transition metals

过渡金属
  • 文章类型: Journal Article
    金属离子执行各种各样的功能,包括酸碱/氧化还原催化,结构功能,信令,和电子传输。了解过渡金属配合物与生物大分子的相互作用对生物学至关重要。药物化学,以及合成金属酶的生产。顺铂偶然发现后,金属络合物在生物化学中的重要性成为探究的重中之重。在这次审查中,对第一行过渡金属络合物的各种合成策略及其通过非共价结合与DNA的相互作用进行了十年的更新。此外,这项工作对理论和实践方法的有效性进行了出色的分析,以系统地生成用于抗癌治疗的新型非铂类金属药物。
    Metal ions carry out a wide variety of functions, including acid-base/redox catalysis, structural functions, signaling, and electron transport. Understanding the interactions of transition metal complexes with biomacromolecules is essential for biology, medicinal chemistry, and the production of synthetic metalloenzymes. After the coincidental discovery of cisplatin, importance of the metal complexes in biochemistry became a top priority for inquiry. In this review, a decade update on various synthetic strategies to first row transition metal complex and their interaction with DNA through non-covalent binding are explored. Moreover, this effort provides an excellent analysis on the efficacy of theoretical and practical approaches to the systematic generation of new non-platinum based metallodrugs for anti-cancer therapeutics.
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  • 文章类型: Journal Article
    四个新的Ni16分子轮,其通式为[L4Ni16(RCOO)16(H2O)x(MeOH)12-x](其中H4L=1,4-双((E)-((2'-羟基苄基)亚氨基)甲基)-2,3-萘二醇,和R=H或Me)已被分离和结构表征。使用乙酸镍(II)形成络合物C1-C3(R=Me),并且呈现为具有相同的带电组分配方的多晶型物。在C4(R=H)中观察到相同的轮状结构,使用甲酸镍(II)制备,展示了该系统进一步多功能性的潜力。与类似的四重对称Ni(II)轮团相反,对C1的静态磁性的测量表明存在主要的反铁磁相互作用和S=0的基态。
    Four new Ni16 molecular wheels with the general formula [L4Ni16(RCOO)16(H2O)x(MeOH)12-x] (where H4L = 1,4-bis((E)-((2\'-hydroxybenzyl)imino)methyl)-2,3-naphthalenediol, and R = H or Me) have been isolated and structurally characterised. Complexes C1 - C3 (R = Me)were formed using nickel(II) acetate and presented as polymorphs with the same formulation of charged components. The same wheel-like architecture was observed in C4 (R = H), which was prepared using nickel(II) formate, demonstrating the potential for further versatility of the system. In contrast to similar four-fold symmetric Ni(II) wheel clusters, measurements of the static magnetic properties of C1 indicated the presence of dominant antiferromagnetic interactions and an S = 0 ground state.
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  • 文章类型: Journal Article
    Petasis反应是醛的多组分反应,胺和有机硼试剂,是构建取代胺的有用方法。尽管Petasis反应自1993年发明以来取得了重大进展,但不对称和非定向Petasis反应的策略仍然有限。迄今为止,催化不对称Petasis反应很少,几乎所有不对称报道都使用手性助剂。同样,醛组分通常需要一个导向基团,最终限制了反应的范围。在这个概念中,讨论了不对称和非定向Petasis反应的关键方法,重点关注如何应用这些概念上的进步来解决Petasis文献中长期存在的空白。
     The Petasis reaction is a multicomponent reaction of aldehydes, amines and organoboron reagents and is a useful method for the construction of substituted amines. Despite the significant advancement of the Petasis reaction since its invention in 1993, strategies for asymmetric and non-directed Petasis reactions remain limited. To date, there are very few catalytic asymmetric Petasis reactions and almost all asymmetric reports employ a chiral auxiliary. Likewise, the aldehyde component often requires a directing group, ultimately limiting the reaction\'s scope. In this concept, key methods for asymmetric and non-directed Petasis reactions are discussed, focusing on how these conceptual advances can be applied to solve long-standing gaps in the Petasis literature.
