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.

绿色荧光蛋白（GFP）被广泛用作荧光生物学成像的生物标记。GFP的发色团仅在蛋白质的β-桶内时才发荧光。类似地，由于在芳基-烯烃键周围的自由旋转和双键的（Z / E）-异构化，GFP的荧光团的合成类似物在溶液中通常是非发射性的。在此，报道了GFP的荧光团的三种类似物的合成和表征。引入更多的给电子取代基会引起吸收和发射的红移。荧光团在固态中比在溶液中发射更多，对它们的晶体结构的研究表明，（Z / E异构化被有效地阻止在晶体中。