O与O2在Au团簇上吸附的密度泛函理论研究

采用基于密度泛函理论(DFT)的Dmol³程序系统研究了O原子与O₂在 Au₁₉与Au₂₀团簇上的吸附反应行为. 结果表明: O在Au₁₉团簇顶端洞位上的吸附较Au₂₀强; 在侧桥位吸附强度相近. O与O₂在带负电Au团簇上吸附较强, 在正电团簇吸附较弱. 从O―O键长看, 当金团簇带负电时, O―O键长较长, 中性团簇次之, 正电团簇中O―O键长较短, 因而O₂活化程度依次减弱. 电荷布居分析表明, Au团簇带负电时, O与O₂得电子数较中性团簇多, 而团簇带正电时, 得电子数较少. 差分电荷密度(CDD)表明, O₂与Au团簇作用时, 金团簇失电子, O₂的π^*轨道得电子, 使O―O键活化. O₂在Au₁₉^-团簇上解离反应活化能为1.33 eV, 较中性团簇低0.53 eV; 而在Au₁₉⁺上活化能为2.27 eV, 较中性团簇高0.41 eV, 这与O₂在不同电性Au₁₉团簇O―O键活化规律相一致.     

含大环[Ni([15]aneN5]2+氰基桥联四核簇合物的合成、结构和磁性质

用1,4,7,10,13-五氮十五烷(cpad)作为端基配体,合成了2个同构化合物[{Ni(cpad)}₃M(CN)₆]₂[M(CN)₆](ClO₄)₃·6H₂O (M=Cr³⁺,1;Fe³⁺,2),其中[M(CN)₆]^3-通过氰基桥联配位,4个[Ni(cpad)]²⁺阳离子形成四核簇[{Ni(cpad)}₃M(CN)₆]³⁺,游离的[M(CN)₆]^3-和ClO₄^-为平衡阴离子。晶体参数如下：1,三方晶系,P3c1空间群,a=1.5144 1(18) nm,c=3.080 7(6) nm,V=6.118 9(15) nm³,Z=2;2,三方晶系,P3c1空间群,a=1.4976 2(17) nm,c=3.087 8(5) nm,V=5.997 6(14) nm³,Z=2。变温磁化率显示在四核簇内氰基桥联的金属离子之间存在铁磁相互作用。     

核酸适体修饰纳米金共振散射光谱探针快速检测痕量Pb2＋

以柠檬酸三钠做稳定剂, 用硼氢化钠还原氯金酸制备了粒径为5 nm的纳米金. 用铅离子核酸适体aptamer保护纳米金获得了检测铅离子的适体纳米金(aptamer-NG)共振散射光谱探针. 在pH 7.0的Na₂HPO₄-NaH₂PO₄缓冲溶液中及30 mmol•L^－1 NaCl存在下, aptamer-NG稳定而不聚集. Pb^2＋可与该探针中的aptamer形成非常稳定的G-四分体结构, 并释放出纳米金. 在NaCl作用下纳米金聚集形成较大的微粒, 导致552 nm处共振散射峰强度增大. Pb^2＋浓度在0.07～42 nmol•L^－1范围内与552 nm处共振散射强度增大值ΔI成线性关系, 其回归方程为ΔI＝12.0c＋9.2, 线性相关系数为0.9965, 方法检出限为0.03 nmol•L^－1 Pb^2＋. 该方法用于水样中铅离子检测, 结果与石墨炉原子吸收光谱法结果一致.     

金(Ⅲ)与杯[4]乙酯合钠(Ⅰ)超分子化合物: [Na(C60H80O12)]+[Au(SCN)4]-的合成、结构及性能

A novel super molecule [Na(C₆₀H₈₀O₁₂)]⁺[Au(SCN)₄]^- was obtained by extraction of calix[4] arene (L) for an aqueous solution containing [AuCl₄]^-, and NaCl into CH₂Cl₂. The crystal structure and properties of the title super molecule were characterized by single-crystal X-ray diffraction, IR and ¹H NMR spectra. The X-ray single crystal structure analysis shows that the crystal was Tetragonal system with space group P4/n and the unit cell parameters were as follows: a=2.880 8(18) nm, b=2.880 8(18) nm, c=2.292 4(5) nm, and final R indices [I>2σ(I)]: R₁=0.048 5, wR₂=0.106 1. CCDC: 243229.     

