Synthesis and luminescence properties of analogues of the green fluorescent protein chromophore

• Published in: Dyes and pigments 2020-06, Vol.177, p.108267, Article 108267
• Main Authors: Esteves, Cátia I.C., da Silva Fonseca, Inês, Rocha, João, Silva, Artur M.S., Guieu, Samuel
• Format: Article
• Language: English
• Subjects: Aggregation-induced emission enhancement; Fluorescence; Green fluorescent protein; Synthesis
• ISSN: 0143-7208; 1873-3743
• DOI: 10.1016/j.dyepig.2020.108267

The green fluorescent protein (GFP) is extensively used as a biomarker for fluorescence biological imaging. The chromophore in GFP is only fluorescent when confined into the β–barrel of the protein. Similarly, synthetic analogues of the fluorophore of GFP are usually non-emissive in solution, due to free rotation around the aryl-alkene bond and (Z/E)-isomerization of the double bond. Here, the synthesis and characterization of three analogues of the fluorophore of GFP are reported. The introduction of more electron donating substituents induces a red-shift in the absorption and emission. The fluorophores are more emissive in the solid state than in solution, and a study of their crystal structure reveals that the (Z/E)-isomerization is efficiently blocked in the crystals. [Display omitted] •A new synthesis of analogues of the Green Fluorescent Protein fluorophore is presented.•They are almost non emissive in solution.•Their emission intensity increases up to a hundred times upon crystallization.•Changing the substituents tunes their absorption and emission spectra.