Heteroatom-Doped Nanographenes with Structural Precision

Abstract

ConspectusNanographenes, which are defined as nanoscale (1–100 nm) graphene cutouts, include quasi-one-dimensional graphene nanoribbons (GNRs) and quasi-zero-dimensional graphene quantum dots (GQDs). Polycyclic aromatic hydrocarbons (PAHs) larger than 1 nm can be viewed as GQDs with atomically precise molecular structures and can thus be termed nanographene molecules. As a result of quantum confinement, nanographenes are promising for next-generation semiconductor applications with finite band gaps, a significant advantage compared with gapless two-dimensional graphene. Similar to the atomic doping strategy in inorganic semiconductors, incorporation of heteroatoms into nanographenes is a viable way to tune their optical, electronic, catalytic, and magnetic properties. Such properties are highly dependent not only on the molecular size and edge structure but also on the heteroatom type, doping position, and concentration. Therefore, reliable synthetic methods are required to precisely control these structural features. In this regard, bottom-up organic synthesis provides an indispensable way to achieve structurally well-defined heteroatom-doped nanographenes.Polycyclic heteroaromatic compounds have attracted great attention of organic chemists for decades. Research in this direction has been further promoted by modern interest in supramolecular chemistry and organic electronics. The rise of graphene in the 21st century has endowed large polycyclic heteroaromatic compounds with a new role as model systems for heteroatom-doped graphene. Heteroatom-doped nanographene molecules are in their own right promising materials for photonic, optoelectronic, and spintronic applications because of the extended π conjugation. Despite the significant advances in polycyclic heteroaromatic compounds, heteroatom-doped nanographene molecules with sizes of over 1 nm and their relevant GNRs are still scarce.In this Account, we describe the synthesis and properties of large heteroatom-doped nanographenes, mainly summarizing relevant advances in our group in the past decade. We first present several examples of heteroatom doping based on the prototypical nanographene molecule, i.e., hexa-peri-hexabenzocoronene (HBC), including nitrogen-doped HBC analogues by formal replacement of benzene with other heterocycles (e.g., aromatic pyrimidine and pyrrole and antiaromatic pyrazine) and sulfur-doped nanographene molecules via thiophene annulation. We then introduce heteroatom-doped zigzag edges and a variety of zigzag-edged nanographene molecules incorporating nitrogen, boron, and oxygen atoms. We finally summarize heteroatom-doped GNRs based on the success in the molecular cases. We hope that this Account will further stimulate the synthesis and applications of heteroatom-doped nanographenes with a combined effort from different disciplines.

Diazaboryl‐naphthyl‐ketone: A New Scaffold with Bright Fluorescence, Aggregation‐Induced Emission, and Application in the Quantitation of Trace Boronic Acids in Drug Intermediates

“…Heteroatom doping is a popular strategy to modulate the electronic properties of graphene, nanographenes, and polyaromatic hydrocarbons (PAHs) [1] . One area of study, beginning with the pioneering work of Dewar and co‐workers in the 1960s, applies the B−N bond as a replacement for C=C bonds in aromatic structures [2–4] .…”

“…Heteroatom doping is ap opularstrategy to modulate the electronic properties of graphene, nanographenes,a nd polyaromatic hydrocarbons (PAHs). [1] One area of study,b eginning with the pioneering work of Dewar and co-workers in the 1960s, appliest he BÀNb ond as ar eplacement for C=Cb onds in aromatic structures. [2][3][4] Thought he two moieties are isoelectronic andi sosteric, BÀNr eplacement can significantly alter the photophysical, aromatic and electronic properties of the molecule, thereby enriching the chemical space of aromatics and diversifying their optoelectronic applications.…”

Pillar[6]arene acts as a biosensor for quantitative detection of a vitamin metabolite in crude biological samples

“…6). Upon addition of 1-MNA, the fluorescence intensity of both P5A and P6A dramatically decreased because of photoinduced electron transfer (PET) [27][28][29][30][31][32] . Even when an excess amount of nicotinamide (100 eq.)…”

Fjord-Edge Graphene Nanoribbons with Site-Specific Nitrogen Substitution

“…29,36,37 Crucially, site-specific doping at the GNR backbone produces a dramatic alteration of its electronics, making such structures the most desirable targets for synthesis. 31,38,39,40 Nitrogen doped GNRs are of particular interest as they produce p-doped materials. 23,36,37,41,42,43,44 Gratifyingly, creative ways to synthesize GNRs bearing novel edge or backbone structures are thriving to this day.…”