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Boron was introduced into carbon papers (CPs) to catalyze their graphitization in this paper. The results showed the graphitization of CPs was moved from 2400 °C to 2100 °C. At 2100 °C, boron substituted carbon atoms in the hexagonal carbon lattices to form a solid solution, and the catalytic mechanism was dissolution and precipitation. CPs with excellent electrical conductivity and good permeability were prepared at lower temperature. Thus, the boron-doping method provides a new way to prepare high performance CPs at lower costs.

The development of greatly stable and cost-effective electrocatalysts for urea electro-oxidation reactions (UERs) is urgent and challenging for promoting urea removal in the wastewater and advanced energy conversion devices. We demonstrated that nickel-iron borate (NiFe-B) electrocatalysts supported on carbon paper (CP) for UERs through a one-pot solvothermal method. NiFe-B electrocatalysts were obtained with numerous Ni/Fe molar ratios in the precursors, and the physicochemical features of the NiFe-B were examined by X-ray diffraction, scanning and transmission electron microscope, and X-ray photoelectron spectroscopy. The optimized NiFe-B/CP exhibited a low onset potential (Eonset = 0.287 V vs. SCE) with a Tafel slope of 27.9 mV/dec on CP, demonstrating much greater performance UERs. Furthermore, the NiFe-B/CP catalysts have shown a superior activity for the UERs in alkaline solution and exhibit more than two-fold enhancement in activity than Ni-B. Facile, cost-effective fabrication and highly efficient urea oxidation create the NiFe-B electrodes as attractive materials for UERs.

Four flame retardants and styrene-acrylic latex were used to make flame-retardant air filter paper via emulsion impregnation. The compositions and flame retardant mechanism of the flame retardants were investigated by using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The flame retardance of air filter paper was evaluated using TGA and limiting oxygen index (LOI) meter, and the physical properties and pore structure of the flame-retardant air filter paper were measured using stiffness tester, burst tester, and aperture analyzer. The results showed that the optimal ratio of flame retardant to styrene-acrylic latex was 1:1.4. The synergistic effect of boron, phosphorus and nitrogen made FR3 have good flame-retardant effect on air filter paper. Air filter paper with FR3 also had good physical strength and suitable pore size distribution.

It is important to remove excessive concentrations of boric acid from water because it can lead to environmental problems. However, current adsorbents are limited in separating boric acid from water due to their low desorption capability and poor selectivity for boric acid. In this study, the authors developed a functional cellulosic paper via crosslinking cellulose and tannic acid with chitosan to efficiently and reversibly remove boric acid from water. The adsorption capacity reached 769 mg/m2 according to the Langmuir model. The corresponding desorption rate of the chitosan/tannic acid-modified paper exceeded 80% in the whole flow rate region ranging from 15 to 250 mL/h. The reversible adsorption and desorption of boric acid were attributed to the formation and dissociation of the borate bond between the tannic acid and boric acid, respectively, at different pH values. This study improved the selectivity, batch adsorption, expensive carriers, and desorption difficulties of existing boric acid adsorption materials. This approach offers a new way to design highly efficient adsorption/desorption materials by constructing reversible chemical bonds for removal of other pollutants.

For the emission gas concentration measurement of sublimable gas phase boron compounds, the optimal collector material applied to the inside stack sampler (the type-I stack sampler developed in our previous article) was examined. The collection efficiency of alkali impregnated filter paper of K2CO3, Na2CO3, LiOH and Ba(OH)2 was investigated by using artificial stack.It was revealed that K2CO3 and Na2CO3 filter papers have a high collection efficiency and fully applicable to the type-I stack sampler. However, LiOH and Ba(OH)2 filter papers have a restricted range of applicable condition.

