Compressed Corannulene in a Molecular Cage

Abstract

Self-assembled coordination cages can be employed as a molecular press, where the bowl-shaped guest corannulene (C20H10) is significantly flattened upon inclusion within the hydrophobic cavity. This is demonstrated by the pairwise inclusion of corannulene with naphthalene diimide as well as by the dimer inclusion of bromocorannulene inside the box-like host. The compressed corannulene structures are unambiguously revealed by single-crystal X-ray analysis.

Dimensional Matching versus Induced‐Fit Distortions: Binding Affinities of Planar and Curved Polyaromatic Hydrocarbons with a Tetragold Metallorectangle

“…The authors found that the encapsulated corannulene showed significant reduction of the energy barrier for the concave‐convex inversion, although the planarization of the bowl‐shaped guest was insignificant. One year later, Fujita and co‐workers described the significant flattening of corannulene upon inclusion within a trigonal prismatic metallosupramolecular assembly . The compression of corannulene was facilitated by the effective donor–acceptor interactions shown within the cavity of the cage when naphthalene diimide was used as a co‐guest within the structure.…”

“…The bowl‐depth (BD) of the encapsulated corannulene is 0.73 Å, therefore significantly reduced compared to the structure of free corannulene (BD=0.87 Å) . This compression is more significant than the one found by Siegel and co‐workers for the encapsulation of corannulene in ExBox 4+ , but much lower than the one described by Fujita for the encapsulation of this bowl‐shaped PAH in a trigonal prismatic metallocage with a co‐guest (BD=0.56 Å) . Noteworthy, the distance between the centroid of the central five‐membered ring of the guest and the plane formed by the pyrene unit of the host is 3.04 Å, which is significantly shorter than the sum of the van der Waals radii for sp 2 ‐hybridized carbon atoms (3.4–3.6 Å).…”

Flat corannulene: when a transition state becomes a stable molecule

“…42 Other interactions can also affect the corannulene bowl depth, such as p-p interactions. 43 Stacking of corannulene 1 with other, planar, aromatic systems shows bowl attening and decrease of the inversion barrier, as was conrmed experimentally with ExBox 4+ by Siegel, 44 and also with other molecular cages serving as hosts, [45][46][47] or as was calculated for graphene 48 and planar aromatic hydrocarbons. 49,50 This study stems from the fundamental question: is it possible to achieve a completely at, metal-free corannulene?…”

A ferrocene-templated Pd-bearing molecular reactor

“…[16][17][18][19] In recent years, an emerging field of application of 1,3,5-triphenylbenzene-type motifs has been the synthesis of symmetric molecular cages. [20][21][22][23][24][25][26][27][28] Such structures are characterized by the organized cavity. In fact, the synthesis of such symmetric molecular cages may be challenging; reported reaction yields vary between 15 and 80%.…”