作者:Oleksandr A. Kucherak、Ludovic Richert、Yves Mély、Andrey S. Klymchenko
DOI:10.1039/c2cp23037b
日期:——
Herein, three environment-sensitive (solvatochromic) fluorescent dyes presenting a strong electron acceptor 3-methoxychromone unit and varied electron donor 2-aryl were developed. All three dyes showed remarkable polarity-dependent shifts of the emission maximum, which increase with extension of the dye conjugation. For the 3-methoxychromone bearing a 7-(diethylamino)-9,9-dimethylfluoren-2-yl donor group the difference between the excited and the ground state dipole moments, estimated from the Lippert–Mataga expression, reached 20 D, which is among the largest reported for neutral dipolar fluorophores. Moreover, the new dyes are characterized by significant two-photon absorption cross-section (up to 450 GM) and large fluorescence quantum yields. The strong decrease in the fluorescence quantum yields of the dyes in polar protic solvents was observed together with the increase in the non-radiative deactivation rates, which can originate from twisted intramolecular charge transfer and intermolecular proton transfer phenomena. In comparison to the parent 3-hydroxychromone derivatives, the new dyes presented significantly improved photostability, which confirms that photodegradation of 3-hydroxychromones occurs from a product of the excited-state intramolecular proton transfer (phototautomer). Finally, an application of the new dyes for probing local binding site polarity of serum albumin was shown. This new class of fluorescent dyes may serve as attractive building blocks for future molecular sensors utilizing environment-sensitive fluorophores.
在此,开发了三种环境敏感(溶剂致变色)荧光染料,它们具有强电子受体 3-甲氧基色酮单元和不同的电子供体 2-芳基。所有三种染料均表现出显着的发射最大值的极性依赖性变化,这种变化随着染料缀合的延长而增加。对于带有 7-(二乙氨基)-9,9-二甲基芴-2-基供体基团的 3-甲氧基色酮,根据 Lippert-Mataga 表达式估计,激发态偶极矩与基态偶极矩之间的差异达到 20 D,即其中最大的中性偶极荧光团报道之一。此外,新型染料还具有显着的双光子吸收截面(高达 450 GM)和大的荧光量子产率。观察到染料在极性质子溶剂中的荧光量子产率急剧下降,同时非辐射失活率增加,这可能源于扭曲的分子内电荷转移和分子间质子转移现象。与母体3-羟基色酮衍生物相比,新染料的光稳定性显着提高,这证实了3-羟基色酮的光降解是由激发态分子内质子转移(光互变异构体)的产物发生的。最后,展示了新染料在探测血清白蛋白局部结合位点极性中的应用。这种新型荧光染料可以作为未来利用环境敏感荧光团的分子传感器的有吸引力的构建模块。