NaY zeolite-containing ceramic papers were prepared by a papermaking technique with a dual polyelectrolyte retention system that implied the use of cationic and anionic polymers. To improve their mechanical properties, we found that some borate compounds could be successfully used as ceramic binders. Three types of sodium and/or calcium borates were tested as binders: colemanite, nobleite, and anhydrous ulexite. The improvement in the mechanical properties depends both on the borate used and on the calcination temperature. By XRD it was determined that the faujasite structure collapsed after calcination at 700°C, which limited the final calcination temperature of zeolitic ceramic papers. Different amounts of NaY zeolite were added to ceramic papers and, as observed by SEM, faujasite particles were well distributed throughout the ceramic paper structure. Ceramic papers containing 1.2 wt.% zeolite after calcination at 650°C resulted in structured catalysts that were easy-to-handle, and which can be adapted to different conformations.

A new screening technique for tolerance to high concentrations of boron, namely a filter paper technique, and a soil experiment were compared to investigate the response of wheat genotypes known to differ in tolerance to high concentrations of boron. Under high boron concentrations in filter papers, the more tolerant genotypes had significantly longer roots than those of the more sensitive genotypes. There was no significant correlation between the root lengths at the control treatment and the other three boron treatments (50, 100, 150 mg B L-1). Thus, the differences in root lengths at the high boron treatments could not be attributed to inherent differences in root growth but to the genetic variation in response to high boron concentrations among varieties. Root lengths at the three boron treatments in filter papers were highly significantly correlated with the three characters determined for plants grown in soil containing high levels of boron, namely the concentrations of boron in the shoots, plant dry weight and plant symptoms, indicating that root length could be used as a selection criterion in a genetic study or breeding program for boron tolerance.

Science of The Total Environment, 447, ISSN:0048-9697, ISSN:1879-1026

This paper presents a novel boron diffusion process using boron paper as the boron source to form a p+ layer. It was found that sheet resistance was invariable with changing the distance between boron paper and Si wafers, and diffusion uniformity was the best at a distance of 0.3 cm. Sheet resistance (Rs) decreased with increasing diffusion temperature, showing a value of 6.9 ?/ at 1050 ?C with a high diffusion uniformity of 99.173%. The junction depth increased from 195 nm to 517 nm with diffusion temperature raised from 900 ?C to 1050 ?C. The influence of diffusion time on the performance of B diffusion from boron paper was similar with that of temperature.

This paper has the following key features. Systematic research on the many types of multicomponent (mainly ternary components) glass formation ranges, such as borate, silicate, germanate, vanadate and tellurite systems, revealed the conditions for multicomponent glass formation. Although the conditions for monocomponent glass formation identified by Zachariasen have been acknowledged since 1932, the conditions for multicomponent glass formation were not proposed at that time. Imaoka introduced general rules for the conditions of multicomponent glass formation on the basis of Zachariasen's rule. The adaptability of these conditions was confirmed by later research. Preciously, the glass formation probability of arbitrary compositions had only been judged by the melting method, but the application of general rules by Imaoka allowed predictions for glass formation possible without experimentation, and this allowed tremendous time savings during the planning of glass compositions.The establishment of multicomponent glass forming conditions clarified, to a certain extent, the relationship between the glass compositions and the glass structure. Therefore, the multicomponent glass forming conditions have been extremely useful in research on material design to predict the relationship between physical properties and the glass structure. Thus, it is now possible to target the research objectives more precisely and save considerable research time. Although not all commercial glass components can be judged by the conditions examined in this study, it is considered to be a reasonable reference for the discussion of commercial glass components.The above-mentioned features have contributed enormously to the research and technological development of glass.

[7,7-(PMe 2 Ph) 2 -9-( η 6 - iso PrC 6 H 4 Me)-7,9-PtRuB 9 H 11 ] has a formal closo Wadian cluster-electron count, but a nido geometry, whereas [1-( η 6 - iso PrC 6 H 4 Me)-4,4-(PMe 2 Ph) 2 -1-4-RuPtB 9 H 9 ], which does have a closo geometry, has a formal sub- closo cluster electron count; both compounds are formed in the reaction between [6-( η 6 - iso PrC 6 H 4 Me)- nido -6 RuB 9 H 13 ], KH and [PtCl 2 (PMe 2 Ph) 2 ].

