Phenanthroline is a fluorophore known for its non-fluorescent complex formation with Fe(II). We present two novel turn-off fluorescence sensors developed based on 5-amino and 5-chloro derivatives of 1,10-phenanthroline for the quantification of Fe(II) with improved sensitivity and selectivity compared to pristine phenanthroline. The fluorescence intensity of 5-amino-1,10-phenanthroline at λ_em 512 nm when λ_ex 280 nm was decreased remarkably mainly due to the 1:3 static quenching by Fe(II), supported by the charge transfer spectra and the temperature studies. The formation of a stable complex with Fe(II) was observed in the range of pH 4.64 to 8.21 with a detection limit of 2.74 × 10^-7 M at 3.3σ and 25 °C. The 5-chloro derivative showed much higher sensitivity and selectivity towards Fe(II) in the range of pH 3.80 to 6.80 with a detection limit of 1.70 × 10^-8 M at 3.3σ and 25 °C when the λ_ex and λ_em were 286 nm and 379 nm, respectively. In both the fluorescence sensors, the observed interference from foreign ions was at a minimum level, indicating the sensors’ specific selectivity towards Fe(II). The interference from cations; Cu(II), Ni(II), and Co(II) was comparatively higher, while the anions showed only a little to no interference.

菲咯啉是一种荧光团，因其与Fe（II）形成非荧光配合物而闻名。我们目前基于1,10-菲咯啉的5-氨基和5-氯衍生物开发的两个新颖的关闭荧光传感器，用于定量Fe（II），与原始菲咯啉相比具有更高的灵敏度和选择性。_λex 280 nm时，在_λem 512 nm处5-氨基-1,10-菲咯啉的荧光强度显着降低，这主要归因于Fe（II）的1：3静态猝灭，由电荷转移谱和温度支持学习。在pH 4.64至8.21的范围内观察到与Fe（II）形成稳定的络合物，检出限为2.74×10 ^-7M在3.3σ和25°C下。5-氯衍生物显示出对铁在pH为3.80的范围高得多的灵敏度和选择性（II）至6.80与1.70×10的检测极限^-8 M达3.3σ和25℃时，λ _EX和λ _EM分别分别为286 nm和379 nm。在两个荧光传感器中，观察到的来自外来离子的干扰均处于最小水平，这表明传感器对Fe（II）的比选择性。阳离子的干扰；Cu（II），Ni（II）和Co（II）相对较高，而阴离子仅显示很少甚至没有干扰。