Corannulene

Chemical functionalization of various hydrocarbons, such as coronene, corannulene, and so forth, shows good promise in electronics applications because of their tunable optoelectronic properties. By using quantum chemical calculations, we have investigated the changes in the corannulene buckybowl structure, which greatly affect its electronic and optical properties when functionalized with different electron-withdrawing imide groups. We find that the chemical nature and position of functional groups strongly regulate the stacking geometry, π-stacking interactions, and electronic structure. Herein, a range of optoelectronic properties and structure–property relationships of various imide-functionalized corannulenes are explored and rationalized in detail. In terms of carrier mobility, we find that the functionalization strongly affects the reorganization energy of corannulene, while the enhanced stacking improves hopping integrals, favoring the carrier mobility of crystals of pentafluorophenylcorannulene-5-monoimide. The study shows a host of emerging optoelectronic properties and enhancements in the charge-transport characteristics of functionalized corannulene, which may find possible semiconductor and electronics applications.

High-level heats of formation for C 60 are obtained through the use of reactions in which C 60 is broken down into its fundamental bowl-shaped aromatic fragments (corannulene and sumanene). The reaction enthalpies are obtained by means of the high-level G4(MP2) thermochemical protocol and reliable experimental (from the Active Thermochemical Tables, ATcT) or theoretical (from W1h theory) heats of formation are used for the molecules involved in these reactions. Our best theoretical estimate, ∆ f Hº 298 [C 60 (g)] = 2511.7 kJ mol-1 , suggests that the experimental value adopted by the NIST thermochemical database (∆ f Hº 298 [C 60 (g)] = 2560 ± 100 kJ mol-1) should be revised downwards.

Using accurate quantum chemical calculations, we show that extended planar polycyclic aromatic hydrocarbons (PAHs) can efficiently catalyze a range of chemical processes involving non-planar aromatic systems. These include (i) bowl-to-bowl inversion of curved PAHs (e.g. corannulene and sumanene), (ii) 'flip-flop' inversion of helicenes (e.g. benzo[c]phenanthrene), and (iii) rotation about the Ph-Ph bond in biphenyls. Non-covalent π-π interactions between the planar catalyst and the substrate stabilize the planar transition structures to a greater extent than they stabilize the non-planar reactants. These result in surprisingly large catalytic enhancements (namely, the reaction barrier heights are reduced by 21-63% of the uncatalyzed reaction barriers). Keywords: polycyclic aromatic hydrocarbons (PAH) • bowl-to-bowl inversion • corannulene • graphene-like structures • π-π interactions • non-covalent catalysis • double-hybrid DFT Cits as: A. Karton, Chem. Phys. Lett. 614, 156-161 (2014).