In this study, effects of KBH4 (PB), NaBH4 (SB), Etibor-48 (E48), Etidot-67 (E67), and colemanite (Col) on kraft pulp and paper properties of Scots pine (Pinus sylvestris L.) wood were evaluated. The control and boron compound-added kraft pulps were obtained under constant cooking conditions. The boron compounds were used as digester additives in different ratios (2 % and 4 %). The addition of boron compounds to kraft cooking liquor resulted in increases screened and total yield of pulps. The highest screened yield (52.05 %) and total yield (55.09 %) were obtained from PB-4 pulp. The lowest reject ratio (0.61 %) and kappa number (34.60) were determined from PB-2 pulp. Furthermore, the highest tensile properties of handsheets were obtained from E67-4 pulp. Also, E48-4 pulp had the highest burst index and tear index values. E48, E67, and Col are cheaper than PB and SB. From these boron compounds, pulps with relatively low pulp yield but stronger can be obtained. © 2023 by the author(s).

Several boron compounds with 2‐(imidazo[1,5‐a]pyridin‐3‐yl)phenols, differentiated by the nature of the substituent (R) in the para position of the hydroxy group, have been synthesized and thoroughly characterized both in solution (1H, 13C, 11B, 19F NMR) and in the solid state (X‐ray). All derivatives displayed attractive photophysical properties like very high Stokes shift, high fluorescence quantum yields and a good photostability in solution. Time‐Dependent Density Functional Theory (TD‐DFT) calculations allowed to define the main electronic transitions as intra ligand transitions (1ILT), which was corroborated by the Natural Transition Orbitals (NTOs) shapes. The homo‐lumo energy gap was correlated to the electronic properties of the substituent R on the phenolic ring, as quantified by its σp Hammett constant., Blue emissive materials: boron containing fluorescent compounds have been prepared starting from imidazo[1,5‐a]pyridine phenols. Large Stokes shift, high absolute quantum yields and good photostability are observed in solution. TD‐DFT calculations allowed to find a linear correlation between the HOMO‐LUMO energy gap of these compounds and the Hammett constants of substituents R para to the hydroxyl group of the phenols.

Boroles are attracting broad interest for their myriad and diverse applications, including in synthesis, small molecule activation and functional materials. Their properties and reactivity are closely linked to the cyclic conjugated diene system, which has been shown to participate in cycloaddition reactions, such as the Diels‐Alder reaction with alkynes. The reaction steps leading to boranorbornadienes, borepins and tricyclic boracyclohexenes from the thermal reaction of boroles with alkynes are seemingly well understood as judged from the literature. Herein, we question the long‐established mechanistic picture of pericyclic rearrangements by demonstrating that seven‐membered borepins (i. e., heptaphenylborepin and two derivatives substituted with a thienyl and chloride substituent on boron) exist in a dynamic equilibrium with the corresponding bicyclic boranorbornadienes, the direct Diels‐Alder products, but are not isolable products from the reactions. Heating gradually converts the isomeric mixtures into fluorescent tricyclic boracyclohexenes, the most stable isomers in the series. Results from mechanistic DFT calculations reveal that the tricyclic compounds derive from the boranorbornadienes and not the borepins, which were previously believed to be intermediates in purely pericyclic processes., New insights into the reactivity of perarylated boroles toward alkynes have been derived from both experimental and computational studies. It is shown that borepins (the formal alkyne insertion products) can readily isomerize to the thermodynamically more favorable boranorbornadienes (the formal Diels‐Alder products), thus obscuring the mechanism of product formation (see Figure). In addition, the fluorescent nature of the tricyclic boracyclohexenes, the most stable isomers of the addition reactions, has been investigated by absorption and emission spectroscopy.

