Unveiling 79‐Year‐Old Ixene and Its BN‐Doped Derivative

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are key components of organic electronics. The electronic properties of these carbon‐rich materials can be controlled through doping with heteroatoms such as B and N, however, few convenient syntheses of BN‐doped PAHs have been reported. Described herein is the rationally designed, two‐step syntheses of previously unknown ixene and BN‐doped ixene (B2N2‐ixene), and their characterizations. Compared to ixene, B2N2‐ixene absorbs longer‐wavelength light and has a smaller electrochemical energy gap. In addition to its single‐crystal structure, scanning tunneling microscopy revealed that B2N2‐ixene adopts a nonplanar geometry on a Au(111) surface. The experimentally obtained electronic structure of B2N2‐ixene and the effect of BN‐doping were confirmed by DFT calculations. This synthesis enables the efficient and convenient construction of BN‐doped systems with extended π‐conjugation that can be used in versatile organic electronics applications.

BN-Embedded Perylenes

“…In this respect, the isosteric substitution of C=C bond with B-N bond is used to influence the electronic density and energy levels of corresponding frontier molecular orbitals (e.g., HOMOs and LUMOs) and hence to modulate molecular properties such as band gap, optoelectronic and catalytic properties [ 21 , 22 , 23 ]. However, the syntheses of BN-substituted PAHs are still in a dormant phase with only sporadic reports and the study of BN-PAHs cannot be further sustained for lack of enumerating stable BN-aromatic building blocks, albeit this contradiction in reality is a shock of startling [ 24 , 25 ]. Furthermore, the paramount challenges also come from the competence for orderly implementation of BN dipoles into the conjugate systems rather than some random choices, to precisely control both the orientation and quantity of the inserted BN dipoles.…”

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).…”

Recent Advances in Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds

“… Reagents and conditions: (a) 260 BBr 3 , i -Pr 2 EtN, o -DCB, 180 °C; (b) 261 PhBCl 2 , Et 3 N, 1,2,4-trichlorobenzene, reflux, 36 h; (c) Pd(OAc) 2 , PCy 3 , Cs 2 CO 3 , o -xylene, reflux, overnight. …”

“…In 2020, Park and Shin et al reported the preparation of B 2 N 2 -ixene ( 128.5 , Scheme 128 ). 261 The key precursor, 2,2′-(buta-1,3-diyne-1,4-diyl)dianiline ( 128.3 ), was obtained from the Glaser coupling of 2-ethynylaniline. Treatment of 128.3 with PhBCl 2 and Et 3 N brought about the chloroboration of alkyne followed by B–N bond formation to yield compound 128.4 in 28% yield.…”