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Borazines are used in chemical vapor deposition processes to produce hybrid graphene–boron nitride nanostructures. As the knowledge on the mechanism of borazine formation is scarce, we studied the mechanism of formation of B,B′,B′′-trichloro-N,N′,N′′-tri(p-fluorophenyl)borazine (3a) from p-fluoroaniline and boron trichloride employing NMR spectroscopy, X-ray single crystal structure analysis, trapping experiments, and computational chemistry methods up to the coupled cluster CCSD(T) level of theory. These studies suggest the initial formation of the 1 : 1 adduct 1a (ArNH2BCl3, Ar = 4-fluorophenyl) with a dative B–N bond that could be fully characterized including single crystal X-ray diffraction. Adduct 1a undergoes unimolecular hydrogen chloride elimination with a first-order rate constant of k1 = 3.03(7) × 10−2 min−1 in toluene at 100 °C. This rate constant is in very good agreement with the one derived (k1 = 3.18 × 10−2 min−1) from computed activation parameters (ΔH‡373.15 = 28.1 kcal mol−1, ΔS‡373.15 = 1.56 eu, ΔG‡373.15 = 27.6 kcal mol−1). The product of the first hydrogen chloride evolution is anilinodichloroborane ArNHBCl2 (2a). Compound 2a cannot be isolated in a pure form due to instability, but its presence as a transient reactive intermediate can be derived from NMR spectroscopy. Reactive intermediates other than anilinodichloroborane cannot be assigned by NMR spectroscopy. We propose that the mechanism of formation of borazine 3a involves the reaction of 2a with 4-fluoroaniline as the rate determining step. [ABSTRACT FROM AUTHOR]

6-Chloro-5,6-dihydro-dibenzo[c,e][1,2]azaborinine (1) reacts with pyridine derivatives to borenium or boronium ions. The boronium ion obtained from reaction with an excess of pyridine could be characterized structurally and transforms into the borenium ion in solution. The reaction of 1 with 2,2'-bipyridine (a) and derivatives (b: 6,6'-dimethyl; c: 4,4'-di-tert-butyl) results in spirocyclic boronium ions 8a-c of which 8b could be characterized by X-ray crystallography. Despite the chelate effect, the spirocyclic boronium ions readily undergo hydrolysis or alcoholysis. Treatment of the spirocyclic boronium ion 8c with potassium hexamethyl disilazide (KHMDS) results in neutral products that are monomers, dimers, or trimers of dibenzo[c,e] [1,2]azaborinine ("BN-phenanthryne") trapped with 4,4'-di-tert-butyl-2,2'-bipyridine by formation of B-C, B-N, or dative B-N bonds, indicative of deprotonation of NH and CH bonds of the boronium ion by KHMDS. [ABSTRACT FROM AUTHOR]

With a 4-aminostyryl group introduced at its 3-position, a BODIPY BDP-ODTAC was derived as a new ratiometric sensor for Ag+ by modifying 4-amino group as a Ag+ chelator, 1-oxa-4,10-dithia-7-azacyclododecane (ODTAC). In addition to the specific Ag+-induced hypsochromic absorption shift from 606 to 562 nm, this sensor demonstrated an excitation shift from 600 to 560 nm due to the internal charge transfer (ICT) effect endowed by the introduced α-4-aminostyryl group. The Ag+-induced recovery and enhancement of the intrinsic local emission band was also observed. The different sensing behavior of ODTAC-BDP with chelator ODTAC substituting on the meso-phenyl group infers that the ratiometric sensing behavior of BDP-ODTAC is correlated to the amino group in ODTAC acting as the electron donor for the ICT effect. With high Ag+ selectivity over interfering cations such as Hg2+ and Pb2+, BDP-ODTAC displays a fluorometric limit of detection (LOD) of ∼17 nM (∼0.002 ppm), which is distinctly lower than EPA and WHO standards for drinking water (500 nM, ∼0.055 ppm). Moreover, the BDP-ODTAC-doped PVC film shows the Ag+ sensitivity of 1 ppm with a color switch from blue to purple, providing this sensor the ability to determine Ag+ in totally aqueous solution sensitively via naked-eye detection. [ABSTRACT FROM AUTHOR]

With a 4-aminostyryl group introduced at its 3-position, a BODIPY BDP-ODTAC was derived as a new ratiometric sensor for Ag+ by modifying 4-amino group as a Ag+ chelator, 1-oxa-4,10-dithia-7-azacyclododecane (ODTAC). In addition to the specific Ag+-induced hypsochromic absorption shift from 606 to 562 nm, this sensor demonstrated an excitation shift from 600 to 560 nm due to the internal charge transfer (ICT) effect endowed by the introduced α-4-aminostyryl group. The Ag+-induced recovery and enhancement of the intrinsic local emission band was also observed. The different sensing behavior of ODTAC-BDP with chelator ODTAC substituting on the meso-phenyl group infers that the ratiometric sensing behavior of BDP-ODTAC is correlated to the amino group in ODTAC acting as the electron donor for the ICT effect. With high Ag+ selectivity over interfering cations such as Hg2+ and Pb2+, BDP-ODTAC displays a fluorometric limit of detection (LOD) of ∼17 nM (∼0.002 ppm), which is distinctly lower than EPA and WHO standards for drinking water (500 nM, ∼0.055 ppm). Moreover, the BDP-ODTAC-doped PVC film shows the Ag+ sensitivity of 1 ppm with a color switch from blue to purple, providing this sensor the ability to determine Ag+ in totally aqueous solution sensitively via naked-eye detection. [ABSTRACT FROM AUTHOR]

