CONFORMATIONAL EQUILIBRIUM AND SPECTROSCOPIC PROPERTIES OF CALlX[4]ARENE: THEORETICAL STUDY USING AS INITIO METHOD

ABSTRACT Molecularstructures were optimizedfor the calix{4]areneby ab initio method at the Hartree-Focklevel of theory using LANL2DZ and 6-311G basis sets. Conformationalequilibrium of four calix{4]arene conformers are reported. The results are compared with experiment, force field, and semiempirical molecular orbital calculations. General trends in relative stabilities of calix{4]arenedecrease in following order: cone> partial-cone> 1,2-alternate> 1,3- alternate. Themost stable conformeris the cone conformerthat is stabilized by an array of four hydrogenbondsand this result agree with the reported experimentalobservations.All structures were analyzed using theoreticallR, UVVis, and \u27H NMR spectra attributed to the conformational equilibrium at the Hartree-Fock level of theory using LANL2DZbasis set. Keywords: ab initio calculation, calix{4]arene, conformations, cone