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  • 文章类型: Journal Article
    过渡金属催化有助于新方法的发现和天然产物的制备,以及增加药物发现计划中化学空间的新机会。在海洋药物的情况下,这一策略被用来实现选择性,可持续和有效的转型,否则无法获得。从这个角度来看,我们的目标是展示在过去几年中,各种过渡金属如何在各种类似海洋药物的支架中提供了富有成效的连接,通过加速这些有价值的分子的生产。
    Transition metal catalysis has contributed to the discovery of novel methodologies and the preparation of natural products, as well as new chances to increase the chemical space in drug discovery programs. In the case of marine drugs, this strategy has been used to achieve selective, sustainable and efficient transformations, which cannot be obtained otherwise. In this perspective, we aim to showcase how a variety of transition metals have provided fruitful couplings in a wide variety of marine drug-like scaffolds over the past few years, by accelerating the production of these valuable molecules.
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  • 文章类型: Journal Article
    多年来,作为药物发现计划的一部分,金属-类黄酮复合物已被广泛研究,但是在过去的十年中,它们在材料科学中的重要性显着增加。对金属离子和类黄酮在构建简单复合物和更先进的混合网络中的作用的更深入理解将促进具有定制结构和功能的材料的组装。在这篇评论中,我们强调了金属-类黄酮系统的最基本数据,在混合无机-有机材料的设计中提出了有希望的替代方案。我们主要关注含有CuII/I和FeIII/II离子的系统,这在天然和工业催化中是必需的。我们讨论了两种通常确保金属-类黄酮系统形成的相互作用,即配位和氧化还原反应。我们的目的是涵盖金属类黄酮系统的基本原理,以展示这些知识如何从小分子转移到复杂的材料。
    For many years, metal-flavonoid complexes have been widely studied as a part of drug discovery programs, but in the last decade their importance in materials science has increased significantly. A deeper understanding of the role of metal ions and flavonoids in constructing simple complexes and more advanced hybrid networks will facilitate the assembly of materials with tailored architecture and functionality. In this Review, we highlight the most essential data on metal-flavonoid systems, presenting a promising alternative in the design of hybrid inorganic-organic materials. We focus mainly on systems containing CuII/I and FeIII/II ions, which are necessary in natural and industrial catalysis. We discuss two kinds of interactions that typically ensure the formation of metal-flavonoid systems, namely coordination and redox reactions. Our intention is to cover the fundamentals of metal-flavonoid systems to show how this knowledge has been already transferred from small molecules to complex materials.
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  • 文章类型: Journal Article
    新型异质结构电极材料的设计和合成对于制造高效的超级电容器器件至关重要。在这方面,过渡金属磷硫族化物(S,Se)由于其奇特的电子特性而成为有希望的候选人。在这里,使用简单的两步水热协议来合成二元和三元金属磷硒化物电极(Mn-Fe-P-Se,V-Fe-P-Se,Mn-V-P-Se,和Mn-Fe-V-P-Se)。化学成分,形态学,和结构的制造材料进行了充分的研究。在1.0Ag-1下的三电极电化学评估表明,三元金属电极(MFVP-Se)表现出1968.63Cg-1的高容量。为了评估合理设计的Mn-Fe-V-P-Se电极材料的实用价值,将Mn-Fe-V-P-Se用作正极,并将活性炭(AC)用作负极,以组装混合超级电容器装置。该Mn-Fe-V-P-Se//AC装置提供1999.96Wkg-1的功率密度,具有149.88Whkg-1的高能量密度,并且在5000个充电/放电循环后没有容量损失。此外,密度泛函理论计算表明,我们的电极对OH-离子表现出合适的吸附能,而对离子的扩散势垒最小。
    The design and synthesis of novel heterostructured electrode materials are crucial to enable the fabrication of efficient supercapacitor devices. In this regard, transition metal phosphochalcogenides (S, Se) are promising candidates owing to their exotic electronic properties. Herein, a facile two-step hydrothermal protocol was used to synthesize binary and ternary metal phospho-selenide electrodes (Mn-Fe-P-Se, V-Fe-P-Se, Mn-V-P-Se, and Mn-Fe-V-P-Se). The chemical composition, morphology, and structure of the as-fabricated materials were fully investigated. The three-electrode electrochemical evaluation at 1.0 A g-1 demonstrated that the ternary metal electrode (MFVP-Se) exhibits a high capacity of 1968.63 C g-1. To assess the practical value of the rationally designed Mn-Fe-V-P-Se electrode material, Mn-Fe-V-P-Se was used as a positive electrode coupled with activated carbon (AC) as a negative electrode to assemble a hybrid supercapacitor device. This Mn-Fe-V-P-Se//AC device delivers a power density of 1999.96 W kg-1 with a high energy density of 149.88 Wh kg-1 coupled with no capacity loss after 5000 charging/discharging cycles. Additionally, density functional theory calculations revealed that our electrode exhibits suitable adsorption energy for OH- ions with a minimal diffusion barrier for ions.
