排序方式: 共有16条查询结果,搜索用时 15 毫秒
1.
LI Yuan-Zuo SUN Yu LI Yong-Qing MA Feng-Cai 《理论物理通讯》2006,46(2):229-232
The first fluorine-substituted hexabenzocoronene has been synthesized and its electronic structure and optical properties have been reported [Q. Zhang, et al., Org. Lett. 7 (2005) 5019]. In this letter, the electronic structure and excited state properties of the fluorine-substituted hexabenzocoronene are studied with quantum chemistry method as well as the transition and the charge difference densities. The transition densities show the orientations and strength of the dipole moments and the charge difference densities reveal the orientation and results of the intramolecular charge transfer. The calculated transition energies and oscillator strengths are consistent with the experimental data, and the theoretical results of transition and charge difference densities are valuable to understanding the excited state properties of the fluorine-substituted hexabenzocoronene. 相似文献
2.
A series of symmetrically and unsymmetrically substituted hexaphenylbenzene (HPB) analogues were efficiently synthesized by using a sterically hindered Suzuki–Miyaura cross‐coupling reaction of arylboronic acids with 1,4‐diiodo‐2,3,5,6‐tetraarylbenzenes under our optimized reaction conditions. The 1,4‐diiodo‐2,3,5,6‐tetraarylbenzenes can be readily prepared by using a one‐pot Hart reaction. Oxidative cyclodehydrogenation of the dibromo derivative with FeCl3 gave the corresponding hexabenzocoronene (HBC) derivative in good yield. 相似文献
3.
Carolin Dusold Dr. Dmitry I. Sharapa Dr. Frank Hampel Prof. Dr. Andreas Hirsch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(7):2332-2341
The synthesis of an unprecedented, π-extended hexabenzocorene (HBC)-based diaza[7]helicene is presented. The target compound was synthesized by an ortho-fusion of two naphthalene diimide (NDI) units to a HBC-skeleton. A combination of Diels–Alder and Scholl-type oxidation reactions involving a symmetric di-NDI-tolane precursor were crucial for the very selective formation of the helical superstructure via a hexaphenyl-benzene (HPB) derivative. The formation of the diaza[7]helicene moiety in the final Scholl oxidation is favoured, affording the symmetric π-extended helicene as the major product as a pair of enantiomers. The separation of the enantiomers was successfully accomplished by HPLC involving a chiral stationary phase. The absolute configuration of the enantiomers was assigned by comparison of circular dichroism spectra with quantum mechanical calculations. 相似文献
4.
Milan Randić Damir Vukičević Alexandru T. Balaban Marjan Vračko Dejan Plavšić 《Journal of computational chemistry》2012,33(11):1111-1122
We report on calculated CC bond currents for a dozen derivatives of hexabenzocoroenene in which one or more proximal carbon atoms at the molecular periphery have been bridged. The approach that we use is graph‐theoretical in nature, following our outline of this method in 2003, which is based on finding all conjugated circuits in all Kekulé valence structures of these molecules. To the π‐electrons having 4n + 2 π‐electrons are assigned anticlockwise π‐electron currents and to conjugated circuits having 4n π‐electrons are assigned π‐electron currents. One may summarize the results reported in this work by stating that CC bond currents in the compounds considered decrease on going from peripheral rings to the central ring of the molecule, and also that CC bond currents decrease by insertion of bridges to proximal peripheral benzenoid rings. © 2012 Wiley Periodicals, Inc. 相似文献
5.
6.
