Functionalized Corannulene Carbocations: A Structural Overview

Abstract

A detailed structural overview of a family of bowl-shaped polycyclic aromatic carbocations of the type [C20 H10 R](+) with different R functionalities tethered to the interior surface of corannulene (C20 H10 ) is provided. Changing the identity of the surface-bound groups through alkyl chains spanning from one to four carbon atoms and incorporating a different degree of halogenation has led to the fine tuning of the bowl structures and properties. The deformation of the corannulene core upon functionalization has been revealed based on X-ray crystallographic analysis and compared for the series of cations with R=CH3 , CH2 Cl, CHCl2 , CCl3 , CH2 CH3 , CH2 CH2 Cl, and CH2 CH2 Br. The resulting carbocations have been isolated with several metal-based counterions, varying in size and coordinating abilities ([AlCl4 ](-) , [AlBr4 ](-) , [(SnCl)(GaCl4 )2 ](-) , and [Al(OC(CF3 )3 )4 ](-) ). A variety of aggregation patterns in the solid state has been revealed based on different intermolecular interactions ranging from cation-anion to π-π stacking and to halogen⋅⋅⋅π interactions. For the [C20 H10 CH2 Cl](+) ion crystallized with several different counterions, the conformation of the R group attached to the central five-membered ring of corannulene moiety was found to depend on the solid-state environment defined by the identity of anions. Solution NMR and UV/Vis investigations have been used to complement the X-ray diffraction studies for this series of corannulene-based cations and to demonstrate their different association patterns with the solvent molecules.

Stack the Bowls: Tailoring the Electronic Structure of Corannulene‐Integrated Crystalline Materials

“…The unique curvature of π‐bowls (πBs) distinguishes them from more traditional flat polycyclic aromatic hydrocarbons (PAHs) and, in combination with an unusual electronic structure, results in a number of intriguing properties including, but not limited to, surface charge stabilization, high reversible lithium capacity, bowl‐to‐bowl inversion, a significant dipole moment, and high charge mobility . This combination of material properties can open a pathway for πB utilization in applications ranging from optoelectronic devices or electrodes to thermoresponsive materials …”

Stretching [8]cycloparaphenylene with encapsulated potassium cations: structural and theoretical insights into core perturbation upon four-fold reduction and complexation

“…This nding is in sharp contrast with open geodesic polyaromatic hydrocarbons such as bowl-shaped corannulene and sumanene, in which the corresponding anions show localization of negative charge on the convex surface. [69][70][71] Transformation of the electronic structure of [8]CPP core from benzenoid to a quinoidal one upon electron acquisition can be rationalized by considering the lowest unoccupied molecular orbitals (LUMOs) of the neutral parent (Fig. 8 3À , and analyzed their spin density distribution (Fig.…”

Stack the Bowls: Tailoring the Electronic Structure of Corannulene‐Integrated Crystalline Materials

“…The unique curvature of p-bowls (pBs) distinguishes them from more traditional flat polycyclic aromatic hydrocarbons (PAHs) and, in combination with an unusual electronic structure,results in anumber of intriguing properties including, but not limited to,s urface charge stabilization, high reversible lithium capacity,b owl-to-bowl inversion, as ignificant dipole moment, and high charge mobility. [1][2][3][4][5][6][7][8] This combination of material properties can open ap athway for pBu tilization in applications ranging from optoelectronic devices or electrodes to thermoresponsive materials. [4,9,10] Herein, we demonstrated, for the first time,h ow pB integration (in particular,c orannulene [pB-C 20 H 10 ]) inside insulating porous scaffolds could tune electronic properties resulting in circa 10 000-fold conductivity enhancement.…”