Synthesis and electrochemical studies of η-monocyclopentadienylruthenium(II) complexes with substituted thiophene nitrile ligands. Crystal structure of [Ru(η-C5H5)(dppe)(NC{SC4H2}2NO2)][PF6]

A systematic series of η⁵-monocyclopentadienylruthenium(II) complexes with substituted thiophene nitrile ligands of general formula [Ru(η⁵-C₅H₅)(P_P)(NC{SC₄H₂}_nNO₂)][PF₆] (P_P = dppe, (+)-diop; n = 1-3) has been synthesized and characterized. Spectroscopic and electrochemical data were used in order to get an insight on the molecular nonlinear optical properties of these complexes when compared to those found for the reported thiophene iron(II) and p-benzonitrile or 1,2-di-(2-thienyl)-ethene derived iron(II)/ruthenium(II) related complexes. The compound [Ru(η⁵-C₅H₅)(dppe)(NC{SC₄H₂}₂NO₂)][PF₆] was also characterized by X-ray diffraction. The solid state nonlinear optical properties of the chiral compounds were also evaluated by Kurtz powder technique with a Nd:YAG laser emitting at 1064 nm.     

Synthesis and characterization of triosmium and triruthenium pyrene clusters

The reaction between 1-pyrenecarboxaldehyde (C₁₆H₉CHO) and the labile triosmium cluster [Os₃(CO)₁₀(CH₃CN)₂] gives rise to the formation of two new compounds by competitive oxidative addition between the aldehydic group and an arene C-H bond, to afford the acyl complex [Os₃(CO)₁₀(μ-H)(μ-COC₁₆H₉)] (1) and the compound [Os₃(CO)₁₀(μ-H) (C₁₆H₈CHO)] (2), respectively. Thermolysis of [Os₃(CO)₁₀(μ-H)(μ-C₁₆H₉CO)] (1) in n-octane affords two new complexes in good yields, [Os₃(CO)₉(μ-H)₂(μ-COC₁₆H₈)] (3) and the pyryne complex [Os₃(CO)₉(μ-H)₂(μ₃-η¹:η¹:η²-C₁₆H₈)] (4).In contrast, when 1-pyrenecarboxaldehyde reacts with [Ru₃(CO)₁₂] only one product is obtained, [Ru₃(CO)₉(μ-H)₂(μ₃-η¹:η¹:η²-C₁₆H₈)] (5), a nonacarbonyl cluster bearing a pyrene ligand. All compounds were characterized by analytical and spectroscopic data, and crystal structures for 1, 2, 4 and 5 were obtained.     

Synthesis and structural characterization of ruthenium(II) and iron(II) complexes containing 1,2-di-(2-thienyl)-ethene derived ligands as chromophores

A new family of three-legged piano stool structured organometallic compounds containing the η⁵-cyclopentadienylruthenium(II)/iron(II) fragments {M(η⁵-C₅H₅) (DPPE)}⁺, {Ru(η⁵-C₅H₅)(PPh₃)₂}⁺ and {Ru(η⁵-C₅H₅)(TMEDA)}⁺ with coordinated thiophene based chromophores, namely 5-(2-thiophen-2-yl-vinyl)-thiophene-2-carbonitrile (L1) and 5-[2-(5-Nitro-thiophen-2-yl)-vinyl]-thiophene-2-carbonitrile (L2) has been synthesized and fully characterized by ¹H, ¹³C, ³¹P NMR, IR and UV-Vis spectroscopies. Also, electrochemical studies were carried out by cyclic voltammetry and all experimental data are interpreted and compared with related compounds under the scope of NLO properties. Compounds [Ru(η⁵-C₅H₅)(DPPE)(NC(C₄H₂S)C(H)C(H)(C₄H₃S))][CF₃SO₃] (1′Ru) [Fe(η⁵-C₅H₅)(DPPE)(NC(C₄H₂S)C(H)C(H)(C₄H₃S))] [PF₆] (1Fe) and [Ru(η⁵-C₅H₅)(DPPE)(NC(C₄H₂S)C(H)C(H)(C₄H₂S)NO₂)][CF₃SO₃] (4′Ru) were also crystallographically characterized.     

