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Diazaboryl‐naphthyl‐ketone: A New Scaffold with Bright Fluorescence, Aggregation‐Induced Emission, and Application in the Quantitation of Trace Boronic Acids in Drug Intermediates
Author(s) -
Hackney Hannah E.,
Paladino Marco,
Fu Hao,
Hall Dennis G.
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202003248
Subject(s) - boronic acid , chemistry , fluorescence , fluorophore , substituent , quantum yield , aryl , photochemistry , homo/lumo , solvatochromism , luminescence , suzuki reaction , combinatorial chemistry , organic chemistry , molecule , materials science , physics , alkyl , optoelectronics , quantum mechanics
This study describes the synthesis, structure, and photophysical properties of a new luminescent polyaromatic boronic acid scaffold, diazaboryl‐naphthyl‐ketones (DNKs). These stable compounds display extremely bright fluorescence, aggregation‐induced emission, positive solvatochromism, and solid‐state fluorescence. DFT calculations and X‐ray crystallographic study revealed notable electronic and structural differences between these compounds and the parent diaminonaphthalene (DAN) adducts. Acylation of the DAN system causes a localization of both HOMO and LUMO onto the DNK unit, which validates the negligible influence of the B‐aryl substituent. The LUMO energy is lowered, and its shape significantly altered. Photophysical data in solution and the solid state revealed blue‐shifted, narrowed, and intense emissions for DNKs (up to 89 % quantum yield). The potential utility of the fluorogenic DNK system was demonstrated with a proof‐of‐concept for the determination of trace boronic acid contaminants in solid samples, down to one‐ppm level, using HPLC with fluorescence detection. This method could be useful in pharmaceutical development for the quantitation of difficult‐to‐detect and potentially mutagenic residual boronic acid from late cross‐coupling reactions in drug syntheses.