NMR study of phthalide-type poly(phenylene)s. Symmetry and additivityстатья
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Дата последнего поиска статьи во внешних источниках: 7 декабря 2017 г.
Аннотация:All H-1 and C-13 NMR signals of the four poly(phenylenephthalides): polydiphenylenephthalide (P(DPh)-1), polyterphenylenephthalide (P(TPh)-2) and two sequentially ordered polymers with different ratios of alternating diphenylenephthalide and terphenylenephthalide units (P(DTPh)-3, P(DDTPh)-4) were assigned unequivocally with two-dimensional NMR techniques (H-1-H-1 COSY and NOESY; H-1-C-13 HSQC and HMBC). There are four types of polyphenylene fragments: not symmetrical end, symmetrical inner, symmetrical pre-end and formally symmetric pre-end. The equivalent carbon atoms in these fragments have different chemical shifts. A full additivity of the chemical shifts for the side phthalide and polyphenylene carbon atoms was revealed. A new structure of diads with a mirror symmetry plane, passing through the middle of aromatic moieties, is proposed.