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101.
Guang‐Ming Liang Jing Shang Kun‐Guo Yang Kai Ma Qing‐Ling Ni 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(4):379-383
The title compounds, bis{μ‐N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine‐κ2N1:P}disilver bis(perchlorate) acetonitrile monosolvate, [Ag2(C18H17N2P)2](ClO4)2·CH3CN, (1), and bis{μ‐N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine‐κ2N1:P}bis[(nitrato‐κ2O,O)silver], [Ag2(C18H17N2P)2(NO3)2], (2), each contain disilver macrocyclic [Ag2(C18H17N2P)2]2+ cations lying about inversion centres. The cations are constructed by two N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine (DPP) ligands linking two Ag+ cations in a head‐to‐tail fashion. In (1), the unique Ag+ cation has a near‐linear coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands. Two ClO4− anions doubly bridge two metallomacrocycles through Ag...O and N—H...O weak interactions to form a chain extending in the c direction. The half‐occupancy acetonitrile molecule lies with its methyl C atom on a twofold axis and makes a weak N...Ag contact. In (2), there are two independent [Ag(C18H17N2P)]+ cations. The nitrate anions weakly chelate to each Ag+ cation, leading to each Ag+ cation having a distorted tetrahedral coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands, and two chelating nitrate O atoms. Each dinuclear [Ag2(C18H17N2P)2(NO3)2] molecule acts as a four‐node to bridge four adjacent equivalent molecules through N—H...O interactions, forming a two‐dimensional sheet parallel to the bc plane. Each sheet contains dinuclear molecules involving just Ag1 or Ag2 and these two types of sheet are stacked in an alternating fashion. The sheets containing Ag1 all lie near x = , , etc, while those containing Ag2 all lie near x = 0, 1, 2 etc. Thus, the two independent sheets are arranged in an alternating sequence at x = 0, , 1, etc. These two different supramolecular structures result from the different geometric conformations of the templating anions which direct the self‐assembly of the cations and anions. 相似文献
102.
Gui‐Xia Wang Li‐Li Shang Zhao‐Hao Li Bang‐Tun Zhao 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(7):715-717
A novel manganese coordination polymer, poly[(μ5‐thiophene‐3,4‐dicarboxylato)manganese(II)], [Mn(C6H2O4S)]n, was synthesized hydrothermally using 3,4‐thiophenedicarboxylate (3,4‐tdc2−) as the organic linker. The asymmetric unit of the complex contains an Mn2+ cation and one half of a deprotonated 3,4‐tdc2− anion, both residing on a twofold axis. Each Mn2+ centre is six‐coordinated by O atoms of bridging/chelating carboxylate groups from five 3,4‐tdc2− anions, forming a slightly distorted octahedron. The Mn2+ centres are bridged by 3,4‐tdc2− anions to give an infinite two‐dimensional layer which incorporates one‐dimensional Mn–O gridlike chains, and in which the 3,4‐tdc2− anion adopts a novel hexadentate chelating and μ5‐bridging coordination mode. The fully deprotonated 3,4‐tdc2− anion exhibits unexpected efficiency as a ligand towards the Mn2+ centres, which it coordinates through all of its carboxylate O atoms to provide the novel coordination mode. The IR spectrum of the complex is also reported. 相似文献
103.
在盘状液晶分子外围柔性链中引入功能不同的基团, 是设计和合成具有良好液晶性能化合物的常用策略. 本工作从苯并菲2,3-二甲酸和酸酐出发, 通过亲核取代和点击反应, 分别合成了两类三唑环修饰的苯并菲二羧酸酯和苯并菲酰亚胺化合物. 热重分析仪(TGA)测试表明, 新制备的主要中间产物与目标化合物失重为5%时的温度在274~389 ℃之间, 均表现出良好的热稳定性. 我们通过差示扫描量热法(DSC)、偏光显微镜(POM)和变温X射线衍射(XRD)实验对这些化合物的热力学行为和介晶性进行了研究. 除三唑环修饰的酯3a和3b无液晶性外, 主要中间产物(2和5)与三唑环修饰的酰亚胺产物(6a和6b)均有一个六方柱状液晶相. 此外, 制备的以三唑为桥联基团的酰亚胺二聚体10为室温液晶, 具有173 ℃的液晶范围. XRD证实了该二聚体中存在有序度不同的两种柱状液晶相(Colh1和Colh2). 另外, 由于三唑环的引入, 三唑环修饰的酯类和酰亚胺两类化合物在某些有机溶剂中都能形成有机凝胶. 其中, 二聚体10在1,2-二氯乙烷和1,4-二氧六环中表现出优异的凝胶能力, 其临界凝胶浓度(CGC)可低至1 mg/mL. 相比之下, 不含三唑环的中间产物2和5则不能形成凝胶, 表明三唑环之间的偶极-偶极作用和液晶刚性核π-π堆积的协同作用对于超分子凝胶的形成起着重要的作用. 因此, 同时表现出液晶和凝胶性质的三唑环修饰的苯并菲2,3-二酰亚胺分子具有成为一种多功能材料的潜在应用价值. 相似文献
104.
105.
