Line tension action on 2D networks of gold nanoparticles obtained by the Bubble Deposition Method

The self-assembling properties of surfactant black films are used to obtain sizeable, dense islands of nanoparticles. Using the "Bubble Deposition Method" (BDM) these films are transferred onto solid substrates. The organisation within the islands evolves when the films are allowed to equilibrate before deposition. The results on model gold particles are discussed in terms of line tension.     

Chiral properties of tetrathiatriarylmethyl spin probes

We report that tetrathiatriarylmethyl (trityl) EPR probes are chiral molecules at room temperature, the two stereoisomers that differ in their helicity being configurationally stable enough to be separated and stored independently.     

The first case of competitive heterogeneously catalyzed enantioselective hydrogenation of ketones

In competitive racemic hydrogenation of methyl benzoylformate (MBF) + ethyl pyruvate (EP) binary mixture over Pt/Al(2)O(3): k(MBF) > k(EP), but in competitive enantioselective hydrogenation k(MBF) < k(EP); the phenomenon verified for the first time is dependent on the adsorption strength of the surface complexes of various compositions (MBF-Pt, EP-Pt, MBF-CD-Pt, EP-CD-Pt, CD = cinchonidine).     

Electrochemical meso-functionalization of magnesium(II) porphine

Regioselective meso-functionalization of the totally unsubstituted magnesium(II) porphine was performed by controlled potential electrolysis with pyridine and triphenylphosphine as nucleophiles leading to the original pyridinium and phosphonium substituted derivatives, respectively. The crystallographic structure of the latter is described as the only meso-phosphonium porphyrin reported to date.     

Treatment of water-induced curvature of the DSC heat flow rate signal

In samples containing a volatile phase, quite often the evaporation of the volatile substance during heating causes appreciable curvature of the DSC heat flow rate signal as function of temperature, making it difficult to quantify thermal transitions and reorganization phenomena occurring in the same temperature range. This is the case for e.g. polyamide–water, polyamide–alcohol, and polypropylene–water systems, thus complicating the study of polymer crystallization, melting, and metastability by DSC. In this study, maleic anhydride-grafted polypropylene particles of sub-micrometer diameters dispersed in water are discussed. These samples show, upon cooling from the melt, different degrees of extra supercooling in crystallization and several phenomena in the subsequent heating, like reorganization of a crystalline phase into another one, perfecting of crystallites, and melting. All these phenomena are difficult to analyze quantitatively due to the mentioned curvature of the DSC trace. In this article two methods, the “Reference” and “Extrapolation from the melt” methods, are described to correct for the influence of evaporation on the DSC heat flow rate signal and for the baseline signal, enabling the discussion of the transitions by way of the excess heat flow rate as function of temperature.     

Soulamarin, a new coumarin from stem bark of Calophyllum soulattri

The extracts of the stem bark of Calophyllum soulattri gave a new pyranocoumarin, soulamarin (1), together with five other xanthones caloxanthone B (2), caloxanthone C (3), macluraxanthone (4), trapezifolixanthone (5) and brasixanthone B (6) one common triterpene, friedelin (7), and the steroidal triterpene stigmasterol (8). The structures of these compounds were established based on spectral evidence (1D and 2D NMR).     

Magnetic and conduction properties in 1D organic radical materials: an ab initio inspection for a challenging quest

The chemical control of magnetic and conduction properties for organic radicals is mainly based on t, the resonance integral, and U, the on-site repulsion, used in the Hubbard model. A qualitative analysis based on the competition between the kinetic and the Coulomb contribution, and the expression of the magnetic exchange coupling suggests that U should be roughly 800 cm(-1) while the resonance integral |t| should be 200 cm(-1) to reach bifunctionality. Ab initio wavefunction-based calculations allowed us to quantitatively measure those quantities for several organic materials considered as 1D systems starting from their reported crystal structures. The extraction of t and U parameters from the exchange coupling constants between neighbouring radicals allowed us to anticipate a possible metallic behaviour. Finally, the impact of chemical changes in the constitutive units is measured to rationalize the macroscopic behaviour modifications. It is shown that the intriguing regime characterized by simultaneous itinerant and localized electrons might be achieved by molecular engineering.