Langmuir-Blodgett films of a Mo-blue nanoring [Mo(142)O(429)H(10)(H(2)O)(49)(CH(3)CO(2))(5)(CH(3)CH(2)CO(2))](30)(-) (Mo(142)) by the semiamphiphilic method

Langmuir monolayers and LB films of the ring-shaped mixed-valence polyoxomolybdate [Mo142O429H10(H2O)49(CH3CO2)5(CH3CH2CO2)](30-) (Mo142) dissolved in the aqueous subphase have been successfully fabricated by using the adsorption properties of a DODA monolayer. Infrared and ultraviolet-visible spectroscopy of the LB films indicates that Mo142 and DODA molecules are incorporated within these LB films. X-ray reflectivity experiments indicate that the LB films exhibit a well-defined lamellar structure formed by bilayers of DODA molecules alternating with monolayers of Mo142. Using behenic acid-modified hydrophobic quartz substrate is critical for the formation of the well-defined lamellar structure. From the values of the periodicity obtained by these experiments it is clear that the Mo142 clusters lie flat along the charged organic layers. AFM images also showed the flat and homogeneous films on the quartz substrates treated with behenic acid. Cyclic voltammograms of Mo142-LB films deposited on ITO substrates showed quasi-reversible oxidation/reduction waves with positive shift of the potential compared to the case of solution.     

4,2-Ribbon like ferromagnetic cyano-bridged Fe(III)2Ni(II) chains: a magneto-structural study

The low-spin iron(III) complex AsPh(4)[Fe(III)(bpy)(CN)(4)].CH(3)CN (1) [AsPh(4) = tetraphenylarsonium cation] and the heterobimetallic chains [{Fe(III)(L)(CN)(4)}(2)Ni(II)(H(2)O)(2)].4H(2)O with L = bpy (2) and phen (3) [bpy = 2,2'-bipyridine and phen = 1,10-phenanthroline] have been prepared and their structures determined by X-ray diffraction methods. The structure of 1 consists of mononuclear [Fe(bpy)(CN)(4)](-) anions, tetraphenylarsonium cations and acetonitrile molecules of crystallization. The iron(III) is hexacoordinated with two nitrogen atoms of the bidentate bpy and four carbon atoms of four terminal cyanide groups building a distorted octahedral surrounding around the metal atom. 2 and 3 are isomorphous compounds whose structure is made up of neutral 4,2-ribbon like bimetallic chains of formula [{Fe(III)(L)(CN)(4)}(2)Ni(II)(H(2)O)(2)] where the [Fe(III)(L)(CN)(4)](-) unit acts as a bis-monodentate bridging ligand toward the trans-diaquanickel(II) units through two of its four cyanide groups in cis positions. The chains exhibit two orientations in the unit cell and they interact with each other through hydrogen bonds involving the coordination and crystallization water molecules together with the uncoordinated cyanide nitrogen atoms of the [Fe(L)(CN)(4)](-) units. Compounds 2 and 3 behave as ferromagnetic Fe(III)(2)Ni(II) chains which interact ferromagnetically at very low temperatures in the case of 2, whereas metamagnetic-like behaviour is observed for with a critical field (H(c)) around 200 G. For H > H(c) the ferromagnetic Fe(III)(2)Ni(II) chains of 3 exhibit a frequency dependence of the out-of-phase ac susceptibility signal at T < 3.5 K.     

Metamorphosis of a butterfly: synthesis, structural, thermal, magnetic and DFT characterisation of a ferromagnetically coupled tetranuclear copper(II) complex

The reaction in water of Cu(OH)(2) with 2,2'-bipyridine (bipy) and (NH(4))(2)HPO(4) in a 4 : 4 : 2 molar ratio under an inert atmosphere leads to the formation of a tetranuclear copper(II) complex of formula {[(H(2)O)(2)Cu(4)(bipy)(4)(mu(4)-PO(4))(2)(mu(2)-OH)] x 0.5 HPO(4) x 15.5 H(2)O}, 1, with butterfly topology. The structure of the tetranuclear core in 1 consists of four crystallographically unique copper(II) ions in approximate square-pyramidal geometry with each coordinated to a bipy ligand and interacting through two mu(4)-O,O',O'-phosphate bridges. Additional bridging between Cu(3) and Cu(4) is provided by a hydroxide ligand, whereas two water molecules cap the Cu(1) and Cu(2) square pyramids to yield a N(2)O(3) chromophore at each copper atom. Adjacent tetranuclear units align in anti-parallel fashion where proximate metal-bound water molecules interact with each other through both intra- and inter-molecular H-bonding to link two such clusters. These pairs then further associate through pi[...]pi interactions between bipy ligands to form a 2D sheet with neighbouring sheets separated by H-bonded lattice water molecules, which form a 2D H-bonded network. Variable-temperature magnetic susceptibility measurements performed upon 1 reveal net intramolecular ferromagnetic coupling between the copper(II) ions and this is supported and rationalized by a DFT study.     

