Carbazole derivatives, carbazole-containing polymers and iridium complexes are of interest due to many possible applications in photonics, electronics and biology, particularly as active or hole-transporting layers in organic as well as perovskite devices due to their interesting properties. Here, a series of carbazole-fluorene conjugated copolymers with various substituents at the -carbazole position (2-methoxycarbonylethyl, 2-carboxyethyl, 2-ethylhexyl, and nonan-2,4-dionatoiridium(III)bis(2-phenylpyridine-,)-9-yl) was prepared by Suzuki coupling. Their photophysical, electrochemical and electroluminescence (EL) properties were studied. Effects of molecular weight and substituents attached to carbazole unit on their properties are reported. The carbazole-fluorene copolymers in dilute solutions exhibited intense photoluminescence (PL) emission in the blue spectral region with high PL quantum yields (78-87%) except for the copolymer with the iridium complex (23%). Similar PL spectra were observed in dilute solutions. More pronounced differences were found in thin film PL and EL properties due to excimer/aggregate formation. Light-emitting devices (LEDs) made of copolymers with 2-ethylhexyl as -carbazole substituent exhibited efficient EL emission with the best performance and the lowest EL onset voltages (3-4 V), while the LEDs made of copolymers with other substituents were not as efficient, but showed anomalous behavior and memory effects in current-voltage characteristics promising also for bio-inspired electronics.
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http://dx.doi.org/10.3390/polym15132932 | DOI Listing |
Chemistry
December 2024
Hiroshima University, Chemistry, 1-3-1 Kagamiyama, 739-8526, Higashi-Hiroshima, JAPAN.
The intermolecular host-guest complexation of head-to-tail monomers consisting of cleft-shaped bisporphyrin and trinitrofluorenone units connected by a chiral binaphthyl linker was employed to construct helically twisted supramolecular polymers. Results from 1H NMR, diffusion-ordered NMR spectroscopy, and viscometry experiments revealed that the supramolecular polymerization of these monomers follows a ring-chain competition mechanism. The introduction of bulky substituents at the linker significantly suppressed the formation of macrocyclic oligomers, whereas smaller alkyl chains facilitated the formation of the cyclic form.
View Article and Find Full Text PDFPolymers (Basel)
November 2024
Chemistry Department, Lomonosov Moscow State University, Leninskye Gory 1, 119991 Moscow, Russia.
To prepare novel biodegradable copolymers with functional substituents that are distributed statistically or randomly over the macromolecule chain and have improved characteristics compared to homopolymers, we conducted a series of synthetic experiments with a novel cyclic monomer, 5-(benzyloxy)-1,3-dioxepan-2-one (). This compound was synthesized, and its homopolymer, as well as its copolymers with L-lactide, ε-caprolactone and trimethylene carbonate, were prepared in a polymerization solution with stannous octoate as the initiator. The formation of the copolymers was confirmed using NMR spectroscopy and DSC data.
View Article and Find Full Text PDFDalton Trans
January 2025
Department of Medicinal and Applied Chemistry, Drug Development and Value Creation Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan, 80708, Republic of China.
A series of aluminum complexes bearing phenolate (O-Al and O2-Al), biphenolate (OO-Al type), aminophenolate (ON-Al), aminobiphenolate (ONO-Al), bis(phenolato)bis(amine) (NNOO-Al), and Salan (ONNO-Al) type ligands were synthesized. ε-Caprolactone (CL) polymerization using these aluminum complexes as catalysts was investigated. The overall polymerization rates of Al catalysts with different ligands were found to be in the following order ( values): ONBr-Al (0.
View Article and Find Full Text PDFMacromol Rapid Commun
November 2024
Dipartimento di Chimica e Biologia "Adolfo Zambelli", Università degli Studi di Salerno, Via Giovanni Paolo II, Fisciano, SA, 84084, Italy.
The advancement of stereoregular polymerization techniques for linear 1,3-dienes has enabled the production of polymers with precise stereocontrol, influencing their physical and chemical properties significantly. While 1,3-butadiene and isoprene yield diverse stereoregular polymers, cyclic dienes have received less attention due to catalyst challenges and limited application in the rubber industry. However, the growing interest in bio-based monomers, particularly those derived from terpenes and terpenoids, has revitalized interest in cyclic monomers with conjugated double bonds.
View Article and Find Full Text PDFPolymers (Basel)
October 2024
Chemistry Department, Nazarbayev University, 53 Kabanbay Batyr Ave., Astana 01000, Kazakhstan.
Conducting polymers are emerging as promising alternatives to rare and expensive platinum for counter electrodes in dye-sensitized solar cells; due to their ease of synthesis, they can be chemically tuned and are suitable for roll-to-roll production. Among these, poly (3,4-ethylenedioxythiophene) (PEDOT)-based counter electrodes have shown leading photovoltaic performance. However, certain conductivity issues remain that affect the effectiveness of these counter electrodes.
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