Interactions of pyridinocalix[4]arene with cations and organic molecules by quantum chemical calculations

Abstract

Two rigidity configurations of 25, 27-di(4-methyl-pyridine)-p-tert-butylcalix[4]arene (L, LI which possesses pyridine methyl groups pointing towards each other were obtained by structural optimization using AM1 method. Potential energies of interactions between the configuration LI and proton, methanol, Li+, Na+, K+, Be2+ and Mg2+ were calculated by ab initio methods using STO-3G and 6-31G basis sets. It was found that LI could form a complex with Na+ and K+ by two types of interactions: Na+ and K+ -oxygen interaction and a Na+ and K+- interaction. Nevertheless, LI could form complexes with Li+, Be2+ and Mg2+ using metal-oxygen interactions. Complexation studies of LII with resorcinol and phthalic acid were found to have stabilization energies of-16.1 and -17.5 kcal mol-1, respectively. The N...H bond distance between the pyridine nitrogen and the acidic protons of phthalic acid was 1.90 A while that between the pyridine nitrogen and the hydroxy protons of resorcinol was 1.90 A. Quantum calculations also showed that resorcinol and phthalic acid could not be included into the cavity of LII in the gas phase