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Title: Structure of cyano-anion ionic liquids: X-ray scattering and simulations

Abstract

Ionic liquids with cyano anions have long been used because of their unique combination of low-melting temperatures, reduced viscosities, and increased conductivities. Recently we have shown that cyano anions in ionic liquids are particularly interesting for their potential use as electron donors to excited state photo-acceptors [B. Wu et al., J. Phys. Chem. B 119, 14790–14799 (2015)]. Here we report on bulk structural and quantum mechanical results for a series of ionic liquids based on the 1-ethyl-3-methylimidazolium cation, paired with the following five cyano anions: SeCN-, SCN-, N(CN)-2N(CN)2-, C(CN)-3C(CN)3-, and B(CN)-4B(CN)4-. By combining molecular dynamics simulations, high-energy X-ray scattering measurements, and periodic boundary condition DFT calculations, we are able to obtain a comprehensive description of the liquid landscape as well as the nature of the HOMO-LUMO states for these ionic liquids in the condensed phase. Features in the structure functions for these ionic liquids are somewhat different than the commonly observed adjacency, charge-charge, and polarity peaks, especially for the bulkiest B(CN)-4B(CN)4- anion. While the other four cyano-anion ionic liquids present an anionic HOMO, the one for Im+2,1Im2,1+/B(CN)-4B(CN)4- is cationic.

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [3];  [3];  [2];  [1];  [3]
  1. Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA
  2. Laboratório de Espectroscopia Molecular, Instituto de Química, Universidade de São Paulo, CP 26077, CEP 05513-970 São Paulo, SP, Brazil
  3. Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
Publication Date:
Research Org.:
Rutgers Univ., Piscataway, NJ (United States); Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; São Paulo Research Foundation (FAPESP); National Council for Scientific and Technological Development (CNPq)
Contributing Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
OSTI Identifier:
1351355
DOE Contract Number:  
SC0001780; SC0008644; AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 145; Journal Issue: 2
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Dhungana, Kamal B., Faria, Luiz F. O., Wu, Boning, Liang, Min, Ribeiro, Mauro C. C., Margulis, Claudio J., and Castner, Edward W. Structure of cyano-anion ionic liquids: X-ray scattering and simulations. United States: N. p., 2016. Web. doi:10.1063/1.4955186.
Dhungana, Kamal B., Faria, Luiz F. O., Wu, Boning, Liang, Min, Ribeiro, Mauro C. C., Margulis, Claudio J., & Castner, Edward W. Structure of cyano-anion ionic liquids: X-ray scattering and simulations. United States. doi:10.1063/1.4955186.
Dhungana, Kamal B., Faria, Luiz F. O., Wu, Boning, Liang, Min, Ribeiro, Mauro C. C., Margulis, Claudio J., and Castner, Edward W. Wed . "Structure of cyano-anion ionic liquids: X-ray scattering and simulations". United States. doi:10.1063/1.4955186.
@article{osti_1351355,
title = {Structure of cyano-anion ionic liquids: X-ray scattering and simulations},
author = {Dhungana, Kamal B. and Faria, Luiz F. O. and Wu, Boning and Liang, Min and Ribeiro, Mauro C. C. and Margulis, Claudio J. and Castner, Edward W.},
abstractNote = {Ionic liquids with cyano anions have long been used because of their unique combination of low-melting temperatures, reduced viscosities, and increased conductivities. Recently we have shown that cyano anions in ionic liquids are particularly interesting for their potential use as electron donors to excited state photo-acceptors [B. Wu et al., J. Phys. Chem. B 119, 14790–14799 (2015)]. Here we report on bulk structural and quantum mechanical results for a series of ionic liquids based on the 1-ethyl-3-methylimidazolium cation, paired with the following five cyano anions: SeCN-, SCN-, N(CN)-2N(CN)2-, C(CN)-3C(CN)3-, and B(CN)-4B(CN)4-. By combining molecular dynamics simulations, high-energy X-ray scattering measurements, and periodic boundary condition DFT calculations, we are able to obtain a comprehensive description of the liquid landscape as well as the nature of the HOMO-LUMO states for these ionic liquids in the condensed phase. Features in the structure functions for these ionic liquids are somewhat different than the commonly observed adjacency, charge-charge, and polarity peaks, especially for the bulkiest B(CN)-4B(CN)4- anion. While the other four cyano-anion ionic liquids present an anionic HOMO, the one for Im+2,1Im2,1+/B(CN)-4B(CN)4- is cationic.},
doi = {10.1063/1.4955186},
journal = {Journal of Chemical Physics},
number = 2,
volume = 145,
place = {United States},
year = {Wed Jul 13 00:00:00 EDT 2016},
month = {Wed Jul 13 00:00:00 EDT 2016}
}