Influence of the Intramolecular Hydrogen Bond on the Fluorescence of 2‐ortho‐Aminophenyl Pyridines

• Published in: Chemistry : a European journal Vol. 28; no. 53; pp. e202201844 - n/a
• Main Authors: Esteves, Cátia I. C., Fontes, Luís F. B., Rocha, João, Silva, Artur M. S., Guieu, Samuel
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 22.09.2022; Wiley Subscription Services, Inc
• Subjects: Chemistry; Chemistry, Multidisciplinary; Dyes; Emission spectra; excited-state intramolecular proton transfer; Fluorescence; Hydrogen bonds; Physical Sciences; Protonation; Pyridines; Science & Technology; Substitutes; synthesis; triarylpyridines; synthesis; excited-state intramolecular proton transfer; ESIPT; fluorescence; hydrogen bonds; triarylpyridines
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202201844

The dynamic nature of excited‐state intramolecular proton transfer (ESIPT) and its effect on emission spectra is an attractive strategy to create multi‐emissive dyes. Here we describe the behavior of a series of hydrogen‐bonded triphenylpyridines with a set of donor–acceptor combinations that allowed us to perceive the influence of each substitution on the photophysical properties of the dyes. The susceptibility of these ESIPT moieties to pH variations was also studied, elucidating that the level of protonation had a significant effect on the emission color. The assignment of each emission band was made by using DFT and td‐DFT calculations that were in agreement with the experimental results. This study emphasizes the versatility of triphenylpyridines that can be synthesized effortlessly with a logical and independent C‐2, C‐4 and C‐6 substitution in order to have the desired ESIPT modulation and subsequent multi‐emission response. A family of 2‐aminophenyl pyridines with a strong intramolecular hydrogen bond displays excited‐state intramolecular proton transfer, as witnessed by their double emission profile. Their protonation or deprotonation modulates their emission properties, thereby making them promising for pH sensing applications.