Crystal and Molecular Structures of Poly(1,4-phenylenesulfone) and Its Trisulfone and Tetrasulfone Oligomers

Abstract

The structures of poly(1,4-phenylenesulfone), [1,4-ArSO2]n (Ar = 1,4-phenylene), and its tetrasulfone oligomer ArSO2ArSO2ArSO2ArSO2Ar (Ar = phenyl or 1,4-phenylene) have been determined from X-ray powder diffraction data interfaced to molecular simulation and diffraction modeling. An initial model for the tetrasulfone oligomer was developed using conformational and packing information obtained from a single-crystal X-ray determination of the structure of the trisulfone ArSO2ArSO2ArSO2Ar, in which the aromatic ring planes lie essentially orthogonal to a plane defined by the bridging C−S−C groups. Energy-minimization and crystallographic refinement of the tetrasulfone structure by Pawley and Rietveld methods yielded an agreement factor (Rwp) of 15.3%., and an analogous approach led to solution of the crystal structure of poly(1,4-phenylenesulfone) (Rwp = 5.5%). In all three structures, the diaryl sulfone units adopt near-perfect open-book conformations and the molecules crystallize with the aromatic rings of laterally adjacent chains essentially parallel. The polymer unit cell is C-centered orthorhombic (two chains per cell), space group Cmcm, with a = 10.79, b = 5.05, and c = 9.97 Å. The polymer chain adopts 21 helical geometry, and crystal packing is dominated by SO···H−C interactions (O···H = 2.68 Å).