Two azo dyes (E)-4-((6-hydroxyquinolin-5-yl)diazenyl)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (6QD) and (E)-4-((8-hydroxyquinolin-5-yl)diazenyl)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (8QD) have been designed and synthesized. The structure of both dyes was confirmed by FTIR, NMR spectroscopy and mass spectrometry. The absorption and emission spectral analysis of 6QD and 8QD confirmed their selective turn-on behaviour towards Al³⁺ and Co²⁺ ions, respectively in MeOH:H₂O (v/v = 1:1, HEPES buffer, pH = 7.2) at room temperature. The emission intensity of 6QD enhanced remarkably by 148-fold upon binding with Al³⁺ ion due to chelation-enhanced fluorescence (CHEF) effect and inhibition of photoinduced electron transfer (PET) phenomenon in the molecule. Emission behaviour of 8QD operates on CHEF and intramolecular charge transfer (ICT) mechanisms in presence of Co²⁺ ion which induced 26-fold enhancement in emission intensity of 8QD. Colorimetric studies showed prominent visual response for Al³⁺ and Co²⁺ ions allowing the real time analysis of these ions in their corresponding solutions. Other coexisting metal ions do not interfere with the detection of these metal ions. Job’s plot analyses revealed 1:1 binding stoichiometry for complexes 6QD-Al³⁺ and 8QD-Co²⁺. Association constants of complexes 6QD-Al³⁺ and 8QD-Co²⁺ were found to be 1.2 × 10⁶ and 4 × 10⁶ M⁻¹, respectively which suggest good association of both probes with respective metal ions. The limit of detection of 6QD and 8QD was determined to be 1 × 10⁻⁸ M and 9.1 × 10⁻⁸ M respectively, which demonstrates the high sensitivity towards corresponding metal ions. Reversible studies confirmed that both probes 6QD and 8QD could be used as secondary sensor for EDTA²⁻ anion. Furthermore, pH based absorption studies revealed that 6QD and 8QD can act as naked eye colorimetric probe for detection of hydroxyl ions at pH > 9.

两种偶氮染料（E）-4-（（6-羟基喹啉-5-基）二氮烯基）-1,5-二甲基-2-苯基-1H-吡唑-3（2H）-一个（6QD）和（E）-设计并合成了4-（（8-羟基喹啉-5-基）二氮烯基）-1,5-二甲基-2-苯基-1H-吡唑-3（2H）-一（8QD）。两种染料的结构通过FTIR，NMR光谱和质谱法确认。6QD和8QD的吸收和发射光谱分析证实了它们分别在MeOH：H ₂ O（v / v = 1：1，HEPES缓冲液，pH = 7.2）中对Al ³⁺和Co ²⁺离子的选择性开启行为。在室温下。6QD的发射强度与铝³⁺离子结合后，由于螯合增强的荧光（CHEF）效应和分子中光诱导电子转移（PET）现象的抑制而显着增强了148倍。在存在Co ²⁺离子的情况下，8QD的发射行为在CHEF和分子内电荷转移（ICT）机制上起作用，这导致8QD发射强度增强26倍。比色法研究表明，Al ³⁺和Co ²⁺离子具有明显的视觉响应，从而可以在相应的溶液中实时分析这些离子。其他共存的金属离子不会干扰这些金属离子的检测。乔布斯的图分析显示复合物的1：1结合化学计量6QD -Al ³⁺和8QD -Co ²⁺。发现配合物6QD -Al ³⁺和8QD -Co ^2+的缔合常数分别为1.2×10 ⁶和4×10 ⁶ M ^-1，这表明两种探针与各自的金属离子良好缔合。确定6QD和8QD的检出限分别为1×10 ^-8 M和9.1×10 ^-8 M，这证明了对相应金属离子的高灵敏度。可逆研究证实，两个探针6QD和8QD可用作EDTA ^2-阴离子的辅助传感器。此外，基于pH的吸收研究表明，6QD和8QD可以作为肉眼比色探针，用于检测pH> 9的氢氧根离子。