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[This corrects the article DOI: 10.1371/journal.pone.0273685.].[This corrects the article DOI: 10.1371/journal.pone.0273685.].

Crystalline borates have received great attention due to their various structures and wide applications. For a long time, the corner-sharing B–O unit is considered a basic rule in borate structural chemistry. The Dy[sub.4]B[sub.6]O[sub.15] synthesized under high-pressure is the first oxoborate with edge-sharing [BO[sub.4]] tetrahedra, while the KZnB[sub.3]O[sub.6] is the first ambient pressure borate with the edge-sharing [BO[sub.4]] tetrahedra. The edge-sharing connection modes greatly enrich the structural chemistry of borates and are expected to expand new applications in the future. In this review, we summarize the recent progress in crystalline borates with edge-sharing [BO[sub.4]] tetrahedra. We discuss the synthesis, fundamental building blocks, structural features, and possible applications of these edge-sharing borates. Finally, we also discuss the future perspectives in this field.

Rare earth europium(II) complexes based on d-f transition luminescence have characteristics of broad emission spectra, tunable emission colors and short excited state lifetimes, showing great potential in display, lighting and other fields. In this work, four complexes of Eu(II) and bis(pyrazolyl)borate ligands, where pyrazolyl stands for pyrazolyl, 3-methylpyrazolyl, 3,5-dimethylpyrazolyl or 3-trifluoromethylpyrazole, were designed and synthesized. Due to the varied steric hindrance of the ligands, different numbers of solvent molecules (tetrahydrofuran) are participated to saturate the coordination structure. These complexes showed blue-green to yellow emissions with maximum wavelength in the range of 490–560 nm, and short excited state lifetimes of 30–540 ns. Among them, the highest photoluminescence quantum yield can reach 100%. In addition, when the complexes were heated under vacuum or nitrogen atmosphere, they finally transformed into the complexes of Eu(II) and corresponding tri(pyrazolyl)borate ligands and sublimated away.

Imbibing watermelon seeds in 1 mM sodium tetraborate (Na[sub.2]B[sub.4]O[sub.7]) for 24 h systemically protected plants against foliar infection by Stagonosporopsis cucurbitacearum in detached leaves and under greenhouse conditions. The treatment resulted in both a reduction in the overall percentage of leaf infection as well as in the size of lesions. Studies of the mechanisms by which Na[sub.2]B[sub.4]O[sub.7] protected watermelon showed that there was no direct effect on the S. cucurbitacearum mycelium growth in vitro. On the other hand, plants raised from seeds primed with Na[sub.2]B[sub.4]O[sub.7] showed a higher frequency of fluorescent epidermal cells compared to the plants treated with water. This indicates that a higher number of cells expressed the hypersensitive response after Na[sub.2]B[sub.4]O[sub.7] priming. In addition, there was an increase in peroxidase activity and an enhanced accumulation of a 45 kDa acidic peroxidase isoform during the early stages of infection in plants treated with Na[sub.2]B[sub.4]O[sub.7] compared to plants treated with water and this was positively correlated to the reduction of leaf infection caused by the pathogen. These results indicate that Na[sub.2]B[sub.4]O[sub.7] is able to induce systemic resistance in watermelon against S. cucurbitacearum by activating the hypersensitive reaction at penetration sites, increasing peroxidase activity and altering the peroxidase isozyme profile. Although each individual response may only have had a minor effect, their combined effects had a reducing effect on the disease.

Despite significant progress in photoelectrochemical (PEC) water splitting, high fabrication costs and limited efficiency of photoanodes hinder practical applications. Bismuth vanadate (BiVO[sub.4]), with its low cost, non-toxicity, and suitable band structure, is a promising photoanode material but suffers from poor charge transport, sluggish surface kinetics, and photocorrosion. In this study, porous monoclinic BiVO[sub.4] films are fabricated via a simplified successive ionic layer adsorption and reaction (SILAR) method, followed by borate treatment and PEC deposition of NiFeO[sub.x]. The resulting B/BiVO[sub.4]/NiFeO[sub.x] photoanode exhibits a significantly enhanced photocurrent density of 2.45 mA cm[sup.−2] at 1.23 V vs. RHE—5.3 times higher than pristine BiVO[sub.4]. It also achieves an ABPE of 0.77% and a charge transfer efficiency of 79.5%. These results demonstrate that dual surface modification via borate and NiFeO[sub.x] is a cost-effective strategy to improve BiVO[sub.4]-based PEC water splitting performance. This work provides a promising pathway for the scalable development of efficient and economically viable photoanodes for solar hydrogen production.

In this paper, the effect of the GeO[sub.2]:TiO[sub.2] molar ratio in glass composition on the spectroscopic properties of germanate glasses was systematically investigated. The visible luminescence bands associated with characteristic [sup.1]D[sub.2] → [sup.3]H[sub.4] (red), [sup.5]S[sub.2], [sup.5]F[sub.4] → [sup.5]I[sub.8] (green), and [sup.1]D[sub.2] → [sup.3]F[sub.4] (blue) transitions of Pr[sup.3+], Ho[sup.3+], and Tm[sup.3+] ions in systems modified by TiO[sub.2] were well observed, respectively. It was found that the luminescence intensity of glasses containing Pr[sup.3+] and Ho[sup.3+] ions increases, whereas, for Tm[sup.3+]-doped systems, luminescence quenching with increasing content of TiO[sub.2] was observed. Based on Commission Internationale de I'Eclairage (CIE) chromaticity coordinates (x, y) analysis, it was demonstrated that the value of chromaticity coordinates for all glasses depends on the GeO[sub.2]:TiO[sub.2] molar ratio. The addition of TiO[sub.2] to system compositions doped with Tm[sup.3+] ions shifts the (x, y) to the center of the CIE diagram. However, chromaticity coordinates evaluated for glasses containing Pr[sup.3+] ions move to a purer red color. Our results confirm that the spectroscopic properties of the studied glasses strongly depend on TiO[sub.2] content. Moreover, it can be stated that germanate-based glass systems modified by TiO[sub.2] can be used for optoelectronics in RGB technology as red (Pr[sup.3+]), green (Ho[sup.3+]), and blue (Tm[sup.3+]) emitters.

