previous methods, the advantages include readily available starting materials without pre-treatment; cheap boron trifluoride etherate; simple operation and easy scaling-up; the reaction does not require dry conditions, an inert atmosphere or a water scavenger; and excellent atom economy and regioselectivity. [ABSTRACT FROM AUTHOR]

Polyethylene glycol 1000 (PEG1000) and epoxy resin E20 were used to synthesize the E20/PEG1000 polymer (EP1K), which was later transformed into a self-emulsifying water-based epoxy curing agent by reacting with m-Xylylenediamine (MXDA). The effects of molecular weight, the molar ratio of the raw materials, the catalyst dosage, and the different co-solvents on the properties of the prepared curing agent were systematically explored. The infrared absorption spectra of E20, EP1K, and the water-based epoxy curing agent were compared and analyzed. The coating properties of the waterborne epoxy varnish, which was based on water-based epoxy curing agents to emulsify and cure the resin E44, were systematically tested. The results demonstrated that with a molar ratio of 1:1:4 of PEG1000, E20, and MXDA, the boron trifluoride etherate (BF3·Et2O) as catalyst accounts for 0.3% of the total mass of E20 and PEG1000, and an applicable period of 3 h for the prepared varnish, the anti-corrosion performance, and mechanical properties of the coatings were excellent. [ABSTRACT FROM AUTHOR]

A vinyl ether containing a five-membered cyclic carbonate group, 2-(2-vinyloxyethoxy)ethyl carbonate (VEECN), was synthesized by adding CO2 to 2-(2-vinyloxyethoxy)ethyl glycidyl ether, which is a vinyl ether containing an epoxy group. Cationic polymerization of VEECN was performed in nitromethane at − 30 °C with boron trifluoride etherate. The resulting poly(VEECN) exhibited a number-average molecular weight of ~ 3500 g/mol and a molecular weight distribution of ~ 1.40. Poly[2-(2-vinyloxyethoxy)ethyl hydroxyurethane]s [poly(VEEHU)-C2 to -C5] were synthesized by reacting the cyclic carbonates in the side chains of the obtained poly(VEECN) with four alkanolamines with different methylene numbers (2–5) to form hydroxyurethane groups. The reaction ratios were adjusted to approximately 50%, 75%, and 100%, and the thermal responses and properties of poly(VEEHU)-C2 to -C5 were investigated. When the urethanization ratio was ~ 50%, the cloud points (Tcp) of 1% w/v poly(VEEHU)-C3 to -C5 aqueous solutions were observed at 46, 27, and 8 °C, respectively, with the temperature decreasing with increasing methylene number. Conversely, the poly(VEEHU)-C2 aqueous solution did not exhibit a Tcp at ≤ 95 °C. The glass transition temperatures of the polymers were − 32 °C for poly(VEECN) and − 28, − 32, − 33, and − 35 °C for poly(VEEHU)-C2 to -C5, respectively. Additionally, the thermal decomposition temperatures of the polymers were 279 °C for poly(VEECN) and 253–262 °C for poly(VEEHU)-C2 to -C5, indicating that poly(VEEHU) were flexible polymers at room temperature with relatively high thermal stabilities. [ABSTRACT FROM AUTHOR]

Ni phosphide and Lewis acid–base pair site of Al2O3 were combined as highly efficient catalyst for direct amination of 1-octanol to 1-octylamine. Due to the higher dehydrogenation activity and the site isolation effect, Ni3P/Al2O3-TPP prepared by organophosphorus was 4.0 times more active than Ni/Al2O3 and increased the selectivity to 1-octylamine from 71.4 to 92.8% at 0.4 MPa NH3. [ABSTRACT FROM AUTHOR]

The coordination behavior of different pnictogenylboranes towards group 6 metal Lewis acids is investigated. The resulting complexes with phosphanylboranes [(CO)4M(PH2BH2 ⋅ NMe3)2] (M=Cr, Mo, W; 1–3), arsanylboranes ([(CO)4M(AsH2BH2 ⋅ NMe3)2] (M=Cr, Mo, W; 4–6) and tBu‐substituted phosphanylboranes [(CO)4M(tBuPHBH2 ⋅ NMe3)2] (M=Cr, W; 7–8) are fully characterized by multinuclear NMR spectroscopy, single crystal X‐ray diffraction and IR spectroscopy. The systematic nature of the approach of the synthesis and the high purity of the compounds enable a comparative investigation of the coordination behavior of pnictogenylboranes. The influences of the metal center, the pnictogen atom and the substituent at the pnictogen atom on the coordination behavior of pnictogenylboranes are compared. [ABSTRACT FROM AUTHOR]

Crystals of two new tetrafluoroborate crystallohydrates M(BF4)2·3H2O (M = Sr, Ba) are prepared by the evaporation of aqueous solutions. The compounds are studied by single crystal XRD and IR spectroscopy. Sr(BF4)2·3H2O crystallizes in the tetragonal crystal system (a = 6.9638(4) Å, c = 18.1671(12) Å, space group P42/mnm); Ba(BF4)2·3H2O crystallizes in the orthorhombic crystal system (a = 7.1996(2) Å, b = 18.0823(5) Å, c = 7.1860(2) Å, space group C2221). Their crystal structure is formed by isolated BF4 tetrahedra and water molecules with alkaline earth metal atoms in between. When cooled to 100 K, Ba(BF4)2·3H2O undergoes a polymorphic transition to the monoclinic modification accompanied by pseudo-merohedral twinning of crystals. [ABSTRACT FROM AUTHOR]