mPW1PW91 Conformational Study of Di-t-butyl-dinitro-tetramethoxysulfonylcalix[4]arene

摘要

The structures of the conformers for 1,3-di-t-butyl-2,4-dinitro-tetramethoxysulfonylcalix[4]arene (1) and 1,2-di-t-butyl- 3,4-dinitro-tetramethoxysulfonylcalix[4]arene (2) were optimized using DFT BLYP and mPW1PW91/6-31G(d,p) (hybrid HF-DF) calculation methods. We have analyzed the total electronic and Gibbs free energies and the differences between the various conformations (cone, partial-cone (PC), 1,2-alternate, and 1,3-alternate) of 1 and 2. For both compounds, the 1,3-alternate (1,3-A) conformers were calculated to be the most stable, which correlate very well with the experimental results. The orderings of the relative stability of 1 and 2 that resulted from the mPW1PW91/6-31G(d,p) calculations are the following: 1: 1,3-A (syn) PC (syn) PC (anti) 1,2-A (anti) CONE (syn); 2: 1,3-A (anti) PC (anti) PC (syn) 1,2-A (anti) 1,2-A (syn) CONE (syn). The BLYP/6-31G(d) calculated IR spectra of the most stable 1,3-A conformers of 1 and 2 are compared.