The Scaled-Charge Additive Force Field for Amino Acid Based Ionic Liquids

Abstract. Ionic liquids (ILs) constitute an emerging field of research. New ILs are continuously introduced involving more and more organic and inorganic ions. Amino acid based ILs (AAILs) represent a specific interest due to their evolutional connection to proteins. We report a new non- polarizable force field (FF) for the eight AAILs comprising 1-ethyl-3-methylimidazolium cation and amino acid anions. The anions were obtained via deprotonation of carboxyl group. Specific cation-anion non-covalent interactions have been taken into account by computing electrostatic potential for ion pairs, in contrast to isolated ions. The van der Waals interactions have been transferred from the CHARMM36 FF with minor modifications. Therefore, compatibility between our parameters and CHARMM36 parameters is preserved. Our FF can be easily implemented using a variety of popular molecular dynamics programs. It will find broad applications in computational investigation of ILs

Storing Energy in Biodegradable Electrochemical Supercapacitors

The development of green and biodegradable electrical components is one of the main fronts of research to overcome the growing ecological problem related to the issue of electronic waste. At the same time, such devices are highly desirable in biomedical applications such as integrated bio-electronics, for which biocompatibility is also required. Supercapacitors for storage of electrochemical energy, designed only with bio-degradable organic matter would contemplate both aspects, that is, they would be ecologically harmless after their service lifetime and would be an important component for applications in biomedical engineering. By means of atomistic simulations of molecular dynamics we propose a supercapacitor whose electrodes are formed exclusively by self-organizing peptides and whose electrolyte is a green amino acid ionic liquid. Our results indicate that this supercapacitor has a high potential for energy storage with superior performance than conventional supercapacitors. In particular its capacity to store energy was estimated to be almost 20 times greater than an analogue one of planar metallic electrodes

Exploding Nitromethane in silico, in real time

Nitromethane (NM) is widely applied in chemical technology as a solvent for extraction, cleaning and chemical synthesis. NM was considered safe for a long time, until a railroad tanker car exploded in 1958. We investigate detonation kinetics and reaction mechanisms in a variety of systems consisting of NM, molecular oxygen and water vapor. State-of-the-art reactive molecular dynamics allows us to simulate reactions in time-domain, as they occur in real life. High polarity of the NM molecule is shown to play an important role, driving the first exothermic step of the reaction. Presence of oxygen is important for faster oxidation, whereas its optimal concentration is in agreement with the proposed reaction mechanism. Addition of water (50 mol%) inhibits detonation; however, water does not prevent detonation entirely. The reported results provide important insights for improving applications of NM and preserving safety of industrial processes.Comment: arXiv admin note: text overlap with arXiv:1408.372

Molecular interactions between fullerene C-60 and ionic liquids

Structural and energetic aspects of solvation of fullerene C-60 in ionic liquids at room temperature were analyzed by using atomistic molecular dynamics simulations. Ethylammonium Nitrate (EAN) and 1-Butyl-3-Methylimidazolium Tetrafluoroborate (BMIMBF4) ionic liquids were conveniently chosen for presenting different polarities. Analysis of the spatial distribution of the ionic liquid revealed different patterns for the solvation of C-60. Energetics indicated that the presence of C-60 weakened the ionic interactions in solution compared to those in pure liquids. Our free energy calculations showed that there is an energy cost of 235 kJ mol(-1) for transferring fullerene C-60 from BMIMBF4 to EAN. (C) 2013 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Univ Fed ABC, Ctr Ciencias Nat & Humanas, BR-09210270 Santo Andre, SP, BrazilUniversidade Federal de São Paulo, Inst Ciencia & Tecnol, BR-12231280 Sao Jose Dos Campos, SP, BrazilUniversidade Federal de São Paulo, Inst Ciencia & Tecnol, BR-12231280 Sao Jose Dos Campos, SP, BrazilWeb of Scienc