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Electronic structural studies of pyrrolidinium‐based ionic liquids for electrochemical application
Author(s) -
Asha Suseeladevi,
Vijayalakshmi Kunduchi Periya,
George Benny K.
Publication year - 2019
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.25972
Subject(s) - hexafluorophosphate , chemistry , ionic liquid , alkyl , electrochemistry , tetrafluoroborate , ionic bonding , hydrogen bond , mulliken population analysis , electrochemical window , density functional theory , binding energy , inorganic chemistry , ion , computational chemistry , molecule , organic chemistry , ionic conductivity , electrolyte , physics , electrode , nuclear physics , catalysis
Electrochemical stability and noncovalent interactions escorting the cyclic ammonium‐based ionic liquids composed of N‐alkyl‐substituted N‐methyl pyrrolidinium (P yr 1R) (R = methyl, ethyl, propyl, butyl, pentyl, hexyl) cations and four anions hexafluorophosphate (PF 6 ), tetrafluoroborate (BF 4 ), bis(trifluoromethylsulfonyl‐imide (TFSI), and trifluoromethane sulfonate (TFO) have been analyzed using the density functional theory. Electronic structures, electrochemical window, frontier orbital energy difference (HOMO‐LUMO gap), binding energies, vibrational spectra of these ion pairs were characterized. It has been established that ion pair formation is largely reigned by CH⋯F interactions between anionic fluorine for BF 4 − and PF 6 − anions and CH⋯O interactions between anionic oxygen for TFSI and TFO anions and pyrrolidinic proton, methyl, or alkyl group protons of the cations. The effect of alkyl chain length and pairing anions of the alkyl substituted N‐methyl pyrrolidinium‐based ionic liquids on the electrochemical window was investigated. The results revealed that the HOMO energy of pairing anions is the key factor to decide the electrochemical window. Further quantification of noncovalent interactions in terms of electrostatic and hydrogen bonding interactions has been brought out employing a novel method with the aid of Mulliken and Merz‐Singh‐Kollman charges, prevailed in pyrrolidinium‐based ionic liquids.