No abstract

Water-soluble, stable nanoparticles of elemental sulphur with a size of 9-52 nm have been synthesised using the stabilising potential of starch. Sulphide anions were used as sulphur precursors that were generated earlier from the bulk powder sulphur in the base-reduction system NaOH-N 2 H 4 •H 2 O followed by their oxidation with molecular oxygen to element sulphur atoms. Using a set of modern spectral and microscopic methods (XRD, optical spectroscopy, DLS, TEM), the phase state, elemental composition of the nanocomposites and their nanomorphological characteristics have been investigated. It was found that nanocomposites are formed as sulphur particles with the shape which is nearly spherical dispersed in the polysaccharide starch matrix with a pronounced tendency to cluster into ring formations. Water solubility and stability of the obtained nanoparticles is ensured by sorption of starch macromolecules on the surface of sulphur nanoparticles, with the thickness of the stabilising shell in a range of 10-171 nm. In vitro experiments were carried out to study the anti-microbial activity of the obtained sulphur nanocomposite (1.6% S) using the propidium iodide fluorescent dye staining method and the diffusion method. It showed that the water solution of the starch-capped sulphur nanoparticles at the concentration of 6.25 µg/ml had a pronounced anti-phytopathogenic activity against the potato ring rot pathogen Clavibacter michiganensis subsp. sepedonicus. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

This study highlights the straight‐forward synthesis of substituted 1,2‐amino alcohols from simple and readily available aromatic methyl ketones. Starting from acetophenone derivatives, the straight‐forward synthesis strategy involved an initial bromination of the alpha‐positioned methyl group in the first step, followed by a simple hydrolysis to the hydroxyketone (2‐hydroxyacetophenone). The hydroxylated intermediate was subsequently converted from Silicibacter pomeroyi to the final 1,2‐amino alcohol by using the transaminase. The transaminase‐catalyzed reaction proceeded with yields up to 62 % and always excellent enantiomeric excess of >99 %. Interestingly, the keto‐enol‐tautomerism of the hydroxyl ketone yields an unexpected amino alcohol isomer.