Noncovalent Interactions Underlying Binary Mixtures of Amino Acid based Ionic Liquids: Insights from Theory. Soniya S. Rao a , Libero J. Bartolotti b and Shridhar P. Gejji a * a Department of Chemistry, Savitribai Phule Pune University, Pune 411 007, India. b Department of Chemistry, East Carolina University, GreenVille, North Carolina 27858, United States. -------------------------------------------------------------------------------------------------------------------------------- Supporting Information Figure S1 Optimized structures of different conformers of [Bmim][Asp] ion pairs. Figure S2 Optimized structures of different conformers of [Bmim][Asn] ion pairs. Figure S3 Optimized structures of different conformers of [Bmim][Glu] ion pairs. Figure S4 Optimized structures of different conformers of [Bmim][Gln] ion pairs. Table S1 Interaction energies (in kJ mol -1 ) and an estimation of the dispersion contribution, ΔE disp for (a) [Bmim][Asp] (b) [Bmim][Asn] (c) [MBmim][Glu] and (d) [Bmim][Gln] ion pairs. Figure S5 Optimized structures of different [Bmim] 2 [Glu][Gln] conformers with different cation orientations. Values in parentheses represent relative stabilization energies with respect to the lowest energy conformer in kJ mol -1 . Table S2 Dispersion corrected relative stabilization energies (R.S.E in kJ mol -1 ) for [Bmim] 2 [Asp][Asn] (I) and [Bmim] 2 [Glu][Gln] (II)systems. Table S3 Calculated interaction energies (in kJ mol -1 ) using B3LYP and B3LYP-D3 level of theory for [Bmim] 2 [Asp][Asn] mixed ILs. Table S4 Calculated interaction energies (in kJ mol -1 ) using B3LYP and B3LYP-D3 level of theory for [Bmim] 2 [Glu][Gln] mixed ILs. Figure S6 Optimized structures of different [Bmim] 2 [Asp][Asn] conformers at B3LYP level of theory with different cation orientations. Values in parentheses represent relative stabilization energies with respect to the lowest energy conformer in kJ mol -1 . Figure S7 Optimized structures of different [Bmim] 2 [Asp][Asn] conformers at B3LYP-D3 level of theory with different cation orientations. Values in parentheses represent relative stabilization energies with respect to the lowest energy conformer in kJ mol -1 . Figure S8 Optimized structures of different [Bmim] 2 [Glu][Gln] conformers at B3LYP level of theory with different cation orientations. Values in parentheses represent relative stabilization energies with respect to the lowest energy conformer in kJ mol -1 . Figure S9 Optimized structures of different [Bmim] 2 [Glu][Gln] conformers at B3LYP-D3 level of theory with different cation orientations. Values in parentheses represent relative stabilization energies with respect to the lowest energy conformer in kJ mol -1 . Figure S10 Color-filled RDG isosurfaces depicting Non-covalent interaction (NCI) regions in (a) [Bmim][Asp] (b) [Bmim][Asn] (c) [MBmim][Glu] and (d) [Bmim][Gln] ion pairs. A plot of reduced density gradient (RDG) on the x-axis versus the sign (λ2)ρ values on the Y-axis for the same have also been shown. Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics. This journal is © the Owner Societies 2017