Determination of poly(4,4′-diphenylsulfonyl terephthalamide) crystalline structure via WAXD and molecular simulations

The crystal structure of poly(4,4′-diphenylsulfonyl terephthalamide) (pt-PSA) is studied by X-ray diffraction and molecular simulation. Although the number of observed reflections is limited to warrant a precise determination of the unit cell structure and symmetry, a reasonable monoclinic unit cell is suggested with dimensions of a = 0.645 nm, b = 0.488 nm, c = 3.010 nm, and γ = 122.5°. A twofold molecule with two monomeric units forming a large zigzag conformation satisfies the X-ray diffraction data. A layer structure is formed in the crystal phase, which is stabilized by the hydrogen bond between NH and Cï£O and the parallel-displaced π-π stacking from the distortional coplanarity of the benzene rings and amide group. A 2/1 helical geometry of pt-PSA molecule in crystal phase with the periodicity 3.01 ± 0.02 nm is determined by wide-angle X-ray diffraction (WAXD) and molecular simulation. A monoclinic unit cell for pt-PSA with the dimensions of a = 0.645 nm, b = 0.488 nm, c = 3.010 nm, and γ = 122.5° is suggested. A layer structure is formed in the crystal phase and is stabilized by the hydrogen bond between NH and Cï£O and the parallel-displaced π-π stacking from the distortional coplanar of benzene rings and amide group.