190-24-9Relevant academic research and scientific papers
Synthesis and crystal packing of large polycyclic aromatic hydrocarbons: Hexabenzo[bc,ef,hi,kl,no,qr]coronene and dibenzo[fg,ij]phenanthro[9,10,1,2,3- pqrst]pentaphene
Kuebel, Christian,Eckhardt, Karin,Enkelmann, Volker,Wegner, Gerhard,Muellen, Klaus
, p. 879 - 886 (2000)
A detailed study of the oxidative cyclodehydrogenation of two oligophenylene precursors resulting in large polycyclic aromatic hydrocarbons (PAHs) which contain up to 42 carbon atoms gave insight into the reaction course. This study confirmed that the reaction occurs exclusively in an intramolecular fashion without the formation of organic side products. X-Ray diffraction, selected area electron diffraction, and low-dose high-resolution electron microscopy were used to analyse the effect of heat treatment and sublimation on the morphology and crystal structure of large PAHs, hexabenzo[bc,ef,hi,kl,no,qr]coronene (HBC) and dibenzo[fg,ij]phenanthro[9,10,1,2,3-pqrst]pentaphene (DBPP). HBC crystallizes in the γ-motif, as has been determined from single crystals previously. The experiments showed that small crystals exhibit some characteristic distortions of the unit cell. DBPP also crystallizes also in the γ-motif, but due to the 'double-bay area' in the periphery of the molecule channels with a diameter of about 4 A are formed in the crystal.
Bottom-up fabrication of photoluminescent graphene quantum dots with uniform morphology
Liu, Ruili,Wu, Dongqing,Feng, Xinliang,Muellen, Klaus
, p. 15221 - 15223 (2011)
Multicolor photoluminescent graphene quantum dots (GQDs) with a uniform size of ～60 nm diameter and 2-3 nm thickness were prepared by using unsubstituted hexa-peri-hexabenzocoronene as the carbon source. This result offers a new strategy to fabricate monodispersed GQDs with well-defined morphology.
A slippery slope: Mechanistic analysis of the intramolecular scholl reaction of hexaphenylbenzene
Rempala, Pawel,Kroulik, Jiri,King, Benjamin T.
, p. 15002 - 15003 (2004)
DFT calculations support an arenium cation-based mechanism for the Scholl reaction converting hexaphenylbenzene to hexa-peri-benzocoronene. The curve connecting fully benzenoid intermediates on the potential energy diagram is convex. This "slippery slope" provides an explanation for the ease of this cascade Scholl reaction. The calculated reaction coordinate predicts that intermediates will not accumulate; this prediction is verified by experiment. Copyright
Investigation of the mechanism of the intramolecular Scholl reaction of contiguous phenylbenzenes
Rempala, Pawel,Kroulik, Jiri,King, Benjamin T.
, p. 5067 - 5081 (2006)
Two mechanisms of the Scholl reaction were investigated in the series 1, 2, ..., n-oligophenylbenzenes (n = 2, 3, 4, 6) at the B3LYP/6-31G(d) level of theory. A mechanism involving generation of a radical cation followed by C-C bond formation and dehydrogenation is unlikely on the basis of unfavorable energies of activation. A mechanism involving generation of an arenium cation followed by C-C bond formation and dehydrogenation is energetically feasible. An explanation for the facile polycondensation of hexaphenylbenzene to hexa-peri-hexabenzocoronene, where six new aryl-aryl bonds are formed, is provided. Kinetic simulations based on the calculated activation energies of the arenium cation mechanism predict that intermediates will not accumulate; this is supported by mass balance experiments. Reaction optimization studies suggest that PhI(O2CCF3)2/BF3OEt2 or MoCl5 are superior to FeCl3 or AlCl 3/CuCl2.
Preparation method for constructing hexabenzocoronene by utilizing polycyclic aromatic hydrocarbon phenanthrene in coal tar
-
Paragraph 7-14, (2020/04/29)
The invention discloses a preparation method for constructing hexabenzocoronene by utilizing polycyclic aromatic hydrocarbon phenanthrene in coal tar. According to the method, polycyclic aromatic hydrocarbon phenanthrene in coal tar is used as a raw material and is subjected to an oxidation addition reaction with chromium trioxide to generate phenanthrenequinone, phenanthrenequinone and dibenzyl ketone are subjected to a nucleophilic addition elimination reaction in a potassium hydroxide methanol solution to generate 9, 10-phenanthro 1, 12-diphenyl cyclopentadiene ketone, 9, 10-phenanthro 1, 12-diphenyl cyclopentadiene ketone and diphenyl acetylene are subjected to a Diels-Alder cycloaddition reaction in a diphenyl ether solution to obtain 1, 2, 3, 4-tetraphenyl triphenylene, and finally,1, 2, 3, 4-tetraphenyl triphenylene and anhydrous ferric chloride are subjected to an oxidative cyclization dehydrogenation reaction to generate hexabenzocoronene. According to the invention, hexabenzocoronene is prepared by taking polycyclic aromatic hydrocarbon substance-phenanthrene in coal tar as a raw material. By reasonably planning the synthesis route, the yield of each step is increased, and the yield of hexabenzocoronene is increased. The method can be popularized and applied to the process of synthesizing graphene from other polycyclic aromatic hydrocarbons in the coal tar, so that high-added-value utilization of coal tar resources is improved.
