Emerging Bottom‐Up Strategies for the Synthesis of Graphene Nanoribbons and Related Structures

Abstract

The solution‐phase synthesis is one of the most promising strategies for the preparation of well‐defined graphene nanoribbons (GNRs) in large scale. To prepare high quality, defect‐free GNRs, cycloaromatization reactions need to be very efficient, proceed without side reaction and mild enough to accommodate the presence of various functional groups. In this Minireview, we present the latest synthetic approaches for the synthesis of GNRs and related structures, including alkyne benzannulation, photochemical cyclodehydrohalogenation, Mallory and Pd‐ and Ni‐catalyzed reactions.

Catalytic Dehydrogenative Cyclization of o‐Teraryls under pH‐Neutral and Oxidant‐Free Conditions

“…[1] In particular, the aromatization reaction involving o-teraryls has emerged as an increasingly important method in preparing polyaromatic hydrocarbons (PAHs), which often exhibit interesting optical and electronic properties. [2] While extensively employed, the Scholl oxidation typically requires excess strong acids (e.g., AlCl 3 , FeCl 3, MoCl 5 , TfOH) and/or strong oxidants (e.g., DDQ), which consequently results in many waste byproducts. In addition, many functional groups could not be tolerated, and side reactions, such as 1,2-aryl shift, over-oxidation, and substrate decomposition, are often observed under such conditions.…”

Degradation of Structurally Defined Graphene Nanoribbons by Myeloperoxidase and the Photo‐Fenton Reaction

“…In recent years, graphene and its derivatives have been widely studied in the fields of medicine and gene delivery, bioimaging, biodetection, immune‐modulation and cancer treatment . As an emerging member in the graphene family, structurally well‐defined graphene nanoribbons (GNRs) have attracted enormous attention due to their controllable structures including length, width and edges . GNRs have proven great potential in various applications such as photothermal therapy, super‐resolution imaging and semiconductor materials.…”

Synthesis of azahelicenes through Mallory reaction of imine precursors: corannulene substrates provide an exception to the rule in oxidative photocyclizations of diarylethenes

“…It is this practicality that allows for daunting synthetic targets to be prepared through Mallory reaction. This can be seen in Bunz's N-heteroarene, 10 Morin's graphene nano-ribbons, 11 Matsuda's [7]helicene, 12 Durola's double [7]helicene, 13 Fujita's [16]helicene, 14 Nuckolls hexabenzocoronenes, 15 Mallory's phenacenes, 16 Autschbach, Crassous, and Réau's metallahelicenes, 17 and corannurylene pentapetalae 18 syntheses employing the photochemical reaction as a key component in the construction of complex aromatic scaffolds. Despite this success, application of stilbene imines as precursors to prepare aza-based aromatic scaffolds is not feasible (Scheme 1).…”