Six novel diacetoxyboron complexes of bis-β-diketones linked thienothiophene moiety were synthesized from acetoacetone by cyclization, Claisen condensation and chelation reaction. The obtained complexes were confirmed by means of 1 H NMR, FTIR, MS and elemental analysis and their electrochemical and photoluminescent properties were investigated by cyclic voltammetry, UV–vis absorption and fluorescence spectroscopy. The results showed that these diacetoxyboron complexes yielded a blue emission in DMF solution and emitted a greenish-yellow emission in powders and PMMA films. Especially, diacetoxyboron bis-β-diketonate with tert-butylphenyl thienothiophene exhibited the most intense photoluminescent intensity, highest quantum efficiency ( Φ u = 0.95) in solution and longest lifetime value ( τ = 38.42 μs) in PMMA film among these complexes. In addition, these diacetoxyboron complexes showed the low-lying LUMO energy levels (2.71–2.75 eV), which was suitable for electron transfer. [ABSTRACT FROM AUTHOR]

Reaction of 2-bromo-1,3,2-diazaborole (1) with excess BBr3 induces 1,2-hydrogen migration, giving 1,3,2-diazaborole-derived carbene complexes of boron bromide (2). Compound 2 exists in a dynamic solution equilibrium with 1. The 1H NMR study shows that the equilibrium lies to the right side of the dissociation reaction of 2. Parallel reaction of 1 with excess BI3 gives the corresponding 1,3,2-diazaborole-derived carbene boron iodide complex (3). Notably, in contrast to 2, the dissociation reaction of 3 largely lies to the left side, favouring the formation of 3. The dynamic solution equilibrium behaviours of 2 and 3 are probed by both experimental and theoretical methods. [ABSTRACT FROM AUTHOR]

Turkey holds 73% of the world's boron deposits. 25.3% of the total deposits are tincal ore and located in Eskişehir Kırka region. During the production of 1 million tons of borax pentahydrate (Na 2 O·2B 2 O 3 ·5H 2 O) from tincal ore, approximately 900.000 tons of solid boron derivative waste generated in a year. The boron derivative waste is stored in waste ponds and causes both economic and environmental problems. The main purpose of this study is to utilize the waste in a widely used material, like cement mortar. For this purpose, first, detailed thermal and mineralogical characterization of the waste was carried out and the heat treatment temperature was determined accordingly as 600 °C. Subsequently, the effects on the cement mortar were investigated by replacing boron derivative waste with cement in weight ratios of 5%, 15%, and 25%. Also, waste-incorporated cement paste samples were prepared with the same replacement ratios to investigate the changes in phase compositions. Compression tests were conducted for all mortars at 7th, 28th and 90th day. Incorporation of waste by the ratio of 5% provided higher strength value (52 MPa) than reference mortar (51 MPa) at the 90th day. For early ages, the strength ratio values were varied from 55% to 94% depending on both the incorporation ratio and the age of the sample. After the compression tests, samples were characterized by XRD analysis and microstructural analysis were conducted for both mortar and paste samples in order to understand the effects of waste replacement on the microstructural evaluation. For strength point of view, heat treated waste is practical to be utilized in the production of cement mortar by 25 wt%. [ABSTRACT FROM AUTHOR]

Boron 2-(2′-pyridyl) imidazole complex (BOPIM) derivatives, BOPIM-1 and BOPIM-2, involving twisted intra-molecular charge transfer (TICT) characteristic, were investigated to probe bovine serum albumin (BSA). BOPIM-1 was demonstrated to be an efficient fluorescence probe to discriminate BSA from other proteins including human serum albumin (HSA). The encapsulation of BOPIM-1 in the hydrophobic subdomain IIA of BSA inhibited the TICT state and resulted in 70-fold emission enhancement of BOPIM-1. Besides, it was found that BOPIM-1 could distinguish denatured BSA from the native, due to the difference of 15 nm emission wavelength at least. The denaturation of BSA leads to the exposure of binding sites and resulted in an increase in the accessibility of the fluorophore to the BSA cavity, which made a great contribution to the further restraint of TICT state of BOPIM-1. The tracking of BSA denaturizing process was easily achieved, through the change of BOPIM-1 emission wavelength from 485 to 465 nm. Thus, a promising pharmacological dual-functional probe was provided for both the selective recognization of BSA and the identification of denatured BSA from the native. [ABSTRACT FROM AUTHOR]

