Ueber die Invarianten der einfachsten Systeme simultaner binärer Formen

Ohne Zusammenfassung     

Crystal structure ofmer,trans-[Ru(NO2)(trpy)(PPr3) 2 + ][ClO 4 − ], a species with disordered PPr3 and NO2 ligands

The complexmer,trans-[Ru(NO₂)(trpy)(PPr₃) ₂ ⁺ ][ClO ₄ ^– ]crystallizes in the centrosymmetric orthorhombic space group Pnma withZ=4. Both the ruthenium(II) cation and the perchlorate ligand lie about crystallographic mirror planes. The nitro ligand is not coplanar with the Ru(trpy) moiety and suffers from two fold disorder about its Ru–N bond such that the two sets of oxygen atoms have symmetry-related sites above or below the crystallographic mirror plane. The n-propyl groups within the PPr₃ ligands suffer from disorder of their C() and C() atoms but share common C() sites. Ruthenium-ligand distances are: Ru–PPr₃=2.398(2)Å, Ru–NO₂=2.053(7) Å, Ru–N(trpy, outer)=2.078(6) and 2.092(6) Å and Ru–N(trpy, central) =1.965(6) Å.     

PHOTOINHIBITION OF CHLOROPLAST REACTIONS

Abstract— An attemlpt was made to localize the site of photoinhibition of photosynthesis by measuring the decay of various chloroplast reactions after exposure to very strong light. A11 substrate reductions coupled to oxygen evolution as well as photophosphorylation mediated by PMS, proved equally sensitive to photoinhibition. Reactions involving only the long wave photosystem, such as TPN reduction with ascorbate as electron donor and photooxidation of cytochromec by detergent-treated chloroplasts were sensitive to a lower degree.
Photoinhibition irreversibly annihilated the 'variable' fraction of fluorescence emission —it decreased the steady state yield 2-3 fold and abolished the slow rise of the emission at the onset of illurnination.
It is concluded that the primary site of light inactivation is in, or close to, the trapping centers of the oxygen evolving step of photosynthesis. Pre-illumination leaves these traps in a state capable of draining light from sensitizing pigments but unable to perform useful photochemistry.     

Etchant solutions for the removal of Cu(0) in a supercritical CO2-based "dry" chemical mechanical planarization process for device fabrication

The microelectronics industry is focused on increasing chip complexity, improving the density of electron carriers, and decreasing the dimensions of the interconnects into the sub-0.25 mum regime while maintaining high aspect ratios. Water-based chemical mechanical planarization or polishing (CMP) faces several technical and environmental challenges. Condensed CO2 has significant potential for replacing current CMP solvents as a "dry" etching medium because of its unique properties. In working toward a condensed CO2-based CMP process, we have successfully investigated the oxidation and chelation of solid copper metal in liquid and supercritical CO2 using ethyl peroxydicarbonate and a beta-diketone chelating agent.     

Composition-Controlled Laser-Induced Alloying of Colloidal Au–Cu Hetero Nanoparticles

Due to their optical properties (localized surface plasmon resonance, LSPR), colloidally dispersed metal nanoparticles are well suited for selective heating by high-energy laser radiation above their melting point without being limited by the boiling point of the solvent, which represents an excellent complement to wet-chemical nanoparticle synthesis. By combining wet-chemical synthesis and postsynthesis laser treatment, the advantages of both methods can be used to specifically control the properties of nanoparticles. Especially in the colloidal synthesis of nanoalloys consisting of two or more metals with different redox potentials, wet-chemical synthesis quickly reaches its limits in terms of composition control and homogeneity. For this reason, the direct synthesis path is divided into two parts to take the strengths of both methods. After preparing Au–Cu hetero nanoparticles by wet-chemical synthesis, nanoalloys with previous adjusted composition can be formed by postsynthesis laser treatment. The formation of these nanoalloys can be followed by different characterization methods, such as transmission electron microscopy (TEM), where the fusion of both metal domains and the formation of spherical and homogeneous Au–Cu nanoparticles can be observed. Moreover, the alloy formation can be followed by different shifts of X-ray diffraction (XRD) reflections and LSPR maxima depending on the composition.     

