Boron–Nitrogen‐Doped Nanographenes: A Synthetic Tale from Borazine Precursors

Abstract

In this work, ac omprehensive account of the authors' synthetic efforts to prepareb orazino-doped hexabenzocoronenes by using the Friedel-Crafts-type electrophilic aromatic substitution is reported. Hexafluoro-functionalized aryl borazines, bearing an ortho fluoride leaving group on each of the N-and B-aryl rings,w as shown to lead to cascade-type electrophilica romatic substitution events in the stepwise CÀCbond formation, giving higher yields of borazinocoronenes than those obtained with borazine precursors bearing fluoride leavingg roups at the ortho positions of the B-aryl substituents. By using this pathway,a nu nprecedented boroxadizine-doped PAHf eaturing ag ulf-type periphery could be isolated,a nd itss tructure proven by single-crystal X-ray diffraction analysis. Mechanistic studies on the stepwise Friedel-Crafts-type cyclization suggestt hat the mechanism of the planarizationr eactionp roceeds through extension of the p system. To appraise the doping effect of the boroxadizine unit on the optoelectronic properties of topology-equivalent molecular graphenes, the all-carbon and pyrylium PAHa nalogues, all featuring ag ulf-type periphery, were also prepared. As already shown for the borazinodoped hexabenzocoronene, the replacement of the central benzene ring by its B 3 N 2 Oc ongener widens the HOMO-LUMO gap and dramaticallye nhances the fluorescence quantum yield.[a] J. Scheme1.Synthetic planarizationp rotocols for preparing borazino-doped hexabenzocoronenes 1 and 2.Figure 7. ESP surfaces mapped on the vdW surface up to an electrondensity of 0.05 electronbohr À3 for a) 11 and b) 18.Side (up) and top (bottom) view of the packingo fc )11 and d) 18.Atom colors:pink B, blue N, red O, gray C. Spacegroups: P2 1 /c and P1.

Heteroatom Cycloaddition at the (BN)2Bay Region of Dibenzoperylene

“…Among the available methods for synthesizing 1,2‐azaborine containing PAHs, the electrophilic borylation, introduced by Dewar [2a] and optimized further, is attractive as both B−N and B−C bonds are constructed in one synthetic step (Scheme 1 a). [2h, 3a, 4] Alternatively, the coupling of carbon‐carbon (CC) bonds around existing BN units has occasionally been employed, e.g., by Piers, [5] Bonifazi, [3b, 6] and our group (Scheme 1 b). [7] The Wagner group [8] described the Au catalyzed NC bond formation as the final step of the synthesis of a doubly BN substituted perylene (Scheme 1 c).…”

“…Perylenes and dibenzoperylenes with BN doping have been synthesized by Wagner, Bonifazi and our group [3b, 4j, 8, 10] . We have developed a multistep synthesis of a dibenzoperylene 1 that features a BNBN unit at its bay region [4j] .…”

Recent Advances in Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds

“…The insoluble unsubstituted 19.9 , previously reported in an on-surface synthesis (CR2017, section 2.3.2 ), was also obtained via the same silane-based protocol. 35 …”

Reactivity Indices for the Coronene Nanocrystals and Their Derivatives: Modeling Approach

“…Coronene nanocrystals have been used in the creation of graphene (Kato et al, 2021;Saha and Bhattacharyya, 2018). The properties of pure coronene and its boron nitride substitution were considered (Dosso et al, 2020;Kurita, 2000;Vessally et al, 2017). Lithium as a dopant has already been reported to reduce the stability of coronene more than three times (Forozmand and Biglari, 2021).…”