![Initial-steps-of-melanin-formation-in-DMSO-1-1](https://cdmf.org.br/wp-content/uploads/2014/01/Initial-steps-of-melanin-formation-in-DMSO-1-1.jpg)
Writers: M. Piacenti-Silva, E.S. Bronze-Uhle, J.V. Paulin, C.F.O. Graeff
Keywords: Melanin Dimethyl sulfoxide Synthesis Temperature Optimization Photoabsorption
Writers: M. Piacenti-Silva, E.S. Bronze-Uhle, J.V. Paulin, C.F.O. Graeff
Keywords: Melanin Dimethyl sulfoxide Synthesis Temperature Optimization Photoabsorption
Abstract: Melanins are a class of pigmentary conjugated macromolecules found in many biological systems. Functionalization of synthetic melanin provides interesting new properties like the greater solubility of melanin synthesized in dimethyl sulfoxide, d-Melanin. In this work we have studied the influence of temperature on d-Melanin synthesis and its properties. To this end, UV–Vis, Fourier-transform infrared (FTIR) spectroscopy and Nuclear Magnetic Resonance (NMR) techniques have been employed to analyze d-Melanin synthesized within the range of 25–100 °C. Our results reveal that by increasing the synthesis temperature up to 100 °C, the synthesis time can be decreased by a factor of 7 when compared to room temperature. From FTIR and 13C CP/MAS NMR analyses the increase in temperature causes a decrease in the number of carbonyl groups from carboxylic acid and from ionized carboxylic acid. The decarboxylation of d-Melanin monomers at higher temperatures shows that the use of higher synthesis temperatures influences the elimination of carbonyls present in the precursor molecules, thus facilitating the polymerization of d-Melanin.
Writers: D. Lukovic Golic, J. C irkovic, M. Scepanovic, T. Sreckovic, E. Longo, J. A. Varela, N. Daneu, V. Stamenkovic, G. Brankovic, Z. Brankovic Keywords: ZnO Nano- and submicron particles; Solvothermal synthesis; Growth mechanism; Structure ordering; Photoluminescence […]
Writers: Vinícius D. Araújo, Maurício M. de Lima Jr., Andrés Cantarero, Maria I.B. Bernardi, Jorge D.A. Bellido, Elisabete M. Assaf, Rosana Balzer, Luiz F.D. Probst, Humberto V. Fajardo Keywords: Ceramics; Chemical synthesis; Oxides; Oxidation Abstract: Ceria-supported copper catalysts […]
Writers: K.F. Moura, J. Maula, A.R. Albuquerque, G.P. Casalia, E. Longo, D. Keysona, A.G. Souza, J.R. Sambrano, I.M.G. Santos Keywords: TiO2; Nanoparticles; Microwave solvothermal synthesis; Computational periodic model; B3LYP-D Abstract: In this study, a microwave assisted solvothermal method […]
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