Initiating Electron Transfer in Doubly Curved Nanographene Upon Supramolecular Complexation of C₆₀

Abstract

The formation of supramolecular complexes between C 60 and am olecular nanographene endowed with both positive and negative curvatures is described. The presence of ac orannulene moiety and the saddle shape of the molecular nanographene allows the formation of complexes with 1:1, 1:2, and 2:1stoichiometries.The association constants for the three possible supramolecular complexes were determined by 1 HNMR titration. Furthermore,t he stability of the three complexes was calculated by theoretical methods that also predict the photoinduced electron transfer from the curved nanographene to the electron acceptor C 60 .T ime-resolved transient absorption measurements on the ns-time scale showed that the addition of C 60 to NG-1 solutions and photo-exciting them at 460 nm leads to the solvent-dependent formation of new species,i np articular the formation of the one-electron reduced form of C 60 in benzonitrile was observed.

Stepwise reduction of a corannulene-based helical molecular nanographene with Na metal

“…The large internal cavity defined by the molecular curvature of the doubly-charged anions 1 2− is similar to previously reported, where two less rigid nanographene units were used to entrap a C 60 molecule. 17,20…”

“…The large internal cavity defined by the molecular curvature of the doubly-charged anions 1 2À is similar to previously reported, where two less rigid nanographene units were used to entrap a C 60 molecule. 17,20 In the solid-state structure of 2, the {Na + (18-crown-6)(THF)} 2 dications are wrapped by two 1 2À anions (C-HÁ Á Áp interactions: 2.417(3)-2.743(3) Å) (green lines in Fig. S11, see ESI †).…”

Nitrogen-doped molecular bowls as electron donors in photoinduced electron transfer reactions

“…Three types of excited states were identified: (1) locally excited (LE) states, in which the excitation is mostly localized either on the guest (LE 1 ) or on the host molecule (LE 2 ) and charge transfer is less than 0.1 e (CT < 0.1 e ); (2) charge transfer (CT) states showing a significant charge separation (CT > 0.8 e ); and (3) mixed states, where both LE and CT states contribute substantially (0.1 e < CT < 0.8 e ). 14,56…”

“…A well-proven COSMO-like model 14,[57][58][59] with dichloromethane (DCM) as a solvent was applied to estimate the effect of the polar environment on electronic excitations. The GS dipole moment of the studied complexes is in the range of 0.2 to 1.9 D. The small dipole moments can be explained by the high symmetry of the units (bowls and fullerene) and their mutual arrangement.…”

“…7 In the early 1990s the development of the ash vacuum pyrolysis (FVP) method enabled materials scientists to evaluate these compounds. [8][9][10][11] This attention to bowl-shaped molecules arises not only from aesthetic pleasure of curved p-conjugated systems, but also from the fact that they contribute to fundamental research of aromaticity, 12 complexation with molecules and metal ions, 13,14 and strain energy. 1,15,16 It is known that the introduction of heteroatoms into a carbon p-conjugated system can dramatically affect its properties.…”