The interaction of sulfenyl- and selenylchloride derivatives of boron difluoride acetylacetonate with ketones, diketones and other dicarbonyl compounds was investigated. In the majority of cases the expected products of substitution of hydrogen atom with γ-hio(selen)acetylacetonate group were obtained. The products with two chelate groups were obtained using the lack of ketone. The unusual interaction of selenylchloride with acetylacetone and acetoacetic ether was revealed. Derivatives of acetylacetone with ketone groups at the central sulfur atom were obtained by soft hydrolysis of boron complexes. [ABSTRACT FROM PUBLISHER]

The binding properties of the adsorption of five different classes of amino acids, namely, alanine (Ala), arginine (Arg), asparagine (Asn), histidine (His) and cysteine (Cys) on the surface of the graphene (Gra) and the born-nitride (BN) nano-sheet structures were studied from molecular viewpoint using quantum mechanics methods. Density functional theory (DFT) and DFT-D3 calculations were carried out to investigate the electronic properties and the dispersion interaction of the amino acid/adsorbent complexes. Several parameters affecting the interactions between the amino acids and the adsorbent surfaces such as solvent effect, adsorption energy and separation distance were investigated. Findings show that Arg forms the most stable complexes with the graphene and the BN nano-sheet compare to the other amino acids used in this study. The observed frequency results which were related to the band gap energies were consistent with the above statement. Results exhibit that adsorption of the amino acids on the surface of the BN nano-sheet and the graphene accompanied with the release of the energy. Calculations show that there are no bonded interactions between the amino acids and adsorbent surfaces. The polarity of the BN nano-sheet provides the more affinity towards the amino acids. These results were proved by the quantum chemistry studies. [ABSTRACT FROM AUTHOR]

Li47B3P14N42, the first lithium nitridoborophosphate, is synthesized by two different routes using a Li3N flux enabling a complete structure determination by single-crystal X-ray diffraction data. Li47B3P14N42 comprises three different complex anions: a cyclic [P3N9]12−, an adamantane-like [P4N10]10−, and the novel anion [P3B3N13]15−. [P3B3N13]15− is the first species with condensed B/N and P/N substructures. Rietveld refinement, 6Li, 7Li, 11B, and 31P solid-state NMR spectroscopy, FTIR spectroscopy, EDX measurements, and elemental analyses correspond well with the structure model from single-crystal XRD. To confirm the mobility of Li+ ions, their possible migration pathways were evaluated and the temperature-dependent conductivity was determined by impedance spectroscopy. With the Li3N flux route we gained access to a new class of lithium nitridoborophosphates, which could have a great potential for unprecedented anion topologies with interesting properties. [ABSTRACT FROM AUTHOR]

The unique glycan-binding ability of chemically synthesized boronic acid derivatives makes them emerging candidates for developing anti-influenza A virus (IAV) drugs. Herein we report the synthesis and the anti-IAV activities of three series of novel boronic acid-modified quindoline derivatives both in vitro and in vivo. Boronic acid-modified compounds 6a and 7a effectively prevented the entry of virus RNP into the nucleus, reduced virus titers in IAV infected cells, and also inhibited the activity of viral neuraminidase. Compound 7a possessed broad antiviral spectrum and was able to inhibit cellular NF-κB and MAPK signaling pathways to block IAV infection. More importantly, IAV infected mice treated with compound 7a showed better survival rates than mice treated with oseltamivir, a popular anti-IAV drug. Thus, our study provides not only an antiviral preclinical candidate but also useful information for further research and development of boronic acid-modified anti-IAV drugs. [ABSTRACT FROM AUTHOR]

A small series of boron dipyrromethene (BODIPY) dyes has been synthesized whereby the boron atom is constrained in a five-membered ring formed from either o-dihydroxypyridine or o-aminophenol. In the latter case, the amino group has been converted into the corresponding amide derivative so as to curtail the possibility for light-induced charge transfer from strap to BODIPY. These compounds are weakly emissive in fluid solution but cleavage of the strap, by treatment with a photoacid generator, restores strong fluorescence. Surprisingly, the same compounds remain weakly fluorescent in a rigid glass at 80 K where light-induced charge transfer is most unlikely. In fluid solution, the fluorescence quantum yield increases with increasing temperature due to a thermally activated step but does not correlate with the thermodynamics for intramolecular charge transfer. It is proposed that the strap causes rupture of the potential energy surface for the excited state, creating traps that provide new routes by which the wave packet can return to the ground state. Access to the trap from the excited state is reversible, leading to the delayed emission. Analysis of the temperature dependent emission intensities allows estimation of the kinetic parameters associated with entering and leaving the trap. [ABSTRACT FROM AUTHOR]

Porphyrins and boron diketonates represent two well studied classes of compounds, and whose photophysical properties make them suitable for application in bioimaging, as photosensitizer agents, or as pH or ion sensors. Compounds that combine the optical properties of these two chromophores in a single molecule are not known. Herein, we report the synthesis and characterization of two porphyrin–boron diketonate dyads and their zinc complexes. Overall, the absorption and emission spectra of these dyads are dominated by the porphyrin core. The nature of the diketonate or the boron diketonate has little effect on the absorption and fluorescence profiles of the dyads, inducing small bathochromic shifts and a slight increase in the fluorescence quantum yield. [ABSTRACT FROM AUTHOR]