A nickel/N‐heterocyclic carbene (NHC) catalytic system has been developed for the borylation of aryl sulfoxides with B2(neop)2 (neop=neopentyl glycolato). A wide range of aryl sulfoxides with different electronic and steric properties were converted into the corresponding arylboronic esters in good yields. The regioselective borylation of unsymmetric diaryl sulfoxides was also feasible leading to borylation of the sterically less encumbered aryl substituent. Competition experiments demonstrated that an electron‐deficient aryl moiety reacts preferentially. The origin of the selectivity in the Ni‐catalyzed borylation of electronically biased unsymmetrical diaryl sulfoxide lies in the oxidative addition step of the catalytic cycle, as oxidative addition of methoxyphenyl 4‐(trifluoromethyl)phenyl sulfoxide to the Ni(0) complex occurs selectively to give the structurally characterized complex trans‐[Ni(ICy)2(4‐CF3‐C6H4){(SO)‐4‐MeO‐C6H4}] 4. For complex 5, the isomer trans‐[Ni(ICy)2(C6H5)(OSC6H5)] 5‐I was structurally characterized in which the phenyl sulfinyl ligand is bound via the oxygen atom to nickel. In solution, the complex trans‐[Ni(ICy)2(C6H5)(OSC6H5)] 5‐I is in equilibrium with the S‐bonded isomer trans‐[Ni(ICy)2(C6H5)(SOC6H5)] 5, as shown by NMR spectroscopy. DFT calculations reveal that these isomers are separated by a mere 0.3 kJ/mol (M06/def2‐TZVP‐level of theory) and connected via a transition state trans‐[Ni(ICy)2(C6H5)(η2‐{SO}‐C6H5)], which lies only 10.8 kcal/mol above 5., A nickel/N‐heterocyclic carbene (NHC) catalytic system has been developed for the borylation of aryl sulfoxides with B2(neop)2 (neop=neopentyl glycolato). A wide range of aryl sulfoxides with different electronic and steric properties were converted into the corresponding arylboronic esters in good yields. Elucidation of key mechanistic features of this newly developed reaction led to the identification of fully characterized nickel intermediates.

Periodontitis is a disease that affects a wide group of people, and there has been an increased interest in the research of finding useful materials that help reduce inflammation and the further loss of tissue. In this study, we have tested a boron-containing compound (BCC) Calcium Fructoborate (CaFB) and Boric Acid (BA) hydrogels on the gingival level on Wistar rats. First, we have induced the periodontal disease at the lower incisors, we have applied the hydrogels and after a week, we have euthanized the rats. Next, the oral soft tissue reaction was clinically and then histologically investigated. Our study has shown good clinical response of the oral tissue, and we have noticed lower levels of inflammation on the experimental groups treated with the BCCs hydrogels. Despite the generally good response of the biological structures to the presence of BA and CaFB on periodontal level, more scientifically proved information is needed to obtain the desired biological responses in all clinical situations.

The boron atoms react with carbon monoxide and dinitrogen forming the end‐on bonded NNBCO complex in solid neon or in nitrogen matrices. The NNBCO complex rearranges to the (η 2‐N2)BCO isomer with a more activated side‐on bonded dinitrogen ligand upon visible light excitation. (η 2‐N2)BCO and its weakly CO‐coordinated complexes further isomerize to the NBNCO and B(NCO)2 molecules with N−N bond being completely cleaved under UV light irradiation. The geometries, energies and vibrational spectra of the molecules are calculated with quantum chemical methods and the electronic structures are analyzed with charge‐ and energy‐partitioning methods., CO‐induced dinitrogen fixation and cleavage mediated by boron atoms is reported. The experimental and theoretical results show that the N≡N activation processes proceed with the initial formation of an end‐on bonded NNBCO complex, which rearranges to the NBNCO and B(NCO)2 isocyanate complexes via a side‐on bonded (η2‐N2)BCO intermediate. The geometries, energies and vibrational spectra of the molecules are calculated with quantum chemical methods and the electronic structures are analyzed with charge‐ and energy‐partitioning methods.

