James C. Barborak

Preparation and characterization of conjugated polymers made by postpolymerization reactions of alternating polyketones.

Conjugated polymers possessing a poly(2,5-dimethylene-2,5-dihydrofuran) backbone were prepared through postpolymerization reaction of styrenic polyketones with bromine in one-pot reactions. The modification is proposed to proceed via condensation of two repeating units to form a fully characterized polymer with a poly(2,5-dimethylenetetrahydrofuran) backbone. Subsequent bromination and elimination of HBr yield a polymer with a fully conjugated carbon backbone. The new conjugated polymers were characterized by NMR, IR, and UV-vis spectroscopies and by CV. These polymers have strong absorption in the visible region, with the absorption peaks shifted to the NIR region upon doping with acids. The ease of the synthesis of the starting polyketone and of the modifications allows large-scale preparation of those conjugated polymers.

Correlated rotation in a conformationally restricted amide

Dynamic two‐dimensional 1H and 13C NMR studies of the conformationally restricted amide N‐(1‐naphthoyl)‐cis‐2,6‐dimethylpiperidine reveal correlated rotation about the aryl–CO and amide bonds. The naphthalene and piperidine rings are tightly meshed and their rotation is virtually entirely (>99%) concerted, as evidenced by separate NMR measurement of the much slower rates of rotation about the individual aryl–CO and amide bonds. A disrotatory cogwheeling mechanism for the concerted rotation is proposed. Copyright