Boron-Stabilized Planar Neutral π-Radicals with Well-Balanced Ambipolar Charge-Transport Properties

Abstract

Organic neutral π-monoradicals are promising semiconductors with balanced ambipolar carrier-transport abilities, which arise from virtually identical spatial distribution of their singly occupied and unoccupied molecular orbitals, SOMO(α) and SOMO(β), respectively. Herein, we disclose a boron-stabilized triphenylmethyl radical that shows outstanding thermal stability and resistance toward atmospheric conditions due to the substantial spin delocalization. The radical is used to fabricate organic Mott-insulator transistors that operate at room temperature, wherein the radical exhibits well-balanced ambipolar carrier transport properties.

Molecular Semiconductors for Logic Operations: Dead‐End or Bright Future?

“…Some neutral π‐radicals behave as semiconductors. For example, a well‐balanced ambipolar charge transport with µ (h + ) = 4.5 × 10 −3 cm 2 V −1 s −1 and µ (e − ) = 1.1 × 10 −2 cm 2 V −1 s −1 has been measured for the boron‐stabilized planar neutral π‐radicals 34 . An interesting situation occurs when a chemical function with a stable radical is anchored, but electronically decoupled, to a π‐system.…”

Effects of the Substituents of Boron Atoms on Conjugated Polymers Containing B←N Units

“…Among the widely‐studied methodologies for electronic tuning, the introduction of a boron atom into π‐conjugated skeletons is an efficient approach . Replacement of carbon atoms with tricoordinate boron atoms can form the p–π* conjugation and thus produce new π‐conjugated systems with broad absorption, near‐IR fluorescence, and good charge‐transporting properties . On the other hand, the vacant p orbital of the boron atom can coordinate with the electron pair of the Lewis basic atom to form a Lewis acid/base pair, which leads to intriguing π‐conjugated systems (tetracoordinate borane) that display narrow band gaps, photoswitchable properties, and enhanced electron‐accepting abilities .…”

“…[10][11][12][13][14][15] Replacement of carbon atoms with tricoordinate boron atoms can form the pp*c onjugation and thus produce new p-conjugated systems with broad absorption, near-IRf luorescence, and good chargetransporting properties. [16,17] On the other hand, the vacant p orbitalo ft he boron atom can coordinate with the electron pair of the Lewis basic atom to form aL ewis acid/base pair, which leads to intriguing p-conjugated systems (tetracoordinate borane) that display narrow band gaps, photoswitchable properties, and enhanced electron-accepting abilities. [18][19][20] Accordingly, variouso rganoboron p-conjugated molecules and polymers have been developed for organico ptoelectronic materials andd evices.…”

Regioselective Functionalization of Stable BN‐Modified Luminescent Tetraphenes for High‐Resolution Fingerprint Imaging

“…However,the real applications of the materials still remain an unknown proposition, because their stability and sensitivity to ambient conditions are important. [8] This novel strategy has been applied to BN-containing compounds,a nd the boron center could be further stabilized by the interaction with the electron-donating nitrogen atom. [5] However, little attention has been paid to applying this approach to BNdoped aromatic compounds,e specially BN-modified conjugated molecules.…”

“…Therefore,n ew strategies are quite beneficial to stabilize the boron center.T he most common strategy is to use sterically bulky groups to kinetically stabilize the boron center, [7] but this is at the expense of preventing solid-state p-p stacking.I nr esponse to these limitations,a ne xciting concept for stabilizing organoboron compounds was introduced by Yamaguchi and Piers,w ho demonstrated that enforced planarity could stabilize boroncontaining p-conjugated materials. [8] This novel strategy has been applied to BN-containing compounds,a nd the boron center could be further stabilized by the interaction with the electron-donating nitrogen atom. While the synthetic challenges in preparing such af ramework are not to be taken lightly,a dvances in synthetic methodology in this rapidly expanding area should allow for many more examples of enforced planarity in the near future.W ith these design concepts in mind, herein, we set our sites on an ovel planar BN-substituted p skeleton with good stability and further explore the post-functionalization strategy on the system with av ariety of chemical transformations.BN-substituted tetraphene derivatives have been explored previously as potential components for optoelectronic materials.T he BN-modified tetraphene was synthesized by metal-catalyzed cyclization of BN-naphthalene with diphenylacetylene following previous work.…”