Palladium-catalyzed Heck reactions of styrene derivatives and 2-iodo-p-carborane

p-Carborane has been vinylated on the 2-B-atom in high yields using the Heck reaction. Thus, the reaction between 2-iodo-p-carborane and various styrenes [4-H-, 4-C(6)H(4)-, 4-Cl-, 4-Br-, 4-NO(2)-, 4-CH(3)O-, and 4-CH(3)-] resulted in the production of the corresponding trans-beta-(2-B-p-carboranyl)styrene in DMF solution when reacted in the presence of silver phosphate and the palladacycle Herrmann's catalyst.     

New Methodology for Obtention of Some α-Methylsulfanyl Sulfones,Synthetic Precursors of Carbonyl Compounds

The reaction of some α-phenylsulfonyl carboxylic acids with NaH in DMSO and dimethyl disulfide leading to α-methylsulfanyl alkyl phenyl sulfones is described.     

Experimental Study of the Influence of Changes in Load Direction on the Performance of a Crown Bearing

Laboratory tests have been carried out in order to investigate the influence of small changes in load direction on the performance of a steadily loaded hydrodynamic crown journal bearing. Hydrodynamic pressures, temperature distribution on the bush internal surface, shaft temperature, oil flow rate and bush torque were measured for fixed sets of operating conditions, at three different groove locations () with respect to the line of load ( = 0, –30, and +30 degrees). For each groove location quantitative information is provided concerning to the influence of applied load and shaft rotational speed on the performance characteristics. Changing the location of the groove around the load line did affect flow rate, bush torque and maximum hydrodynamic pressure, but only had a slight effect on bush maximum temperature.     

The use of microspectrofluorimetry for the characterization of lake pigments

In this paper, the potential of confocal microfluorescence spectroscopy is explored for the characterization of selected red lake pigments and paints based on alizarin, purpurin and eosin (weak, medium and strong emitters). The anthraquinone pigments have been used since ancient times by artists, and eosin lakes were used by impressionist painters. Reconstructions of artists paints based on 19th century recipes are examined. The paints were made using the lake pigments bound in a range of binding media including gum arabic, collagen, a vinyl emulsion and linseed oil. The acquisition of the spectra is rapid, with high spatial resolution and the data reliable and reproducible. Together with full emission spectra, it was possible to acquire well-resolved excitation spectra for purpurin, alizarin and eosin based colors. The present investigation suggests that micro-emission fluorescence can also be used as a semi-quantitative method for madder lake pigments, enabling the determination of purpurin lake ratio in a mixture of purpurin and alizarin, which is important for provenance studies. The data obtained with microfluorescence emission with those acquired with fiber-optic fluorimetry are compared. The spatial resolution used, 8microm, is appropriate for the analysis of individual pigments particles or aggregates in a paint film. Micro-emission molecular fluorescence proved to be a promising analytical tool to identify the presence of selected red lake pigments combined with a range of binding media.     

Effect of hydrogen bonding in the vibrational spectra of trans‐cinnamic acid

A computationally‐assisted methodology to assign the vibrational spectra of molecular materials (PiMM) has been successfully applied to the Raman and infrared (IR) spectra of trans‐cinnamic acid (t‐CIA) in the solid state. The effects of molecular association through O H···O hydrogen‐bonding in both the wavenumber and the intensity of the bands are accurately described by a single dimer structure. This supports the discrimination between the possible conformers in the solid, the complete evaluation of hydrogen‐bonding effects, and the full assignment of the vibrational spectra of t‐CIA. Copyright © 2008 John Wiley & Sons, Ltd.     

Hydrogen bonding in nitrofurantoin polymorphs: a computation‐assisted spectroscopic study

The importance of hydrogen‐bond formation in the molecular packing arrangements of two anhydrous forms of nitrofurantoin is investigated, combining computational methods and spectroscopic data. The overall results indicate, as expected, that the vibrational modes related to the CO, N H and C H groups are strongly affected by intermolecular hydrogen‐bond formation. Moreover, the importance of weak C‐H···O interactions in conferring additional stability to molecular associations in biological systems is evidenced in this study. The complete assignment of the Raman and infrared spectra of both polymorphs is accomplished by means of a computationally based methodology, which accounts for the effects of intermolecular interactions in the crystal. The vibrational shifts due to crystal packing interactions are evaluated from DFT calculations for a set of suitable molecular pairs, using the B3LYP/6‐31G* approach. This methodology provides an answer to the current demand for a reliable and complete assignment of the vibrational spectra of pharmaceutically active compounds such as nitrofurantoin. Copyright © 2009 John Wiley & Sons, Ltd.     

Electrochemical deposition onto self-assembled monolayers: new insights into micro- and nanofabrication

Pattern transfer with high resolution is a frontier topic in the emerging field of nanotechnologies. Electrochemical molding is a possible route for nanopatterning metal, alloys and oxide surfaces with high resolution in a simple and inexpensive way. This method involves electrodeposition onto a conducting master covered by a self-assembled alkanethiolate monolayer (SAMs). This molecular film enables direct surface-relief pattern transfer from the conducting master to the inner face of the electrodeposit, and also allows an easy release of the electrodeposited film due their excellent anti-adherent properties. Replicas of the original conductive master can be also obtained by a simple two-step procedure. SAM quality and stability under electrodeposition conditions combined with the formation of smooth electrodeposits are crucial to obtain high-quality pattern transfer with sub-50 nm resolution.     

Hydrogen‐Bond Dynamics of C?H⋅⋅⋅O Interactions: The Chloroform⋅⋅⋅Acetone Case

Spectroscopic evidence for C? H ??? O hydrogen bonding in chloroform ??? acetone [Cl₃CH ??? O?C(CH₃)₂] mixtures was obtained from vibrational inelastic neutron scattering (INS) spectra. Comparison between the INS spectra of pure samples and their binary mixtures reveals the presence of new bands at about 82, 130 and 170 cm^?1. Assignment of the 82 cm^?1 band to the νO ??? H anti‐translational mode is considered and discussed. In addition, the βC? H mode of CHCl₃ at 1242 cm^?1 is split in the spectra of the mixtures, and the high‐wavenumber component is assigned to the hydrogen‐bonded complex. The plot of the integrated intensity of this component shows a maximum for x=0.5, in agreement with the 1:1 stoichiometry of the chloroform ??? acetone complex, with a calculated complexation constant of 0.15 dm³ mol^?1. Results also show that the complex behaves as an independent entity, that is, despite being weak, such interactions play a key role in supramolecular chemistry.