NMR study of dyadic and triadic splitting in copoly(arylene)phthalides based on diphenyl oxide and diphenyl sulfide

Abstract

All ¹³ C NMR signals of the poly(arylene) polymers, O-1, S-7, OS-4, OOS-3, OOOS-2, SSO-5, and SSSO-6 (where O is a diphenyleneoxiphthalide unit and S is a diphenylenethiophthalide unit) in dyads and triads were assigned unequivocally with two-dimensional NMR techniques (ge-2D [¹ H-¹ H] COSY, ge-2D [¹ H-¹³ C] HSQC, and ge-2D [¹ H-¹³ C] HMBC), and for each atom, the increments of the shifts are determined. For structurally similar carbon atoms of the phthalide cycle and heteroaromatic fragments of the skeletal chain, additive signal splitting schemes in phthalide centered dyads and in diphenylene oxide and in diphenylene sulfide centered triads are considered, based on taking into account the contributions to their shielding of adjacent and distant substituents. It was shown that the nature of the splitting of the signals of each of the 20 carbon atoms in 3,3-bisphenylphthalide fragments is determined by the type of carbon atom (tertiary or quaternary, even or odd), the type of heteroatoms in adjacent heteroaromatic fragments, their distance from the identified carbon nucleus, and their polyad symmetry. The results obtained in this article will greatly facilitate our further studies and, in particular, will allow us to study the microstructure of statistical copolymers based on the asymmetric OS monomer at the dyad and triad levels.

Keywords: 13С; 1H; NMR; additivity; dyads; increments; poly(arylene)phthalides; triads.