This work describes the synthesis and coordination behavior of a new mixed‐donor ligand PhC(NtBu)2SiC6H4PPh2 (1) containing both silylene and phosphine donor sites. Ligand 1 was synthesized from a reaction of ortho‐lithiated diphenylphosphinobenzene (LiC6H4PPh2) with chlorosilylene (PhC(NtBu)2SiCl). Treatment of 1 with Se and GeCl2 resulted in SiIV compounds 2 and 3 by selective oxidation of the silylene donor. This strong σ‐donor ligand induces dissociation of CuCl and PhBCl2 leading to formation of ionic complexes 4 and 5 respectively. The reaction of 1 with ZnCl2 and AlCl3 resulted in the formation of chelate complexes 5 and 7, respectively, while treatment with EtAlCl2 and GaCl3 forms monodentate complexes 8 and 9. X‐ray analysis of 4 showed that the copper is in the spiro center of the two five‐membered rings. Moreover, the copper(I)chloride has not been oxidized but dissociates to Cu+ and [CuCl2]−. All the compounds are well characterized by mass spectrometry, elemental analysis, NMR spectroscopy, and single‐crystal X‐ray diffraction studies., A ligand with different Lewis base donor sites of phosphorus(III) and silicon(II). The ligands are arranged in 1,2‐position at the benzene ring to generate mainly five‐membered ring compounds containing a metal atom. The exceptions of the compounds show clearly that the metal is preferentially coordinated to the silylene atom rather than to the phosphane site of the ligand.

We have quantum chemically investigated the bonding between archetypical Lewis acids and bases. Our state‐of‐the‐art computations on the X3B−NY3 Lewis pairs have revealed the origin behind the systematic increase in B−N bond strength as X and Y are varied from F to Cl, Br, I, H. For H3B−NY3, the bonding trend is driven by the commonly accepted mechanism of donor−acceptor [HOMO(base)−LUMO(acid)] interaction. Interestingly, for X3B−NH3, the bonding mechanism is determined by the energy required to deform the BX3 to the pyramidal geometry it adopts in the adduct. Thus, Lewis acids that can more easily pyramidalize form stronger bonds with Lewis bases. The decrease in the strain energy of pyramidalization on going from BF3 to BI3 is directly caused by the weakening of the B−X bond strength, which stems primarily from the bonding in the plane of the molecule (σ‐like) and not in the π system, at variance with the currently accepted mechanism., That's strainful! The stability of Lewis pairs involving boron trihalides and ammonia is driven by the energy required to deform the Lewis acids upon complexation, while the stability of Lewis pairs between borane and nitrogen trihalides is determined by the strength of orbital interactions.

Three different perfluoroalkylated borafluorenes (F Bf) were prepared and their electronic and photophysical properties were investigated. The systems have four trifluoromethyl moieties on the borafluorene moiety as well as two trifluoromethyl groups at the ortho positions of their exo‐aryl moieties. They differ with regard to the para substituents on their exo‐aryl moieties, being a proton (F XylFBf, FXyl: 2,6‐bis(trifluoromethyl)phenyl), a trifluoromethyl group (F MesFBf, FMes: 2,4,6‐tris(trifluoromethyl)phenyl) or a dimethylamino group (p ‐NMe2‐FXylFBf, p‐NMe2‐FXyl: 4‐(dimethylamino)‐2,6‐bis(trifluoromethyl)phenyl), respectively. All derivatives exhibit extraordinarily low reduction potentials, comparable to those of perylenediimides. The most electron‐deficient derivative F MesFBf was also chemically reduced and its radical anion isolated and characterized. Furthermore, all compounds exhibit very long fluorescent lifetimes of about 250 ns up to 1.6 μs; however, the underlying mechanisms responsible for this differ. The donor‐substituted derivative p ‐NMe2‐FXylFBf exhibits thermally activated delayed fluorescence (TADF) from a charge‐transfer (CT) state, whereas the F MesFBf and F XylFBf borafluorenes exhibit only weakly allowed locally excited (LE) transitions due to their symmetry and low transition‐dipole moments., Having your cake and eating it too: Functionalization of 9‐borafluorenes with trifluoromethyl groups makes them exceptionally easy to reduce while maintaining excellent stability towards hydrolysis. The systems also exhibit long‐lived fluorescence or thermally activated delayed fluorescence (TADF) depending on the exo‐aryl para‐substituent.

