Synthesis and Study of the Optical Properties of a New Green Fluorescent Protein Chromophore Analogue with an sp-Hybridized Carbon Fragment

Objective: A new green fluorescent protein chromophore analogue with an sp-hybridized carbon fragment was presented. Methods: The introduction of a protecting group, Sonogashira coupling, and subsequent hydrolysis were used for the synthesis of aldehyde. The formation of imine of the corresponding aldehyde with the subsequent 3+2 cycloaddition and deprotection were used for the synthesis of arylpropynylidene-imidazolone. The optical properties of the new compound were studied. Results and Discussion: We discovered that the new substance, which has a triple bond in conjugation with the aromatic part of the molecule, is characterized by a bathochromic shift of the absorption and emission maxima. The resulting compound is comparable in its spectral characteristics with the previously synthesized arylallylidene-imidazolone. Conclusions: We designed a new green fluorescent protein chromophore analogue with an sp-hybridized carbon fragment that demonstrates a bathochromic shift of spectral maxima. The new substance can be potentially used as a fluorogenic dye for living systems.