Strategic Bromine Substitution in Aryl Aminoboranes Unlocks Photochemical Route to Narrow-Band Emitting Azaborines
Abstract
The development of UV/deep-blue emitters with high color purity remains a central challenge in OLED research, where conventional fluorophores suffer from broad emission and triplet-harvesting systems compromise stability. Here we show that strategic ortho-bromine substitution in bis-aryl aminoboranes unlocks an intramolecular photo-cyclization that allows direct access to azaborine frameworks under mild conditions and near quantitative yield. The high triplet energy of the aminoborane precursors enables efficient population of the T1 state, triggering ring closure and suppressing the twisted intramolecular charge-transfer (TICT) behavior characteristic of the open scaffolds. The resulting azaborines display deep-blue to near-UV emission, with remarkably narrow bandwidths (FWHM down to 0.09 eV in solution and 0.04 eV in glassy matrix) and localized excited states (LE). A systematic library screening unveils the modularity of this approach and shows that cyclization rate correlate with spin-orbit coupling (SOC) and triplet-state localization on the B-N bond. This work establishes the first photochemical route to azaborines and provides a synthetically versatile platform for high-purity emitters, suited for next-generation optoelectronic applications.
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BibTeX
@misc{bussolari2026strategic,
title = {{Strategic Bromine Substitution in Aryl Aminoboranes Unlocks Photochemical Route to Narrow-Band Emitting Azaborines}},
author = {Alessio Bussolari and Nunzio Matera and Andrea Pellegrini and Nicolò Mazzini and Sven Reese and Wojciech Mróz and Christian Merten and Andrea Mazzanti and Michele Mancinelli},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009178/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009178/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Strategic Bromine Substitution in Aryl Aminoboranes Unlocks Photochemical Route to Narrow-Band Emitting Azaborines
AU - Alessio Bussolari
AU - Nunzio Matera
AU - Andrea Pellegrini
AU - Nicolò Mazzini
AU - Sven Reese
AU - Wojciech Mróz
AU - Christian Merten
AU - Andrea Mazzanti
AU - Michele Mancinelli
PY - 2026
DA - 2026/09/21
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009178/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009178/v1
AB - The development of UV/deep-blue emitters with high color purity remains a central challenge in OLED research, where conventional fluorophores suffer from broad emission and triplet-harvesting systems compromise stability. Here we show that strategic ortho-bromine substitution in bis-aryl aminoboranes unlocks an intramolecular photo-cyclization that allows direct access to azaborine frameworks under mild conditions and near quantitative yield. The high triplet energy of the aminoborane precursors enables efficient population of the T1 state, triggering ring closure and suppressing the twisted intramolecular charge-transfer (TICT) behavior characteristic of the open scaffolds. The resulting azaborines display deep-blue to near-UV emission, with remarkably narrow bandwidths (FWHM down to 0.09 eV in solution and 0.04 eV in glassy matrix) and localized excited states (LE). A systematic library screening unveils the modularity of this approach and shows that cyclization rate correlate with spin-orbit coupling (SOC) and triplet-state localization on the B-N bond. This work establishes the first photochemical route to azaborines and provides a synthetically versatile platform for high-purity emitters, suited for next-generation optoelectronic applications.
ER -