5-МЕРКАПТОТЕТРАЗОЛ-1-ИЛ УКСУСНАЯ КИСЛОТА – СТАБИЛИЗАТОР НАНОЧАСТИЦ БЛАГОРОДНЫХ МЕТАЛЛОВ В ВОДНЫХ СРЕДАХ

The novel stabilizing ligand, 5-mercaptotetrazole-1-acetic acid, has been applied for a simple synthesis of noble metal nanoparticles in the aqueous medium. This method is based on the reduction of metal salts in water in the presence of available 5-mercaptotetrazole-1-acetic acid. The interaction of the nanoparticle surface with the ligand has been investigated. According to quantum chemical calculations, the most stable structure has been realized when the capping ligand binds with the surface of nanoparticles through both sulphur and nitrogen N4 atoms. Free carboxyl groups provide good redissolvation in water.Obtained particles are attractive as precursors for catalysts, as well as biologically active systems with antibacterial and fungicidal properties.Предложен простой способ получения устойчивых в воде золей серебра, золота и палладия в присутствии динатриевой соли меркаптотетразол-1-ил уксусной кислоты (МТУК), выступающей в качестве стабилизатора. Исследовано взаимодействие частицы и стабилизатора, на основании квантовохимических расчетов предложена модель адсорбции оболочки на поверхность частиц. Установлено, что наиболее устойчивой является структура, при которой взаимодействие между поверхностью частицы и стабилизатором осуществляется при одновременном взаимодействии серы и атома азота N4 МТУК, при этом свободная карбоксильная группа обеспечивает хорошую диспергируемость частиц в воде.Полученные частицы представляют интерес для создания катализаторов и биологически активных систем, проявляющих антибактериальные и фунгицидные свойства

Strategies for the growth of fungi under conditions of nitrogen deficiency

Xylotrophic fungi are in the focus of scientists because of their capacity to grow under conditions of marked nitrogen deficiency. Basidiomycetes growing on wood developed some strategies that allow them find and consume nitrogen not easy accessible for many other organisms. In our experiments it was demonstrated that xylotrophic fungi, in contrast to basidiomycetes preferred rich organic substrates, are capable of not only prolonged searching growth (f-growth or forage growth) but also developed specific strategy to life in the wood (x-growth or xylotrophic growth). F-growth is characterized by a predominant use of resources accumulated by fungal mycelium before — that is such kind of growth is limited. X-growth is quite similar to f-growth but it is required additional nitrogen consumption and let the fungus occupy wooden substrates without limitation. Both types of growth are required recycling, but xylotrophic basidiomycetes belonging to different ecological groups use not compatible strategies to get nitrogen. While oyster mushroom could search for the rich nitrogen sources (living micro- and macroorganisms and so on) aphyllophoroids are able to extract of the trace nitrogen and include it in the recycling.Работа выполнена при финансовой поддержке РФФИ (проекты 12–04–00684, 14–04–00864, 15–04–06881) и Программы научного развития МГУ (ПНР–10)

Understanding the Role of Hyponitrite in Nitric Oxide Reduction

Herein, we review the preparation and coordination chemistry of cis and trans isomers of hyponitrite, [N2O2](2-). Hyponitrite is known to bind to metals via a variety of bonding modes. In fact, at least eight different bonding modes have been observed, which is remarkable for such a simple ligand. More importantly, it is apparent that the cis isomer of hyponitrite is more reactive than the trans isomer because the barrier of N2O elimination from cis-hyponitrite is lower than that of trans-hyponitrite. This observation may have important mechanistic implications for both heterogeneous NOx reduction catalysts and NO reductase. However, our understanding of the hyponitrite ligand has been limited by the lack of a general route to this fragment, and most instances of its formation have been serendipitous