Direct arylation polycondensation for synthesis of optoelectronic materials

Direct arylation polycondensation has been investigated to develop efficient methods for the preparation of conjugated polymeric materials for use in optoelectronic applications. The reaction conditions have been examined to achieve high molecular weights and minimal structural defects in the recurring structures. Under optimal conditions, the direct arylation method has several advantages over conventional methods, e.g., it has fewer synthetic steps and yields a high-molecular-weight and high-purity polymer. The high-quality polymeric materials that were obtained exhibited superior performance to those obtained using a conventional method when used in optoelectronic devices such as organic photovoltaics and field-effect transistors. Recent developments in C–H/C–H coupling polycondensation are also described

Aggregation-induced emission behavior of a pincer platinum(II) complex bearing a poly(ethylene oxide) chain in aqueous solution

An amphiphilic pincer platinum(II) complex with a poly(ethylene oxide) (PEO) chain exhibited aggregation-induced emission (AIE) because of micelle formation in water. The AIE activity was enhanced by the addition of 1,3,5-benzenetricarboxylic acid, which induced micelle formation through hydrogen-bonding interactions with the PEO chain

Synthesis and characterization of a thermally crosslinkable polyolefin from oleic acid

A novel thermally crosslinkable polyolefin was synthesized from biorenewable oleic acid. The obtained polymer exhibited a unique structure, bearing an inner olefin moiety in the long side chain. Since thermal auto‐oxidation and crosslinking reactions occurred at the inner olefin moiety of polymer, it could be cured by heating in air. The resultant polymer exhibited good adhesion properties to various substrates

Synthesis of n-type semiconducting polymer consisting of benzodipyrrolidone and thieno-[3,4-c]-pyrrole-4,6-dione via CH direct arylation

Direct arylation polycondensation of 3,​7-​bis(4-​bromophenyl)​-​1,​5-​bis(2-​octyldodecyl)​benzo[1,​2-​​b:4,​5-​b\u27]​dipyrrole-​2,​6(1H,​5H)​-​dione with 5-(2-ethylhexyl)-thieno-[3,4-c]-pyrrole-4,6-dione gave the corresponding benzodipyrrolidone-based conjugated polymer with a molecular weight of 147,000 in 92% yield. The optical and thermal properties of the polymer were evaluated. The polymer showed n-type semiconducting behavior in organic field-effect transistors with an electron mobility of 1.3 ± 0.2 × 10−3 cm2 V−1 s−1

Template-directed synthesis of macrocyclic aminopyridines: azacalix[n](2,6)pyridines (n = 3, 4)

Template-induced synthetic routes for azacalix[n](2,6)pyridines (n = 3, 4) have been elaborated. The proton and nickel ion served as the efficient template for the cyclization reactions, and the presence of the templates preferentially afforded the cyclic trimers and tetramers in moderate to good yields, respectively. The compatibility of the cyclic tetramer with nickel ion was also confirmed by X-ray crystallography

Luminescent Ir(III) complexes containing benzothiazole-based tridentate ligands: synthesis, characterization, and application to organic light-emitting diodes

Ir(III) complexes that contain benzothiazole-based tridentate ligands were synthesized and their crystal structures and luminescent properties were examined. A neutral complex had a high quantum yield (89%) and performed well as an emissive material for organic light-emitting diodes

Facile one-pot access to π-conjugated polymers via sequential bromination/direct arylation polycondensation

The synthesis of π-conjugated polymers starting from unfunctionalized aromatic monomers via sequential bromination/direct arylation polycondensation was investigated. The developed protocol provides a step-economical access to the polymers in a one-pot fashion, without the need for prior preparation and purification of dibrominated aromatic monomers or organometallic monomers. Benzyltrimethylammonium tribromide was effective for the bromination of 10-(2-octyldodecyl)phenothiazine and 4,4′-didodecyl-2,2′-bithiophene, and the obtained dibrominated aromatic monomers were used for the subsequent direct arylation polycondensation without isolation and purification. The direct arylation polycondensation reaction yielded the corresponding donor–acceptor-type π-conjugated polymers in moderate to good yields. The sequential protocol was also applicable to the synthesis of poly(3-hexylthiophene-2,5-diyl) from 3-hexylthiophene. The obtained polymers served as semiconducting materials in organic light-emitting diodes and organic photovoltaics

Luminescent Ir(III) complexes bearing benzothiazole or benzoxazole-based pincer ligand

Ir complexes bearing pincer ligands are expected to be efficient phosphorescent materials. This work investigated the solid-state structures and photophysical properties of Ir(III) complexes that contain different NCN pincer ligands (NCN = 1,3-bis(2-benzothiazolyl)benzene, 1,3-bis(2-benzoxazoyl)benzene, or 1,3-bis(2-benzimidazoyl)benzene derivatives), bidentate cyclometalating NC ligands (NC = 2-phenylpyridine or 2-phenylbenzothiazole), and anionic ancillary ligands. The structure of the NCN pincer ligands is a dominant factor for determining the emission wavelength, rather than the bidentate NC and ancillary ligands. The organic light emitting diodes (OLEDs) with an Ir(III) complex show electroluminescence with 14% external quantum efficiency at 1 mAcm−2. Modification of the device structure improved the efficiency at the high current density region

Facile synthesis of fluorene-based π-conjugated polymers via sequential bromination/direct arylation polycondensation

The synthesis of fluorene-based π-conjugated polymers via sequential bromination and Pd-catalyzed direct arylation polycondensation was demonstrated; the protocol allows dual functionalization of each aromatic monomer in one-pot fashion. This synthetic protocol afforded the corresponding polymers with high molecular weights in good yields (up to yield 80%, Mn 34,500)

Emission from Charge-Transfer States in Bulk Heterojunction Organic Photovoltaic Cells Based on Ethylenedioxythiophene-Fluorene Polymers

We investigated the electroluminescence (EL) from charge-transfer (CT) in the interface state of PEDOTF/PC70BM, known to be empirically related to Voc, to elucidate a difference in Voc of 0.24 V in bulk heterojunction (BHJ) organic photovoltaic cells (OPVs) based on two polymers (H-PEDOTF and S-PEDOTF with a high and low molecular weight, respectively) having almost the same HOMO energy levels. The difference in the energies of CT EL peaks is relatively small (0.06 eV) compared to the difference in the Vocs. Consequently, we mainly attribute the excessive loss of Voc in S-PEDOTF-based OPVs to a trap assisted recombination mechanism