Dibenzo corannulene

Corannulene, C2oH10, dibenzo y/ /, mno] fluoranthene, shown in Fig. 1(a), is a bowl-shaped PAH with 5-fold symmetry [6], and has a one-third skeleton of C60 (see Figs 1(c) and (d)). Recently, convenient synthesis for corannulene [7,8] has been developed. On the other hand, coronene, C24H12, hexabenzobenzene, shown in Fig. 1(b), has a flat structure with a 6-fold symmetry axis. 

The X-ray crystallographic analysis of 9 provided experimental structural data of the new corannulene-type aromatic system. The bond alternation found in 9 closely follows the pattern found in an X-ray crystal structure of tetramethyl fused corannulene [38c]. Such agreement of the bond alternation patterns indicates that the fullerene framework and the dibenzo conjugation added to the parent corannulene structure have a small structural effect in spite of the rather large difference in hybridization of the carbon atoms between 9 p-orbital axis vector (POAV) angles [40] = 8.0-12.8° and C (POAV = 0.0-11.0°). 

Absorption and Emission of [10]Cyclophenacenes and Dibenzo Fused Corannulenes... 

Synthesis of the p-phenylene-bridged dibenzo-fused corannulene C60Me5Ph3H2 (10) To a solution of 4 (40 mg, 38 pmol) in PhCN (10 mL) in a Schlenk tube was added a solution of lithium naphthalenide (1.5 mL, 0.76 M in THF, 1.1 mmol) under an argon atmosphere. The color of the solution changed immediately from yellow to... 

Dibenzo[a, ]corannulene (116), a fullerene fragment, was obtained by cycliza-tion of 7,10-di(2-bromophenyl)fluoranthene (115). A Herrmann palladacycle (XVIII-1) as a catalyst and excess DBU as a base were used under rather severe conditions (150" C, 72 h) [32], Also the as -indaceneo[3.2.1.8.7.6-pqrstuv]picene derivative 118 was prepared from the dichloride 117 in 91% yield. PCyg and DBU were used for activation of the less reactive dichloride 117 [33]. 

Dibenzo[a,g]corannulene (88) was prepared from fluoranthene 9 under FVP conditions at 1,000 °C (Scheme 25) [117]. Compotmd 88 was also accessed from the same material by Pd-catalyzed intramolecular arylations [16], In that report, Scott and coworkers tested various palladium catalysts, bases, and reaction conditions, and the best result (57% yield) was obtained under conditions employing the combination of palladacycle/DBU/DMF at 150 °C. A synthetic method has been reported to prepare 7,10-disubstimted fluoranthenes, including 9, in good to excellent yields by Rh-catalyzed [(2+2)+2] cycloadditions of l,8-di(ethynyl) naphthalenes 87 with NBD [118]. 

Similar to dibenzo[a,g]corannulene (88), l,2-dihydrocyclopenta[, c]dibenzo-[g,m]corannulene (90) [119] and iV-octyldibenzo[ /,/M]-l,2-corannulimide (91) [120] were synthesized by Pd-catalyzed cyclization (Scheme 26). The OFET devices of 91 show interesting electron and hole motihties, and may have potential applications in organic electronic devices. Dibenz[f,Z]acecorannulene (93) [121] can be directly prepared from 92 under FVP conditions. 

Benzo[g]acecorannulene (96) is an tmexpected product generated from 95. According to the successful synthesis of dibenzo[a,g]corannulene (88) from 7,10-bis(2-bromophenyl)fluoranthene (9), an attempt was made to prepare aza-bowl 94 from 95. However, this protocol gave 96 as the only identifiable product (Scheme 27) [122]. 

On the basis of crystallographic analysis, the corannulene cores in dibenzo[u,g]-corannulene (88) and A-octyldibenzo[ Z,m]-l,2-corannulimide (91) are shallow with a bowl depth of 0.83 and 0.65 A, respectively [120, 123]. The cyclopenta-annulated buckybowl 90 is much deeper, and its bowl depth was determined as 1.03 A. The maximum POAV pyramidalization angle of 90 was found to be 10.7°, which is very close to that of acecorannulene (69) [119]. However, the bowl inversion barrier for 90 was experimentally estimated as 23.5-23.6 kcal/mol, which is much smaller than that of acecorannulene (69, 27.6 kcal/mol). 

Dibenzo[a,g]corannulene (88) and fullerenes Cso and C70 form cocrystals [88-C6o] and [(88)2-C7o], respectively [123]. The bowl depth of the corannulene moiety in dibenzocorannulene are slightly deceased upon co-crystallization, and the... 

Rim-benzoannulated corannulenes have been of interest since they represent an obvious extension of the fullerene surface and could potentially serve as precursors for larger bowl syntheses. Several of these derivatives including benzocorannulene 23 [26], dibenzo[a,d]corannulene 24 [26a], dibenzo[a,g]corannulene 25 [16, 27] and tribenzo[a,d,j]corannulene 26 [26] were recently synthesized by FVP and/or non-pyrolytic methods. X-ray crystal structure determination of 25 was very recently achieved [28] on a crystal grown by sublimation and revealed an assembling of... 

The PAHs indenocorannulene (39), dibenzo[a,g]corannulene (40), and diben-zo[o,g]cyclopenta[h,I]corannulene (41) are three examples of extended corannulenes, which contain a central corannulene system fused to five- and six-membered rings. The reduction of these systems [119, 120] focused on the following issues. First, what is the aromaticity of these curved PAHs anions, will they behave like large polycyclic systems, or have aimulenic character Secondly, what is the possibility of aggregation and dimerization in these systems The third subject of interest was the effect of different alkali metals on the reduction process. 

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