The synthesis, electrochemical, optical and cation-sensing properties of ferrocene-imidazoquinoxaline dyads 6, are presented. Dyad 6a behaves as a highly selective redox, chromogenic and fluorescent chemosensor molecule for Pb2+ cations in CH3CN solutions; the oxidation redox peak is anodically shifted (ΔE1/2 = 110 mV); in the absorption spectrum a new low-energy band appeared at λ = 463 nm, and the emission band is red-shifted (Δλ = 31 nm) along with an important chelation-enhanced fluorescence factor (CHEF = 276), upon complexation with this metal cation. The dyad 6b, bearing two additional pyridine rings as substituents, has shown its ability for sensing Hg2+ cations through three different channels: the oxidation peak is anodically higher shifted (ΔE1/2 = 300 mV), a new low-energy band appears in the absorption spectrum at λ = 483 nm, and the emission band was also red-shifted (Δλ = 28 nm) and underwent an important chelation-enhanced fluorescent factor (CHEF = 227). The changes in their absorption spectra are accompanied by color changes from yellow to orange which allow their potential use for the “naked eye” detection of these metal cations. Linear sweep voltammetry revealed that Cu2+ cations induced oxidation of the ferrocene unit in both dyads, which is accompanied by an important increase of the emission band.
本文介绍了
二茂铁-
咪唑喹喔啉二元化合物 6 的合成、电
化学、光学和阳离子传感特性。二元化合物 6a 在 CH3CN 溶液中对 Pb2+ 阳离子具有高选择性氧化还原、发色和荧光
化学传感器分子的作用;氧化还原峰呈阳极移动(ΔE1/2 = 110 mV);在吸收光谱中,λ = 463 nm 处出现了一个新的低能带;与该
金属阳离子络合后,发射带发生了红移(Δλ = 31 nm),并出现了一个重要的螯合增强荧光因子(CHEF = 276)。二元化合物 6b 含有两个额外的
吡啶环作为取代基,通过三个不同的途径显示了其感知 Hg2+ 阳离子的能力:氧化峰阳极偏移更高(ΔE1/2 = 300 mV),吸收光谱中出现了一个新的低能谱带,波长为 λ = 483 nm,发射带也发生了红移(Δλ = 28 nm),并出现了一个重要的螯合增强荧光因子(CHEF = 227)。其吸收光谱的变化伴随着从黄色到橙色的颜色变化,这使得它们有可能用于 "肉眼 "检测这些
金属阳离子。线性扫描伏安法显示,Cu2+ 阳离子诱导了这两种二元化合物中
二茂铁单元的氧化,并伴随着发射带的显著增加。