A series of carbazole/quinoxaline hybrids have been synthesized by classic Ullmann and Pd/Cu-catalyzed Sonogashira coupling reaction. Their photophysical, thermal, and electrochemical properties were investigated. The introduction of electron rich carbazole and electron deficient quinoxaline on to the 1,3,5-benzene center leads to a twisted structure with good glass forming property and imparts a bipolar character. The triplet energies in the range of 2.34-2.53 eV indicate them as potential host materials in phosphorescent OLEDs. 相似文献
Two new carbazole derivatives with the oxadiazole moiety substituted at the 9 position of carbazole have been facilely synthesized by an aromatic nucleophilic substitution reaction of arylamine and fluoroarenes. Alternating copolymers with spirobifluorene were then prepared by a Suzuki coupling reaction. Spirobifluorene units together with the bulky oxadiazole pendant significantly enhance the morphological stability of the copolymers. An increased π‐electron delocalization in P2 with 2,7‐coupling of carbazole results in a decrease of absorption and phosphorescence emission energies as compared to P1 with 3,6‐coupling of the carbazole. The bandgaps and energy levels of the polymers can be tuned by different coupling positions between carbazole and the spirobifluorene moieties.
The synthesis and full characterization of new derivatives of indolo[3,2-b]carbazole with differently substituted phenyl groups at nitrogen atoms is reported. Comparative study on their thermal, optical electrochemical, and photoelectrical properties is presented. The synthesized compounds are electrochemically stable. Their highest occupied molecular orbital energy values range from -5.14 to -5.07 eV. The electron photoemission spectra of the films of synthesized materials revealed the ionization potentials of 5.31-5.47 eV. Hole drift mobility of the amorphous film of 5,11-bis(3-methoxyphenyl)-6-pentyl-5,11-dihydroindolo[3,2-b]carbazole exceed 10(-3) cm(2)/V·s at high electric fields, as it was established by xerographic time-of-flight technique. In contrast to diphenylamino substituted derivatives of carbazole, no effect of the position of methoxy groups on the photoelectrical properties was observed for the synthesized methoxyphenyl-substituted derivatives of indolo[3,2-b]carbazole. The indolo[3,2-b]carbazole core has a larger resonance structure that includes 3 phenyl rings, and thus the energy gap of the HOMO and LUMO π orbitals is lower as compared to that of carbazoles. With a larger energy difference between the phenyl substituents and the core moiety, the indolo[3,2-b]carbazole derivatives studied all have a weaker coupling between the phenyl group and a much weaker dependence of the molecular properties on the position of substituents on the phenyl groups as compared to those observed in substituted carbazoles. 相似文献
Summary: Carbazole‐based oligomeric and polymeric materials have been studied for almost 25 years for their unique electrical, electrochemical and optical properties. Interestingly, carbazole units can be linked in two different ways leading to either poly( 3,6 ‐carbazole) or poly( 2,7 ‐carbazole) derivatives. While the former class seems to be very interesting for electrochemical and phosphorescence applications, the latter shows very promising optical properties in the visible range for light emitting diodes (LED). The major intrinsic difference between these two classes is the effective conjugation length: poly(2,7‐carbazole) materials having the longer one, due to their poly(p‐phenylene)‐like structure. Using different synthetic strategies and substitution patterns, the physico‐chemical properties of both classes can be fine‐tuned, leading to high performance materials for a large number electronic applications.
Chemical structures for poly(3,6‐carbazole) and poly(2,7‐carbazole) and the materials used as the starting points for their respective syntheses. 相似文献
A series of new 7,7′bis(3,6-di-tert-butylcarbazol-N-yl)-substituted fluorenyl-oligothiophenes bearing 0-, 2-, 4-, 6-, and 8-thiophene rings, namely BCFTn, were synthesized using palladium catalyzed Stille dimerization coupling reactions of their corresponding brominated thiophenes. The relationship between the chemical structure and the properties of these oligomers was evaluated. With respect to the electronic properties, the longest wavelength absorptions, emissions, and also the oxidation potentials can be tuned by varying the conjugation length of the oligothiophene segments. The terminal carbazole and fluorene moieties of the resulting materials are beneficial for their morphology, conjugation length, and solubility. 相似文献
Attachment of triarylamino‐functional groups at the 9‐position of 2,7‐linked carbazole polymers results in blue‐emitting materials with two independent redox processes that were attributed to the triarylamino groups and the polymer backbone, respectively. This new class of blue‐emitting conjugated polymers was prepared via a Suzuki cross‐coupling reaction and showed low turn‐on voltages in electroluminescent devices as a result of their low ionisation potentials. The photophysical, electrochemical and electroluminescent properties of these materials are discussed.
The homoleptic complexes [Ph(4)P](2)[Co[N(CN)(2)](4)] and [Ph(4)P][M[N(CN)(2)](3)] [M = Co, Mn] have been structurally as well as magnetically characterized. The complexes containing [M[N(CN)(2)](4)](2-) form 1-D chains, which are bridged via a common dicyanamide ligand in [M[N(CN)(2)](3)](-) to form a 2-D structure. The five-atom [NCNCN](-) bridging ligands lead to weak magnetic coupling along a chain. The six [NCNCN](-) ligands lead to a (4)T(1g) ground state for Co(II) which has an unquenched spin-orbit coupling that is reflected in the magnetic properties. Long-range magnetic ordering was not observed in any of these materials. 相似文献