A class of nonbenzenoid analogues of poly-(p-phenylenevinylene)-s (PPVs), 2,6-azulene-vinyl-based conjugated polymers (CPs) r -PAzV, hhtt -PAzV, and ht -PAzV, have been reported with different dipole arrangements of azulene units, where the five-membered ring and seven-membered ring of azulene core are defined as head (H) and tail (T), respectively. The PAzV polymers exhibit diverse backbone structures, proton responsiveness, an unusual relationship between crystallinity and regioregularity relative to conventional CPs, and balanced ambipolar charge transport. In regiorandom r -PAzV, the proportions of the H-T, H-H, and T-T linkages are about 40, 20, and 40%, respectively. The studies on solubility, thermal/optical properties, and microstructures of these PAzV polymers reveal that the presence of H-H and T-T arranged moieties in r -PAzV and hhtt -PAzV strengthens interchain interactions. Grazing-incidence wide-angle X-ray scattering measurements demonstrate enhanced long-range order with up to four orders of side-chain stacking reflections in as-spun films of r -PAzV and hhtt -PAzV. Williamson-Hall and Scherrer's analyses indicate that the lamellar crystallites in films of ht -PAzV have a much smaller size and lower crystallite quality relative to r -PAzV and hhtt -PAzV. Therefore, organic thin-film transistors based on r -PAzV and hhtt -PAzV display 2-4 orders higher charge carrier mobilities than those of ht -PAzV-based devices. The poor device performance of ht -PAzV might be attributed to the gradient electrostatic potential distribution and localized distribution of the Frontier molecular orbitals of the main chain. Our work enriches the family of PPV-like polymers, achieves the regulation of dipole arrangements of 2,6-azulene units together with clear structural analysis, and discloses that the dipole arrangements of azulene units along the polymer backbone have a great influence on the assembly of polymer chains.

A feasible protocol for Cu-catalyzed asymmetric alkynylallylic dimethylamination is developed with the discovery of tetramethyldiaminomethane as a new, stable and convenient surrogate of dimethylamine. A series of enantioenriched 1,4-enynes are constructed in reasonable yields, high regioselectivities and moderate to good enantioselectivities. Mechanistic experiments show that the tertiary amine works as a nucleophile directly followed by the release of the expected dialkylamine unit, different from the conventional primary and secondary amines with the cleavage of a proton as the nucleophile. DFT calculations elucidate the origin of regio- and enantioselectivity for the present transformation. A reliable protocol for asymmetric Cu-catalyzed alkynylallylic dimethylamination is described with the discovery of tetramethyldiaminomethane as a new, stable and convenient surrogate of the dimethylamine nucleophile.

Compared with the extensively reported hydrogen atom transfer (HAT) at sp(3) C-H, abstraction of hydrogen atoms at the sp(2) carbon is extremely rare. Here, we communicate the site-selective cyanation of the sp(2) C-H bond of allenes using the strategy of copper-catalyzed radical relay. The reactions afford various allenyl nitriles directly from simple allenes with a broad substrate scope and a remarkable functional group compatibility under mild conditions. These reactions exhibit excellent site-selectivity toward sp(2) C-H, which can be attributed to the unique pocket created by the Cu-bound nitrogen-centered radical. The favorable HAT on sp(2) C-H is due to crucial hydrogen bonding between the fluoride bonded to the Cu(II) center and the hydrogen atom at the allylic position. These features enable the late-stage functionalization of druglike bioactive molecules containing an allene motif.