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101.
Wen‐Jing Shi Dr. Mohamed E. El‐Khouly Dr. Kei Ohkubo Prof. Shunichi Fukuzumi Prof. Dennis K. P. Ng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(34):11332-11341
An efficient functional mimic of the photosynthetic antenna‐reaction center has been designed and synthesized. The model contains a near‐infrared‐absorbing aza‐boron‐dipyrromethene (ADP) that is connected to a monostyryl boron‐dipyrromethene (BDP) by a click reaction and to a fullerene (C60) using the Prato reaction. The intramolecular photoinduced energy and electron‐transfer processes of this triad as well as the corresponding dyads BDP‐ADP and ADP‐C60 have been studied with steady‐state and time‐resolved absorption and fluorescence spectroscopic methods in benzonitrile. Upon excitation, the BDP moiety of the triad is significantly quenched due to energy transfer to the ADP core, which subsequently transfers an electron to the fullerene unit. Cyclic and differential pulse voltammetric studies have revealed the redox states of the components, which allow estimation of the energies of the charge‐separated states. Such calculations show that electron transfer from the singlet excited ADP (1ADP*) to C60 yielding ADP.+‐C60.? is energetically favorable. By using femtosecond laser flash photolysis, concrete evidence has been obtained for the occurrence of energy transfer from 1BDP* to ADP in the dyad BDP‐ADP and electron transfer from 1ADP* to C60 in the dyad ADP‐C60. Sequential energy and electron transfer have also been clearly observed in the triad BDP‐ADP‐C60. By monitoring the rise of ADP emission, it has been found that the rate of energy transfer is fast (≈1011 s?1). The dynamics of electron transfer through 1ADP* has also been studied by monitoring the formation of C60 radical anion at 1000 nm. A fast charge‐separation process from 1ADP* to C60 has been detected, which gives the relatively long‐lived BDP‐ADP.+C60.? with a lifetime of 1.47 ns. As shown by nanosecond transient absorption measurements, the charge‐separated state decays slowly to populate mainly the triplet state of ADP before returning to the ground state. These findings show that the dyads BDP‐ADP and ADP‐C60, and the triad BDP‐ADP‐C60 are interesting artificial analogues that can mimic the antenna and reaction center of the natural photosynthetic systems. 相似文献
102.
Philipp Bissinger Prof. Dr. Holger Braunschweig Dr. Alexander Damme Dr. Rian D. Dewhurst Dr. Katharina Kraft Thomas Kramer Dr. Krzysztof Radacki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13402-13407
The synthesis of base‐stabilized boryl and borylene complexes is reported. An N‐heterocyclic carbene (NHC)‐stabilized iron–dihydroboryl complex was prepared by two different routes including methane liberation and salt elimination. A range of base‐stabilized iron–dichloroboryl complexes was prepared by addition of Lewis bases to boryl complexes. Base‐stabilized, cationic monochloroborylene complexes were synthesized from these boryl complexes by halide abstraction by using weakly coordinating anions. 相似文献
103.
Ti0.26Zr0.07V0.24Mn0.1Ni0.33Bx(x=0~0.10)系列合金均有V基固溶体相和C14型Laves相两相组成。添加B可提高Ti0.26Zr0.07V0.24 Mn0.1Ni0.33合金的放电容量, Ti0.26Zr0.07V0.24Mn0.1Ni0.33B0.1合金电极在60 mA·g-1电流放电时的放电容量达到476.7 mAh·g-1.B的添加不同程度地降低了合金的高倍率放电性能, 使合金电极表面上电化学反应的电荷转移电阻(Rct)显着增加, 交换电流密度(I0)显着降低。添加B可显着改善Ti0.26Zr0.07V0.24Mn0.1Ni0.33合金电极的高温放电性能, Ti0.26Zr0.07V0.24Mn0.1Ni0.33B0.025合金电极在343 K高温下其放电容量达到525.6 mAh·g-1. 相似文献
104.
105.