发光的二维Cu(Ⅰ)分子箱[CuCl(DBBD)2]n

Hydrothermal treatment of CuCl and atropisomeric ligand racemic-diethyl (R,S)-4,4′-biquinoline-6,6′-diethyl-3,3′-dicarboxylate (DBBD) (1) in the presence of H₂O and C₂H₅OH over 4 days at 104～109 ℃ yielded colorless block crystals [CuCl(DBBD)₂]_n (2). The compound exhibits strong red fluorescent emission with a wavelength of 650 nm. The crystal of [CuCl(DBBD)₂]_n belongs to monoclinic system with space group C2/c, and a=1.656 58(17) nm, b=2.025 0(2) nm, c=1.548 73(16) nm, β=107.879(2)°, V=4.944 4(9) nm³, D_c=1.417 g·cm^-3, Z=8. CCDC: 292932.     

桥联双核配合物[(DPC)2Co2(H2O)5]·2H2O的合成与晶体结构

The new complex formulated [(DPC)₂Co₂(H₂O)₅]·2H₂O (HDPC^- is pyridine-2,6-dicarboxylate) has been synthesized and the crystal structure was determined by X-ray diffraction. The crystal structure of the complex belongs to monoclinic system with space group P2₁/c, a=0.83850(10) nm, b=2.7386(4) nm, c=0.9610(2) nm, β=98.280 (10) °, V=2.1838(6) nm³, Z=4, D_c=1.746 g·cm^-3, μ=1.597 mm^-1. In the crystal the two Co²⁺ are in distorted octahedrons. The part of [Co(DPC)₂] possess an approximate D_2d symmetry, while the part of [OCo₍₂₎(OH₂)₅] has an approximate C₂ symmetry.     

配合物[Mn(C13H8N2OBr)2(C5H5N)2]·3C5H5N的结构与磁性研究

The complex [Mn(C₁₃H₈N₂OBr)₂(C₅H₅N)₂]·3C₅H₅N has been synthesized and characterized by X-Ray diffraction, IR and variable temperature (～10 to ～278K) magnetic susceptibility. X-Ray diffraction result for the single crystal shows that the crystal belongs to monoclinic, space group P2₁/c, a=1.0969(3)nm, b=2.0903(5)nm, c=2.0481(6)nm, β=97.366(6), V=4.657(2)nm³, Z=4, D_c=1.47g·cm^-3。     

具有经典ACO拓扑开放结构的三维多孔多钒氧酸盐的水热合成和晶体结构

本文采用水热技术合成了一种具有经典ACO拓扑结构的多钒氧酸盐{[Cu₄(V^Ⅳ₁₁V^Ⅴ₇O₄₂(PO₄))(C₃H₁₀N₂)₈]·4H₂O}_n (1,C₃H₁₀N₂=1,2-丙二胺),并且通过元素分析、红外、热重、单晶X-射线衍射对化合物1进行了表征。晶体学分析表明,阴离子簇[V^Ⅳ₁₁V^Ⅴ₇O₄₂(PO₄)]^8-与8个过渡金属配合物阳离子[Cu(C₃H₁₀N₂)₂]²⁺相连而产生具有经典ACO拓扑结构的三维孔道结构。化合物1为四方晶系,P4/nnc空间群,a=b=1.505 91(10) nm,c=1.871 3(3) nm,V=4.243 8(7) nm³,Z=2。化合物1沿c轴方向具有0.753 nm×0.753 nm孔道。     

