Effect of dielectric constant on estimation of properties of ionic liquids: an analysis of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

A series of different cationic structures based on 1-alkyl-3-methylimidazolium were combined with a single anion, bis(trifluoromethylsulfonyl)imide (CnmimNTf2, n = 1 to 12) for analyzing the quality of COSMO-RS based estimations. For this purpose, we have studied the structure as well as the estimations of several properties of one ionic liquid (IL). These estimations are obtained from polarization charge distribution in which the IL is embedded. Special attention has been paid to the effect of the dielectric constant value in the predictions. For this purpose, polarization charge density has been modeled using several values of dielectric constant, and properties have been estimated in each case. Thus, σ-profiles and, σ-potentials have been computed and used with COSMO-RS for estimating vapor pressure, as a function of temperature, as well as theoretical values of vaporization enthalpy, density, and viscosity at 298.15 K. The influence of the length of the alkyl chain of ionic liquid in the estimation of these properties has also been tested. Finally, the results have been compared with experimental dataThe authors thank the “Ministerio de Ciencia e Innovación” (Project: CTQ2010-19232) and “Comunidad de Madrid” (Project: LIQUORGAS-S2013/MAE-2800) financial suppor

Progress toward standardized diagnosis of vascular cognitive impairment: Guidelines from the Vascular Impairment of Cognition Classification Consensus Study

INTRODUCTION: Progress in understanding and management of vascular cognitive impairment (VCI) has been hampered by lack of consensus on diagnosis, reflecting the use of multiple different assessment protocols. A large multinational group of clinicians and researchers participated in a two-phase Vascular Impairment of Cognition Classification Consensus Study (VICCCS) to agree on principles (VICCCS-1) and protocols (VICCCS-2) for diagnosis of VCI. We present VICCCS-2. METHODS: We used VICCCS-1 principles and published diagnostic guidelines as points of reference for an online Delphi survey aimed at achieving consensus on clinical diagnosis of VCI. RESULTS: Six survey rounds comprising 65-79 participants agreed guidelines for diagnosis of VICCCS-revised mild and major forms of VCI and endorsed the National Institute of Neurological Disorders-Canadian Stroke Network neuropsychological assessment protocols and recommendations for imaging. DISCUSSION: The VICCCS-2 suggests standardized use of the National Institute of Neurological Disorders-Canadian Stroke Network recommendations on neuropsychological and imaging assessment for diagnosis of VCI so as to promote research collaboration

Molecular modeling and physicochemical properties of 1-alkyl-3-methylimidazolium-FeX4 and -Fe2X7 (X = Cl and Br) magnetic ionic liquids

Magnetic Ionic Liquids (MILs) are room temperature ionic liquids composed of a metal–containing anion and an organic cation, which present paramagnetic properties that make them interesting materials for industrial applications. Molecular modeling calculations of MILs from the combinations of four 1-N-alkyl-3-methylimidazolium (NMIm) cations and the anions: tetrachlorideferrate (III), tetrabromideferrate (III), heptachlorideferrate (III) and heptabromideferrate (III) have been carried out using DFT methods. The dependence of properties, such as energies, dipole moments and magnetic couplings, on the chain length has been studied and compared with similar nonmagnetic ionic liquids containing chloride aluminate anions. Density and viscosity were estimated using COSMO-RS obtaining good agreement with experimental data.The authors acknowledge the financial support rendered by Comunidad de Madrid (Project:LIQUORGAS-S2013/MAE-2800) and the CCC-UAM for computational facilitie

Predictions of Physicochemical Properties of Ionic Liquids with DFT

Nowadays, density functional theory (DFT)-based high-throughput computational approach is becoming more efficient and, thus, attractive for finding advanced materials for electrochemical applications. In this work, we illustrate how theoretical models, computational methods, and informatics techniques can be put together to form a simple DFT-based throughput computational workflow for predicting physicochemical properties of room-temperature ionic liquids. The developed workflow has been used for screening a set of 48 ionic pairs and for analyzing the gathered data. The predicted relative electrochemical stabilities, ionic charges and dynamic properties of the investigated ionic liquids are discussed in the light of their potential practical applications

Understanding the Structure and Properties of Cholinium Amino Acid Based Ionic Liquids

The molecular structure of novel ionic liquids based on cholinium amino acids (ChAA-ILs) has been analyzed. The polarization charge density for all ion pairs has been examined as a function of the hydrophobicity of the anion. The COnductor-like Screening MOdel σ-profiles and σ-potentials have been obtained and used to interpret the chemical behavior of ChAA-ILs. Some physicochemical properties such as density and viscosity have been estimated using the COnductor-like Screening MOdel for Realistic Solvation method. Furthermore, the effects of polarization on the molecular structure, physicochemical properties, and hydrophobicities have been evaluated. Finally, the results obtained have been compared with experimental data

Density Functional Theory Study of Ionic Liquid Adsorption on Circumcoronene Shaped Graphene

Carbon materials have a range of properties such as high electrical conductivity, high specific surface area, and mechanical flexibility are relevant for electrochemical applications. Carbon materials are utilized in energy conversion-and-storage devices along with electrolytes of complementary properties. In this work, we study the interaction of highly concentrated electrolytes (ionic liquids) at a model carbon surface (circumcoronene) using density functional theory methods. Our results indicate the decisive role of the dispersion interactions that noticeably strengthen the circumcoronene–ion interaction. Also, we focus on the adsorption of halide anions as the electrolytes containing these ions are promising for practical use in supercapacitors and solar cells