Synthesis of Azaaromatic?Borane Intramolecular Complexes by Palladium‐Catalyzed Reaction of Azaaromatic Halides with Alkynyl(triaryl)borates

A diversity‐oriented method to synthesize (E)‐azastilbenes having an intramolecular B? N coordination bond from alkynyl(triaryl)borates and azaaromatic halides is described. The obtained π‐conjugated compounds exhibit an intense blue fluorescence and a high electron affinity, indicating their potential to be used as n‐type light‐emitting materials.     

Deoxygenation/dimerization of sugar derivatives with BF3·Et2O-Et3SiH: synthesis of a β-isonucleoside

Lewis acid-Et₃SiH induced deoxygenation of anomeric carbon of sugars generates tetrahydrofuran derivatives, accompanied by hitherto unknown dimeric products. If the reagent addition steps are reversed, tetrahydrofuran derivatives are obtained as the sole products, while only the dimeric products are isolated if Et₃SiH is excluded. One of the deoxygenated products has been transformed into a β-isonucleoside.     

DFT study of boron trichloride adsorption on the surface of Al12N12 nanocluster

In the present study, ability of Al₁₂N₁₂ nanocluster as a new adsorbent for boron trichloride is studied by using density functional theory (DFT) calculations. Two distinct relaxed geometries of Al₁₂N₁₂-BCl₃ complex are located. The dominant configuration (B) involves chemisorption of BCl₃ on aluminum nitride nanocluster with an adsorption energy of ?303 kJ/mol compared to ?33 kJ/mol for a less favourable configuration A (based on wB97XD functional). The enthalpy and Gibbs free energy of interaction for each relaxed was also analysed for better understanding of the thermochemistry of adsorption process. The charge transfer analysis reveals opposing trend in both configurations. Configuration A showed transfer of charge from BCl₃ to nanocluster (+0.123 e), whereas reverse direction of charge transfer was found for the other configuration (?0.083 e). Furthermore, the frontier molecular orbital as well as densities of states of all systems are analysed to follow the changes in the electronic structure of Al₁₂N₁₂ upon adsorption of BCl₃.     

Effect of boron ion implantation on the structural, optical and electrical properties of ZnSe thin films

Zinc Selenide (ZnSe) thin films were deposited onto well cleaned glass substrates using vacuum evaporation technique under a vacuum of 3×10⁻⁵ mbar. The prepared ZnSe samples were implanted with mass analyzed 75 keV B⁺ ions at different doses ranging from 10¹² to 10¹⁶ ions cm⁻². The composition, thickness, microstructures, surface roughness and optical band gap of the as-deposited and boron-implanted films were studied by Rutherford backscattering (RBS), grazing incidence X-ray diffraction, Atomic force microscopy, Raman scattering and transmittance measurements. The RBS analysis indicates that the composition of the as-deposited and boron-implanted films is nearly stoichiometric. The thickness of the as-deposited film is calculated as 230 nm. The structure of the as-deposited and boron-implanted thin films is cubic. It is found that the surface roughness increases on increasing the dose of boron ions. In the optical studies, the optical band gap value decreases with an increase of boron concentration. In the electrical studies, the prepared device gave a very good response in the blue wavelength region.     

非金属元素的同素异形体(一)——氢和硼的同素异形体概述

进行了同素异形体概念的探讨。简要叙述了氢和硼2种典型非金属元素形成的各种同素异形体的存在、组成以及结构、制备和性质,首次将多种硼富勒烯、硼纳米管、硼单层平面等晶态硼的内容补充在硼的同素异形体中,并强调了计算化学对同素异形体的预测和现代科学技术发展对制备的作用及其在材料中的应用。     

Cover Feature: Rare Spin Avoided σ-σ Diradical Planar Tetracoordinate Boron Cluster: A Proto-Star for Planar Pentacoordination (ChemPhysChem 18/2023)

We report a global planar star-like cluster B₃Li₃ featuring three planar tetracoordinate boron centres with a rare spin avoided σ-σ diradical character. The cluster was found to be stable towards dissociation into different fragments. The spin density was found to be localized solely on the three boron atoms in the molecular plane. This spin avoided σ-σ diradical character leads to the extension of the coordination number to yield a neutral B₃Li₃H₃ and a cationic B₃Li₃H₃⁺ cluster with three planar pentacoordinate boron centres in their global minimum structures. The planar geometry of the aninonic B₃Li₃H₃⁻ cluster is slightly higher in energy. The planar global clusters were found to maintain planarity in their ligand protected benzene bound complexes, B₃Li₃(Bz)₃, B₃Li₃H₃(Bz)₃ and B₃Li₃H₃(Bz)₃⁺ with high ligand dissociation energies offering candidature for experimental detection.     