Efficient Oxidative Coupling of Arenes via Electrochemical Regeneration of 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) under Mild Reaction Conditions
R?se, Philipp,Emge, Steffen,K?nig, Christoph Alexander,Hilt, Gerhard
, p. 1359 - 1372 (2017/04/18)
The intramolecular dehydrogenative carbon-carbon bond formation of aromatic rings in the presence of catalytic amounts of an oxidising agent is herein described. The oxidative coupling is realised under indirect anodic conditions, utilising 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an efficient redox mediator under acidic conditions. In comparison, for the stoichiometric oxidative coupling reaction of hexakis(4-tert-butylphenyl)benzene on a 1.0 gram scale, 1.56 g of DDQ were applied, whereas in the present indirect electrochemical version, only 15 mg of DDQ were needed, resulting in significantly easier purifications of the products. The reaction proceeds smoothly using a variety of polyaromatics including terphenyl, quaterphenyl and heptaphenyl derivatives to give polyphenylenes in excellent yields and current efficiencies. A detailed optimisation study, investigations on the electrochemical behaviour of the redox mediator and synthetic applications of the method are discussed. (Figure presented.).
Well-Defined Thiolated Nanographene as Hole-Transporting Material for Efficient and Stable Perovskite Solar Cells
Cao, Jing,Liu, Yu-Min,Jing, Xiaojing,Yin, Jun,Li, Jing,Xu, Bin,Tan, Yuan-Zhi,Zheng, Nanfeng
supporting information, p. 10914 - 10917 (2015/09/15)
Perovskite solar cells (PSCs) have been demonstrated as one of the most promising candidates for solar energy harvesting. Here, for the first time, a functionalized nanographene (perthiolated trisulfur-annulated hexa-peri-hexabenzocoronene, TSHBC) is employed as the hole transporting material (HTM) in PSCs to achieve efficient charge extraction from perovskite, yielding the best efficiency of 12.8% in pristine form. The efficiency is readily improved up to 14.0% by doping with graphene sheets into TSHBC to enhance the charge transfer. By the HOMO-LUMO level engineering of TSHBC homologues, we demonstrate that the HOMO levels are critical for the performance of PSCs. Moreover, beneficial from the hydrophobic nature of TSHBC, the devices show the improved stability under AM 1.5 illumination in the humidity about 45% without encapsulation. These findings open the opportunities for efficient HTMs based on the functionalized nanographenes utilizing the strong interactions of their functional groups with perovskite.
Hexa-peri-hexabenzocoronenes by efficient oxidative cyclodehydrogenation: The role of the oligophenylene precursors
Feng, Xinliang,Wu, Jishan,Enkelmann, Volk,Muellen, Klaus
, p. 1145 - 1148 (2007/10/03)
Oligophenylene precursors based on 1,3,5-tris-(2′-biphenyl)ylbenzene (4a) and 1,4-bis-(2′-biphenyl)yl-2,5-diphenylbenzene (5a) were prepared and utilized for efficient hexabenzocoronene (HBC) synthesis by cyclodehydrogenations. Parent HBC 6a was efficiently synthesized from the 1,3,5-tris-(2′-biphenyl)ylbenzene precursor, and novel D3h symmetrical HBCs were prepared from 1,3,5-tris-(2′-biphenyl)ylbenzenes with various substitution types. For the preparation of a tert-butyl containing HBC 7 with D2h symmetry, a two-step cyclodehydrogenation was required because of changes in the spin density distribution.
HEXA-PERI-BENZOCORONENE, A CANDIDATE FOR THE ORIGIN OF THE DIFFUSE INTERSTELLAR VISIBLE ABSORPTION BANDS ?
Hendel, W.,Khan, Z. H.,Schmidt, W.
, p. 1127 - 1134 (2007/10/02)
Large polycyclic aromatic hydrocarbons (PAH's) have recently been suggested to be abundant in the interstellar medium surrounding carbon rich stars.To aid in the identification of the species responsible for the astronomical UV and IR data, a new synthesis is reported for hexa-peri-benzocoronene and its dimethyl derivative.The UV, fluorescence, phosphorescence, photoelectron and IR spectra of this extremely stable hydrocarbon are presented and compared with the available astronomical spectra.Experiments useful to check the PAH hypothesis are suggested.
