IEFPCM conformational studies of 12c4(aq) were performed using density functional theory. The C-1 structure was diagnosed to be the most populated conformer while the population of C-i conformers is also relatively high. Ensemble averaged DFT vibrational spectra of 12c4(aq) were compared with the experimental ATR-FTIR spectra for the first time. Our CAM-B3LYP averaged spectra were in excellent agreement with experimental spectra. Due to the nonzero dipole moment of C-1 conformers, calculated average dipole moment (3.08 D) is also reported. (C) 2010 Elsevier B.V. All rights reserved.