Conjugated polymer nanowires with long-range order can significantly enhance charge carrier mobility. However, nanowires of P­(NDI2OD-T2) with lengths up to the micron scale have not been reported yet due to fast backbone aggregation. Herein, we proposed to prepare P­(NDI2OD-T2) nanowires through slow nucleation via side chain ordering first and then backbone planarization by enhancing the side chain interaction. For this purpose, two selective solvents were used, with bromonaphthalene (BrN) dissolving the P­(NDI2OD-T2) backbone and toluene (Tol) dissolving the side chain, respectively. For BrN, the initial solution contained only P­(NDI2OD-T2) unimer coils with both the backbone and side chain disordered. In the subsequent aging process, P­(NDI2OD-T2) side chain ordering took place first then inducing backbone planarization. The resulting extended chains stacked slowly into nuclei upon the side chain interaction. During the final film-drying process, these nuclei grew into well-defined nanowires with lengths up to tens of micrometers and a width of 20 nm. Structural analysis revealed that the polymer chains aligned parallel to the long axis of the nanowire in an edge-on orientation. In contrast, in Tol, P­(NDI2OD-T2) chains aggregated immediately into too many rod-like nuclei upon strong backbone interaction, which resulted in high-density small fibrils in the film. The results obtained herein reveal the subtle role of the backbone and side chain in nucleation and demonstrate that the nucleation pathway can be readily controlled using selective solvents, thereby manipulating the final film morphology of conjugated polymers.

Semiconducting polymers with high mobility and mechanical robust properties are strongly dependent on their molecular weight. However, the relationship between molecular weights and solution chain entanglements, film microstructures, charge carrier mobility, and mechanical properties for donor−acceptor conjugated polymers remains less understood. Herein, P(NDI2OD-T2) with a weight-average molecular weight (M w ) from 34.0 to 280 kDa was investigated as a model system. The polymer chain exhibited three regions in chloroform solutions: fewer entanglements (34.0−77.7 kDa), enhanced entanglements (170 kDa), and severe entanglements (280 kDa). This chain solution behavior resulted in three distinct film microstructures: (1) 34.0−77.7 kDa, liquid-crystalline-like morphologies with highly ordered chain arrangements and large crystallite lengths (l c ) yet relatively low tie-chain densities that increased with M w ; (2) 170 kDa, small fibril morphology with less ordered chain arrangements and a decreased l c of only 5.6 nm yet a high tie-chain density; and (3) 280 kDa, a seemingly amorphous film with vast wellconnected local aggregates embedded in an entangled network. The structural change in films significantly affected the electrical and mechanical performances. The electron mobility increased continuously with M w , correlating well with the tie-chain density. By contrast, the crack-onset strain was less than 3% at 34.0−77.7 kDa and then jumped to 36.4 ± 0.9 and 60.4 ± 2.1% for 170 and 280 kDa, showing a close correlation with the solution entanglement density, which could be inherited into films. This study contributes to structural development of rigid chains with M w and demonstrates that the microstructure containing vast well-connected local aggregates and adequate entanglements is promising toward mechanically robust semiconducting films.

Transition metal-catalyzed cross-coupling reactions using organoindium reagents have witnessed rapid and comprehensive development in the past two decades. In comparison with many other organometallic reagents, the preparation of organoindium reagents and the subsequent transition metal-catalyzed cross-coupling reactions with various electrophiles showed a wider tolerance to important functional groups and protic solvents. In addition, in many cases, cross-coupling reactions employing organoindium reagents exhibited remarkable chemo- and stereoselectivity. In this tutorial review, we summarize and highlight the most important developments in this rapidly advancing area, with special emphasis on their utilities in organic synthesis and materials science.

Combined Lewis acid, consisting of two or more Lewis acids, sometimes shows unique catalytic ability, and it may promote reactions which could not be catalyzed by any of the Lewis acids solely. On the other hand, the development of efficient methods for the facile synthesis of cyclobutenes and densely functionalized decalins is an attractive target for synthetic chemists due to their versatile synthetic utilities and widespread occurrence in natural products. Herein, we wish to report an efficient method for the assembly of cyclobutenes and densely functionalized decalin skeletons through In(tfacac)-TMSBr catalyzed selective [2 + 2]-cycloaddition and dearomatizing cascade reaction of aryl alkynes with acrylates with high chemo- and stereoselectivity. The obtained cyclobutene could be easily converted into cyclobutane as well as synthetically useful 1,4- and 1,5-diketones with high chemo- and stereoselectivity. On the basis of mechanistic studies, plausible reaction mechanisms were proposed for both the [2 + 2]-cycloaddition and the dearomatizing cascade reaction. Finally, the computational studies of reaction mechanisms were conducted, and the results suggest that the combined Lewis acid could efficiently promote both reactions.

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A stereoselective Cu(OTf)2-mediated C(sp2)–H sulfonylation of enamides with arylsulfonyl radicals generated in situ from DABSO and diazonium salts is developed.

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