Characterization of self-assembled monolayers from lithium dialkyldithiocarbamate salts

We report the formation of self-assembled monolayers (SAMs) onto gold substrates by exposure to lithium dialkyldithiocarbamate salts [(Li+(R2DTC-), where R = n-propyl, n-butyl, n-octyl, n-decyl, n-dodecyl, or n-octadecyl] in ethanol or methylene chloride. The crystallinity and composition of the monolayers were assessed by polarized modulation infrared reflection absorption spectroscopy (PM-IRRAS), wettability was characterized by contact angles of water and hexadecane, thickness was measured by spectroscopic ellipsometry, and barrier properties determined by electrochemical impedance spectroscopy. While the shorter R2DTC-s formed monolayers with liquid-like packing, monolayers prepared from the longest R2DTC- (where R = n-octadecyl) exhibit similar thickness, crystallinity, wettability, and capacitance as monolayers prepared from n-octadecanethiol. The hydrocarbon chains within the monolayers prepared from (C18)2DTC- are less canted on average than those prepared from n-octadecanethiol. Nonetheless, the (C18)2DTC- SAM exhibits an order of magnitude lower resistance against the penetration of redox probes, which is attributed to a higher density of pinhole defect sites.     

Crystal structure of the hemitoluene solvate of racemiccis-bis(bipyridyl)chloro(tri-n-propylphosphine)ruthenium(II) perchlorate,a species with disordered PPr3 and toluene moieties

The complexcis-[Ru(bpy)₂(PPr₃)Cl⁺][ClO ₄ ^– ] · 0.5 (toluene) crystallizes as a racemate in the monoclinic space group P2₁/n. Both the PPr₃ ligand and the toluene of crystallization are subject to disorder. Ruthenium—ligand distances are: Ru–PPr₃=2.348(2) Å, Ru–Cl=2.426(2) Å and Ru–N(bpy)=2.035(6)–2.112(5) Å.     

Oxidative dissolution of copper and zinc metal in carbon dioxide with tert-butyl peracetate and a beta-diketone chelating agent

A series of beta-diketone ligands, R(1)COCH(2)COR(2) [tmhdH (R(1) = R(2) = C(CH(3))(3)); tfacH (R(1) = CF(3); R(2) = CH(3)); hfacH (R(1) = R(2) = CF(3))], in combination with tert-butyl peracetate (t-BuPA), have been investigated as etchant solutions for dissolution of copper metal into carbon dioxide solvent. Copper removal in CO(2) increases in the order tfacH < tmhdH < hfacH. A study of the reactions of the hfacH/t-BuPA etchant solution with metallic copper and zinc was conducted in three solvents: scCO(2) (supercrical CO(2)); hexanes; CD(2)Cl(2). The etchant solution/metallic zinc reaction produced a diamagnetic Zn(II) complex, which allowed NMR identification of the t-BuPA decomposition products as tert-butyl alcohol and acetic acid. Gravimetric analysis of the amount of zinc consumed, together with NMR studies, confirmed the 1:1:2 Zn:t-BuPA:hfacH reaction stoichiometry, showing t-BuPA to be an overall two-electron oxidant for Zn(0). The metal-containing products of the copper and zinc reactions were characterized by elemental analysis, IR spectroscopy, and, as appropriate, NMR spectroscopy and single-crystal X-ray diffraction [trans-M(hfac)(2)(H(2)O)(CH(3)CO(2)H) (1, M = Cu; 2, M = Zn)]. On the basis of the experimental results, a working model of the oxidative dissolution reaction is proposed, which delineates the key chemical variables in the etching reaction. These t-BuPA/hfacH etchant solutions may find application in a CO(2)-based chemical mechanical planarization (CMP) process.     

Synthesis ofcis-[Ru{4,4′-(t-Bu)2bpy}2(PPh3)Cl+][ClO 4 − ] and the crystal structure of its disordered hemiacetonitrile,hemitoluene solvate

The complexcis-[Ru{4,4-(t-Bu)₂bpy}₂(PPh₃)Cl⁺][ClO ₄ ^– ·0.5(toluene)·0.5(MeCN), where 4,4-(t-Bu)₂bpy=4,4-di(t-butyl)-2,2-bipyridyl crystallizes with an ordered racemic mixture of the chiral cations in the centrosymmetric triclinic space group (No. 2). The structure was refined toR=4.42% for those 6426 reflections with 20=5–50^o and |F _o|>6(F). Ruthenium ligand distances are Ru–Cl=2.423(2)Å, Ru–PPh₃=2.346(2)Å and Ru–N=2.056(4)–2.098(4)Å. Both the Ru(II)-containing cation and the perchlorate anion are ordered, but the toluene and acetonitrile exhibit an interesting type of scrambled disorder about the inversion center atx=1,y=1/2,z=0.