STUDY ON THE CONFORMATIONS OF p-(NITRO)METHOXYCALIX[4]ARENE AND p-(tert-BUTYL)METHOXYCALIX[4]ARENE USING HIGH LEVEL AB INITIO METHOD

Hanggara Sudrajat (Austrian-Indonesian Centre for Computational Chemistry, Department of Chemistry, Faculty of Mathematics and Natural Sciences, Gadjah Mada University, Sekip Utara, Yogyakarta 55281)
Danis Sriwijaya (Austrian-Indonesian Centre for Computational Chemistry, Department of Chemistry, Faculty of Mathematics and Natural Sciences, Gadjah Mada University, Sekip Utara, Yogyakarta 55281)
Herman Siagian (Physics Education Department, Faculty of Mathematics and Natural Sciences State University of Yogyakarta, Karangmalang, Yogyakarta 55283)
Ria Armunanto (Austrian-Indonesian Centre for Computational Chemistry, Department of Chemistry, Faculty of Mathematics and Natural Sciences, Gadjah Mada University, Sekip Utara, Yogyakarta 55281)

Indonesian Journal of Chemistry
Vol 9, No 1 (2009)

Ab initio calculations have been performed in order to investigate the conformational characteristics of p-(nitro)methoxycalix[4]arene and p-(tert-butyl)methoxycalix[4]arene. The structures of four types (cone, partial cone, 1,2-alternate and 1,3-alternate) of conformers for each compound have been optimized by ab initio method at the restricted Møller-Plesset fourth-order perturbation (RMP4) level of theory using 6-311G and 6-311G++(d,p) basis sets. General trends in relative stabilities of p-(nitro)methoxycalix[4]arene and p-(tert-butyl)methoxycalix[4]arene are similar and decrease in following order: partial cone > cone > 1,3-alternate > 1,2-alternate. The calculated results of the most stable conformation of partial cone structure agree with the reported NMR experimental observations.