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Unsymmetrical 2,4,6‐Triarylpyridines as Versatile Scaffolds for Deep‐Blue and Dual‐Emission Fluorophores
Author(s) -
Fontes Luís F. B.,
Nunes da Silva Raquel,
Silva Artur M. S.,
Guieu Samuel
Publication year - 2020
Publication title -
chemphotochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.13
H-Index - 18
ISSN - 2367-0932
DOI - 10.1002/cptc.202000134
Subject(s) - intramolecular force , pyridine , photochemistry , anisole , excited state , luminescence , phenol , chemistry , fluorescence , hydrogen bond , ring (chemistry) , materials science , molecule , optoelectronics , organic chemistry , physics , quantum mechanics , nuclear physics , catalysis
Pyridines substituted with different aromatic groups at C‐2, C‐4 and C‐6 were prepared following a Kröhnke synthetic route. Introducing ortho ‐anisole at C‐2 resulted in deep blue emitters in solution, with quantum yields up to 74 %. On the other hand, when ortho ‐phenol was introduced, forming a strong hydrogen bond with the pyridine nitrogen, excited‐state intramolecular proton transfer was witnessed by the dual emission of the fluorophores, which is sensitive to the dye environment. The phenyl ring at C‐4 was used to introduce electron‐donating or withdrawing groups, to fine‐tune the photophysical properties of the dyes. Crystal structures of the fluorophores, together with theoretical studies using DFT/TD‐DFT calculations, were used to rationalize the experimental photophysical properties of the two families of dyes. Unsymmetrical 2,4,6‐triarylpyridines are therefore versatile scaffolds for the preparation of deep‐blue and dual emission fluorophores, and are promising building blocks for luminescent devices and sensors.