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Based on the equilibrium geometries of [ Cu2( dbdmed)2 O2]2+ and [ Cu2( en)2 O2]2+ obtained within density-functional theory, we investigate their molecular electronic structure and optical response. Thereby results from occupation-constrained as well as time-dependent DFT (ΔSCF and TDDFT) are compared with Green's function-based approaches within many-body perturbation theory such as the GW approximation (GWA) to the quasiparticle energies and the Bethe-Salpeter equation (BSE) approach to the optical absorption. Concerning the ground-state energies and geometries, no clear trend with respect to the amount of exact exchange in the DFT calculations is found, and a strong dependence on the basis sets is to be noted. They affect the energy difference between bis-μ-oxo and μ-η2:η2-peroxo complexes by as much as 0.8 eV (18 kcal/mol). Even stronger, up to 5 eV is the influence of the exchange-correlation functional on the gap values obtained from the Kohn-Sham eigenvalues. Not only the value itself but also the trends observed upon the bis-μ-oxo to μ-η2:η2-peroxo transition are affected. In contrast, excitation energies obtained from ΔSCF and TDDFT are comparatively robust with respect to the details of the calculations. Noteworthy, in particular, is the near quantitative agreement between TDDFT and GWA+BSE for the optical spectra of [ Cu2( en)2 O2]2+. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

An abstract for the article "Dissecting the Role of Guanidine Copper Complexes in Atom Transfer Radical Polymerization by Density Functional Theory," by S. Herres-Pawlis, R. Hasse and O. Bienemann is presented.

An abstract is presented of the research paper "Mechanistic Studies on the Ring-Opening Polymerisation of D,L-Lactide With Zinc Guanidine Complexes," by J. Börner and colleagues, which was presented at the 5th German Conference on Chemoinformatics held in Germany on November 8-10, 2009.

Abstract: The bisfacial cobalt(II) complex [(HC(3-Phpz)2(5-Phpz))2Co][BF4]2 (1) was prepared by reaction of the tris(pyrazolyl)methane HC(3-Phpz)3 with Co(BF4)2·6H2O. A remarkable ligand rearrangement reaction occurs resulting in incorporation of the new ligand HC(3-Phpz)2(5-Phpz). Complex 1 was characterised by X-ray crystallography, mass spectrometry, IR spectroscopy and elemental analysis. DFT studies on both ligands as well as on complex 1 complement the experimental investigation. [Copyright &y& Elsevier]

• FTLE and LCS reveal persistent vortical structure in wake of Taylor bubble. • Residence times in bubble wake peak for intermediate rise velocities of Taylor bubble. • Coherent structure can restrict availability of gas phase for chemical reaction. Timescales and residence times in reactive multiphase flows are essential for product selectivity. For instance when a gas species is consumed, e.g., by a competitive consecutive reaction with moderate reaction kinetics where reaction timescales are comparable to relevant mixing timescales. To point out the importance of the details of the fluid flow, we analyze experimental velocity data from a Taylor bubble wake by means of Lagrangian methods. By adjusting the channel diameter in which the Taylor bubble rises, and thus the rise velocity, we obtain three different wake regimes. Remarkably, the residence times of passive particles advected in the bubble wake's velocity field show a peak for intermediate rise velocities. This observation seems unintuitive at first glance because one expects a faster removal of passive tracers for a faster overall flow rate. However, the details of the flow topology analyzed using Finite Time Lyapunov Exponent (FTLE) fields and Lagrangian Coherent Structures (LCS) reveal the existence of a coherent vortical pattern in the bubble wake which explains the long residence times. The increased residence times within the vortical structure in combination with the close bubble interface acting as a constant gas species source could enhance side product generation of a hypothetical competitive consecutive reaction, where the first reaction with the gas species forms the desired product and the second the side product. [ABSTRACT FROM AUTHOR]

We present a micro-jet sample delivery system for Raman measurements. Compared to cuvette measurements, the observed Raman signal is enhanced by more than one order of magnitude and does not contain signal distortions from the liquid-glass interface. Furthermore, the signal stability of repeated measurements is enhanced due to reduced sample damage effects by constantly replenishing the sample. This allows the study of sensitive samples that can only be produced in low concentrations. Our setup consists of a controlled sample environment that can be either under vacuum or an exchange gas, which allows the study of samples that are unstable in air. Finally, by matching the effective source point of the Raman instrument with the diameter of the jet, controlled experiments using laser beams of different wavelengths are possible. We see future applications of our setup for resonance Raman and time-resolved Raman measurements of bioinorganic samples. [ABSTRACT FROM AUTHOR]

An abstract for the article "MoSGrid- A Molecular Simulation Grid as a New Tool in Computational Chemistry, Biology and Material Science," by G. Birkenheuer, D. Blunk, S. Breuers, A. Brinkamann, I. dos Santos Vieira, G. Fels, S. Gesing, R. Grunzke, S. Herres-Pawlis and colleagues is presented.

An abstract for the article "Studies on the Mechanism of the Lactide Polymerization With Highly Active Zinc Guanidine Catalyst," by I. dos Santos Vieira, J. Börner, U. Flörke and S. Herres-Pawlis is presented.