Preparation of alkyl-modified silicon nanosheets by hydrosilylation of layered polysilane (Si6H6)

Alkyl-modified crystalline silicon nanosheets 2 were synthesized and maintained the crystal structure of a Si(111) plane, in which the dangling silicon bond is stabilized by capping with the alkyl group. 2 was characterized using UV-vis, Fourier transform-infrared, and X-ray photoelectron spectroscopies; X-ray diffraction; and X-ray absorption near edge structure analysis. A model structure is proposed that has a periodicity through the nanosheet surface.     

Formation of tetrahydrocurcumin by reduction of curcumin with cultured plant cells of Marchantia polymorpha

Cultured plant cells of Marchantia polymorpha, Nicotiana tabacum, Phytolacca americana, Catharanthus roseus, and Gossypium hirsutum were examined for their ability to reduce curcumin. Only M. polymorpha cells converted curcumin into tetrahydrocurcumin in 90% yield in one day. Time-course experiment revealed a two-step formation of tetrahydrocurcumin via dihydrocurcumin.     

Molecular gel-mediated UV-to-visible spectral conversion for enhancement of power-conversion efficiency

Here, we present the first application of molecular gel-mediated power-conversion enhancement of solar cells, which is based on the excimer emission from a transparent and colourless polymer film that encapsulates a pyrene nano-fibrillar assembly.     

Self-Assembled Nanofibrillar Aggregates with Amphiphilic and Lipophilic Molecules

Summary: This article gives a review on self-assembled nanofibrillar aggregates such as helical, twisted ribbon-like and tubular forms, those are produced in aqueous bilayer membrane and organogel systems. Two common features necessary for the chemical structure that yields special morphology are a chiral carbon atom and moieties feasible for intermolecular interactions although there are some exceptions. In aqueous systems, a hydrophobic effect is also an essential driving force for molecular aggregates in aqueous solution systems but almost disappear in organic media. More positive intermolecular interactions play an important role in molecular aggregation in organic media. Hydrogen bonding interaction is especially effective and many organogelators are classified into this category. Some lipophilic peptides have been investigated not only as organogelators but also with respect to their self-assembling behaviors. This latter property gives them distinct advantages compared with conventional gel systems because the gels include highly-ordered structures supramolecular functions like aqueous lipid membranes through molecular orientation. This article also introduces applicability of the organogel system.     

Adsorption of ammonia and water on functionalized edge-rich carbon nanofibers

The preparation, characterization and ammonia and water adsorption properties of edge-rich carbon nanofibers (CNFs) were studied, including platelet CNFs (PCNFs) and cup-stacked CNFs (CSCNFs). Since PCNFs and CSCNFs have many chemically active exposed edges, functionalization by oxidizing the edges was carried out by ozone stream and by nitric acid. Transmission electron microscopy, N₂ adsorption isotherms and temperature-programmed desorption analysis showed that the nitric acid treatment partly destroyed the graphite structure of the PCNFs and created acid functional groups and micropores, whereas the ozone treatment created functional groups without damaging the structure. Ammonia adsorption isotherms clarified that NH₃ adsorption on PCNFs and CSCNFs occurred mainly on oxygen-containing groups, whereas the adsorption on activated carbon fibers (ACFs) occurred on both oxygen-containing groups and the carbon surface without the functional groups, and the CSCNFs showed larger amounts of adsorbed ammonia compared to the PCNFs. Especially at a relatively low pressure range (<0.2 atm), the PCNFs/CSCNFs/ACFs showed the same ammonia adsorption mechanism; that is, the one-to-one interaction between oxygen atoms in the functional groups and hydrogen atoms in ammonia molecules. In addition, the adsorption on the ACFs appeared to occur mainly by interaction with the carbon surface at relatively high pressure (0.3–1.0 atm). Our experimental results and previous findings suggest that NH₃ adsorption on PCNFs is due mainly to NH…O hydrogen bonding between oxygen-containing groups and ammonia rather than to chemical bonding.     

Compounds having thiourea moiety as derivatization reagents in liquid chromatography/electrospray ionization–tandem mass spectrometry (LC/ESI‐MS/MS): synthesis of derivatization reagents for carboxylic acids

The derivatization reagents for carboxylic acids, N‐(Pyridin‐3‐yl)hydrazinecarbothioamide, N‐[4‐(dimethylamino)phenyl]hydrazinecarbothioamide, 1‐(2‐aminoethyl)‐3‐(pyridin‐3‐yl)thiourea, 1‐(2‐aminoethyl)‐3‐[4‐(dimethylamino)phenyl]thiourea and 4‐(2‐aminoethyl)‐N‐phenylpiperazine‐1‐carbothioamide were synthesized. These reagents reacted with carboxylic acids at 60°C for 45 min in the presence of the condensation reagents. The generated derivatives were favorably separated on the reversed‐phase column and sensitively detected by electrospray ionization tandem mass spectrometry. These reagents enhanced the electrospray ionization response of the analyte and generated a particular product ion efficiently by collision‐induced dissociation, and thus they were suitable for MS/MS detection. Copyright © 2010 John Wiley & Sons, Ltd.