Yanhong Chao Wenshuai Zhu Jiaxin Chen Peiwen Wu Huaming Li 《Green Chemistry Letters and Reviews》2014,7(4):330-336
Graphene-like layered hexagonal boron nitride (g-BN) was prepared and characterized. The performance of using g-BN as an adsorbent for removal of fluoroquinolone antibiotic gatifloxacin (GTF) from aqueous solution was evaluated. g-BN showed an excellent adsorption capability with notable GTF adsorption ratio of more than 90%. Data of equilibrium adsorption of GTF onto g-BN at different temperatures were represented by Langmuir, Freundlich and Tempkin isotherm models, and Langmuir exhibited the best fitting with the maximum adsorption capacity of 88.5 mg·g?1 at 288 K. GTF adsorption was insignificantly affected by solution pH. Competitive role of Na+ and Ca2+ in the solution inhibited the adsorption of GTF and decreased the adsorption capacity a bit. The adsorption process was spontaneous and exothermic. The adsorption was probably governed by π–π interaction between GTF and g-BN, and electrostatic interaction may also exist in the adsorption process. 相似文献
106.
107.
Constanze Keck Dr. Jennifer Hahn Divanshu Gupta Prof. Dr. Holger F. Bettinger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(5):e202103614
The boron-nitrogen analogue of ortho-benzyne, 1,2-azaborinine, is a reactive intermediate that features a formal boron-nitrogen triple bond. We here show by combining experimental and computational techniques that the Lewis acidity of the boron center of dibenzo[c,e][1,2]azaborinine allows interaction with the silicon containing single bonds Si−E through the silicon bonding partner E (E=F, Cl, OR, H). The binding to boron activates the Si−E bonds for subsequent insertion reaction. This shows that the BN-aryne is a ferocious species that even can activate and insert into the very strong Si−F bond. 相似文献
108.
基于第一性原理, 系统地研究了Ben (n=1~3)对B12团簇结构的调控. 结果表明: 团簇BeB12全局极小结构为Cs对称性准平面结构, 而Be2B12和Be3B12最稳定的结构均为笼状结构, 对称性分别为Cs和C2v. 随着Ben (n=1~3)原子数的增加, 团簇B12由准平面结构过渡到笼状结构, 且Be倾向内嵌在B12笼状结构表面的B7或B8单元环中, 通过离子和共价作用形成稳定Be&B7和Be&B8单元, 从而稳定笼状结构. 自然键轨道(NBO)分析表明, 团簇Cs BeB12, Cs Be2B12, C2v Be3B12内部存在电子转移情况, Be原子2s轨道上失去电子, Be—B键主要以离子作用为主, 同时也存在共价作用. 成键分析显示Cs Be2B12和C2v Be3B12的π键遵循球状芳香性2(n+1)2 (n=1)电子计数规则, 表明该团簇具有球状芳香性. 预测了三个结构的红外和拉曼光谱, 为以后的合成实验和数据表征提供了理论基础. 相似文献
109.
Mingming Huang Dr. Jiefeng Hu Shasha Shi Dr. Alexandra Friedrich Johannes Krebs Prof. Dr. Stephen A. Westcott Prof. Dr. Udo Radius Prof. Dr. Todd B. Marder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(24):e202200480
Defunctionalization of readily available feedstocks to provide alkenes for the synthesis of multifunctional molecules represents an extremely useful process in organic synthesis. Herein, we describe a transition metal-free, simple and efficient strategy to access alkyl 1,2-bis(boronate esters) via regio- and diastereoselective diboration of secondary and tertiary alkyl halides (Br, Cl, I), tosylates, and alcohols. Control experiments demonstrated that the key to this high reactivity and selectivity is the addition of a combination of potassium iodide and N,N-dimethylacetamide (DMA). The practicality and industrial potential of this transformation are demonstrated by its operational simplicity, wide functional group tolerance, and the late-stage modification of complex molecules. From a drug discovery perspective, this synthetic method offers control of the position of diversification and diastereoselectivity in complex ring scaffolds, which would be especially useful in a lead optimization program. 相似文献
110.
Daniel Vogler Maximilian Schöner Dr. Elisabeth Kaifer Prof. Dr. Dr. Hans-Jörg Himmel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(49):e202201389
In this work we report the first cycloaddition reactions between a diazido diborane(4) and terminal alkynes, providing unique access to bis-1,2,3-triazoles connected by a B−B bridge. The catalyst-free reactions are highly selective, yielding exclusively the thermodynamically disfavored bis-1,4-triazoles. The reactions are enabled by the high thermal stability of the diazido-diborane [B(hpp)(N3)]2 (hpp=1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-α]pyrimidinate). Due to the tetra-coordinate boron atoms in this reagent, the reactions are tolerant with respect to the introduction of Lewis-basic groups at the alkyne. The scope and limitations of the new reactions are discussed. 相似文献