干法灰化-发射光谱法测定植物样品中B和Sn

地球化学样品中的元素硼和锡属于难溶易挥发元素,湿法样品前处理技术相对较难,目前基本以一米光栅发射光谱法测定为主,其固体进样方式避免了复杂的样品前处理,实现了对地球化学样品中元素硼和锡的绿色分析。植物样品经过适宜的高温灰化后,基体成分基本一致,体积质量均发生富集现象,称取的样品灰分成分和基物、缓冲剂(比例1:1:2)经过研磨充分混匀,在优化的实验条件下,以国家一级合成硅酸盐光谱分析标准物质制作校准曲线,构建植物样品中硼和锡的分析方法,该方法硼和锡的检出限分别为0.042μg·g-1、0.019μg·g-1,方法经过国家一级标准物质验证,硼方法精密度:5.6%~13%,正确度(RE)的绝对值均小于10%;锡方法精密度:7.2%~18%,正确度(RE)的绝对值均小于28%。实验结果表明:植物样品经过干法灰化富集后,对植物样品中元素硼基本能够实现精准测定,对元素锡含量接近于检测下限的值测定结果相对较差,对高含量值也能够实现精准测定,方法具有较好的应用价值。     

Ag3PO4/PBN复合材料的制备及可见光催化性能研究

在空气氛围下,900℃热解硼酸-三聚氰胺前驱体制备多孔氮化硼(PBN),然后通过原位沉淀法制备出Ag₃PO₄/PBN复合光催化剂。利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外-可见漫反射光谱(UV-Vis DRS)、荧光分光光度计(PL)等方法对复合物的结构和形貌进行分析。以罗丹明B(RhB)为降解底物,对光催化性能进行评价。使用异丙醇(PA)、乙二胺四乙酸二钠(EDTA-2Na)、对苯醌(BQ)和AgNO₃捕获.OH、h₊^、.O_2-^和e_-^,对光催化机理进行研究。结果表明, Ag₃PO₄/PBN在PBN含量为70mg时催化效果最好,在可见光照射10min后,0.03g复合光催化剂对RhB溶液(50ml,30mg/L)降解率达到99.6%,具有优良的降解性能;3次重复实验后,催化剂的催化性能几乎没有发生变化,.OH、h₊^和.O_2-^在Ag₃PO₄/PBN光催化降解过程中起主要作用。     

Catalytic Formal [2π+2σ] Cycloaddition of Aldehydes with Bicyclobutanes: Expedient Access to Polysubstituted 2-Oxabicyclo[2.1.1]hexanes

Synthesis of bicyclic scaffolds has attracted tremendous attention because they are playing an important role as saturated bioisosteres of benzenoids in modern drug discovery. Here, we report a BF₃-catalyzed [2π+2σ] cycloaddition of aldehydes with bicyclo[1.1.0]butanes (BCBs) to access polysubstituted 2-oxabicyclo[2.1.1]hexanes. A new kind of BCB containing an acyl pyrazole group was invented, which not only significantly facilitates the reactions, but can also serve as a handle for diverse downstream transformations. Furthermore, aryl and vinyl epoxides can also be utilized as substrates which undergo cycloaddition with BCBs after in situ rearrangement to aldehydes. We anticipate that our results will promote access to challenging sp³-rich bicyclic frameworks and the exploration of BCB-based cycloaddition chemistry.     

Efficient Narrowband Circularly Polarized Light Emitters Based on 1,4-B,N-embedded Rigid Donor–Acceptor Helicenes

Narrow-band emission is essential for applicable circularly polarized luminescence (CPL) active materials in ultrahigh-definition CP-OLEDs. One of the most promising classes of CPL active molecules, helicenes, however, typically exhibit broad emission with a large Stokes shift. We present, herein, a design strategy capitalizing on intramolecular donor-acceptor interactions between nitrogen and boron atoms to address this issue. 1,4-B,N-embedded configurationally stable single- and double helicenes were synthesized straightforwardly. Both helicenes show unprecedentedly narrow fluorescence and CPL bands (full width at half maximum between 17–28 nm, 0.07–0.13 eV) along with high fluorescence quantum yields (72–85 %). Quantum chemical calculations revealed that the relative localization of the natural transition orbitals, mainly on the rigid core of the molecule, and small values of root-mean-square displacements between S₀ and S₁ state geometries, contribute to the narrower emission.