The development of an efficient method for the site-selective substitution of unprotected phenols has long been considered as an attractive but challenging task. Herein, we describe a highly chemo- and ortho-selective substitution reaction of phenols with α-aryl α-diazoacetates with commercially available (C6F5)3B as the catalyst. This reaction proceeds under simple and mild conditions with high efficiency, it features a wide substrate scope and can be easily scaled up. [ABSTRACT FROM AUTHOR]

Absorption electronic spectra, singlet-triplet energy gaps and spin–orbit matrix elements of thienopyrrole BODIPY derivatives, recently synthesized and proposed as potential photosensitizers in photodynamic therapy (PDT), have been computed by means of density functional theory (DFT) and time-dependent DFT approaches. A benchmark on structural parameters and maximum absorption wavelengths of different exchange-correlation functionals in combination with two basis set has been performed. The singlet-triplet energy gaps found are consistent with their possible application in PDT. The investigated molecules possess two excited triplet states (T 1 and T 2 ) that lie below and approximately at the same energy of the excited singlet one (S 1 ), respectively. Both the radiationless transitions between S 1 and triplet states contribute to the intersystem spin crossing efficiency, which in turn increases the production of singlet oxygen. Comparing their properties with those of agents currently used in PDT, one of them could be potentially used as photosensitizer for singlet oxygen production. [ABSTRACT FROM AUTHOR]

Three novel BODIPY-based heterodinuclear complexes, [salen(3,5-tBu)2Al-(OC6H4-BODIPY)] (6), [salen(3,5-tBu)2Al-(OC6F2H2-BODIPY)] (7), and [(mq)2Al-(OC6H4-BODIPY)] (8) (salen = N,N′-bis(salicylidene)ethylenediamine, BODIPY = 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene, and mq = methyl-8-quinolinolato) were prepared and characterized by multinuclear NMR spectroscopy. The specific structures of 6–8 were also determined by single crystal X-ray analysis. In particular, the salen-based heterodinuclear complexes 6 and 7 exhibited higher thermal stability (Td5 = 309 and 306 °C, respectively) than that of the closely related mononuclear aluminum or BODIPY compounds, except for 8. The UV/vis absorption and PL spectra for 6 and 7 indicated a significant photoinduced energy transfer from the aluminum–salen moiety to the BODIPY group in an intramolecular manner. Theoretical calculations revealed independent transition states of the aluminum–salen moiety or the BODIPY group in the AlIII–BODIPY dyads, further supporting these experimental results. [ABSTRACT FROM AUTHOR]

High resolution X-ray diffraction (HRXRD) and Photoluminescence (PL) spectroscopies have been utilized to achieve structural and optical BInGaAs/GaAs quantum well properties, grown by metal organic vapor phase epitaxy (MOVPE). A significant fraction of indium (36% and 46%) has been incorporated into BGaAs which show that a B x In y Ga 1-x-y As can be grown lattice matched to GaAs. At room temperature PL energy emission is at 1.19 eV for lower indium composition and 1.14 eV for the higher. It has been revealed that the PL band shifts significantly to low energy side to 50 meV with increasing indium solid composition. This confirms that the BInGaAs semiconductor material is well suited for active cell layers in multi-junction solar emitting near 1.1 eV. [ABSTRACT FROM AUTHOR]

By introducing triarylamino and dimesitylboron groups into fluorene derivatives, two symmetric compounds 2,7-bis(dimesitylboryl)-9,9-spirobifluorene (SFMB) and 2,7-bis(dimesitylboryl)-9,9-bis(4-diphenylaminophenyl)fluorene (PAFMB) were prepared. SFMB and PAFMB exhibited solvatochromism in the different polarities of solvents. Devices A1, A2, A3 and A4 based on SFMB displayed emissions at 444, 448, 528, and 444 nm with current efficiencies of 1.06, 1.41, 0.84, and 1.52 cd/A, respectively. The blue light was close to the National Television Standards Committee standard blue color ( x = 0.14, y = 0.08). Devices B1, B2, B3 and B4 based on PAFMB emitted lights centered at 484, 472, 513 and 472 nm, their current efficiencies were 1.80, 0.1, 1.23 and 1.93 cd/A, respectively. The results demonstrated that SFMB and PAFMB were multifunctional materials acted as emitters, and hole- and electron-transporting materials. [ABSTRACT FROM AUTHOR]

We designed a “turn-on” type fluorescent probe based on a BODIPY–pyridine conjugate which exhibits high selectivity towards Au(iii) ions and, also responds to changes in the pH within the acidic pH range. The probe offers features such as a rapid response time, a low detection limit, and high sensitivity and selectivity. The detection of Au(iii) is recognized by a distinct change in the emission intensity which relies on a reversible “ligand to ion” binding mechanism. We also document the utility of the probe for the quantification of gold ion residues in synthetic end products prepared via gold catalysis. [ABSTRACT FROM AUTHOR]