This clear and self-contained review of the last four decades of research highlights in the hot field of nonlinear optical (NLO) crystals, particularly of borate-based ultraviolet and deep-ultraviolet NLO crystals, covers three major subjects: the structure-property relationship in borate crystals, the structural and optical characteristics of various promising borate crystals, and their fruitful applications in a wide range of scientific and technological fields. Edited by the discoverers and users of these optical borate crystals, this is a readily accessible reading for semiconductor, applied and solid state physicists, materials scientists, solid state chemists, manufacturers of optoelectronic devices, and those working in the optical industry.

The CO[sub.2] capture from flue gas using biomass-derived porous carbons presents an environmentally friendly and sustainable strategy for mitigating carbon emissions. However, the conventional fabrication of porous carbons often relies on highly corrosive activating agents like KOH and ZnCl[sub.2], posing environmental and safety concerns. To address this challenge, in the present work sodium metaborate tetrahydrate (NaBO[sub.2]·4H[sub.2]O) has been utilized as an alternative, eco-friendly activating agent for the first time. Moreover, a water chestnut shell (WCS) is used as a sustainable precursor for boron-doped porous carbons with varied microporosity and boron concentration. It was found out that pyrolysis temperature significantly determines the textural features, elemental composition, and CO[sub.2] adsorption capacity. With a narrow micropore volume of 0.27 cm[sup.3]/g and a boron concentration of 0.79 at.% the representative adsorbent presents the maximum CO[sub.2] adsorption (2.51 mmol/g at 25 °C, 1 bar) and a CO[sub.2]/N[sub.2] selectivity of 18 in a 10:90 (v/v) ratio. Last but not least, the as-prepared B-doped carbon adsorbent possesses a remarkable cyclic stability over five cycles, fast kinetics (95% equilibrium in 6.5 min), a modest isosteric heat of adsorption (22–39 kJ/mol), and a dynamic capacity of 0.80 mmol/g under simulated flue gas conditions. This study serves as a valuable reference for the fabrication of B-doped carbons using an environmentally benign activating agent for CO[sub.2] adsorption application.

Polycrystalline Sr sub(3)Sm sub(2)(BO sub(3 )) sub(4) borate has been synthesized through a solid-state reaction, and the title compound is stable in air and water. Its crystal structure was investigated from powder X-ray diffraction data using the Rietveld method. The fundamental building units of the crystal Sr sub(3)Sm sub(2)(BO sub(3 )) sub(4) are isolated BO sub(3) anionic groups, distorted Sm-O polyhedra, and irregular Sr-O polyhedra, with the crystal structure isostructural to Sr sub(3)Nd sub(2)(BO sub(3 )) sub(4). The infrared spectrum of Sr sub(3)Sm sub(2)(BO sub(3 )) sub(4) has been measured, which is consistent with the crystallographic study. According to diffuse reflection measurement of Sr sub(3)Sm sub(2)(BO sub(3 )) sub(4) powders, the absorption edge is in the deep UV range and UV-vis transmittance is very high. Phosphor Sr sub(3)Sm sub(2)(BO sub(3 )) sub(4) exhibits an orange-red emission.

The reaction of molybdenum complexes with a tris(pyrazolyl)borate ligand (Et[sub.4]N[TpMo(CO)[sub.3]] and Et[sub.4]N[Tp*Mo(CO)[sub.3]] (Tp = hydridotris(pyrazolyl)borate, Tp* = hydridotris(3,5-dimethylpyrazolyl)borate)) and InBr[sub.3] at a 1:1 molar ratio afforded molybdenum–indane complexes (Et[sub.4]N[TpMo(CO)[sub.3](InBr[sub.3])] 1 and Et[sub.4]N[Tp*Mo(CO)[sub.3](InBr[sub.3])] 2). In addition, tungsten–indane complexes, Et[sub.4]N[TpW(CO)[sub.3](InBr[sub.3])] 3 and Et[sub.4]N[Tp*W(CO)[sub.3](InBr[sub.3])] 4, were obtained by the reaction of corresponding tungsten complexes. Complex 4 reacted with H[sub.2]O to form the hydrido complex Tp*W(CO)[sub.3]H, in which the W–In bond was cleaved. On the other hand, 4 reacted with three equiv. of AgNO[sub.3] to form Et[sub.4]N[Tp*W(CO)[sub.3]In(ONO[sub.2])] 5, in which three substituents on the In were exchanged while retaining the W–In dative bond. Complexes 1–5 were fully characterized using NMR measurements and elemental analyses, and the structures of 1–5 and Et[sub.4]N[Tp*W(CO)[sub.3]] were determined via X-ray crystallography. These are the first examples of mononuclear molybdenum– and tungsten–indane complexes with Mo–In and W–In dative bonds.