Electron-Deficient Polycyclic π-System Fused with Multiple B←N Coordinate Bonds

Abstract

An extensive polycyclic π-system with 23 fused rings is synthesized via a highly efficient borylation reaction, in which four B–N covalent bonds and four B←N coordinate bonds are formed in one pot. B←N coordinate bonds not only lock the backbone into a near-coplanar conformation but also decrease the LUMO energy level to around −3.82 eV, demonstrating the dual utility of this strategy for the synthesis of extensive rigid polycyclic molecules and the development of n-type conjugated materials for organic electronics and organic photovoltaics.

N–B ← N Bridged Bithiophene: A Building Block with Reduced Band Gap to Design n-Type Conjugated Polymers

“…B←N has been extensively reported to greatly lower the energies of the LUMO/HOMO of π-conjugated molecules and π-conjugated polymers. − In this work, the N–B←N bridge with proper substitutes leads to greatly lowered LUMO energy, nearly unchanged HOMO energy as well as decreased band gap. This is attributed to the increased quinoid structure of the thiophene/thiazole rings with the N–B←N bridge in BNTzT.…”

Multiple-boron–nitrogen (multi-BN) doped π-conjugated systems for optoelectronics

“…47). 211 This large ladder-type molecule 154 exhibited intensive absorption in the NIR region with a decreased LUMO level of –3.82 eV.…”

“…The gain of electrons and loss of electrons of compound 153 were accompanied by the interconversion of different forms of its central core between a 47). 211 This large ladder-type molecule 154 exhibited intensive absorption in the NIR region with a decreased LUMO level of -3.82 eV.…”

Robust chain aggregation of low-entropy rigid ladder polymers in solution

“…11,12 Many cLPs have been synthesized with unique electrical and optical properties, including poly( p -phenylene)(LPPP), 13 poly(benzimidazole benzophenanthroline) (BBL), 14 and cLPs derived from perylene-3,4,9,10-tetracarboxylic acid diimides (PDIs), 15 carbazole 16 or fluorene 17 moieties, as well as those ladder structures bridged by intramolecular coordinate bonds. 18,19 cLPs are promising materials for a wide range of applications, such as photodetectors, 20 light emitting diodes, 21 field-effect transistors, 22 thermoelectric devices, 23 and high performance organic photovoltaics. 24–28 For most of these applications, cLPs demonstrated significantly higher stability compared to their non-ladder counterparts thanks to the presence of multiple strands of bonds and the thermodynamically stable fused-ring aromatic backbones.…”