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991.
Jun‐Qing Wen Zhen‐Yi Jiang Jun‐Qian Li Li‐Ke Cao San‐Yan Chu 《International journal of quantum chemistry》2010,110(7):1368-1375
Density‐functional with generalized gradient approximation (GGA) for the exchange‐correlation potential has been used to calculate the energetically global‐minimum geometries and electronic states of NinAl (n = 2–8) neutral clusters. Our calculations predict the existence of a number of previously unknown isomers. All structures may be derived from a substitution of a Ni atom at marginal positions by an Al atom in the Nin+1 cluster. Aluminum atom remains on the surface of the geometrical configurations. Moreover, these species prefer to adopt three‐dimensional (3D) spacial forms at the smaller number of nickel atoms compared with the pure Nin+1 (n ≥ 3) configuration. Atomization energies per atom for NinAl (n = 2–8) have the same trend as the binding energies per atom for Nin (n = 3–9). The stabilization energies reveal that Ni5Al is the relatively most stable in this series. In comparison with the magnetic moment of pure metal nickel (0.6 μB), the average magnetic moment of Ni atom increases in Ni Al clusters except the Ni3Al. Moreover, except the case of Ni5Al, Ni average magnetic moment decreases when alloyed with Al atoms than that in pure Ni clusters, which originate the effective charge transferring from Al to Ni atoms. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
992.
Yu‐Bo Wang Tong‐Hen Pan Qian Liang Dong‐Sheng Liu Chang‐Cang Huang 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(5):m127-m129
The asymmetric unit of the title complex, [CdCl2(C14H12N4O2S)2]n, consists of one CdII ion located on the crystallographic inversion centre, one 4‐benzoyl‐1‐isonicotinoylthiosemicarbazide ligand and one chloride ligand. The central CdII ion adopts a distorted octahedral coordination geometry formed by two pyridyl N atoms of two ligands, two S atoms of two other ligands and two chloride ligands. The thiosemicarbazide ligands act as bridges, linking the metal ions into a two‐dimensional layered structure parallel to the bc plane. Intermolecular N—H...O hydrogen bonds and C—H...π interactions exist between adjacent layers. 相似文献
993.
Thomas J. Payne Chad R. Thurman Hao Yu Qian Sun Dillip K. Mohanty Philip J. Squattrito Mark‐Robin Giolando Christopher R. Brue Kristin Kirschbaum 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(7):o369-o373
N,N′‐Diethyl‐4‐nitrobenzene‐1,3‐diamine, C10H15N3O2, (I), crystallizes with two independent molecules in the asymmetric unit, both of which are nearly planar. The molecules differ in the conformation of the ethylamine group trans to the nitro group. Both molecules contain intramolecular N—H...O hydrogen bonds between the adjacent amine and nitro groups and are linked into one‐dimensional chains by intermolecular N—H...O hydrogen bonds. The chains are organized in layers parallel to (101) with separations of ca 3.4 Å between adjacent sheets. The packing is quite different from what was observed in isomeric 1,3‐bis(ethylamino)‐2‐nitrobenzene. 2,6‐Bis(ethylamino)‐3‐nitrobenzonitrile, C11H14N4O2, (II), differs from (I) only in the presence of the nitrile functionality between the two ethylamine groups. Compound (II) crystallizes with one unique molecule in the asymmetric unit. In contrast with (I), one of the ethylamine groups, which is disordered over two sites with occupancies of 0.75 and 0.25, is positioned so that the methyl group is directed out of the plane of the ring by approximately 85°. This ethylamine group forms an intramolecular N—H...O hydrogen bond with the adjacent nitro group. The packing in (II) is very different from that in (I). Molecules of (II) are linked by both intermolecular amine–nitro N—H...O and amine–nitrile N—H...N hydrogen bonds into a two‐dimensional network in the (10) plane. Alternating molecules are approximately orthogonal to one another, indicating that π–π interactions are not a significant factor in the packing. Bis(4‐ethylamino‐3‐nitrophenyl) sulfone, C16H18N4O6S, (III), contains the same ortho nitro/ethylamine pairing as in (I), with the position para to the nitro group occupied by the sulfone instead of a second ethylamine group. Each 4‐ethylamino‐3‐nitrobenzene moiety is nearly planar and contains the typical intramolecular N—H...O hydrogen bond. Due to the tetrahedral geometry about the S atom, the molecules of (III) adopt an overall V shape. There are no intermolecular amine–nitro hydrogen bonds. Rather, each amine H atom has a long (H...O ca 2.8 Å) interaction with one of the sulfone O atoms. Molecules of (III) are thus linked by amine–sulfone N—H...O hydrogen bonds into zigzag double chains running along [001]. Taken together, these structures demonstrate that small changes in the functionalization of ethylamine–nitroarenes cause significant differences in the intermolecular interactions and packing. 相似文献
994.
995.
