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传统的BODIPY荧光染料具有荧光量子效率高、摩尔消光系数大、紫外吸收和荧光发射峰窄等优点,然而这类荧光染料普遍存在荧光发射波长短和Stokes位移小的缺点,因而限制了它们在体内生物传感及成像方面的广泛应用。为了得到荧光发射波长较长和Stokes位移大的BODIPY荧光染料,以BODIPY母核为基本结构,通过在它的8位连接吸电子性质的酯基来增加分子内电荷转移程度,同时在其3,5位引入供电子的芳香取代基增加分子的π共轭结构,合成得到了一类8位酯基取代的新型BODIPY荧光染料。所得到的新型BODIPY荧光染料的化学结构经过1 H NMR,13 C NMR和HR-MS得以确认。光谱测试结果表明,这类染料的紫外吸收光谱(λabs=536nm)和荧光发射光谱(λem=592nm)与普通的BODIPY相比都发生显著红移(80nm),并且保持了较高的荧光量子效率(Ф=0.43)。此外,这类BODIPY荧光染料的紫外可见吸收光谱和荧光发射光谱几乎完全分开,Stokes位移长达60nm,可以有效地避免自吸收和生物样品的背景干扰。密度泛函理论计算结果表明,这种相对较大的Stokes位移主要是由于染料分子在基态和激发态下不同的几何构型所造成的。该类化合物的光物理性能受溶剂的影响小,是一类性能优良的新型荧光染料。细胞成像结果表明,染料1具有良好的细胞渗透性和光稳定性,可以实现对细胞的荧光成像。
The traditional BODIPY fluorescent dyes have the advantages of high fluorescence quantum efficiency, large molar extinction coefficient, narrow ultraviolet absorption and fluorescence emission peaks. However, such fluorescent dyes generally have the shortcomings of short fluorescence emission wavelength and small Stokes shift, thus limiting their in vivo Biosensing and imaging of the wide range of applications. In order to obtain a BODIPY fluorescent dye with a longer fluorescence emission wavelength and a large Stokes shift, the BODIPY nucleus is taken as the basic structure, and the intramolecular charge transfer is increased by connecting the electron-withdrawing ester group at its 8-position. Meanwhile, A new type of BODIPY fluorescent dye with 8-position ester group was synthesized by introducing aromatic donors with 5 substituents to increase the π-conjugated structure of the molecule. The chemical structure of the new BODIPY fluorescent dye obtained was confirmed by 1 H NMR, 13 C NMR and HR-MS. The results of spectroscopy showed that the UV absorption spectra (λabs = 536nm) and fluorescence emission spectrum (λem = 592nm) of these dyes all showed a significant red shift (80nm) compared with the conventional BODIPY, and maintained high fluorescence quantum efficiency (Ф = 0.43). In addition, the UV-visible and fluorescence emission spectra of these BODIPY fluorescent dyes are almost completely separated and Stokes shifts up to 60 nm, effectively avoiding self-absorption and background interference with biological samples. The results of density functional theory calculations show that this relatively large Stokes shift is mainly due to the different geometry of dye molecules in the ground and excited states. The photophysical properties of these compounds are less affected by the solvent and are a new class of fluorescent dyes with excellent properties. Cell imaging results showed that dye 1 has good cell permeability and photostability and can achieve fluorescence imaging of cells.