Synthesis by oxidative polymerization with FeCl3 of a fully aromatic twisted poly(3,6-carbazole) with a blue-violet luminescence

Hollow microspherical carbazole-based conjugated polymers by photoinduced step-growth polymerization

A new photochemical approach for the synthesis of metal-free three-dimensional hollow spherical conjugated polymers is described.

Structure and Reactivity of Aromatic Radical Cations Generated by FeCl3

This paper describes the isolation and characterization of an aromatic radical cation generated by FeCl₃. X-ray crystallographic analysis and kinetic studies reveal the mechanism of the generation of aromatic radical cation. In the solid state, a tight ion-pair of a radical cation with FeCl₄^- is observed. Leveraging the efficient generation of the radical cation-FeCl₄^- ion pair, we explore a radical cation-induced cycloaddition of trans-anethole initiated by catalytic amount of FeCl₃. Both [4+2] cycloaddition and [2+2] cycloaddition with a broad substrate scope are also described. Moreover, a 100 g-scale reaction is demonstrated with the use of 1 mol % of FeCl₃ as a simple and a highly active initiator.

C3-C3' and C6-C6' Oxidative Couplings of Carbazoles

9-Substituted carbazoles are widely used units in materials science, and their oxidative reactions have been utilized for the synthesis and characterization of polymers. Though the oxidative mechanism of carbazoles has been known for a few decades, structural definition has remained difficult, because their polymers are generally insoluble with incomplete characterization and unknown dependence of the electrochemical potentials. The oxidative reactions of 9-substituted carbazoles should be carefully considered under specific oxidative conditions; otherwise, structure definitions could be wrong, because the IR and NMR spectra used previously cannot quantitatively analyze 3,3'-coupling and 6,6'-coupling of carbazoles. In this review, the best understanding of the C3-C3' and C6-C6' oxidative couplings of 9-substituted carbazoles is presented, and the benefit of these oxidative reactions from the viewpoints of electrochemical synthesis, film engineering, and the synthesis and processing of polymers is highlighted.

Simultaneous doping and crosslinking of polythiophene films

We present a click chemistry approach for the synthesis of conjugated redox polymers based on highly regioregular polythiophenes with tunable amounts of pendant redox-active triphenylamine (TPA) groups. Solution-deposited films can be simultaneously doped and crosslinked by electrochemical or chemical oxidation.

Synthesis and characterization of poly(arylene ether ketone)s with 3,6-diphenyl-9H-carbazole pendants using C–N coupling reaction

3,6-Diphenyl-9 H-carbazole pendants are grafted herein to poly(arylene ether ketone)s (PAEKs) via the Ullmann C–N coupling reaction. To the best of our knowledge, this is the first time that PAEKs containing a carbazole pendant (Cz) have been synthesized through the Ullmann C–N coupling reaction. The high molecular weights of PAEK-Cz (PAEKs with 3,6-diphenyl-9 H-carbazole pendants) are inherited from their precursors, owing to the high reactivity of their monomers. The obtained PAEK-Cz- x polymers exhibit good solubility in most common organic solvents and excellent thermal stabilities, with the 5% weight loss temperatures for all products being above 598°C under a nitrogen atmosphere. The glass transition temperatures are all above 199°C and can be controlled by adjusting the feed ratio of monomers. The polymer membranes obtained by the casting method are tough and thus have strong potential for practical applications.

Novel Carbazole (Cbz)-Based Carboxylated Functional Monomers: Design, Synthesis, and Characterization

A series of novel functional carbazole (Cbz)-based carboxylated monomers were synthesized and characterized. A Clauson-Kaas procedure, a deprotection step, amide coupling, and hydrolysis were utilized as key chemical reactions towards the multistep synthesis of monomers in good to excellent isolated yields. The design strategy was further extended to complex carbazole-COOH monomers incorporated arylazo groups as photoreactive moieties. In addition, photoreactive hybrid carbazole (Cbz)-pyrrole (Pyr)-based carboxylated monomers, comprising a pyrrole core linking a carbazole and a photoreactive phenylazide or benzophenone moiety through an amide spacer in the molecular structure, were also synthesized. The latter can be utilized for surface modification of polymeric films in their monomeric form or as polymeric microparticles (MPs).

Synthesis and characterization of 2,7-linked carbazole oligomers

A set of monodisperse 2,7-linked carbazole oligomers (3-mer, 5-mer, 7-mer, and 9-mer) was synthesized, and their photophysical, electrochemical, and thermal properties were investigated. In solutions, these oligomers exhibited bright blue emission with almost quantitative fluorescence quantum yield. The emission spectra of these oligomers in films are quite different. 3-Mer and 5-mer exhibited featureless emission spectra, whereas 7-mer and 9-mer showed well-resolved emission spectra.

Solar-energy production and energy-efficient lighting: photovoltaic devices and white-light-emitting diodes using poly(2,7-fluorene), poly(2,7-carbazole), and poly(2,7-dibenzosilole) derivatives

World energy needs grow each year. To address global warming and climate changes the search for renewable energy sources with limited greenhouse gas emissions and the development of energy-efficient lighting devices are underway. This Review reports recent progress made in the synthesis and characterization of conjugated polymers based on bridged phenylenes, namely, poly(2,7-fluorene)s, poly(2,7-carbazole)s, and poly(2,7-dibenzosilole)s, for applications in solar cells and white-light-emitting diodes. The main strategies and remaining challenges in the development of reliable and low-cost renewable sources of energy and energy-saving lighting devices are discussed.

High Triplet Energy Polymer as Host for Electrophosphorescence with High Efficiency

We report the conjugated polymer P(tBu-CBP) as a host with high triplet energy (E(T) 2.53 eV) and suitable HOMO (5.3 eV) and LUMO (2.04 eV) energy levels. Upon doping with green and red emission Ir-complexes, it gives devices with high luminous and external quantum efficiencies for green emission (23.7 cd/A, 6.57%) and for red emission (5.1 cd/A, 4.23%), respectively, and low turn-on voltage (3 V). For both devices, the efficiencies are higher than those of the corresponding devices with the same backbone P(3,6-Cz) as a host by a factor of 4, even though the latter has an E(T) (2.6 eV) slightly higher than that of the former. The results reflect that, in phosphorescent devices, the difference in E(T) between the host and guest is not the only factor that determines the device efficiency, and the present side group modification via the 9 position of carbazole also plays an important role, which allows a tuning of HOMO and LUMO levels to provide more balance in electron and hole fluxes and provides prevention from formation of excimer.

Ultraviolet-emitting conjugated polymer poly(9,9′-alkyl-3,6-silafluorene) with a wide band gap of 4.0 eV

An ultraviolet-emitting conjugated polymer, poly(9,9'-alkyl-3,6-silafluorene) with a wide band gap of 4.0 eV, has been synthesized and characterized.