Negatively Charged Metallacarborane Redox Couples with Both Members Stable to Air

The metallacarborane [3,3′‐Co(1,2‐closo‐C₂B₉H₁₁)₂]^? has been synthesized. This species allows the formation of redox couples in which both partners are negatively charged. The E_1/2 potential can be tuned by adjusting the nature and number of substituents on B and C. The octaiodinated species [3,3′‐Co(1,2‐closo‐C₂B₉H₇I₄)₂]^? is the most favorable, as it is isolatable and stable in air. A DFT study on stability and redox potentials of complexes has been performed.     

Vector potential theory on nonsmooth domains in R<Superscript>3</Superscript> and applications to electromagnetic scattering

We study boundary value problems for the time-harmonic form of the Maxwell equations, as well as for other related systems of equations, on arbitrary Lipschitz domains in the three-dimensional Euclidean space. The main goal is to develop the corresponding theory for L^p-integrable bounday data for optimal values of p's. We also discuss a number of relevant applications in electromagnetic scattering.     

Organocatalysis: quantum chemical modeling of nucleophilic addition to α,β‐unsaturated carbonyl compounds

One of the successful transformations within the field of organocatalysis, the organocatalytic asymmetric addition of nitromethane to α,β‐unsaturated aldehydes and ketones, has been studied by quantum chemical modeling. The level of accuracy of the hybrid density functional theory method B3LYP/6‐31G(d) was compared to a high level ab initio benchmark for this reaction. It is concluded that B3LYP/6‐31G(d) performs very well for this reaction type, giving good estimates of critical energies. The reaction between acrolein and nitromethane was studied in detail. The reaction mechanism revealed an intermediate oxazolidin structure, which is currently unknown. Alkyl substitution in various positions on the amine catalyst or α,β‐unsaturated carbonyl compound influences the reactivity in a predictive fashion. The iminium ion, prop‐2‐en‐iminium, is less activated towards nucleophilic attack compared to protonated acrolein. Copyright © 2007 John Wiley & Sons, Ltd.     

Sur quelques problèmes de probabilités géométriques pour des réseaux irréguliers dans l'espace euclidienE 2 etE n

Dans ce travail on détermine quelques probabilités géométriques concernant des réseaux irréguliers dans le plan euclidienE ₂ et dans l'espace euclidienE _n . Les propriétés généralisent certains résultats de Buffon, Deltheil et Stoka. Travail effectué avec l'aide du MURST (40%, 60%).     

RECURSIVE BAIRE CLASSIFICATION AND SPEEDABLE FUNCTIONS

Using recursive variants of Baire notions of nowhere dense and meagre sets we study the topological size of speedable and infinitely often speedable functions in a machine-independent framework. We show that the set of speedable functions is not “small” whereas the set of infinitely often speedable functions is “large”. In this way we offer partial answers to a question in [4].     

Wellposedness for the Navier–Stokes flow in the exterior of a rotating obstacle

In this paper we study the Navier–Stokes boundary‐initial value problem in the exterior of a rotating obstacle, in two and three spatial dimensions. We prove the local in time existence and uniqueness of strong solutions. Moreover, we show that the solutions are global in time, in two spatial dimensions. Copyright © 2005 John Wiley & Sons, Ltd.     

Ferromagnetic coupling through spin polarization in the hexanuclear [MnII(3)CuII(3)] complex

A novel Cu(II)-Mn(II) hexanuclear complex of formula [[MnCuL](3)(tma)](ClO(4))(3).8H(2)O [H(2)L = macrocyclic Robson proligand; H(3)tma = trimesic acid] has been obtained by connecting three heterobinuclear [Cu(II)Mn(II)L](2+) cationic species through the trimesate anion. The complex exhibits a C(3) rotational symmetry, imposed by the geometry of the bridging ligand. The interaction within each Mn(II)-Cu(II) pair is antiferromagnetic (J = -16.7 cm(-1)). A weak ferromagnetic coupling among the three S = 2 resulting spins through the tricarboxylato bridge leads to a S = 6 ground spin state, for which the spin polarization mechanism is responsible.     

Pfropfcopolymerisation von Cellulose mit zwei Vinylmonomeren

Zusammenfassung Die vorliegende Arbeit stellt eine Beschreibung von Experimenten dar, die die Erhöhung der Pfropfbereitschaft von trägen Komponenten durch Beimischung von aktiveren zum Ziele hatten.Das Trägermolekül war in allen Fällen Cellulose in Form von hochgradig gereinigtem Zellstoff. Durch die Verwendung von Mischsystemen aus Styrol und Methylmethacrylat gelang es, das trägere Styrol in bedeutend größerer Menge auf die Cellulose aufzupfropfen, als es bei Abwesenheit des aktiven Methylmethacrylats der Fall war.

---

Grafting Polymerization of Cellulose with Two Vinyl Monomers

This paper describes experiments to increase the grafting of cellulose with components of poor reactivity by mixing them with highly reactive ones. A highly purified wood pulp was used as backbone. Using combinations of styrene and methyl methacrylate it was possible to graft considerably higher amounts of the poorly reacting styrene than in the absence of the highly reactive methyl methacrylate.

---

---

Nach einem Vortrag, den der erstgenannte der Autoren im Rahmen der Arbeitstagung des Vereins Österreichischer Chemiker am 27. September 1968 in Wien gehalten hat.     

DECONVOLUTION OF THE RED P700 DIFFERENCE SPECTRUM BASED ON A SET OF THREE GAUSSIAN COMPONENTS: FURTHER EVIDENCE FROM LITERATURE SPECTRA

Abstract Literature data on the light induced difference spectrum of the photosynthetic reaction centre complex P700 were analysed in the spectral region from 670-700 nm. In accordance to our previous Gaussian deconvolution of the flash induced difference spectrum and the linear dichroism spectrum of photosystem I particles from green plants, we present here fits of three representative difference spectra that were recorded at room temperature and at low temperature conditions, respectively. These fits are generated by using the same set of only three Gaussian components that we specified previously: (1) a disappearing wide band around 695 nm representing the absorption of the reduced special-pair of chlorophyll- a ; (2) an appearing narrower band at slightly shorter wavelength (In agreement with our previous results, this band shows half the oscillatory strength of the former band. It is therefore attributed to the non-oxidized chlorophyll- a in the special pair); and (3) a bathochromic bandshift centered around 688 nm, which indicates the local electrochromic response of chlorophyll-a antennae molecule(s) close to the site of the primary donor. Among the reports by several authors we attribute the variation of the difference spectra of P700 in the region from 670-720 nm mainly to a variation in the magnitude of the third component, the local electrochromic one. We can also account for the peculiar shape of the low temperature spectra, mainly by alteration of the extent of the electrochromic component. It seems reasonable that the electrochromic component reacts most sensitively against structural changes of the reaction centre protein complex (brought forth by different degrees of depletion from antennae or by variation of the temperature).