鲱鱼精DNA修饰纳米金催化Fehling反应——共振散射光谱法检测痕量Hg2＋

用鲱鱼精DNA (hsDNA)修饰10 nm的纳米金制备了Hg^2＋的hsDNA修饰纳米金共振散射光谱探针(AuhsDNA). 在pH 7.0 Tris-HCl缓冲溶液中及0.017 mol/L NaCl存在下, Hg^2＋与AuhsDNA形成稳定的Hg^2＋-DNA结合物, 引起AuhsDNA中的纳米金析出并聚集形成纳米金簇. 该溶液用150 nm滤膜过滤后, 滤液中过量的AuhsDNA可催化Fehling试剂-葡萄糖反应生成氧化亚铜微粒, 该微粒在580 nm处有一个较强的共振散射峰. 随着汞离子浓度增大, 形成的纳米金簇越多, 滤液中AuhsDNA越少, 生成的氧化亚铜微粒减少, 580 nm处氧化亚铜微粒的共振散射光强度线性降低, 其共振散射光强度降低值?I₅₈₀ nm与汞离子浓度在1～833 nmol/L范围内成线性, 回归方程、相关系数、检出限分别为 ?I_{580 nm}＋0.9, 0.9990, 0.3 nmol/L Hg^2＋. 该法用于废水中Hg^2＋的检测.     

含硫、氮Schiff碱配合物—二水二分之一二甲基亚砜醋酸四邻香草醛缩胺基硫脲合镉(Ⅱ)的合成及晶体结构

X射线单晶衍射结果表明,三核镉配合物Cd₃[CH₃O(O)C₆H₃CH=NNHC(S)NH₂]4·[CH₃COO]₂·1/2[CH₃S(O)CH₃]·2H₂O为单斜晶系,空间群为C2/c,a=3.4214(4),b=1.1581(2),c=1.7932(5)nm,β=119.76(1)°,V=6.168nm³,Mr=1427.43,Z=4,D_c=1.54g/cm³,μ=12.48cm^-1,F(000)=2860,最后偏离因子R=0.066.     

[μ‐4,5‐Bis(diphenylphosphino)‐9,9‐dimethylxanthene]bis[(trifluoroacetato)gold(I)] and its dichloromethane 0.58‐solvate

The dinuclear Au^I complex containing the 4,5‐bis(diphenylphosphino)‐9,9‐dimethylxanthene (xantphos) ligand and trifluoroacetate anions exists in a solvent‐free form, [μ‐4,5‐bis(diphenylphosphino)‐9,9‐dimethylxanthene]bis[(trifluoroacetato)gold(I)], [Au₂(C₂F₃O₂)₂(C₃₉H₃₂OP₂)], (I), and as a dichloromethane solvate, [Au₂(C₂F₃O₂)₂(C₃₉H₃₂OP₂)]·0.58CH₂Cl₂, (II). The trifluoroacetate anions are coordinated to the Au^I centres bridged by the xantphos ligand in both compounds. The Au^I atoms are in distorted linear coordination environments in both compounds. The phosphine substituents are in a syn arrangement in the xantphos ligand, which facilitates the formation of short aurophilic Au...Au interactions of 2.8966 (8) Å in (I) and 2.9439 (6) Å in (II).     

Homoleptic Alkynyl‐Protected Gold Nanoclusters: Au44(PhC≡C)28 and Au36(PhC≡C)24

For the first time total structure determination of homoleptic alkynyl‐protected gold nanoclusters is reported. The nanoclusters are synthesized by direct reduction of PhC≡CAu, to give Au₄₄(PhC≡C)₂₈ and Au₃₆(PhC≡C)₂₄. The Au₄₄ and Au₃₆ nanoclusters have fcc‐type Au₃₆ and Au₂₈ kernels, respectively, as well as surrounding PhC≡C‐Au‐C₂(Ph)Au‐C≡CPh dimeric “staples” and simple PhC≡C bridges. The structures of Au₄₄(PhC≡C)₂₈ and Au₃₆(PhC≡C)₂₄ are similar to Au₄₄(SR)₂₈ and Au₃₆(SR)₂₄, but the UV/Vis spectra are different. The protecting ligands influence the electronic structures of nanoclusters significantly. The synthesis of these two alkynyl‐protected gold nanoclusters indicates that a series of gold nanoclusters in the general formula Au_x (RC≡C)_y as counterparts to Au_x (SR)_y can be expected.     

