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Cation–π Interactions between a Free‐Base Porphyrin and an Ionic Liquid: A Computational Study
Author(s) -
Cao Zhen,
Li Shu,
Yan Tianying
Publication year - 2012
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201100868
Subject(s) - porphyrin , ionic liquid , ionic bonding , chemistry , free base , base (topology) , chemical physics , computational chemistry , nanotechnology , ion , materials science , photochemistry , organic chemistry , salt (chemistry) , catalysis , mathematical analysis , mathematics
A cation–π stacking structure consisting of a free‐base porphyrin (FBP) and 1‐butyl‐3‐methylimidazolium (BMIM + ) cation is demonstrated by both ab initio theory and polarizable force field. The isolated FBP–BMIM + complex forms a face‐to‐face alignment, and the polarizable force‐field‐optimized complex reproduces that by ab initio theory reasonably well. Molecular dynamics simulation finds that the stacking structure is slightly altered for the FBP dissolved in the bulk ionic liquid (IL) due to the complexity of the solution structure. In the bulk IL, the FBP is sandwiched between two BMIM + cations stacking on both sides of the FBP ring plane with a slipped‐parallel alignment. Furthermore, the FBP–BMIM + stacking structure is found to be more stable than the BMIM + –PF 6 − ion pair in the IL.