Pentaindenocorannulene (C H , 1), a deep bowl polynuclear aromatic hydrocarbon, accepts 4 electrons, crystallizes in columnar bowl-in-bowl assemblies and forms a nested C @1 complex. Spectra, structures and computations are presented.

Pentaindenocorannulene (C50H20 , 1), a deep bowl polynuclear aromatic hydrocarbon, accepts 4 electrons, crystallizes in columnar bowl‐in‐bowl assemblies and forms a nested C60@12 complex. Spectra, structures and computations are presented.

Cascade reactions are valuable tools for building complex molecular architectures with high efficiency, selectivity, and atom economy. These processes have a proven record in the preparation of natural products and biologically relevant molecules.[1] In a similar manner, cascade transformations would greatly benefit the field of advanced materials science, where they offer opportunities for rapid and divergent synthetic elaboration, thereby expanding the chemical space for functional materials.Allenes are particularly interesting candidates for the development of cascade reactions, given the diversity and specificity of their reaction modes.[2] Our interest in alleno-acetylenic scaffolding prompted us to introduce allenes as building blocks in the construction of three-dimensional chiral carbon-rich structures. To be able to prepare stable alleno-acetylenic chromophores, the 1,3-di-tert-butyl-1,3-diethynylallene (DEA) moiety was developed.[3] The introduction of tert-butyl substituents provides steric hindrance to the allene core, reducing its reactivity considerably. Taking advantage of the kinetic stability of these alleno-acetylenic scaffolds, we were able to resolve their enantiomers, [4] and use them to build enantiopure chiral push-pull chromophores, [4,5] macrocycles, [6] and helical foldamers. [7] Here, we explore the potential of the allene core of DEAs to participate in cascade pericyclic reactions, which lead to highly substituted complex carbon skeletons in a one-pot fashion, with excellent chemo-, regio-, and stereoselectivities. [8] We first investigated the reaction between racemic DEA (AE)-1 and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) and 1,1,2,2-tetracyanoethene (TCNE), to give butadienes (AE)-2 a and (AE)-2 b, respectively, by a formal [2 + 2] cycloaddition, followed by cycloreversion (CA/CR).[9] While the reaction with TCNE proceeded cleanly at room temperature, [4] we noticed that when the reaction with TCNQ was carried out at 40 8C, a significant amount of a by-product was formed. Isolation and characterization of this compound showed that adduct (AE)-2 a undergoes a 4p electrocyclization (EC) between the allene core and the proximal dicyanovinyl moiety, to give cyclobutene 3 a (Scheme 1). In a similar way, butadiene (AE)-2 b could be transformed into cyclobutene 3 b, in which water was eliminated from the acetonide protecting group. The molecular structures of cyclobutenes 3 a and 3 b were unambiguously assigned by X-ray diffraction studies (Scheme 1; for details, see the Supporting Information).[10]The triple CA/CR/EC cascade also produced dicyanocyclobutenes 18 and 19 (see Scheme SI1 in the Supporting Information) in high yield (82-87 %) with the acetonide protecting group replaced by an iPr 3 Si substituent. We found that addition of 10 equivalents of trifluoroacetic acid (TFA) accelerates the reaction and increases the yields significantly. It can be inferred that TFA protonates the aniline nitrogen, quenching the intramolecular charge-transfer interaction, and in turn making the dic...

The modification of metal electrode surfaces with functional organic molecules is an important part of organic electronics. The interaction of the buckminsterfullerene fragment molecule pentaindenocorannulene with a Cu(100) surface is studied by scanning tunneling microscopy, dispersion‐enabled density functional theory, and force field calculations. Experimental and theoretical methods suggest that two adjacent indeno groups become oriented parallel to the surface upon adsorption under mild distortion of the molecular frame. The binding mechanism between molecule and surface is dominated by strong electrostatic interaction owing to Pauli repulsion. Two‐dimensional aggregation at room temperature leads to a single lattice structure in which all molecules are oriented unidirectionally. Their relative arrangement in the lattice suggests noncovalent intermolecular interaction through C−H⋅⋅⋅π bonding.

The growth of carbon layers, defective graphene, and graphene by deposition of polycyclic aromatic hydrocarbons (PAHs) on Cu(111) is studied by scanning tunneling microscopy and X‐ray photoelectron spectroscopy. Two different PAHs are used as starting materials: the buckybowl pentaindenocorannulene (PIC) which contains pentagonal rings and planar coronene (CR). For both precursors, with increasing sample temperature during deposition, porous carbon aggregates (350 °C), dense carbon layers (400–450 °C), disordered defective graphene (500 °C–550 °C), and extended graphene (≥600 °C) are obtained. No significant differences for defective graphene grown from PIC and CR are observed. C 1s X‐ray photoelectron spectra of PIC and CR derived samples grown at 350–550 °C exhibit a characteristic C−Cu low binding energy component. Preparation at ≥600 °C eliminates this C−Cu species and only C−C bonded carbon remains.