Ryuichi Yamaguchi Satoru Ito Byung Sun Lee Dr. Satoru Hiroto Prof. Dr. Dongho Kim Prof. Dr. Hiroshi Shinokubo 《化学:亚洲杂志》2013,8(1):178-190
We have demonstrated that the iridium‐catalyzed direct borylation of hexa‐peri‐hexabenzocoronene (HBC) enables regioselective introduction of boryl groups to the para‐, ortho‐, and meta‐substituted HBCs in high yields. The boryl groups have been transformed into various functionalities such as hydroxy, cyano, ethynyl, and amino groups. We have elucidated that the substituents significantly influence the photophysical properties of HBCs to enhance fluorescence quantum yields. DFT calculations revealed that the origin of the substituent effect is the lift in degeneracy in the frontier orbitals by an interaction with electron‐donating and electron‐withdrawing substituents at the para‐ and ortho‐positions. The change in molecular orbitals results in an increase of the transition probability from the S0→S1 states. In addition, the two‐photon absorption cross‐section values of para‐substituted HBCs are significantly larger than those of ortho‐ and meta‐substituted HBCs. 相似文献
7.
Alternating Donor–Acceptor Arrays from Hexa‐peri‐hexabenzocoronene and Benzothiadiazole: Synthesis,Optical Properties,and Self‐Assembly
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Felix Hinkel Dr. Don Cho Dr. Wojciech Pisula Prof. Dr. Martin Baumgarten Prof. Klaus Müllen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):86-90
Donor–acceptor (D–A) structures were obtained by alternating arrays of hexa‐peri‐hexabenzocoronene (HBC) and benzo[c][1,2,5]thiadiazole (BTZ). Optoelectronic investigations revealed a charge transfer due to strong push–pull interactions. 2 D wide‐angle X‐ray scattering (WAXS) data indicated an arrangement in liquid‐crystalline columnar assemblies, in which the π‐stacking distances and molecular orientation depend on the number of HBC units in the molecules. 相似文献
8.
Dr. Max M. Martin Dr. Frank Hampel Prof. Dr. Norbert Jux 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(45):10210-10212
A synthetic route towards a novel hexabenzocoronene-based helical nanographene motif was developed. A hexaphenylbenzene precursor was therefore designed, which cannot undergo, due to steric restrictions, a complete planarization reaction. This precursor was transformed under oxidative cyclodehydrogenation conditions to a π-extended [5]helicene, which was fully characterized including X-ray diffraction analysis. 相似文献
9.
Carolin Dusold Benedikt Platzer Philipp Haines David Reger Prof. Dr. Norbert Jux Prof. Dr. Dirk. M. Guldi Prof. Dr. Andreas Hirsch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(5):1670-1679
Synthesis and characterization of a series of rylene-diimide substituted hexaphenylbenzenes (HPBs) is presented. The direct connection of the rylene-diimide units to the HPBs via the imide-N-position without any linkers as well as the use of naphthalene-diimides (NDIs) next to perylene-diimides (PDIs) is unprecedented. While mono-substituted products were obtained by imidization reactions with amino-HPB and the respective rylene-monoimides, key step for the formation of tri- and hexa-substituted HPBs is the Co-catalysed cyclotrimerization. Particular emphasis for physic-chemical characterization was on to the number of NDIs/PDIs per HPB and the overall substitution patterns. Lastly, Scholl oxidation conditions were applied to all HPB systems to generate the corresponding hexa-peri-hexabenzocoronenes (HBCs). Importantly, the efficiency of the transformation strongly depends on the number of NDIs/PDIs. While three rylene-diimide units already hinder the Scholl reaction, the successful synthesis of mono-substituted HBCs is possible. 相似文献
10.
Thomas B. J. Hall Bryce R. Hoggard Christopher B. Larsen Nigel T. Lucas 《化学:亚洲杂志》2019,14(8):1106-1110
Hexa‐peri‐hexabenzocoronenes with a bay‐fused five‐membered ring are synthesized from fluorenyl precursors. The key oxidative cyclodehydrogenation step is accompanied by regioselective chlorination that is enhanced by methylation at the cyclopenta‐ring or increased reaction concentration. The CpHBC products undergo mild electrophilic aromatic bromination, without catalyst, to afford adducts suitable for π‐extension by cross‐coupling. 相似文献