An EXAFS study of some gold and palladium cluster compounds

Gold L₃-edge EXAFS measurements at 80 K on Au₅₅(PPh₃)₁₂Cl₆ confirm that the Au-Au distances in this amorphous metal cluster compound are significantly shorter than in bulk gold. The nearest-neighbour Au-Au distances are all equal within experimental uncertainty. Outer-shell Au-Au distances have also been resolved. The results are consistent with the cuboctahedral structure originally proposed for this cluster, but not the polyicosahedral one recently suggested. Very similar results have been obtained from the sulphonated water-soluble derivative Au₅₅(PPh₂C₆H₄SO₃Na)₁₂Cl₆. In contrast, EXAFS of Au₁₁{PPh₂(p-ClC₆H₄)}₇I₃ has clearly resolved the two nearest-neighbour Au-Au distances associated with its icosahedral structure.Palladium K-edge EXAFS has been used to study the cluster Pd₅₆₁(phen)₃₆O₂₀₀. The Pd-Pd distance is nearly equal to that in bulk palladium. The results show a cubic close-packed cluster structure for this material, in contrast to the icosahedral structure reported for Pd₅₆₁(phen)₆₀(OAc)₁₈₀.     

Theoretical study of the electronic spectrum of binuclear gold(I) complexes

The electronic structure and the spectroscopic properties of [Au₂(CS₃)₂]^?2, [Au₂(pym‐2‐S)₂] (pym = pyrimidethiolate), [Au₂(dpm)₂]⁺² (dpm = bis(diphosphino)methane) were studied using density functional theory (DFT) at the B3LYP level. The absorption spectrum of these binuclear gold(I) complexes was calculated by single excitation time‐dependent (TD) method. All complexes showed a ¹(5dσ* → 6pσ) transition associated with a metal–metal charge transfer, which is strongly interrelated with the gold–gold distance. Furthermore, we have calculated the frequency of the gold–gold vibration (ν_Au2) on the above complexes. The values obtained are theoretically in agreement with experimental range. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

[N(PPh3)2]2[{Au3Ag2(C2Ph)6} {Au3Cu2(Cu2Ph)6}]: Co-crystallized pentanuclear bimetallic gold-silver and gold-copper clusters

The X-ray structural study of the reaction product of equimolar amounts of [Au₃Cu₂(C₂Ph)₆]. [{Au(C₂Ph)} _n ], and [Ag(C₂Ph)} _n ] revealed two bimetallic anionic [N(PPh₃)₂] + [Au₃Ag₂(C₂Ph)₆]^– and [N(PPh₃)₂]⁺[Au₃Cu₂ (C₂ Pg)₆] — clusters co-crystallized in one asymmetric unit. Each cluster has trigonal bipyramidal geometry with three gold atoms occupying equatorial planes and two silver or copper atoms in the apical positions. Our earlier conclusion based upon spectroscopic characterization describing the product of be above reaction as trimetallic cluster containing three coinage-metals with an overall composition [Au₃CuAg(C₂Ph)₆]^–, was erroneous.Presented at the 210th ACS Meeting, August 19–24, 1995, Chicago, Illinois.     

1,2‐Di­cyano‐1,2‐bis­(imidazolidine‐2‐thione)­digold(I) and 2,2‐di­cyano‐1,1‐bis­(di­methyl­thio­urea)­digold(I)

Gold(I) cyanide forms complexes with imidazolidine‐2‐thione (etu) and di­methyl­thio­urea (dmtu) with the formula [Au₂(CN)₂L₂], i.e. the title complexes di­cyano‐1κC,2κC‐bis(imidazolidine‐2‐thione)‐1κS,2κS‐digold(I)(Au—Au), [Au₂(CN)₂(C₃H₆N₂S)₂], and di­cyano‐1κ²C‐bis(N,N′‐di­methyl­thio­urea)‐2κ²S‐digold(I)(Au—Au), [Au₂(CN)₂(C₃H₈N₂S)₂]. In the etu complex, two approximately linear (etu)AuCN groups are held together by a weak homopolar Au—Au bond [3.117 (1) Å], with a torsion angle of 61 (3)° between the two groups. In the dmtu complex, an approximately linear Au(dmtu)₂ group is bound to an approximately linear Au(CN)₂ group by a weak heteropolar Au—Au bond [3.091 (1) Å], with a torsion angle of 83 (5)° between the two groups.     