In this work, a series of novel nitric oxide (NO) probes and the corresponding reaction products are designed based on boron dipyrromethene (BODIPY) and heteroaryl-fused BODIPY or 3,5-distyryl substituted BODIPY (KFL). Furthermore, the mechanism of recognizing NO controlled by intramolecular photoinduced electron transfer (PET) is verified by theoretical chemistry computation in this work. More importantly, the two-photon absorption properties of these novel chromophores are explored by using DALTON program. The results of our study show that the two-photon absorption cross sections of the designed molecules are as large as 1056.9–39702.5 GM with the wavelengths ranging from 700 to 850 nm, especially for KFLs based on the 3,5-distyryl substituted BODIPY core, which have more potential for applications in two-photon absorption fluorescence imaging with larger two-photon absorption cross sections in the near-infrared region, because of their better rigidity and π-conjugation that are more conducive to intramolecular charge transfer. Finally, this work presents structure modification strategies for increasing two-photon response. We hope the study can provide helpful information for further investigating two-photon NO probes. [ABSTRACT FROM AUTHOR]

Apart from external environmental factors, we herein show with ultra-violet photoemission spectroscopy (UPS) studies that degradation in organic photovoltaic (OPV) devices can also be caused by internal deterioration of the donor/acceptor interface. Albeit with impressive initial open circuit voltage (Voc), boron subphthalocyanine chloride (SubPc)/fullerene (C 60 ) device shows a fast Voc decade upon operation. UPS results show that the energy offset between the highest occupied molecular orbit (HOMO) of SubPc and the lowest unoccupied molecular orbit (LUMO) of C 60 is reduced from 1.66 to 1.45 eV after aging in ultra-high vacuum (UHV) condition. This result is consistent with the change in built-in voltage of the corresponding device upon operation. The related charge interaction and degradation mechanism in the SubPc/C 60 device are discussed. [ABSTRACT FROM AUTHOR]

Boron-neutron capture therapy (BNCT) is a binary anticancer therapy that requires boron compound for nuclear reaction during which high energy alpha particles and lithium nuclei are formed. Unnatural, boron-containing nucleoside with hydrophobic pinacol moiety was investigated as a potential BNCT boron delivery agent. Biological properties of this compound are presented for the first time and prove that boron nucleoside has low cytotoxicity and that observed apoptotic effects suggest alteration of important functions of cancer cells. Mass spectrometry analysis of DNA from cancer cells proved that boron nucleoside is inserted into nucleic acids as a functional nucleotide derivative. NMR studies present very high degree of similarity of natural dG–dC base pair with dG–boron nucleoside system. [ABSTRACT FROM AUTHOR]

NHC-B,N-heterocyclic compounds have been found to act as convenient precursors for obtaining either 1,3-azaborinine or 1 H-imidazo[1,2-a]indole derivatives, which are two different and rare classes of compounds. The formation of these two classes of compounds from the NHC-B,N-heterocycles is highly selective depending on the external stimuli employed, and the resulting products have been studied for their interesting chemical and photophysical properties. The mechanism and possible reaction pathways of the unusual transformation are established by computational studies. [ABSTRACT FROM AUTHOR]

BODIPY derivatives showing a strong variation in photoluminescence quantum yield in solvents of different polarity were prepared. Further elaboration of these compounds with dithiacrown ether substituents provides additional Hg2+ and Pb2+ sensing functionality. [ABSTRACT FROM AUTHOR]

Boroxines have emerged as an important class of compounds with diverse applications in many fields. However, there are limited experimental and/or computational structural and thermal data available for these compounds or for their corresponding boronic acids. In this investigation, we report structural parameters for a variety of aliphatic monosubstituted boroxines (RHBO) and their enthalpies of formation via the dehydration reactions from the boronic acids (R-B(OH)), i.e., R-B(OH) + 2H-B(OH) → RHBO + 3HO. Equilibrium geometries of all the boronic acids and monosubstituted boroxines involved in this article were obtained using second-order Møller-Plesset perturbation theory with the Dunning-Woon aug-cc-pVDZ and aug-cc-pVTZ basis sets; heats of formation were calculated at the G3 level of theory. The specific substituents, R, include all the second- and third-period hydrides, as well as a selection of electron-donating/electron-withdrawing groups. [ABSTRACT FROM AUTHOR]

The three-component Petasis borono-Mannich reaction starting with easily accessible N-protected α-amino aldehydes produces efficiently and diastereoselectively 1,2-trans-diamines with an enantiomeric excess of up to 98%. [ABSTRACT FROM AUTHOR]

The article discusses the physicochemical properties of benzoxaboroles which is a derivatives of boronic acids. It mentions the structure, methods of synthesis, properties and fields of application of benzoxaboroles. It notes the medicinal application, acidic properties, and synthetic utility of benzoxaboroles.