The reaction of dioxygen with nitrenes can have significant energy barriers, although both reactants are triplet diradicals and the formation of nitroso‐O‐oxides is spin‐allowed. By means of matrix‐isolation infrared spectroscopy in solid argon, nitrogen, and neon, and through high‐level computational quantum chemistry, it is shown herein that a 3‐nitreno‐1,3,2‐benzodioxaborole CatBN (Cat=catecholato) reacts with dioxygen under cryogenic conditions thermally at temperatures as low as 7 K to produce two distinct products, an anti‐nitroso‐O‐oxide and a nitritoborane CatBONO. The computed barriers for the formation of nitroso‐O‐oxide isomers are very low. Whereas anti‐nitroso‐O‐oxide is kinetically trapped, its bisected isomer has a very low barrier for metathesis, yielding the CatBO+NO radicals in a strongly exothermic reaction; these radicals can combine under matrix‐isolation conditions to give nitritoborane CatBONO. The trapped isomer, anti‐nitroso‐O‐oxide, can form the nitritoborane CatBONO only after photoexcitation, possibly involving isomerization to the bisected isomer of anti‐nitroso‐O‐oxide., Overcoming barriers: The reaction of dioxygen with nitrenes can have significant energy barriers. The reaction mechanism of borylnitrene 1 is investigated through matrix‐isolation infrared spectroscopy and high‐level computational quantum chemistry. Borylnitrene 1 reacts with dioxygen to form nitritoborane 3 a via nitroso‐O‐oxide isomer 2 c. Nitroso‐O‐oxide isomer 2 a is stable towards thermal reaction to 3 a, but dyotropic rearrangement can be achieved photochemically.

The 1,3‐bis(tricyanoborane)imidazolate anion 1 was obtained in high yield from lithium imidazolate and B(CN)3−pyridine adduct. Anion 1 is chemically very robust and thus allowed the isolation of the corresponding H5O2 + salt. Furthermore, monoanion 1 served as starting species for the novel dianionic N‐heterocyclic carbene (NHC), 1,3‐bis(tricyanoborane)imidazoline‐2‐ylidenate anion 3 that acts as ditopic ligand via the carbene center and the cyano groups at boron. First reactions of this new NHC 3 with methyl iodide, elemental selenium, and [Ni(CO)4] led to the methylated imidazolate ion 4, the dianionic selenium adduct 5, and the dianionic nickel tricarbonyl complex 6. These NHC derivatives provide a first insight into the electronic and steric properties of the dianionic NHC 3. Especially the combination of properties, such as double negative charge, different coordination sites, large buried volume and good σ‐donor and π‐acceptor ability, make NHC 3 a unique and promising ligand and building block., Unprecedentedly stable salts of the 1,3‐bis(tricyanoborane)imidazolate ion with different types of counterions were obtained on large scale. Deprotonation of the imidazolate ion provided access to the corresponding dianionic NHC that acts as ditopic ligand.

