Evidence for a Ag adatom-molecule complex in surface enhanced raman scattering

The SERS spectrum of molecules adsorbed on Ag sols show, lines, in the 200–300 cm^?1 region in the absence of Cl^? ions These lines are attributed to a Ag-N complex and frequency calculations show that they correspond to the vibrations of the molecule bound to a single silver atom.     

Transient ESR nutation signals in excited aromatic triplet states

Transient ESR nutation signals following laser pulse excitation are analyzed for the case of the photoexcited triplet state of acridine in a molecular crystal matrix. Essential features, in particular the short rise-time (< 10^?7) of the signals, can be related to the inhomogeneous nature of the ESR linewidth. Applications are discussed.     

Particulates formed by a stabilized high voltage spark discharge

Light scattering was used to demonstrate the presence of small (?1 μm) particles in the immediate surroundings of a stable spark discharge. Several parameters, including electrode composition and surface condition, which are of importance in emission spectrochemical analysis, were found to be of importance in affecting the scattering signal. Electron micrographs of the heaviest particles revealed two distinct types of particles. Analytical implications are discussed.     

An unusual reaction of terramycin with methyl iodide

An unusual fragmentation reaction was observed when terramycin is treated with MeI in acetone at room temp. The reaction proceeds with quaternization, loss of trimethylamine, fission of bonds 4a,5 and 12,12a with formation of an aldehydo-lactone derived from rings B, C and D. Additionally some transformations of this lactone are described.     

Highly stereoselective synthesis of (Z)-3-methoxy-1-methyleneisoindoles via DMAP catalyzed cyclization of methyl 2-alkynylbenzimidates

A DMAP (4-dimethylaminopyridine) catalyzed cyclization of methyl 2-alkynylbenzimidates has been developed, which affords 3-methoxy-1-methyleneisoindoles with excellent Z-stereoselectivity under mild and transition-metal-free conditions. The (Z)-3-methoxy-1-methyleneisoindole products can be converted to corresponding 3-amino-1-methyleneisoindoles, 3-methoxy-isoindoles, 3-methyleneisoindolinones and isoindolinones with high efficiency.     

Copper-catalyzed aryldifluoromethylenation of N-arylacrylamides to synthesis of the diheterocyclic compounds linked by gem-difluoromethylene moiety

An efficient method of copper-catalyzed aryldifluoromethylenation of N-arylacrylamides is described to step-economic synthesis of the various biologically important biheterocyclic compounds linked by gem-difluoromethylene moiety through addition of benzo-1,3-azolic (oxa- or thia-)difluoromethyl radicals generated in situ to terminal of C–C double bond of N-arylacrylamides then cyclization cascade. This protocol has demonstrated to have broad substrate scope and excellent functional-group tolerance under mild reaction conditions.     

More QACs,more questions: Recent advances in structure activity relationships and hurdles in understanding resistance mechanisms

Quaternary ammonium compounds (QACs) are a class of antimicrobials that have been around for over a century; nevertheless, they have found continued renewal in the structures to which they can be appended. Ranging from antimicrobial polymers to adding novel modes of action to existing antibiotics, QACs have found ongoing use due to their potent properties. However, resistance against QACs has begun to emerge, and the mechanism of resistance is still only partially understood. In this review, we aim to summarize the current state of the field and what is known about the mechanisms of resistance so that the QACs of the future can be designed to be evermore efficacious and utilized to unearth the remaining mysteries that surround bacteria’s resistance to them.     

Three new dibromopyrrole alkaloids from the South China Sea sponge Agelas nemoechinata

Three new dibromopyrrole alkaloids, 9-N-methylcylindradine A (1), 1-N-methylugibohlin (2), nemoechine H (3), together with one known dibromopyrrole alkaloid N-methyldibromoisophakellin (4) were isolated from the South China Sea sponge Agelas nemoechinata. Their structures were elucidated by comprehensive spectroscopic methods including HRESIMS and NMR, and the absolute configuration of compound 1 was further confirmed by comparison of optical rotation. Compound 3 exhibited moderate cytotoxic activity against K562 and L-02 with IC₅₀ values of 6.1 μM and 12.3 μM, respectively.     

Catalyst- and organic solvent-free synthesis of thioacids in water

Thioacids and thioamino acids were synthesized in excellent yields from readily available acyl benzotriazoles and sodium hydrosulfide in water at room temperature. The new methodology features mild reaction conditions, high yields, short reaction times, and does not involve the use of organic solvents or bases. The reaction is eco-friendly, and the workup procedure is simple and does not require chromatographic separation.