Biosurfactants have many advantages over synthetic surfactants but have higher production costs. Identifying microorganisms with high production capacities for these molecules and optimizing their growth conditions can reduce cost. The present work aimed to isolate and identify a fungus with high biosurfactant production capacity, optimize its growth conditions in a low cost culture medium, and characterize the chemical structure of the biosurfactant molecule. The fungal strain UFSM-BAS-01 was isolated from soil contaminated with hydrocarbons and identified as Fusarium fujikuroi. To optimize biosurfactant production, a Plackett-Burman design and a central composite rotational design were used. The variables evaluated were pH, incubation period, temperature, agitation and amount of inoculum in a liquid medium containing glucose. The partial structure of the biosurfactant molecule was identified by nuclear magnetic resonance spectrometry. F. fujikuroi reduced surface tension from 72 to 20mNm under the optimized conditions of pH 5.0, 37°C and 7 days of incubation with 190rpm agitation. The partial identification of the structure of the biosurfactant demonstrated the presence of an α,β-trehalose. The present study is the first report of the biosynthesis of this compound by F. fujikuroi, suggesting that the biosurfactant produced belongs to the class of trehalolipids.
This work provides a systematic study of how the electronic effect of EDG or EWG in selenium-containing ligands influences the nuclearity of PdII complexes. The solid-state, solution and gas phase behaviors were evaluated for the complexes.
A synthetic route to obtain [p‐H2NC6H4Se]2 (1) in good yield was developed, and the crystal structure of the product was characterized for the first time. The synthesis and structure of the mercury(II) derivative [Hg(SeC6H4NH2)2] (2) was also investigated and is reported herein. The versatile coordination chemistry of [Hg(SeC6H4NH2)2] with halides of the same metal and PCy3 allows the synthesis of [Hg(X)(SeC6H4NH2)(PCy3)] (X = Cl, Br, I) (3–5). The products 1, 3–5 were isolated in crystalline form and characterized by X‐ray structure analysis.
Neste artigo estamos apresentando a síntese do composto [Cd 8 Cl 2 (µ 4 -Se) (SePh) 12 (PCy 3 ) 2 ]·2.5CH 3 OH pela reação de Cd(SePh) 2 com CdCl 2 e triciclohexilfosfina em metanol em um reator de aço inoxidável sob condições solvotérmicas a 130 °C. Esse composto corresponde ao último resultado de uma série sistemática de reações e visando ao crescimento de clusters moleculares a partir de Cd(SePh) 2 como reagente de partida. A importância desta síntese não está baseada somente nas propriedades do produto preparado, mas também no seu possível uso, por exemplo, no desenvolvimento de novas metodologias via estratégias "bottom up" para a obtenção de clusters a partir de uma mesma classe de reagentes -M(ER) 2 (M = metal, E = calcogênio, R = alquil ou aril). O composto apresentado neste artigo foi caracterizado por difração de raios X em monocristal, análise elementar, análise termogravimétrica e espectroscopia no UV-Vis. Estes últimos resultados foram correlacionados com dados calculados por DFT, teoria do funcional de densidade.In this article we present the synthesis of the compound [Cd 8 Cl 2 Se(SePh) 12 (PCy 3 ) 2 ]·2.5CH 3 OH by the reaction of Cd(SePh) 2 with CdCl 2 and PCy 3 in methanol in a stainless steel sealed reactor under solvothermal conditions at 130 °C. This compound represents the latest result of our systematic work on the growth of molecular clusters from Cd(SePh) 2 as starting material. Their importance is based not only on the properties of the new compounds, but also by their possible use, for example, in the development of new methods via a ''bottom up" strategy to obtain different clusters from single components like M(ER) 2 (M = metal, E = chalcogen, R = alkyl or aryl). The title compound was characterized by single crystal X-ray diffractometry, elemental analysis, thermogravimetrical analysis and the UV-Vis spectroscopy. These results were correlated with data calculated by DFT, density functional theory.
Keywords: cadmium(II) complexes, selenium, tellurium, clusters
IntroductionOrganylchalcogen groups bound to metal atoms to generate nanoclusters have become increasingly important due to their potential as semiconductors, among other materials and biological applications. [1][2][3][4] The unique optical and electronic properties inherent to these "quantumconfined particles" (quantum-dots) have been attributed to modifications of the electronic structure -depending upon the particle size -which lead to very different structures than those found in molecular solids or bulk materials. [5][6][7] Our search for new metalchalcogen-containing building blocks is of great interest for many reasons, principally because the variable size of the blocks produces tunable optoeletronic properties of the bulk products, [8][9][10] This emerging field -super lattices of crystalline chalcogenideslinks two traditional, but distinct, areas of research: chalcogenide clusters and reticular materials. [11][12][13][14][15][16][17][18][19] Some authors have proposed alternative ways for the development of metal-...
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