Cationic Nitrogen‐Doped Helical Nanographenes

Abstract

Herein, we report the design and synthesis of a series of novel cationic nitrogen-doped nanographenes (CNDNs) with nonplanar geometry and axial chirality. Single-crystal X-ray analysis reveals helical and cove-edged structures. Compared to their all-carbon analogues, the frontier orbitals of the CNDNs are energetically lower lying, with a reduced optical energy gap and greater electron-accepting behavior. Cyclic voltammetry shows all the derivatives to undergo quasireversible reductions. In situ spectroelectrochemical studies prove that, depending on the number of nitrogen dopants, either neutral radicals (one nitrogen dopant) or radical cations (two nitrogen dopants) are formed upon reduction. The concept of cationic nitrogen doping and introducing helicity into nanographenes paves the way for the design and synthesis of expanded nanographenes or even graphene nanoribbons with cationic nitrogen dopants.

Non-K Region Disubstituted Pyrenes (1,3-, 1,6- and 1,8-) by (Hetero)Aryl Groups—Review

“…The synthesis of boroorganic derivatives of pyrene was described for 1,6-isomer (Scheme 4 and Scheme 5). 1,6-Bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-yl)pyrene 10 can be obtained in the commonly used reaction between the bromo derivative with bis(pinacolato)diboron in the presence of the catalyst [PdCl 2 (dppf)] and AcOK as a base, which results in a product with 99% yield [41].…”

“…Xinliang Feng et al reported the synthesis of 1,6-di(pyridin-2-yl)pyrene based on the Suzuki-Miyaura coupling reactions between 10 and 2-bromopyridine with catalytic system [Pd(PPh 3 ) 4 ]/Na 2 CO 3 in PhMe/MeOH/H 2 O, which obtained product 16 with 96% yield (Scheme 7) and which was further used in synthesis of target cationic nitrogen-doped helical nanographenes [41].…”

Triple Helical Ir(ppy)3 Phenylene Cage Prepared by Diol‐Mediated Benzannulation: Synthesis, Resolution, Absolute Stereochemistry and Photophysical Properties

“…Using ruthenium(0)-catalyzed diol-dieneb enzannulations developedi no ur laboratory,t he syntheses of oligo(o,p-phenylenes) and relatedp olycyclic aromatic hydrocarbons (PAHs), [5][6][7][8][9][10] including triple helical all-benzene cagesh as been reported. [7a] Notably,t he ruthenium(0)-catalyzed diol-diene benzannulation tolerates aryl halide functional groups, enabling synthetic strat-egies whereind iol-diene benzannulation is followedby latestage diversification of the resulting bromo-terminated oligo(o,p-phenylenes) through classical biaryl cross-coupling reactions.H erein, we extend this protocolt ot he synthesis of an N-dopedP AH cage, [11,12] and describe its cyclometalation to form an all-aryl caged fac-Ir(ppy) 3 analogueo ft riple helicalt opology. Additionally,t he enantiomeric resolution and absolutes tereochemicala ssignmento ft his all-arylc aged fac-Ir(ppy) 3 compound, andt he characterization of its photophysical properties are reported.…”

“…[13] The resulting triene 3 was obtained in good yield as am ixture of stereoisomers. [6,7] After somee ffort, it was found that use of the ruthenium(0) catalyst derived from Ru 3 (CO) 12 (6 mol %) and P(tBu) 2 Me·HBF 4 (36 mol %) in the presence of KOtBu (36mol %) enabled formation of the desired tris-cycloadduct 5 in 73 %i solated yield. [6,7] After somee ffort, it was found that use of the ruthenium(0) catalyst derived from Ru 3 (CO) 12 (6 mol %) and P(tBu) 2 Me·HBF 4 (36 mol %) in the presence of KOtBu (36mol %) enabled formation of the desired tris-cycloadduct 5 in 73 %i solated yield.…”

“…Dihydroxylationo ft riene 3 wasc omplicated by competing alkene oxidative cleavage, which was minimized upon application of Upjohn conditions, [14] providing tris-diol 4 in 45 %y ield as am ixture of stereoisomers.A ttempted ruthenium(0)-catalyzedc ycloaddition of tris-diol 4 with 1,3-butadiene under previously reported conditions using dppe or dppp as ligand were ineffective. [6,7] After somee ffort, it was found that use of the ruthenium(0) catalyst derived from Ru 3 (CO) 12 (6 mol %) and P(tBu) 2 Me·HBF 4 (36 mol %) in the presence of KOtBu (36mol %) enabled formation of the desired tris-cycloadduct 5 in 73 %i solated yield. Remarkably,d ebrominated side-products were not observed.E achd iol moiety of tris-cycloadduct 5 are of the cis-configuration, but the relative stereochemistry between the three cis-diols is not controlled.…”