Theoretical study on the structure, stability, and electronic properties of the guanine-Zn-cytosine base pair in M-DNA

M-DNA is a type of metalated DNA that forms at high pH and in the presence of Zn, Ni, and Co, with the metals placed in between each base pair, as in G-Zn-C. Experiments have found that M-DNA could be a promising candidate for a variety of nanotechnological applications, as it is speculated that the metal d-states enhance the conductivity, but controversy still clouds these findings. In this paper, we carry out a comprehensive ab initio study of eight G-Zn-C models in the gas phase to help discern the structure and electronic properties of Zn-DNA. Specifically, we study whether a model prefers to be planar and has electronic properties that correlate with Zn-DNA having a metallic-like conductivity. Out of all the studied models, there is only one which preserves its planarity upon full geometry optimization. Nevertheless, starting from this model, one can deduce a parallel Zn-DNA architecture only. This duplex would contain the imino proton, in contrast to what has been proposed experimentally. Among the nonplanar models, there is one that requires less than 8 kcal/mol to flatten (both in gas and solvent conditions), and we propose that it is a plausible model for building an antiparallel duplex. In this duplex, the imino proton would be replaced by Zn, in accordance with experimental models. Neither planar nor nonplanar models have electronic properties that correlate with Zn-DNA having a metallic-like conductivity due to Zn d-states. To understand whether density functional theory (DFT) can describe appropriately the electronic properties of M-DNAs, we have investigated the electronic properties of G-Co-C base pairs. We have found that when self-interaction corrections (SIC) are not included the HOMO state contains Co d-levels, whereas these levels are moved below the HOMO state when SIC are considered. This result indicates that caution should be exercised when studying the electronic properties of M-DNAs with functionals that do not account for strong electronic correlations.     

制备大直径无气泡聚苯乙烯空心微球

 高品质聚苯乙烯（PS）空心微球是惯性约束聚变（ICF）实验用多层塑料微球靶的重要芯轴,常由乳液技术制备。针对由乳液技术制备的PS微球壳壁内容易形成气泡而且大直径微球制备困难的问题,实验研究了对壳壁内存在的气泡以及消除方法和制备大直径PS微球的制备技术。     

Monitoring the Phase Transition of C12E5/Water/Alkane Microemulsions Through Excimer Formation

The phase transition of microemulsions involving the nonionic surfactant C₁₂E₅ [C₁₂H₂₅(OCH₂-CH₂)₅OH], water, and alkanes (heptane, decane and tetradecane) has been investigated through the excimer formation of pyrene. On going to the microemulsion bicontinuous phase, by changing either composition or temperature, pronounced changes in the pyrene excimer-to-monomer fluorescence intensity ratio, I _E/I _M, are observed. Several differences in the steady-state emission spectra and in fluorescence decay curves show that as a probe pyrene is well suited to follow the transition from the water continuous to the oil continuous phase, through an intermediate bicontinuous (continuous in both water and oil) region. The results provide information about the different characteristics and structure of these three regions (water continuous, bicontinuous, and oil continuous) of the phase diagram for C₁₂E₅/water/alkane systems.     

氨基羧酸纤维分离富集水中痕量铅镉

铅、镉是有毒元素,严重危害人体健康,因此水中铅镉的含量历来是水质监测评价中的必测项目。但由于水样中铅镉含量较低,且基体干扰严重,所以测定前必须采取一定的富集与分离方法。本文在原螯合纤维制备的基础上［１,２］改换某些原料［３,４］,制备了氨基乙酸纤维滤...     

氯化钇与水杨醛类杂环息夫碱配合物的合成与表征

由水杨醛制得的息夫碱及其配合物具有显著的抗癌活性［１］。近年来,过渡金属离子与此类配合物的研究已有文献报道［２］。为了研究钇与此类息夫碱的配位能力,我们在无水乙醇体系中合成了氯化钇与水杨醛类杂环息夫碱的三种新的固体配合物,并对其组成和配位方式进行了研...     

水杨醛及邻香草醛缩丙醇胺与锰形成的配合物的合成与红外光谱

锰的配位化学由于其生物功能,而愈来愈引起人们的广泛兴趣。在某些生物酶中,锰的配位环境多为咪唑的氮和羧基及水分子的氧原子配位［１,２］。由于Ｓｃｈｉｆ碱以氮原子和氧原子配位,与生物环境接近,在模型配合物研究方面,以多齿Ｓｃｈｉｆ碱为配体的锰的配合物,特...     

The Iowa connection

A summary of the Fluorinated Ylide Chemistry, Organometallic Chemistry, Phosphonate Chemistry, Single-Electron-Transfer Chemistry and Metal Hydride Chemistry carried out at the University of Iowa is described.