A molecular dyad, comprising two disparate extended boron dipyrromethene (BODIPY) units, has been identified as a potential component of artificial light-harvesting arrays. Highly efficient, intramolecular electronic energy transfer takes place under illumination but there is some competition from light-induced electron transfer along the molecular axis. The primary energy acceptor has a somewhat shortened excited-state lifetime and reduced emission quantum yield due to charge transfer from a terminal amine residue, the latter being required for the molecular system to operate in organic solar cells. Under continuous illumination with simulated solar light, the dyad undergoes very slow decomposition. In a protic solvent, both BODIPY units degrade at the same rate via an autocatalytic process. The products, one of which is a protonated analogue of the donor, degrade further by independent routes. In aprotic solvents or thin plastic films, the acceptor BODIPY dye absorbing at lowest energy undergoes photochemical degradation as above but the donor is much more stable under these conditions. At each stage of degradation, the molecule retains the ability to sensitize an amorphous silicon solar cell and the overall turnover number with respect to absorbed photons exceeds 10 million. The optical properties of the target compound nicely complement those of the solar cell and sensitization helps to avoid Staebler–Wronski photo-degradation. [ABSTRACT FROM AUTHOR]

A new series of Schiff base ligands (L 1 –L 3 ) and their corresponding fluorine/phenyl boron hybrid complexes [L n BF 2 ] and [L n BPh 2 ] ( n = 1, 2 or 3) have been synthesized and well characterized by both analytical and spectroscopic methods. The Schiff base ligands and their corresponding fluorine/phenyl boron hybrid complexes have been characterized by NMR ( 1 H, 13 C and 19 F), FT-IR, UV–Vis, LC–MS, and fluorescence spectroscopy as well as melting point and elemental analysis. The fluorescence efficiencies of phenyl chelate complexes are greatly red-shifted compared to those of the fluorine chelate analogs based on the same ligands, presumably due to the large steric hindrance and hard π → π ∗ transition of the diphenyl boron chelation, which can effectively prevent molecular aggregation. The boron hybrid complexes were applied to the transfer hydrogenation of acetophenone derivatives to 1-phenylethanol derivatives in the presence of 2-propanol as the hydrogen source. The catalytic studies showed that boron hybrid complexes are good catalytic precursors for transfer hydrogenation of aromatic ketones in 0.1 M iso -PrOH solution. Also, we have found that both steric and electronic factors have a significant impact on the catalytic properties of this class of molecules. [ABSTRACT FROM AUTHOR]

Photo-crosslinking agents have emerged as critical tools to investigate protein–protein interactions in complex proteomes, but there are few photocrosslinkers available at the moment. Here, we report the first rational design of a photo-crosslinking BODIPY fluorophore (pcBD) and its biological application for biomolecule labeling. As a photosensitizing functional motif, an aryl ketone group was incorporated into the BODIPY fluorophore, and a series of proteins were labeled by pcBD compounds upon UV irradiation. In order to investigate protein–protein interactions in a protein mixture, amino-functionalized pcBD was prepared and covalently attached to a ubiquitin ligase binding peptide. Upon UV irradiation, we could successfully visualize the substrates in the total lysate. These results provided a proof of concept for spatially controllable tagging via photo-activation of the pcBD scaffold, and demonstrated its potential usage for in situ labeling applications. [ABSTRACT FROM AUTHOR]

Alkali metal tricyanoborates M2B(CN)3 (M = Na, K) are accessible by the reaction of tricyanofluoroborates with alkali metals (i) in liquid NH3 or (ii) in THF–naphthalene. The M2B(CN)3 are versatile starting materials for the synthesis of K[RB(CN)3] (R = Et, C6F5, CH2=CHCH2). [ABSTRACT FROM AUTHOR]

The switchable second-order nonlinear optical properties of a series of dithienylethene-containing boron compounds possessing reversible photochromic behavior have been systemically investigated based on density functional theory. The significant differences on the static first hyperpolarizabilities caused by the photoisomerization reaction confirm the switchable nonlinear optical behavior. Results show that the closed-ring 1c- 4c possess large static first hyperpolarizabilitieswith respect to their corresponding open-ring 1o- 4o, which is due to the better π-conjugation and a more obvious degree of charge transfer. Specifically, the static first hyperpolarizability values increase in the range of 2.4-5.2 times with the strengthening electron-withdrawing ability of the substituent R (R = H, CF3, NO2) on the pyridine and elongating the conjugated chains. It indicates that introducing boron-based functional groups to the dithienylethene monomer and modifying the pyridine ring can effectively improve the switching nonlinear optical responses. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of the cationic mixed metal Ga/Zn cluster [Zn2(GaCp*)6]2+ (1) is presented. The reaction of [Zn2Cp*2] with [Ga2Cp*][BAr4F] leads to the formation of the novel complex being the first example of a [Zn2]2+ core exclusively ligated by metalloid group-13 organyl-ligands. Compound 1 exhibits two different coordination modes: In the solid state, two of the six GaCp* ligands occupy bridging positions, whereas VT ¹H NMR indicates the coexistence of a second isomer in solution featuring six terminal GaCp* ligands. Quantum chemical calculations have been carried out to assign the gallium and zinc positions; the bonding situation in 1 is characterized and the importance of dispersion forces is discussed. [ABSTRACT FROM AUTHOR]

