Coronene derivatives

Therefore, photoreactions via pentahelicenic intermediates may lead to undesired products. In the synthesis of a 3,15-disubstituted heptahelicene (20) starting from a (3 + 1 + 1) derivative (19) the coronene derivative (21) was formed as a side product20). 

The data obtained from the ECD and reduction potentials can be used to interpret PES data. Three examples for molecules are the lower values for the electron affinities of nitromethane, anthracene, and coronene. Based on the observation of excited states in anthracene and tetracene in the ECD data, it is reasonable to assume that the lower value for coronene derives from the population of an excited state. In Figure 6.8 the PES of coronene is shown with two sets of peaks. If the ground-state Ea for coronene is taken from the initial onset, it is much lower than the value obtained from reduction potential or electronegativity data. In addition, the second onset must be explained [38—42]. 

FIGURE 8.11 Polyaromatic coronene derivatives found or suspected to be in fuels hydrocracker bottoms streams. 

AIE luminescence from aggregates of a tetraphenylethene (TPE)-incorp-orated polymer (39 ) or a coronene derivative (40 ) shows drastic quenching in the presence of picric acid due, respectively, to energy or electron transfer from the excited AIE luminophores to picric acid (Scheme 11). 

As both symmetrical and unsymmetrical stilbenes can be readily synthesized by employing Wittig [126], Heck [127], or McMurry [128] reactions, various graphene-type molecules have been prepared via photolytic cyclodehydrogenation, some of which will be discussed at this point A typical example of photocyclization is the irradiation of the [2.2.2]paracydo-phane 96 in the presence of an oxidant, such as iodine, leading to the corresponding coronene derivatives 97 in high yield. This offers a versatile method for the preparation of new coronene derivatives with different functionality and substitutional symmetry (Scheme 13.26) [129]. 

Scheme 13.26 Photoqfclization of [2.2.2]paraqfclophanes 96 in the synthesis of coronene derivatives 97.

Figure 43 Liquid crystalline coronene derivative and perylene diimide used to produce self-organized donor/acceptor architectures for organic solar cells. °...

A Short and Efficient Synthesis of Coronene Derivatives via Ruthenium-Catalyzed Benzannulation... 

Shen, H.-Ch., Tang, J.-M., Chang, H.-K., Yang, C.W. and Liu, R.S. (2005) Short and efficient synthesis of coronene derivatives via ruthenium-catalyzed benzannulation protocol. Journal of Organic Chemistry, 70(24), 10113-10116. 

Scheme 4.36 [202], Some of these coronene derivatives, e.g., having dodecyl and 3,7-dimethyloctyl peripheral chains, exhibit mesomorphic behavior, just like the precursor HBCs from which they were derived. These materials also exhibit high charge carrier mobilities. It is extremely intriguing that on the one hand, HBC exists in the atmosphere of stars, threby indicating its remarkable stability, but on the other hand, it undergoes facile catalytic hydrogenation, despite being an all-benzenoid polycyclic hydrocarbon.

Several interesting features emerge from a study of Appendix, p. 205 The most efficient compound yet synthesized is the benzoperylene hydrazide (1) 0ql being 0.07. About 50% of the hydrazide molecules must lead to excited states on oxidation since the fluorescence quantum yield of benzoperylene dicarboxylic acid dianion is only 0.14 [14]. Interestingly the still more highly condensed coronene derivative (2) was only found to exhibit a 0ql of 0.043 [15]. 

Although the benzoperylene and the coronene derivatives (1) and (2), respectively, easily surpass luminol in chemiluminescence efficiency, suggesting an advantage of higher condensed aromatic systems, no anthracene or phenan-threne derivative has been found which even reaches the 0cl of the best naphthalene derivatives, e.g. (4). 

The synthetically most valuable intermediate in heterofullerene chemistry so far has been the aza[60]fulleronium ion C59N (28). It can be generated in situ by the thermally induced homolytic cleavage of 2 and subsequent oxidation, for example, with O2 or chloranil [20-24]. The reaction intermediate 28 can subsequently be trapped with various nucleophiles such as electron-rich aromatics, enolizable carbonyl compounds, alkenes and alcohols to form functionalized heterofullerenes 29 (Scheme 12.8). Treatment of 2 with electron-rich aromatics as nucleophilic reagent NuH in the presence of air and excess of p-TsOH leads to arylated aza[60]fullerene derivatives 30 in yields up to 90% (Scheme 12.9). A large variety of arylated derivatives 30 have been synthesized, including those containing cor-annulene, coronene and pyrene addends [20, 22-25]. 

Fig. 231. Coronene. (a) Form of the molecule. (6) hOl section of the weighted reciprocal lattice (areas of spots proportional to structure amplitudes), (c) Derivation of foreshortening of tilted molecule from peaks in reciprocal space. Alt A9, etc., are the positions of the benzene peaks derived from (b) perpendiculars to the A vectors are drawn at Blt B%, etc., at distances from the origin equal to reciprocals of A vectors these lines give the projected shape of the benzene ring.

Figure 4. Plot of the average supercritical CC>2 extraction recoveries vs. GLC derived retention indexes for anthracene, pyrene, perylene, benzo[ghi]perylene, and coronene using a extraction cell of two different cell geometries (1 1 and 1 8) completely filled and the 1 8 dimensions cell with ca. 70% dead volume.

In this article, we report solution ESR spectra of coronene monoanion, to compare with that of corannulene monoanion. Moreover, we present ab initio molecular orbital (MO) calculation on the JT potentials of monoanionic state of corannulene and coronene, and consider the temperature dependence of the ESR spectra based on these results. Furthermore, the analytical JT potential surfaces of corannulene monoanion and coronene monoanion are derived using group theory. 

Since the ab initio calculation on coronene monoanion indicates that the stable configuration has C2h symmetry, we must take higher-order anharmonic terms up to sixth order into consideration which is not considered in the derivation of the epikernel principle to obtain a JT surface with the adequate structure. We will discuss this point later. 

In this section, we will derive the analytical JT potential for corannulene and coronene monoanion using group theory to elucidate roles of anharmonic vibration and nonlinear vibronic coupling. 

On the other hand, Margrave et al. reported that the condensed polynuclear aromatic compounds such as anthracene, pyrene and coronene, were easily fluorinated even at ambient temperature and that the various perfluoro-derivatives were obtained depending upon the starting materials [9-12]. In their method, fluorine gas was introduced into the reactor at a slow rate such that the initial concentration of the fluorine was a mere trace and the concentration of fluorine was then gradually increased up to 100%. Such fiuorination condition was quite different from that of the graphite in spite of the common feature of the existence of the graphite-like layers and 7r-bond. 

Fig. 8. A semi-logarithmic plot of the /e decay time of the conductivity, T, versus the calculated disk diameter, Z), for hexa-alkyl derivatives of hexa-Z W-hexabenzo-coronene (filled circles) and octa-alkoxy derivatives of phthalocyanine (open squares). The straight line drawn through the points corresponds to an exponential dependence of on D. [Reprinted WPh permission from Ref. 98. Copyright 2005 American Chemical Society.]...

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