Unsymmetrical 2,4,6-Triarylpyridines as Versatile Scaffolds for Deep-Blue and Dual-Emission Fluorophores


Pyridines substituted with different aromatic groups at C-2, C-4 and C-6 were prepared following a Krohnke 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.



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Fontes, LFB; da Silva, RN; Silva, AMS; Guieu, S

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Thanks are due to University of Aveiro, FCT/MEC for the financial support to the QOPNA research Unit (FCT UID/QUI/00062/2019), to the LAQV-REQUIMTE (UIDB/50006/2020), to the CICECO-Aveiro Institute of Materials (UIDB/50011/2020 & UIDP/50011/2020), and also to the Portuguese NMR Network. SG acknowledges the funding from national funds (OE), through FCT - Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19, and from the Integrated Programme of SR&TD pAGE - Protein aggregation Across the Lifespan (reference CENTRO-01-0145-FEDER-000003), including R. Nunes da Silva Post-Doctoral grant (BPD/UI98/6327/2018).

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