The secondary amine piperidine and the tertiary amine quinuclidine (l-azabicyclo[2.2.2]octane) were reacted in THF with one equivalent of triphenylphosphinegold(I) tetrafluoro­ borate, [Ph3PAu]+ BF4“, to give the monoaurated ammonium salts of formula [R„NHp_„)AuPPh3]+ BF4~ (n = 2, 3). The compounds were obtained as crystalline solids in good yields, and were characterized by IR and NM R spectro...

We have developed an efficient chemoenzymatic synthesis of heparan sulfate oligosaccharides employing the para-nitrophenyl (p-NP) β-glucuronide as an acceptor compatible with enzymatic elongation and one that significantly simplifies oligosaccharide purification on C-18 resin. Employing ceric ammonium nitrate as oxidative reagent to remove the p-NP group unexpectedly also removed the glucuronic...

The effect of ammonium on the fermentative production of gentamicin in Micromonospora purpurea has been studied using a chemically defined medium. Ammonium chloride concentrations ranging from 20 to 150 mM resulted in a proportional stimulation of growth and antibiotic formation. The use of other ammonium salts exerted a similar effect. Among the products of ammonium assimilation, glutamate and...

An in situ IR technique was applied in the selective synthesis of the key intermediate for rapamycin derivatives, which made the reaction endpoint easily defined. This technology solved a bothersome problem in the preparation of rapamycin derivatives, and based on this technique, the 31-OH and 42-OH of rapamycin were chemically modified by a series of quaternary ammonium salts to generate 11 co...

The work is devoted to the problem of increasing gas condensate production in fields. It was found that ammonium carbonate salts, absence calcium chloride type waters, interact with rocks, increase permeability reservoirs. Solutions salts when interacting formation water form chemically precipitated chalk pore space, while rocks decreases. A set experimental studies carried out study displacing...

Gold nanoparticles capped with cucurbituril[7] have been prepared in the absence of metallic cations and organic ligands. Remarkably, these nanohybrids encapsulate dissolved oxygen and are highly active in electrochemical reduction. The effect of the presence of sodium and ammonium salts on this catalysed process is also analysed.

This combined experimental, theoretical and comparative study details the syntheses and chemical characterisation of two new energetic polynitromethyl tetrazole derivatives, namely, 2-(2-nitro-2-azapropyl)-5-(trinitromethyl)-2 H-tetrazole and its fluorine-containing analogue 2-(2-nitro-2-azapropyl)-5-(fluorodinitromethyl)-2 H-tetrazole. Their crystal structures and energetic behaviour are compa...

Single crystals for two polymorphs of the ammonium carbamate self-derivative salt of prolinamide have been successfully obtained and characterized. Decarbonation of the carbamate salts was monitored by calorimetry, confirming stabilization of the reactive carbonated adducts in the solid state. Sublimation of the salts afforded crystals of prolinamide, leading to the first crystal structure of t...

New dimeric, trimeric and tetrameric quaternary ammonium salts were accomplished by reaction of tertiary alkyldimethyl amines with appropriate bromomethylbenzene derivatives. A series of new cationic surfactants contain different alkyl chain lengths (C4-C18), aromatic spacers and different numbers of quaternary nitrogen atoms. The structure of the products was confirmed by spectral analysis (FT...

Derivatization of peptides as quaternary ammonium salts (QAS) is a promising method for sensitive detection by electrospray ionization tandem mass spectrometry (Cydzik et al. J. Pept. Sci. 2011, 17, 445-453). The peptides derivatized by QAS at their N-termini undergo fragmentation according to the two competing mechanisms - charge remote (ChR) and charge directed (ChD). The absence of mobile pr...