Heterobimetallic Re–Pd,Re–Au and Re–Cu complexes derived from diphenylphosphino cyrhetrene: Synthesis and X-ray structure

Diphenylphosphinecyrhetrene ligand (η⁵-C₅H₄PPh₂)Re(CO)₃ (1) reacts with 1 equiv. of PdCl₂(NCPh)₂ to form, after workup, the square-planar trans-[(η⁵-C₅H₄PPh₂)Re(CO)₃]PdCl₂(NCMe) (2). Similarly, reaction of 1 with (tetrahydrothiophene)AuCl produces, in excellent yield, the bimetallic complex [(η⁵-C₅H₄PPh₂)Re(CO)₃]AuCl (3) with a linear P–Au–Cl moiety. From the reaction of 2 equiv. of 1 with CuBr(SMe₂) the planar-trigonal complex [(η⁵-C₅H₄PPh₂)Re(CO)₃]₂CuBr (4) was obtained. ³¹P NMR and X-ray crystallography demonstrate, for the three cases, that (η⁵-C₅H₄PPh₂)Re(CO)₃ acts as a monodentate ligand. The structural parameters of the bimetallic complexes are compared with related diphenylphosphinoferrocene metal complexes, described in the literature.     

Trimming algorithms for clustering contaminated grouped data and their robustness

We establish an affine equivariant, constrained heteroscedastic model and criterion with trimming for clustering contaminated, grouped data. We show existence of the maximum likelihood estimator, propose a method for determining an appropriate constraint, and design a strategy for finding reasonable clusterings. We finally compute breakdown points of the estimated parameters thereby showing asymptotic robustness of the method.     

TFA-MOD法制备YBCO薄膜生长速率研究

采用原位电阻法对TFA-MOD法高温热处理阶段YBCO薄膜生长速率进行了研究。实验结果和分析表明原位电阻测量法是一种估算YBCO层生长速率的有效方法,不同条件下的测量结果表明薄膜生长速率随管式炉内的温度、水分压、气体流量的上升而明显增加,但随薄膜面积的增加而减小。实验结果为进一步探索和优化热处理过程提供了重要的基础。     

Manipulation of Supramolecular Columnar Structures of H-Bonded Donor-Acceptor Units through Geometrical Nanoconfinement

Ambipolar organic semiconductors are considered promising for organic electronics because of their interesting electric properties. Many hurdles remain yet to be overcome before they can be used for practical applications, especially because their orientation is hard to control. We demonstrate a method to control the orientation of columnar structures based on a hydrogen (H)-bonded donor-acceptor complex between a star-shaped tris(triazolyl)triazine and triphenylene-containing benzoic acid, using physicochemical nanoconfinement. The molecular configuration and supramolecular columnar assemblies in a one-dimensional porous anodic aluminium oxide (AAO) film were dramatically modulated by controlling the pore-size and by chemical modification of the inner surface of the porous AAO film. In situ experiments using grazing-incidence X-ray diffraction (GIXRD) were carried out to investigate the structural evolution produced at the nanometer scale by varying physicochemical conditions. The resulting highly ordered nanostructures may open a new pathway to effectively control the alignment of liquid crystal ambipolar semiconductors.     

The INPHARMA technique for pharmacophore mapping: A theoretical guide to the method

During the process of drug discovery, INPHARMA can be used to derive the structure of receptor/lead compound complexes binding to each other with a K_d in the μM to mM range. To be successful, the methodology needs adjustment of various parameters that depend on the physical constants of the binding event and on the receptor size. Here we present a thorough theoretical analysis of the INPHARMA interligand NOE effect in dependence of experimental parameters and physical constants. This analysis helps the experimentalist to choose the correct experimental parameters and consequentially to achieve optimal performance of the methodology.     

Physical properties of 8OS5 thioester studied by complementary methods

ABSTRACT

Properties of 4-n-pentylphenyl-4’-n-octyloxythiobenzoate (8OS5), belonging to the nOS5 homologous series, have been studied by complementary methods. The phase sequence, the phase transition temperatures, the thickness of molecular layers, the average distance between long axes of molecules and the correlation length were determined during cooling and heating. For the first time, simultaneous X-ray diffraction and differential scanning calorimetry measurements have been used to study mesomorphic properties. The results are compared with the ones obtained in standard measurements by means of differential scanning calorimetry, X-ray diffraction and polarizing optical microscopy. Meaning of experimental procedures applied in investigations of monotropic mesophases below a melting point is discussed.     

Stability and Extinction for Lotka–Volterra Systems with Infinite Delay

The paper deals with the global stability of a saturated equilibrium \({x^{\ast} = (x_1^{\ast}, \ldots, x_n^{\ast}) \ge 0}\) for a multi-species Lotka–Volterra model with infinite delay. We assume the existence of non-delayed diagonal intraspecific competition terms, but relax the usual conditions of dominance which permit to control the infinite delay effect. Our results also apply to non-autonomous Lotka–Volterra systems without saturated equilibria, by studying the stability of their limiting equations. Some known results in the literature are improved and generalized.