An amine-embedded flexible alkyl strap has been incorporated into an emissive boryl-substituted dithienylpyrrole skeleton as a new entity of excited-state intramolecular proton transfer (ESIPT) chromophores. The p-electron system shows a dual emission, which covers a wide range of the visible region depending on the solvent polarity. The incorporation of the aminoalkyl strap as well as the terminal boryl groups efficiently stabilize the zwitterionic excited-state species resulting from the ESIPT even in an aqueous medium. [ABSTRACT FROM AUTHOR]

A borinic acid derived catalyst enablesregioselective and β-selectivereactions of 2-deoxy- and 2,6-dideoxyglycosyl chloride donors withpyranoside-derived acceptors having unprotected cis-1,2- and 1,3-diol groups. The use of catalysis to promote a β-selectivepathway by enhancement of acceptor nucleophilicity constitutes a distinctapproach from previous work, which has been aimed at modulating donorreactivity by variation of protective and/or leaving groups. [ABSTRACT FROM AUTHOR]

A simple 4-aniline boron-dipyrromethene (BODIPY) dye (1) was developed as a highly sensitive acidic pH fluorescent probe excitable with visible light based on a photoinduced electron transfer (PeT) mechanism. The pH titration indicates that the fluorescence intensity increases more than 500-fold within the pH range of 4.12-1.42 with a pKa value of 3.24 in methanol-water (1 : 1, v/v) solution, which is valuable for studying strongly acidic conditions. Density functional theory (DFT) calculations reproduce the fluorescence off-on behavior. 1 has also been used as a fluorescent chemosensor for the visual detection of dissolved carbon dioxide (CO2) gas. The underlying mechanism of the sensing process is rationalized. This probe can be recovered by bubbling nitrogen (N2) gas into CO2-treated solutions for over 10 cycles. In addition, two logic gates (OR and INH) have been achieved at the molecular level by changing the initial states of system 1 and chemical inputs. [ABSTRACT FROM AUTHOR]

The antenna process from an energy donor (BODIPY; 4',4'-difluoro-1',3',5',7'-tetramethyl-4'-bora-3a',4a'-diaza-s-indacene) in its singlet state to two acceptors (two zinc(II) 5,15-p-tolyl-10-phenylporphyrin) bridged by a central truxene residue (5',5'',10',10'',15',15''-hexabutyltruxene), 5, has been analysed by means of comparison of the energy transfer rates with those of a structurally similar β-substituted BODIPY-(zinc(II) 5,10,15-p-tolyl-porphyrin), 6, where no conjugation is present between the donor and the two acceptors using the Förster resonance energy transfer (FRET) approximation. It is estimated that the energy transfer in 5 operates mostly via a Dexter mechanism (>99%), and the remaining proceeds via a Förster mechanism (<1%). This information is useful for the design of future molecular devices aimed at harvesting light. [ABSTRACT FROM AUTHOR]

Abstract: A series of substituted 2-hydroxysalicylidine benzohydrazides were converted into their phenyl-boron complexes in good yields upon reaction with phenylboronic acid. All new compounds were characterized by NMR, UV, IR, spectroscopy and mass spectrometry. The X-ray structures of two complexes demonstrate that the boron atoms adopt a tetrahedral geometry. The 11B NMR chemical shifts of the boron atom in the complexes are also consistent with the presence of tetracoordinate boron centres. The photophysical properties of the free benzohydrazide ligands and their boron complexes have been determined and display quantum yields below 1% with lifetimes in the range 10−10–10−11 s. [Copyright &y& Elsevier]

Eine solide Grundlage: 2 ‐ Boryl ‐ 1,3 ‐ butadiene mit verschiedenen Substitutionsmustern wurden in guten bis hohen Ausbeuten in einer Kupfer ‐ katalysierten Borylierung von α ‐ Alkoxyallenen mit Bis(pinakolato)dibor gebildet (siehe Schema; Bn=Benzyl, pin=Pinakolat, L ist ein N ‐ heterocyclisches Carben). Die Produkte sind nützliche Zwischenstufen für die Synthese von cyclischen Vinylboranen, α,β ‐ ungesättigten Ketonen und funktionalisierten mehrfach substituierten Dienen. [ABSTRACT FROM AUTHOR]

Abstract: Density functional theory predicts the chemistry of the binuclear cyclopentadienylrhodium boronyls Cp2Rh2(BO) n (n =4, 3, 2) derivatives to be considerably more complicated than that of the related cyclopentadienylrhodium carbonyls Cp2Rh2(CO) n owing to the greater variety of BO coordination modes in energetically competitive structures. In this connection, the Cp2Rh2(BO) n structures resemble to a certain extent the previously studied isoelectronic cyanide complexes Cp2Rh2(CN) n . All of the energetically low-lying Cp2Rh2(BO) n structures prefer coaxial geometries with terminal Cp rings and bridging BO groups. By considering the bridging BO groups as neutral ligands, both one-electron donor bridging μ-BO groups bonded to the Rh atoms exclusively through their B atoms and three-electron donor η2–μ-BO groups bonded to the Rh atoms through both their B and O atoms are found in low energy structures. The three-electron donor bridging η2-μ-BO groups exhibit longer B–O distances and lower ν(BO) frequencies than their one-electron donor bridging μ-BO counterparts. The thermodynamic stabilities predicted for the binuclear Cp2Rh2(BO) n derivatives suggest them as possible synthetic objectives. [Copyright &y& Elsevier]

