Double Direct C-H Bond Arylation of Thiophenes with Aryl Chlorides Catalyzed by the N-Heterocyclic Carbene-PdCl2-1-methylimidazole Complex

With the combination of the N-heterocyclic carbene-PdCl2-1-methylimidazole complex and Cu2O, we succeeded in the first example of double direct C-H bond arylation reactions between thiophenes and aryl chlorides, giving the desired 2,5-diarylated thiophenes in moderate to high yields under suitable conditions, consistent with the density functional theory calculations.

Pd-Free synthesis of dithienothiophene-based oligoaryls for effective hole-transporting materials by optimized Cu-catalyzed annulation and direct C–H arylation

For the first time, [Cu]-catalyzed annulation and direct C–H/C–I couplings were used as key transformations to access new DTT-based hole-transporting materials (HTMs), CHC05–07. Perovskite solar cells with CHC07 display PCEs of up to 14.7%.

Development of Step-Saving Alternative Synthetic Pathways for Functional π-Conjugated Materials

Synthetic organic chemists endeavor to develop new reaction conditions, improve product yields, and enhance atom economy (synthetic methodologies), whereas the material scientists strive to create novel functional molecules/structures, increase device stabilities, and promote power conversion efficiencies via device engineering (organic optoelectronics). However, these two prominent research fields seem to have no intersections. Since joining national central university in 2012, our research philosophy aims to narrow, or rather to bridge the gap between synthetic methodologies and π-functional organic materials. In contrast to using multistep synthetic approaches based on Suzuki- or Stille coupling reactions, this personal account describes various step-saving and viable synthesis-shortcuts developed by our group, to access thiophene-based small molecules for optoelectronic applications. We expect these succinct and user-friendly alternative pathways designed by synthetic chemists would help material scientists to reach their target molecules in a more step-economical manner.

Efficient OLEDs Fabricated by Solution Process Based on Carbazole and Thienopyrrolediones Derivatives

Four low molecular weight compounds-three of them new, two of them with carbazole (Cz) as functional group and the other two with thienopyrroledione (TPD) group-were used as emitting materials in organic light emitting diodes (OLEDs). Devices were fabricated with the configuration ITO/PEDOT:PSS/emitting material/LiF/Al. The hole injector layer (HIL) and the emitting sheet were deposited by spin coating; LiF and Al were thermally evaporated. OLEDs based on carbazole derivatives show luminances up to 4130 cd/m², large current efficiencies about 20 cd/A and, cautiously, a very impressive External Quantum Efficiency (EQE) up to 9.5%, with electroluminescence peaks located around 490 nm (greenish blue region). Whereas, devices manufactured with TPD derivatives, present luminance up to 1729 cd/m², current efficiencies about 4.5 cd/A and EQE of 1.5%. These results are very competitive regarding previous reported materials/devices.

Copper catalyzed synthesis of conjugated copolymers using direct arylation polymerization

As an effort to replace palladium catalysts, we report the first example of a Copper-catalyzed Direct Arylation Polymerization (DArP).

Palladium-catalyzed intramolecular C–H arylation of 2-halo-N-Boc-N-arylbenzamides for the synthesis of N–H phenanthridinones

A palladium catalyzed synthesis of N–H phenanthridinones was developed via C–H arylation. The protocol gives phenanthridinones regioselectively by one-pot reaction without deprotection. It exhibits broad substrate scope and affords targets in up to 95% yields. Importantly, it could be applied for the less reactive o-chlorobenzamides.

Pd(t-Bu₃P)₂/KOAc proved to be a good combination for one-pot synthesis of N–H phenanthridinones with up to 95% yield.

Small Molecules Derived from Thieno[3,4-c]pyrrole-4,6-dione (TPD) and Their Use in Solution Processed Organic Solar Cells

In this work, microwave synthesis, chemical, optical and electrochemical characterization of three small organic molecules, TPA-TPD, TPA-PT-TPD and TPA-TT-TPD with donor-acceptor structure and their use in organic photovoltaic cells are reported. For the synthesis, 5-(2-ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione was used as electron withdrawing fragment while the triphenylamine was used as electron donating fragment. Molecular electronic geometry and electronic distribution density were established by density functional theory (DFT) calculations and confirmed by optical and chemical characterization. These molecules were employed as electron-donors in the active layer for manufacturing bulk heterojunction organic solar cells, where [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) was used as electron-acceptor. As cathode, Field's metal (FM), an eutectic alloy (Bi/In/Sn: 32.5%, 51%, and 16.5%, respectively) with a melting point above 62 °C, was easily deposited by drop casting under vacuum-free process and at air atmosphere. Prepared devices based on TPA-TPD:PC71BM (1:4 w/w ratio) presented a large VOC = 0.97 V, with JSC = 7.9 mA/cm², a FF = 0.34, then, a power conversion efficiency (PCE) of 2.6%.

Connecting Direct C-H Arylation Reactions with Dye-Sensitized Solar Cells: A Shortcut to D-A-π-A Organic Dyes

A step-economical synthetic strategy is developed to target thieno[3,4-c]pyrrole-4,6-dione (TPD)-based D-A-π-A organic dyes for dye-sensitized solar cells (DSSCs). Through sequential Pd-catalyzed direct C-H (hetero)arylation reaction, synthesis of the push-pull-type small molecules is reduced from the traditional six steps to two steps. In this report, we focus on the optimization of the key C-H monoarylation of TPD by screening ligands, acid additives, bases, and solvents. The reaction proves versatile toward new D-A-π-A organic dyes with a variety of different donor groups, and several derivatives are efficiently prepared under optimum reaction conditions. The sensitive aldehyde functionality that is a required intermediate for conversion into anchoring groups for TiO2 is well tolerated. Based on our synthetic study, DSSCs are fabricated and characterized using two designed sensitizers. The photovoltaic characterization of the devices affords an open-circuit voltage of 0.60-0.69 V, a short-circuit current density of 10.85-11.07 mA cm(-2), and a fill factor of 69.9-70.8 %, which corresponds to an overall power conversion efficiency of 4.61-5.33 %.

The effect of a solvent on direct arylation polycondensation of substituted thiophenes

A suitable solvent for direct arylation polycondensation is related to an electronic nature of thiophene derivatives.