DFT Calculated Structures and IR Spectra of the Conformers of para-Bromocalix[4]aryl Derivatives

Abstract

Molecular structures of the various conformers of para-bromocalix[4]aryl derivatives 1-4 were optimized using the DFTB3LYP calculation method. The total electronic and Gibbs free energies and normal vibrational frequencies of the different structures (CONE, partial cone (PACO), 1,2-Alternate(1,2-A) and 1,3Alternate(1,3-A)) were calculated from the four kinds of para-bromocalix[4]aryl derivatives. The B3LYP/63 1G(d,p) calculations suggested the following: l(PACO) is the most stable among four conformers of 1; 2(CONE) is the most stable among five conformers of 2; 3(PACO) is the most stable among four conformers of 3; 4(1,3-A) is the most stable among four conformers of 4. All the most stable structures optimized by the B3LYP calculation method were in accordance with the experimental crystal structures of 1-4. The calculated IR spectra of the various conformers (CONE, PACO, 1,2-A and 1,3-A) of 1-4 were compared.