The selective removal of Cs and Sr from high-activity-level water (HALW) has been studied by the use of various zeolites. The rate of adsorption of Cs and Sr increased with a decrease in size of zeolite particles, and the adsorption reached almost 100% after 5 h and 10 h of shaking for Cs and Sr, respectively. High distribution coefficients of Cs (K_=10^4～10^5) were obtained in the solution/zeolite ratio (V/m) region of about 300 to 1000. The presence of sodium ion fairly affected the distribution of Cs^+ and Sr^, and K_d values decreased with increasing concentration of Na^+. While the presence of boron almost had no effect on the distribution of Cs ; high K_ values (K_≧10^5) were obtained below 5000 ppm of boron. Distribution coefficients of Cs and Sr were also independent of the equilibrium pH in neutral and alkaline regions at the ionic strength of 0.1. The removal of Cs and Sr from simulated HALW was effectively achieved by the use of mixed zeolites, and the K_d value was 7.0×10^3ml/g at the mixing ratio of 48/52 of X/chabazite.

A series of group 13 complexes of the general type [{(WCA‐IDipp)EX3}Li(solv)] (E=B, Al, Ga, In; X=Cl, Br) that bear an anionic N‐heterocyclic carbene ligand with a weakly coordinating borate moiety (WCA‐IDipp, WCA=B(C6F5)3 and IDipp=1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene) were prepared by the reaction of the respective group 13 trihalides (EX3) with the lithium salt [(WCA‐IDipp)Li ⋅ toluene]. The molecular structures of the BBr3, AlCl3, AlBr3, GaCl3 and InCl3 adducts were established by X‐ray diffraction analyses, revealing the formation of coordination polymers linked by halide‐lithium interactions, except for the indium derivative, which consists of isolated [Li(THF)4]+ and [(WCA‐IDipp)InCl3]− ions in the solid state., Expanding the library: Several group 13 complexes of the type [((WCA‐IDipp)EX3)Li] (E=B, Al, Ga and In; X=Cl, Br) that bear anionic N‐heterocyclic carbene ligands with a weakly coordinating borate moiety were prepared.

Herein reported are the reactions of an electron‐rich, Lewis acidic diborane with N‐heterocyclic aromatics to give first members of an unprecedented family of highly charged cationic cyclophanes with diboranyl units. Tetracationic cyclophanes with 4,4‘‐bipyridine/ 1,2‐bis(4‐pyridyl)ethylene and diboranyl units were synthesized and their redox chemistry was studied. Cyclisation of two diboranyl and two pyrazine units is accompanied by electron transfer from the diboranyl unit to the pyrazine. Our results pave the way for the integration of redox‐active diboranyl units into cyclophanes and supramolecular structures., Electron‐Rich cyclophanes: Unprecedented, highly charged cyclophanes with diboranyl units are synthesized and their redox and optical properties studied.

Borosulfates provide fascinating structures and properties that go beyond a pure analogy to silicates. Mg3[H2O→B(SO4)3]2 is the first borosulfate featuring a boron atom solely coordinated by three tetrahedra. Thus, the free Lewis acidic site forms a Lewis acid–base adduct with a water molecule. This is unprecedented for borosulfate chemistry and even for borates. Quantum chemical calculations on water exchange reactions with BF3 and B(C6F5)3 revealed a higher Lewis acidity for the borosulfate anion. Moreover, proton exchange reactions showed a higher Brønsted acidity than comparable silicates or phosphates. Additionally, Mg3[H2O→B(SO4)3]2 was characterised by X‐ray diffraction, infrared spectroscopy, thermogravimetric analysis, and density functional theory (DFT) calculations., The ever‐expanding chemistry of borosulfates is enriched by the novel borosulfate Mg3[H2O→B(SO4)3]2 featuring an unprecedented Lewis acid–base adduct of water to the anion [B(SO4)3]3−. Isodesmic exchange calculations revealed high Lewis and Brønsted acidity, opening new insights and perspectives for this fascinating silicate‐analogous material class.