Fluorescent Gold Nanoclusters with Interlocked Staples and a Fully Thiolate‐Bound Kernel

The structural features that render gold nanoclusters intrinsically fluorescent are currently not well understood. To address this issue, highly fluorescent gold nanoclusters have to be synthesized, and their structures must be determined. We herein report the synthesis of three fluorescent Au₂₄(SR)₂₀ nanoclusters (R=C₂H₄Ph, CH₂Ph, or CH₂C₆H₄^tBu). According to UV/Vis/NIR, differential pulse voltammetry (DPV), and X‐ray absorption fine structure (XAFS) analysis, these three nanoclusters adopt similar structures that feature a bi‐tetrahedral Au₈ kernel protected by four tetrameric Au₄(SR)₅ motifs. At least two structural features are responsible for the unusual fluorescence of the Au₂₄(SR)₂₀ nanoclusters: Two pairs of interlocked Au₄(SR)₅ staples reduce the vibration loss, and the interactions between the kernel and the thiolate motifs enhance electron transfer from the ligand to the kernel moiety through the Au?S bonds, thereby enhancing the fluorescence. This work provides some clarification of the structure–fluorescence relationship of such clusters.     

Co‐Adsorption of O2 and CO on Au2−: Infrared Photodissociation Spectroscopy and Theoretical Study of [Au2O2(CO)n]− (n=2–6)

The co‐adsorption of O₂ and CO on anionic sites of gold species is considered as a crucial step in the catalytic CO oxidation on gold catalysts. In this regard, the [Au₂O₂(CO)_n]^? (n=2–6) complexes were prepared by using a laser vaporization supersonic ion source and were studied by using infrared photodissociation spectroscopy in the gas phase. All the [Au₂O₂(CO)_n]^? (n=2–6) complexes were characterized to have a core structure involving one CO and one O₂ molecule co‐adsorbed on Au₂^? with the other CO molecules physically tagged around. The CO stretching frequency of the [Au₂O₂(CO)]^? core ion is observed around =2032–2042 cm^?1, which is about 200 cm^?1 higher than that in [Au₂(CO)₂]^?. This frequency difference and the analyses based on density functional calculations provide direct evidence for the synergy effect of the chemically adsorbed O₂ and CO. The low lying structures with carbonate group were not observed experimentally because of high formation barriers. The structures and the stability (i.e., the inertness in a sense) of the co‐adsorbed O₂ and CO on Au₂^? may have relevance to the elementary reaction steps on real gold catalysts.     

A Chiral Gold Nanocluster Au20 Protected by Tetradentate Phosphine Ligands

The chirality of a gold nanocluster can be generated from either an intrinsically chiral inorganic core or an achiral inorganic core in a chiral environment. The first structural determination of a gold nanocluster containing an intrinsic chiral inorganic core is reported. The chiral gold nanocluster [Au₂₀(PP₃)₄]Cl₄ (PP₃=tris(2‐(diphenylphosphino)ethyl)phosphine) has been prepared by the reduction of a gold(I)–tetraphosphine precursor in dichloromethane solution. Single‐crystal structural determination reveals that the cluster molecular structure has C₃ symmetry. It consists of a Au₂₀ core consolidated by four peripheral tetraphosphines. The Au₂₀ core can be viewed as the combination of an icosahedral Au₁₃ and a helical Y‐shaped Au₇ motif. The identity of this Au₂₀ cluster is confirmed by ESI‐MS. The chelation of multidentate phosphines enhances the stability of this Au₂₀ cluster.     

Alkynyl‐Protected Au23 Nanocluster: A 12‐Electron System

A 23‐gold‐atom nanocluster was prepared by NaBH₄‐mediated reduction of a solution of PhC?CAu and Ph₃PAuSbF₆ in CH₂Cl₂. The cluster composition was determined to be [Au₂₃(PhC?C)₉(Ph₃P)₆]²⁺ and single‐crystal X‐ray diffraction revealed that the cluster has an unprecedented Au₁₇ kernel protected by three PhC₂‐Au‐C₂(Ph)‐Au‐C₂Ph motifs and six Ph₃P groups. The Au₁₇ core can be viewed as the fusion of two Au₁₀ units sharing a Au₃ triangle. Electronic structure analysis from DFT calculations suggests that the stability of this unusual 12‐electron cluster is a result of the splitting of the superatomic 1D orbitals under D_3h symmetry of the Au₁₇ kernel. The discovery and determination of the structure of the Au₂₃ cluster demonstrates the versatility of the alkynyl ligand in leading to the formation of new cluster compounds.