Miaojing Chen Hong Li Qian Li Zhenghe Xu 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(5):1566-1570
The luminescence properties of [Ru(bpy)2MDHIP]2+ (bpy = 2,2′-bipyridine, MDHIP = 2,4-dihydrophenyl-imidazo[4,5-f][1,10]phenanthroline) in the absence and presence of DNA modulated by the introduction of Cu2+ ion and EDTA have been investigated. It is found that the ruthenium(II) complex can insert and stack between the base pairs of calf thymus DNA with MDHIP ligand, and the intramolecular hydrogen bond is located inside of the DNA. The presence of DNA can enhance the luminescence intensities of [Ru(bpy)2MDHIP]2+ both in buffer solution and on an ITO surface. Moreover, the luminescence intensities of [Ru(bpy)2MDHIP]2+ and DNA-bound [Ru(bpy)2MDHIP]2+ are quenched by Cu2+, and next recovered by the addition of EDTA. The repetitive luminescence-modulations have been achieved through the introduction of equimolar Cu2+ and EDTA, respectively. In addition, it becomes evident that the number of luminescence-modulation cycles for [Ru(bpy)2MDHIP]2+ in the absence and presence of DNA is influenced by the cumulative concentrations of CuEDTA, generated successively by the strong coordination of Cu2+ to EDTA. 相似文献
996.
探讨了核苷类化合物指纹图谱用于不同海洋动物药真伪鉴别的可行性, 为贵重动物药的鉴别提供了一种新方法. 采用亲水色谱-电喷雾飞行时间质谱(HILIC-ESI-TOF/MS)对不同海洋动物药中的16种核苷类化合物进行分析, 构建了基于16种核苷类化合物的特征指纹图谱, 结合相似度分析和聚类分析, 用于不同海洋动物药的鉴别. 结果表明, 基于核苷类化合物HILIC-ESI-TOF/MS分析的指纹图谱能反映不同海洋动物药各自的固有特征, 结合相似度分析和聚类分析可实现对不同海洋动物药的正确区分. 说明核苷类化合物指纹图谱有望成为动物药鉴别的新方法. 相似文献
997.
研究了离子液体分散液相微萃取(ILDLPME)机理, 建立了简单、快速、灵敏的ILDLPME-HPLC(高效液相色谱)同时测定中药白附子中5种低丰度苯丙烯酸类化合物含量的方法, 对不同产地白附子的质量进行了比较和评价. 在最佳的ILDLPME-HPLC条件下, 测得咖啡酸的线性范围为1.28×10-3~2.60 μg/mL, 对羟基桂皮酸及阿魏酸的线性范围为1.28×10-4~2.60 μg/mL, 桂皮酸及对甲氧基桂皮酸的线性范围为1.28×10-3~4.00 μg/mL, 检出限分别为0.13, 0.01, 0.01, 0.13和0.13 ng/mL, 日内精密度RSD<7.9%, 日间精密度RSD<9.7%, 药材中分析物的回收率在86.9%~112.6%之间, ILDLPME 对5种分析物的富集倍数分别在56.0~159.3倍之间. 结合5种苯丙烯酸类化合物ILDLPME萃取前后紫外光谱的变化, 提出了ILDLPME萃取苯丙烯酸羧基-离子液体电荷转移超分子(CTSMCIL)机理. 本研究为建立中药白附子的质量控制方法提供了理论依据和实验基础. 相似文献
998.
Zhao XH Xie GH Liu ZD Li WJ Yi MD Xie LH Hu CP Zhu R Zhao Q Zhao Y Zhao JF Qian Y Huang W 《Chemical communications (Cambridge, England)》2012,48(32):3854-3856
A 3-D platinum(II)-based spirometal complex has been designed and synthesized to suppress aggregation and excimer emission. A prototype phosphorescent organic light-emitting device exhibits the high-performance orange emission with an external quantum efficiency of up to 5.2%. 相似文献
999.
Xi Q Chen X Evans DG Yang W 《Langmuir : the ACS journal of surfaces and colloids》2012,28(25):9885-9892
A uniform three-dimensional (3D) gold nanoparticle (AuNP)-embedded porous graphene (AuEPG) thin film has been fabricated by electrostatic layer-by-layer assembly of AuNPs and graphene nanosheets functionalized with bovine serum albumin and subsequent thermal annealing in air at 340 °C for 2 h. Scanning electron microscopy (SEM) investigations for the AuEPG film indicate that an AuNP was embedded in every pore of the porous graphene film, something that was difficult to achieve with previously reported methods. The mechanism of formation of the AuEPG film was initially explored. Application of the AuEPG film in electrochemical sensing was further demonstrated by use of H(2)O(2) as a model analyte. The AuEPG film-modified electrode showed improved electrochemical performance in H(2)O(2) detection compared with nonporous graphene-AuNP composite film-modified electrodes, which is mainly attributed to the porous structure of the AuEPG film. This work opens up a new and facile way for direct preparation of metal or metal oxide nanoparticle-embedded porous graphene composite films, which will enable exciting opportunities in highly sensitive electrochemical sensors and other advanced applications based on graphene-metal composites. 相似文献
1000.
A room-temperature Ni-catalyzed reductive method for the coupling of aryl bromides with secondary alkyl bromides has been developed, providing C(sp(2))-C(sp(3)) products in good to excellent yields. Slight modification of this protocol allows efficient coupling of activated aryl chlorides with cyclohexyl bromide and aryl bromides with allylic acetate. 相似文献