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  • 文章类型: Journal Article
    氨(NH3)是通过Haber-Bosch工艺从二氮(N2)和二氢(H2)工业生产的,尽管H2是由化石燃料制备的,反应需要苛刻的条件。另一方面,微生物在环境反应条件下具有固定的氮。最近,已经发现明确定义的分子过渡金属络合物作为催化剂,通过在环境反应条件下与化学还原剂和质子源反应将N2转化为NH3。其中,发现N2分裂途径和质子耦合电子转移的参与对于高催化活性非常有效。此外,最近已经实现了N2到NH3的直接电催化和光催化转化。除了催化形成NH3之外,已经报道了将N2选择性催化转化为肼(NH2NH2)和将N2催化甲硅烷基化为甲硅烷基胺。最近已经建立了催化C-N键形成以在环境反应条件下提供氰酸酯阴离子(NCO-)。预计将N2直接转化为含氮化合物以及绿色氨合成的进一步发展,从而将氨用作能量载体。
    Ammonia (NH3) is industrially produced from dinitrogen (N2) and dihydrogen (H2) by the Haber-Bosch process, although H2 is prepared from fossil fuels, and the reaction requires harsh conditions. On the other hand, microorganisms have fixed nitrogen under ambient reaction conditions. Recently, well-defined molecular transition metal complexes have been found to work as catalyst to convert N2 into NH3 by reactions with chemical reductants and proton sources under ambient reaction conditions. Among them, involvement of both N2-splitting pathway and proton-coupled electron transfer is found to be very effective for high catalytic activity. Furthermore, direct electrocatalytic and photocatalytic conversions of N2 into NH3 have been recently achieved. In addition to catalytic formation of NH3, selective catalytic conversion of N2 into hydrazine (NH2NH2) and catalytic silylation of N2 into silylamines have been reported. Catalytic C-N bond formation has been more recently established to afford cyanate anion (NCO-) under ambient reaction conditions. Further development of direct conversion of N2 into nitrogen-containing compounds as well as green ammonia synthesis leading to the use of ammonia as an energy carrier is expected.
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  • 文章类型: Journal Article
    污染物对水质的定性影响主要与其性质及其浓度有关,但无论如何,它们决定了对相关生态系统的强烈影响。特别是,难熔有机化合物代表了一个关键的挑战,并且已经研究和开发了几种降解过程来去除它们。其中,非均相Fenton处理是一种有前途的废水和液体废物修复技术。这里,我们开发了基于Co的单金属和双金属配方,Cu,Fe,Mn,对三种模型有机染料(亚甲基蓝,罗丹明B,和孔雀石绿)。然后通过UV-vis分光光度法技术分析处理的样品。双金属铁基材料在非常短的时间内实现了所有三种模型分子的几乎完全降解。Mn-Fe催化剂产生了最佳配方,在pH5下5分钟内几乎完全降解了亚甲基蓝和孔雀石绿,在pH3下30分钟内几乎完全降解了罗丹明B。结果表明,这些制剂可用于处理包含复杂和可变有机污染物的大范围液体废物。与文献中报道的其它体系相比,所研究的催化剂是非常有前途的。
    The qualitative impact of pollutants on water quality is mainly related to their nature and their concentration, but in any case, they determine a strong impact on the involved ecosystems. In particular, refractory organic compounds represent a critical challenge, and several degradation processes have been studied and developed for their removal. Among them, heterogeneous Fenton treatment is a promising technology for wastewater and liquid waste remediation. Here, we have developed mono- and bimetallic formulations based on Co, Cu, Fe, and Mn, which were investigated for the degradation of three model organic dyes (methylene blue, rhodamine B, and malachite green). The treated samples were then analyzed by means of UV-vis spectrophotometry techniques. Bimetallic iron-based materials achieved almost complete degradation of all three model molecules in very short time. The Mn-Fe catalyst resulted in the best formulation with an almost complete degradation of methylene blue and malachite green at pH 5 in 5 min and of rhodamine B at pH 3 in 30 min. The results suggest that these formulations can be applied for the treatment of a broad range of liquid wastes comprising complex and variable organic pollutants. The investigated catalysts are extremely promising when compared to other systems reported in the literature.
