Synthesis, structure and properties of various molecules based on the 4,8,12-trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrene system with an evaluation of the effect differing molecular substitution patterns has on the space group symmetry

Abstract

4,8,12-Trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrene (3), 2,6,10-tri-tert-butyl-4,8,12-trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrene (11) and 2,6,10-tri-tert-butyl-4,8,12-trioxa-12c-methyl-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrene (12) have been synthesised and their crystal structures determined. The crystal structure of 4,8,12-trioxa-12c-oxophospha-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrene (13) has also been determined for comparison. Compounds 3 and 11 crystallise in non-centrosymmetric space groups. Compound 12 also crystallises in a non-centrosymmetric space group but molecules of opposite chirality are present within the unit cell. Finally compound 13 crystallises in a centrosymmetric space group. The room temperature pyroelectric coefficient of 3 has been determined. The spatial extent of the trioxatriangulene ground system has been perturbed by chemical substitution and the effect of the substitutions upon the space group symmetry of the chemical derivative has been uncovered by X-ray structural resolution. The non-centrosymmetric point group symmetry of the molecules is reflected in a non-centrosymmetric space group symmetry whenever the spatial perturbations do not prohibit the stacking of the molecules.