Access to dithiophene‐fused oxadiborepins and the first azadiborepins attained via a modular synthesis route are presented. The new compounds emit intense blue light, some of which demonstrate fluorescence quantum yields close to unity. Cyclic voltammetry (CV) revealed electrochemically reversible one‐electron reduction processes. The weak aromatic character of the novel 1,2,7‐azadiborepin ring is demonstrated with in‐depth theoretical investigations using nucleus‐independent chemical shift (NICS) scans and anisotropy of the induced current density (ACID) calculations., Dithienooxa‐ and ‐azadiborepins are accessible in a modular way from a common precursor. These BNB‐doped polycyclic aromatic hydrocarbons (PAHs) are highly efficient blue‐light emitters with quantum yields up to 96 %. In‐depth theoretical studies reveal that the previously unknown azadiborepin ring system is weakly aromatic.

Reactions of the diborane(4) B2(o‐tolyl)4 and monohydridoboranes are shown to give B(o‐tolyl)3 and (o‐tolyl)BR2 (R2=(C8H14) 3, cat 4, pin 5, (C6F5)2 6) as the major products. The corresponding reaction with BH3‐sources gives complex mixtures, resulting from hydride/aryl exchange, dimerization and borane elimination. This led to the isolation of the first tetra‐substituted pentaborane(9) HB[B(o‐tolyl)(μ‐H)]4 8. The reaction pathways are probed experimentally and by computations., The diborane(4) B2(o‐tolyl)4 reacts with species with B−H bonds giving a complex mixture arising from hydride/aryl exchange, dimerization and borane elimination. Use of BH3 sources led to the isolation of the first tetra‐substituted pentaborane(9) HB[B(o‐tolyl)(μ‐H)]4.

Boron reluctantly forms B=X (X=O, S, Se, Te) moieties, which has stimulated the quest for such species in the past few years. Based on the N,N′‐chelating β‐diketiminato ligand (HNacNac), a new amido imidazoline‐2‐imine ligand system (HAmIm) is presented, giving rise to the isolation of an exhaustive series of Lewis acid free, monomeric chalcogen B=X boranes with documented π‐bond character between boron and the chalcogen. The chalcogenoboranes are isoelectronic and isolobal to the respective ketones. The chemical behavior of the oxoborane (B=O) strongly resembles the classical carbonyl reactivity in C=O bonds. The improved stability provided by HAmIm arises from the formation of more‐stable five‐membered boron chelates versus the six‐membered NacNac analogues and from the imidazoline‐2‐imine moiety providing enhanced σ‐ and π‐donation. The HAmIm ligand class may supersede the widely employed NacNac system in certain applications., The new N,N′‐chelating amido imidazoline‐2‐imine ligand (HAmIm) was designed to supersede the widely employed β‐diketiminato ligand (HNacNac). The superior stability of the HAmIm system is exemplified for a series of chalcogenoboranes with confirmed B=X double bonds (X=O, S, Se, Te), which are isoelectronic and isolobal to ketones, including their heavier analogues.

The synthesis, photophysical, and electrochemical properties of selectively mono‐, bis‐ and tris‐dimethylamino‐ and trimethylammonium‐substituted bis‐triarylborane bithiophene chromophores are presented along with the water solubility and singlet oxygen sensitizing efficiency of the cationic compounds Cat1+ , Cat2+ , Cat(i)2+ , and Cat3+ . Comparison with the mono‐triarylboranes reveals the large influence of the bridging unit on the properties of the bis‐triarylboranes, especially those of the cationic compounds. Based on these preliminary investigations, the interactions of Cat1+ , Cat2+ , Cat(i)2+ , and Cat3+ with DNA, RNA, and DNApore were investigated in buffered solutions. The same compounds were investigated for their ability to enter and localize within organelles of human lung carcinoma (A549) and normal lung (WI38) cells showing that not only the number of charges but also their distribution over the chromophore influences interactions and staining properties., Four selectively mono ‐, bis ‐ and tris ‐trimethylammonium‐substituted, bithiophene‐bridged bis‐triarylboranes were synthesized and their potential biological applications were investigated including live cell imaging and photo‐induced cell death. It is demonstrated that their photophysical and electrochemical properties and their interactions with DNAs, RNA and cells, are strongly influenced by the number and distribution of charges within the compounds.