Wehave successfully identified one new inhibitor and one new fluorescentrecognition agent for the botulinum neurotoxin subtype A (BoNT/A)using the virtual screening protocol “protein scanning withvirtual ligand screening” (PSVLS). Hit selection used an in-housedeveloped holistic binding scoring method. Selected hits were testedexperimentally for inhibitory activity using fluorescence resonanceenergy transfer (FRET) assays against the light chain (catalytic domain)of BoNT/A. Ligand binding was determined against the light and heavychain BoNT/A complex through either radiolabeled ligand binding assays(nonfluorescent ligands) or fluorescence intensity assays (fluorescentligands). These experimental assays have confirmed one compound (paclitaxel)to inhibit BoNT/A’s proteolytic activity experimentally withan IC50of 5.2 μM. A fluorescent derivative was alsoconfirmed to bind to the toxin and therefore is a suitable candidatefor the rational design of new detection agents and for the developmentof fluorescence-based multiprobe detection assays. [ABSTRACT FROM AUTHOR]

Abstract: A series of boron dipyrromethene derivatives bearing an electron-donating 4-(dimethylamino)phenylethynyl group and an electron-withdrawing 4-nitrophenylethynyl group in the opposite 2- and 6-positions have been synthesized by Knoevenagel condensation followed by sequential Sonogashira coupling reactions. The compounds have been fully characterized with various spectroscopic methods. Their electrochemical properties have also been studied by cyclic voltammetry in CH2Cl2. It has been found that expansion of the π systems by introduction of the 4-dodecyloxystyryl or 4-(dimethylamino)phenylethynyl group results in lowering of the first oxidation potential, while the first reduction potential remains relatively unaffected. The second-order nonlinear optical properties of these compounds have also been studied by electric-field-induced second-harmonic generation method in CHCl3. The values of the dot product μ·β are in the range from 94×10−48 to 330×10−48 esu at 1907nm, depending the substituents at the 3- and 5-positions. [Copyright &y& Elsevier]

The readily prepared borenium salt [(IiPr2)(BC8H14)][B(C6F5)4] (2) [IiPr2= C3H2(NiPr)2] is shown to activate H2 heterolytically in the presence of tBu3P. Compound 2 also acts as a catalyst for the metal-free hydrogenation of imines and enamines at room temperature. [ABSTRACT FROM AUTHOR]

Abstract: A simple BODIPY derivative is demonstrated to fluorescently sense Hg2+ in a ratiometric manner. The probe, an 8-methylthio-BODIPY, undergoes Hg2+-promoted hydrolysis to produce the corresponding 8-hydroxy-BODIPY, which conversion is accompanied with a large emission wavelength change. The probe can selectively detect Hg2+ over various other metal cations, with a detection limit of 1 ppb. [Copyright &y& Elsevier]

Reactions of secondary amines, aldehydes, and ketene silyl acetals were efficiently promoted by catalytic amounts of diarylborinic acid esters, Ar2B(OR), affording β-amino esters selectively with no formation of the corresponding β-hydroxy esters. [ABSTRACT FROM AUTHOR]

Thetotal synthesis of (−)-goniomitine has been accomplishedin 11 steps starting from commercially available diethyl l-malate. The synthesis features a chiral pool approach to preparethe chiral C-9 unit containing a quaternary carbon center, an Ir-catalyzedC–H borylation to synthesize the 2-indoleboronic acid pinacolester, and a Suzuki reaction to couple together the two key intermediates.Notably, the high degree of convergence of this strategy makes itparticularly amenable to the total synthesis of other aspidospermafamily natural products. [ABSTRACT FROM AUTHOR]

A novel access to allylic boronates is described. [ABSTRACT FROM AUTHOR]

The adsorption of small molecules (NH3, N2, H2 and CH4) on all-boron fullerene B40 is investigated by density functional theory (DFT) and the non-equilibrium Green’s function (NEGF) for its potential application in the field of single-molecular gas sensors. The high adsorption energies (−1.09 to −0.75 eV) of NH3 on different adsorption sites of the B40 surface indicate that NH3 strongly chemisorbs to B40. The charge transfer induced by the NH3 adsorption results in a modification of the density of states (DOS) of B40 near the Fermi level, and therefore changes its electronic transport properties. For all possible adsorption sites, the adsorption of NH3 exclusively leads to a decrease of the conductance of B40. Taking into consideration that the non-polar gas molecules (e.g. N2, H2 and CH4) are only physisorbed and show negligible effect on the conductance properties of B40, we would expect that B40 can be used as a single-molecular gas sensor to distinguish NH3 from non-polar gas molecules at low bias. [ABSTRACT FROM AUTHOR]

Review: 8 refs. [ABSTRACT FROM AUTHOR]