One-shot K-region-selective annulative π-extension for nanographene synthesis and functionalization.

Kyohei Ozaki,Mari Shibata,Hideto Ito,Kenichiro Itami,Katsuaki Kawasumi

doi:10.1038/ncomms7251

Kyohei Ozaki, Mari Shibata + Show 3 more

Open Access

https://doi.org/10.1038/ncomms7251

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Journal: Nature Communications	Publication Date: Feb 16, 2015
Citations: 168	License type: CC BY 4.0

Affiliation: Nagoya University

Abstract

The optoelectronic nature of two-dimensional sheets of sp2-hydridized carbons (for example, graphenes and nanographenes) can be dramatically altered and tuned by altering the degree of π-extension, shape, width and edge topology. Among various approaches to synthesize nanographenes with atom-by-atom precision, one-shot annulative π-extension (APEX) reactions of polycyclic aromatic hydrocarbons hold significant potential not only to achieve a ‘growth from template’ synthesis of nanographenes, but also to fine-tune the properties of nanographenes. Here we describe one-shot APEX reactions that occur at the K-region (convex armchair edge) of polycyclic aromatic hydrocarbons by the Pd(CH3CN)4(SbF6)2/o-chloranil catalytic system with silicon-bridged aromatics as π-extending agents. Density functional theory calculations suggest that the complete K-region selectivity stems from the olefinic (decreased aromatic) character of the K-region. The protocol is applicable to multiple APEX and sequential APEX reactions, to construct various nanographene structures in a rapid and programmable manner.

Highlights

The optoelectronic nature of two-dimensional sheets of sp2-hydridized carbons can be dramatically altered and tuned by altering the degree of p-extension, shape, width and edge topology
We have not yet investigated this possible mode of reaction extensively, we envisage that the present annulative p-extension (APEX) reaction could be applied to even larger molecules through judicious choice of solubilizing substituents on the substrates
The present APEX methodology is complementary to the stateof-the-art two-step nanographene synthetic methods, thereby finding significant use in the ‘growth from template’ nanographene synthesis and in the late-stage fine-tuning of nanographene properties

Summary

Introduction

The optoelectronic nature of two-dimensional sheets of sp2-hydridized carbons (for example, graphenes and nanographenes) can be dramatically altered and tuned by altering the degree of p-extension, shape, width and edge topology. We illustrate the significant potential of one-shot APEX reactions of template PAH molecules with p-extending agents (Fig. 1b) as an enabling concept that is complementary to the aforementioned two-step methodology.

Results

Conclusion