Organic π-conjugated small molecules and polymers, owing to their light weight, solution processability, mechanical flexibility, and large synthetic variety of finely tunable structures and properties, are promising semiconducting materials for a new generation of optoelectronic devices such as light-emitting diodes (LEDs), field-effect transistors (FETs), photovoltaic devices and sensors. A vast library of π-conjugated systems have been synthesized through conventional tools of coupling (e.g. Suzuki coupling, Stille coupling) and have been used in the fabrication of organic optoelectronic devices. In recent years an emerging synthetic technique called direct C–H arylation has been extensively studied as a facile, atom-efficient and environmentally benign pathway for the synthesis of conjugated polymers and small molecules. C–C bond formation between two heteroaryls can be carried out via the activation of C–H bonds in a transition-metal catalytic cycle, thereby overcoming additional pre-functionalization steps involving toxic reagents. Direct arylation has been applied to a broad range of monomers and its reaction conditions have been optimized to produce defect-free polymers as well as small molecules that exhibit performances comparable with those made from conventional reactions. In this review, we summarize the recent progress in the synthesis of conjugated small molecules, linear polymers and porous polymers by direct C–H arylation. In particular, small molecules and linear polymers based on benzothiadiazole (BT), diketopyrrolopyrrole (DPP), napththalenediimide (NDI), isoindigo (IG), thienoisoindigo (TIIG) and thienothiadiazole (TTD) are discussed in detail. Device performances of some representative polymers synthesized via direct arylation polymerization (DAP) in FETs and bulk heterojunction solar cells are summarized. We finally discuss the present challenges and perspectives of DAP towards future “greener” and more industrially scalable synthesis of π-conjugated semiconducting polymers for a variety of applications.

Stimuli-responsive nonporous silica prodrug nanoparticles are developed by covalently encapsulating anticancer drugs camptothecin (CPT) and doxorubicin (DOX) into silica matrices through glutathione (GSH)-responsive disulfide and pH-responsive hydrazone bonds.

Amphiphilic star-like block copolymers form robust biocompatible unimolecular micelles that are efficient in the delivery of anticancer drugs such as doxorubicin.

This article describes the synthesis of donor–acceptor (D–A) type copolymers based on benzo[1,2-b:4,5-b′]dithiophene and 2,1,3-benzothiadiazole via direct-arylation cross-coupling polycondensation. To achieve high performance polymerization, we have systematically investigated the reaction factors including catalysts, solvents, ligands, bases, additives, concentration of reactants and phase transfer agents. In particular, 1,2-dimethylbenzene (ODMB), as a nonpolar high boiling point solvent, is a superior medium to perform this direct-arylation polymerization. In this nonpolar aromatic solvent, Pd₂dba₃/(o-MeOPh)₃P, accompanied with a base potassium carbonate and an additive pivalic acid, serves as an efficient catalyst system to obtain high-quality polymers. Our optimized condition gave the polymer with a weight-average molecular weight (M_w) as high as 60 kg mol⁻¹ in nearly quantitative yield and excellent C–H selectivity.

Solar cells involving organic small molecules and polymers have attracted intense attention from chemists, physicists and materials scientists in the past decade. Efforts in materials synthesis and device processing have led to significant improvement of the power conversion efficiency, approaching 10%. In organic solar cells (OSCs), the morphology and the interface of the donor–acceptor (D–A) heterojunctions play a critical role in determining the device efficiency. In this article, we highlight recent progress on both materials synthesis and self-assembly and lithography techniques toward ordered nanostructures and well-defined D/A interfaces that are expected to enhance the performance of OSCs.

Thiophene-flanked benzothiadiazole derivatives (DTBTs) have been among the most widely used building blocks for the synthesis of a myriad of high-performance conjugated polymers for applications in optoelectronic devices, sensing and bioimaging. We first report that these building blocks could be synthesized via a facile and straightforward method called direct arylation coupling. Our optimization of Pd₂dba₃-catalyzed direct arylation coupling gave DTBTs with a comparable yield to that of the Suzuki or Stille coupling reaction. DTBTs were further polymerized with fluorene dibromide via direct arylation polycondensation to give well-defined alternating copolymers. One-pot direct arylation polymerizations were also carried out between benzothiadiazole dibromide, fluorene dibromide and thiophene derivatives, to form DTBT-containing random copolymers. These random copolymers showed typical multichromophore characteristics. The differences in optical properties between the alternating copolymers and random copolymers were evaluated.