Pentakis corannulenes

Very recently, l,3,5,7,9-pentakis(Bpin)corannulene (47) was successfully prepared in Scott s laboratory (Scheme 12) [82]. In the presence of catalytic amotmts of [Ir(OMe)COD]2 and 4,4 -dimethylbipyridyl, the reaction of corannulene with bis... 

Nanographene 171 was prepared by cyclodehydrogenation of 1,3,5,7,9-pentakis (2-biphenylyl)corannulene 50, which was synthesized by a Suzuki coupling of the resulting l,3,5,7,9-pentakis(Bpin)corannulene (47) with 2-bromobiphenyl (Scheme 55) [181]. Based on X-ray crystallography, 171 adopts a warped stmcture, and the central corannulene moiety is very shallow with a bowl depth of 0.37 A. The presence of five helical hexa[7]circulene moieties causes 171 to be chiral. Theoretical analysis indicated that activation energies for the inversion and the racemization are 1.7 and 18.9 kcal/mol, respectively. 

In contrast to the packing types described above, several compounds, such as pentakis(phenylthio)corannulene 48 (XR=SPh) (Siegel et ak, unpublished results), pentaarylcorannulenes 50 (R=manisyl, 2,6-C6H3Cl2) [70,180], decaarylcoraimulene 57 (R=4-C6H4C1) [74], and decakis(phenylthio)corannulene 58a [75], have bulky substituents at rim positions, which avoid the intermolecular interaction between any two corannulyl cores. Equally notable is that, unlike tetrakis(arylethynyl) corannulenes 41 and pentakis(arylethynyl)corannulenes 49 [39], decakis... 

The synthesis of a plethora of sym-pentakis substituted corannulenes was recently published by Siegel et al. [37]. The authors introduced various substituents, including sp (37), sp (38) and sp hybridized carbon atoms (39) directly connected to 1 as well as some -SR (40) and -OR (41) derivatives [37]. The UV/vis absorption and emission properties of the derivatives were also studied, as well as the inversion barriers of some of the derivatives vide infra). The Stokes shifts were found to be in the range of 130 nm in all derivatives investigated [37]. 

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