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  • 文章类型: Journal Article
    我们已经开发了一种方法来预测无序金属合金中有效热载流子生成的趋势。我们提供了一个简单的论据,说明在存在无序的情况下间接过渡的重要性,从而证明使用联合国家密度(JDOS)类量来探索这些趋势是合理的。我们引入了一个新的类似JDOS的数量,JDOSK,它启发式地结合了粒子寿命的差异,这取决于它们的激发能量。为了证明这个新数量的有效性,我们将其应用于Cu50X50的研究,其中X=Ag,Au,Pd和Y50Pd50,其中Y=Au,Ni.我们预测Ni50Pd50在所考虑的合金中产生最多的热载流子。与所用的基础合金相比,激发光载流子的密度有所提高,Cu50Ag50,对于800nm是3.4倍,对于1550nm是19倍。热载流子产生的这种增加是Ni合金的铁磁性质的结果。我们认为,我们的方法可以对合金的低偏置光电导进行有效的材料特定预测。
    We developed and tested an approach for predicting trends for efficient hot carrier generation among disordered metal alloys. We provide a simple argument for the importance of indirect transitions in the presence of disorder, thus justifying the use of joint density of states (JDOS)-like quantities for exploring these trends. We introduce a newJDOS-like quantity,JDOSK, which heuristically accounts for longer lifetimes of quasiparticles close to the Fermi energy. To demonstrate the efficacy of this new quantity, we apply it to the study of Cu50X50where X = Ag, Au, Pd and Y50Pd50where Y = Au, Ni. We predict that Ni50Pd50produces the most hot carriers among the alloys considered. The improvement in the density of excited photocarriers over the base alloy used, Cu50Ag50, is 3.4 times for 800 nm and 19 times for 1550 nm light. This boost in hot-carrier generation is consequence of the ferromagnetic nature of the Ni alloy. We argue that our method allows efficient material-specific predictions for low bias photoconductivity of alloys.
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  • 文章类型: Journal Article
    卡宾金属酰胺(CMA)是用于有机发光二极管(OLED)应用的新兴延迟荧光材料。CMA拥有快速,由于快速的正向和反向系统间交叉(ISC)速率而产生的高效排放。单重态和三重态自旋歧管之间的动态平衡使CMA与大多数纯有机热激活延迟荧光发射体区分开。然而,CMA中的直接实验三重态表征未得到充分利用,限制了我们对ISC机制的详细了解。在这项工作中,我们将时间分辨光谱与通过环境极性和金属替代来调节状态能量相结合,重点研究电荷转移(3CT)和局部激子(3LE)三重态之间的相互作用。与以前的光物理工作不同,我们研究了蒸发的宿主:CMA和小分子宿主的客体膜,以增加设备相关性。瞬态吸收揭示了三重激发态吸收(ESA)的演变,这与具有不同介电常数的主体之间的轨道特性变化相一致。利用量子化学计算,我们模拟最低三重态的ESA,强调只有3CT和供体部分3LE状态对光谱特征的贡献,没有强有力的证据表明低洼的以受体为中心的3LE。因此,我们的工作为理解三重激发态在CMA中的作用提供了蓝图,这将使这种有前途的材料能够进一步智能优化。
    Carbene-metal-amides (CMAs) are emerging delayed fluorescence materials for organic light-emitting diode (OLED) applications. CMAs possess fast, efficient emission owing to rapid forward and reverse intersystem crossing (ISC) rates. The resulting dynamic equilibrium between singlet and triplet spin manifolds distinguishes CMAs from most purely organic thermally activated delayed fluorescence emitters. However, direct experimental triplet characterization in CMAs is underutilized, limiting our detailed understanding of the ISC mechanism. In this work, we combine time-resolved spectroscopy with tuning of state energies through environmental polarity and metal substitution, focusing on the interplay between charge-transfer (3CT) and local exciton (3LE) triplets. Unlike previous photophysical work, we investigate evaporated host : guest films of CMAs and small-molecule hosts for increased device relevance. Transient absorption reveals an evolution in the triplet excited-state absorption (ESA) consistent with a change in orbital character between hosts with differing dielectric constants. Using quantum chemical calculations, we simulate ESAs of the lowest triplet states, highlighting the contribution of only 3CT and donor-moiety 3LE states to spectral features, with no strong evidence for a low-lying acceptor-centered 3LE. Thus, our work provides a blueprint for understanding the role of triplet excited states in CMAs which will enable further intelligent optimization of this promising class of materials.
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