An Electron‐Accepting aza‐BODIPY‐Based Donor–Acceptor–Donor Architecture for Bright NIR Emission

Abstract

A bright near‐infrared (NIR) fluorescent molecule was developed based on the donor–acceptor–donor (D–A–D) approach using an aza‐BODIPY analog called pyrrolopyrrole aza‐BODIPY (PPAB) as an electron‐accepting chromophore. Directly introducing electron‐donating triphenylamine (TPA) to develop a D–A–D structure caused redshifts of absorption and emission of PPAB into the NIR region with an enhanced fluorescence brightness of up to 5.2×104 m−1 cm−1, whereas inserting a phenylene linker between the TPA donor and the PPAB acceptor induced solvatochromic behavior in emission. Transient absorption spectra and theoretical calculations revealed the presence of a highly emissive hybridized locally excited and charge‐transfer state in the former case and the contribution of the dark charge‐separated state to the excited state in the latter case. The bright D–A–D PPAB as a novel emitter resulted in a NIR electroluminescence with a high external quantum efficiency of 3.7 % and a low amplified spontaneous emission threshold of ca. 80 μJ cm−2, indicating the high potential for NIR optoelectronic applications.

Nature‐Inspired Functional Chromophores from Biomimetic o‐Quinone Chemistry

“…Conventional access routes to tailored functional chromophores with specific features are based either on the combination of preformed chromophores via suitable functional groups, spacers, linkers or tethers, or on synthetic approaches leading to de novo construction of the light-absorbing scaffold based on traditional or multicomponent methodologies. [12,13] In the past decade, as research on functional chromophores and dyes has increased in scope to encompass a broad range of fields and disciplines, there has been a need to expand the toolbox of chromophoric scaffolds to meet the increasing demand for new functions and properties, as well as improved performances.…”

“…Conventional access routes to tailored functional chromophores with specific features are based either on the combination of preformed chromophores via suitable functional groups, spacers, linkers or tethers, or on synthetic approaches leading to de novo construction of the light‐absorbing scaffold based on traditional or multicomponent methodologies [12,13] …”

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.…”

Rational Design and Facile Synthesis of Dual‐State Emission Fluorophores: Expanding Functionality for the Sensitive Detection of Nitroaromatic Compounds

“…For 4 f , there is only one absorption peak near 300 nm, indicating that it may have no obvious ICT effect. Furthermore, compounds 4 a – 4 f show essentially unchanged absorption spectra in common solvents with varying polarities, suggesting that the ground state is not affected by solvent polarity [44] …”