Ti(O-i-Pr)4/Me3SiCl/Mg-mediated reductive cleavage of sulfonamides and sulfonates to amines and alcohols

A low-valent titanium generated in situ from Ti(O-i-Pr)(4), Me(3)SiCl, and Mg powder in THF reacted with aryl- and alkyl-sulfonamides of aryl and alkyl amines in a reductive N-S/S-O/S-C bond cleaving pathway to provide the corresponding amines and hydrocarbons (and thiols) derived from the sulfonyl moiety. The reagent could also cleave sulfonates to the corresponding alcohols.     

Fabrication of the smallest organic nanocolloids by a top‐down method based on laser ablation

Stable aqueous colloids of 10‐nm sized organic nanoparticles were tailored by laser ablation of microcrystalline quinacridone in water. The nanocolloids were flaky in shape and had the dimension of a width of 13 (±5) nm and a height of 1.4 (±0.5) nm. The formation mechanism is discussed in terms of laser‐induced fragmentation of organic solids and the potential application of aqueous organic nanocolloids free from any additives and chemicals is considered.     

Effects of freeze-drying of samples on metabolite levels in metabolome analyses

Freeze-drying (FD) is a useful technique for removing water from biological tissues, such as food samples. Cellular components freeze at once, and the ice sublimates under conditions of high vacuum and low temperatures. Because biological activity is restricted during FD, the degradation of cellular metabolites is often believed to be limited. However, the cellular structure is damaged by several factors, such as the increase in cell volume during freezing, and this has serious effects on the levels of some cellular metabolites. We studied these effects of FD on metabolite levels when using it as a sample preparation step in metabolome analysis. We observed significant decreases in the levels of some metabolites, such as succinate and choline, in Arabidopsis and pear, respectively. We also found that the effects of FD on certain metabolite levels differed between Arabidopsis plants and pear fruits. These results suggest that it is necessary to confirm the metabolite recovery in each sample species when FD is used for sample preparation.     

Chemical wiring and soldering toward all-molecule electronic circuitry

Key to single-molecule electronics is connecting functional molecules to each other using conductive nanowires. This involves two issues: how to create conductive nanowires at designated positions, and how to ensure chemical bonding between the nanowires and functional molecules. Here, we present a novel method that solves both issues. Relevant functional molecules are placed on a self-assembled monolayer of diacetylene compound. A probe tip of a scanning tunneling microscope is then positioned on the molecular row of the diacetylene compound to which the functional molecule is adsorbed, and a conductive polydiacetylene nanowire is fabricated by initiating chain polymerization by stimulation with the tip. Since the front edge of chain polymerization necessarily has a reactive chemical species, the created polymer nanowire forms chemical bonding with an encountered molecular element. We name this spontaneous reaction "chemical soldering". First-principles theoretical calculations are used to investigate the structures and electronic properties of the connection. We demonstrate that two conductive polymer nanowires are connected to a single phthalocyanine molecule. A resonant tunneling diode formed by this method is discussed.     

Palmaenones A and B, two new antimicrobial chlorinated cyclopentenones from discomycete Lachnum palmae

Two new antimicrobial chlorinated cyclopentenones, palmaenones A (1) and B (2) were isolated from the culture broth of discomycete Lachnum palmae (NBRC-106495), and the structures of 1 and 2 were elucidated by spectroscopic data and the stereochemistry of 1 was directly determined by a single-crystal X-ray diffraction analysis. Palmaenones A (1) and B (2) are cyclopentenones containing three chlorines. Compound 1 exhibited potent antimicrobial activity against Micrococcus luteus, Mycobacterium smegmatis, Escherichia coli, Xanthomonas campestris, and Mucor racemosus, while the activities of compound 2 were weaker than 1.     

Myrseguinosides A-E, five new glycosides from the fruits of Myrsine seguinii

Chemical investigation of the 1-BuOH soluble fraction of the dried fruits of Myrsine seguinii (Myrsinaceae) led to the isolation of five new glycosides, named myrseguinosides A-E (1-5), together with eight known compounds (6-13). The absolute structures of the new glycosides were elucidated by spectroscopic and chemical analyses to be a monoterpene glucoside (1), two flavonol glycosides (2, 3), and two oleanane-type triterpene saponins (4, 5). Myrseguinosides B (2), D (4), and E (5) exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and growth inhibitory activity toward human cancer cells, respectively.     

Four new iridoid glucosides from Ajuga reptans

Four new iridoid glucosides were isolated from the whole plant of Ajuga reptans L. (Labiatae) along with four known iridoid glucosides, one known diterpenoid glycoside, one known aliphatic alcohol glycoside, and three known ecdysteroids. Their chemical structures were determined on the basis of spectroscopic data and chemical evidence. The diterpenoid glycoside exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and H?O? scavenging activities.     

Isolation of salsolinol, a tetrahydroisoquinoline alkaloid, from the marine sponge Xestospongia cf. vansoesti as a proteasome inhibitor

Salsolinol (1), a tetrahydroisoquinoline alkaloid, was isolated from the marine sponge Xestospongia cf. vansoesti collected in Indonesia as a proteasome inhibitor, along with three salsolinol derivatives, norsalsolinol (2), cis-4-hydroxysalsolinol (3), and trans-4-hydroxysalsolinol (4). Compounds 1 and 2 inhibited the chymotrypsin-like activity of the proteasome with IC(50) values of 50 and 32 μg/ml, respectively, but 3 and 4 showed no inhibitory effect even at 100 μg/ml.     

Nonlinear normal modes and primary resonance of horizontally supported Jeffcott rotor

The nonlinear normal modes of a horizontally supported Jeffcott rotor are investigated. In contrast with a vertically supported rotor, there are localized and nonlocalized nonlinear normal modes because the linear natural frequencies in the horizontal and vertical directions are slightly different due to both gravity and the nonlinearity of restoring force. Reflecting such nonlinear normal modes, the frequency response curves are characterized in the primary resonance. In the case where the eccentricity is small, i.e., the response amplitude is small, the whirling motion is localized in the horizontal or vertical direction in the resonance. On the other hand, when the eccentricity is large, two kinds of whirling motion, which are localized in the vertical direction and nonlocalized in any direction, coexist simultaneously in a region of rotational speed. Experiments are conducted, and the theoretically predicted nonlinear responses based on localized and nonlocalized nonlinear normal modes are observed.