Negatively Curved Warped Nanographene Self-Assembled on Metal Surfaces

Abstract

We report the investigation of a conjugated polycyclic hydrocarbon containing multiple nonbenzenoid rings and exhibiting negative curvature-the warped nanographene C 80 H 30-adsorbed on several noble metal surfaces in an ultrahigh vacuum environment. From a detailed analysis of the molecular self-assembly at different molecular coverages via scanning tunneling microscopy and spectroscopy measurements in combination with theoretical modeling, the nature of the intermolecular interactions is unraveled. For high molecular coverages on Cu(111), the formation of homochiral porous networks is observed, which is rationalized by (i) intermolecular π-π interactions between neighboring C 80 H 30 molecules that promotes the formation of molecular dimers, and (ii) enantioselective intermolecular CH•••π interactions between the dimers. Such interactions are also observed after deposition of C 80 H 30 molecules on Au(111) and Ag(111) substrates. Our results provide perspectives for the on-surface study of negatively-curved nanographenes which give prospects for the design of novel and functional chiral structures with potential use in the field of organic optoelectronics.

Synthetic Applications of Oxidative Aromatic Coupling—From Biphenols to Nanographenes

“…Indeed, in contrast to earlier assumptions, the Scholl reaction is capable of proceeding even if ring closure is accompanied by the introduction of significant steric strain that leads to nonplanar molecules . Progress has been particularly impressive in the case of surface‐assisted dehydrogenation, which has enabled the synthesis of nanographenes of unprecedented size by scanning tunneling microscopy …”

Flat corannulene: when a transition state becomes a stable molecule

“…Here we report that a sufficiently strong substituent steric effect stabilizes the at geometry to such an extent that this highly unstable geometry, which has been considered so far only in the context of a potential transition state, becomes a minimum on the potential energy surface for decakis(t-butylsuldo)-corannulene (8). Interestingly, this corannulene derivative is unique because it has two different possible stable structuresone with a at core and one with a bowl structure.…”

“…[2][3][4] Combinations of multiple substitutions create more complex architectures, 5 such as Scott's warped nanographenes. [6][7][8] One of the simplest examples of a bowl-shaped structure created by the introduction of a pentagonal ring is the corannulene molecule [9][10][11][12][13] (1) which represents a sub-structure of many threedimensional graphene objects, such as the fullerenes and carbon nanotubes. Considering the great scientic and practical signicance of the curved graphene structures and other materials with 5-fold symmetry, the ability to understand and control the extent of their curvature is of fundamental importance for any architectural design of such molecules.…”

Syntheseanwendungen der oxidativen aromatischen Kupplung – von Biphenolen zu Nanographenen

“…Entgegen früheren Annahmen ist die Scholl‐Reaktion in der Tat in der Lage, auch dann stattzufinden, wenn der Ringschluss, der zu nicht‐planaren Molekülen führt, mit der Einführung einer signifikanten sterischen Hinderung einhergeht . Die Entwicklung war besonders beeindruckend bei der oberflächenunterstützten Dehydrierung, die die Synthese von Nanographenen beispielloser Größe in Rastertunnelmikroskopen ermöglicht hat …”