我们通过包覆炭化的方法制备得到了石墨烯包覆的天然球形石墨(G/SG)材料,并使用扫描电子显微镜、X射线衍射仪以及多种电化学测试手段考察了不同石墨烯含量的复合材料的形貌结构及电化学性能。我们发现,在不添加乙炔黑(AB)的情况下,G/SG复合材料表现出较高的首次库伦效率,很好的循环稳定性和高倍率性能。当石墨烯包覆量为1%时,材料50次循环后的可逆容量可与添加10%AB的天然石墨电极(SG)等同;当石墨烯包覆量为2.5%时,材料的比容量完全高于添加10%AB的石墨电极。材料电化学性能的改善归因于石墨烯的包覆。一方面,石墨烯的柔软可变性可以保证天然石墨颗粒在充放电过程中的结构完整性,从而有效改善材料的循环稳定性;另一方面,石墨烯的存在提高了电极的导电性,促进更好导电网络的形成。因此,石墨烯包覆天然球形石墨材料中,石墨烯不仅是活性物质,也发挥导电剂的作用。当添加5%的乙炔黑时,在50 mA·g-1电流循环50次后,5%G/SG电极的可逆容量从381.1 mAh·g-1提高到404.5 mAh·g-1,在1 A·g-1电流时可逆容量从82.5 mAh·g-1提高到101.9 mAh·g-1,这表明G/SG电极仍然需要乙炔黑导电剂。乙炔黑颗粒填充在复合材料的空隙中,通过点接触的形式连接到G/SG颗粒,与石墨烯协同作用形成了更加有效的导电网络。尽管石墨烯包覆和乙炔黑添加对天然石墨电极具有积极的影响,例如增加了天然石墨电极的导电性和储锂性能(包括可逆容量,倍率性能和循环性能),但随着石墨烯或乙炔黑的增加,电极密度通常会降低。因此,在实际应用中应考虑石墨负极材料的质量和体积容量的平衡。这些结果对天然石墨的进一步商业应用具有重要意义。我们的工作为天然石墨电极在锂电池中的电化学行为提供了一种新的认识,并且有助于制备更高性能的负极材料。 相似文献
106.
Saiji Shen Chu Wu Yinghui Shang Hongdou Shen Yue Liao Yuting Guo Min Hu Xia Wang Gang Li Qigang Wang 《中国科学:化学(英文版)》2022,65(1):153-161
There are several natural materials which have evolved functional gradients,ingeniously attaining maximal efficacy from limited components.Herein,we utilized the spatiotemporal distribution of initiator acetylacetone to regulate the multienzyme polymerization and fabricate a chitosan-polymer hydrogel.The temporal priority order of acetylacetone was higher than phenolmodified chitosan by density functional theory calculation.The acetylacetone within the gelatin could gradually diffuse spatially into the chitosan hydrogel to fabricate the composite hydrogel with gradient network structure.The gradient hydrogel possessed a transferring topography from the two-dimensional pattern.A continuously decreased modulus along with acetylacetone diffusion was confirmed by atomic force microscope-based force mapping experiment.The water-retaining ability of various regions was confirmed by low-field nuclear magnetic resonance(NMR)and thermogravimetric analysis(TG)analysis,which led to the spontaneous actuation of gradient hydrogel with maximum 1821°/h curling speed and 227°curling angle.Consequently,the promising gradient hydrogels could be applied as intelligent actuators and flexible robots. 相似文献
107.
Weidong Shang Sheng‐Nan Su Rong Shi Ze‐Dong Mou Guo‐Qiang Yu Xia Zhang Dawen Niu 《Angewandte Chemie (International ed. in English)》2021,60(1):385-390
We here report glycosyl sulfoxides appended with an aryl iodide moiety as readily available, air and moisture stable precursors to glycosyl radicals. These glycosyl sulfoxides could be converted to glycosyl radicals by way of a rapid and efficient intramolecular radical substitution event. The use of this type of precursors enabled the synthesis of various complex C‐linked glycoconjugates under mild conditions. This reaction could be performed in aqueous media and is amenable to the synthesis of glycopeptidomimetics and carbohydrate‐DNA conjugates. 相似文献
108.
José Carlos Velasco Calderón Shang Jiang Prof. Dr. Samir H. Mushrif 《Chemphyschem》2021,22(21):2222-2230
The addition of aprotic solvents results in higher reactivities and selectivities in many key aqueous phase biomass reactions, including the acid-catalyzed conversion of fructose to 5-hydroxyl methyl furfural (HMF). The addition of certain co-solvents inhibits the formation of humins via preferential solvation of key functional groups and can alter reaction kinetics. An important factor in this context is the relative stability of the hydronium ion (the catalyst) in the vicinity of the biomass moiety as compared to that in bulk, as it could determine its efficacy in the protonation step. Hence, in the present work, molecular dynamics (MD) simulations of HMF (the model product) and fructose (the model reactant) in acidic water and water-DMSO mixtures are performed to analyze their interaction with the hydronium ions. We show that the presence of DMSO favors the interaction of the hydronium ion with fructose, whereas it has a detrimental effect on the interaction of hydronium ion with HMF. Well-tempered metadynamics (WT-MTD) simulations are performed to determine the relative stability of the hydronium ion in the immediate vicinity of fructose and HMF, as compared to that in the bulk solvent phase, as a function of solvent composition. We find that DMSO improves the stabilization of the hydronium ions in the first solvation shell of fructose compared to that in the bulk solvent. On the other hand, hydronium ions become less stable in the immediate vicinity of HMF, as the concentration of DMSO increases. 相似文献
109.
近年来,具有聚集诱导发光(aggregation-induced emission,AIE)特性的化合物由于在聚集态或固态发光量子效率较高而受到很多关注.含氟的功能化合物,由于氟原子的存在,往往具有独特的结构和物理、化学及生物学性质.根据中心金属和配体的种类,汇总了具有A IE性质的且含有氟代配体的有机金属配合物的研究进展.这些含氟有机金属配合物主要是铱、铂、金配合物,在发光器件、化学传感、细胞成像、数据存储等方面具有潜在应用.还简要讨论了相关研究的发展前景. 相似文献