In this study, imine compounds were synthesized using a vacuum-purging system and molecular sieves for dehydration and deoxygenation, followed by vacuum distillation to purify aniline. The distillation temperature was estimated based on the Clausius–Clapeyron equation. The purity and polarity of the synthesized compounds were analyzed by TLC through Rf value comparison. UV-Vis spectroscopy revealed that SA exhibited an absorption peak at 383 nm under pH 6, which blue-shifted to 326 nm when acidified to pH 4. Time-scan measurements confirmed that the acid–base transformation occurred as an instantaneous fast reaction. Thermodynamic parameters (ΔH, ΔS) were determined from the Van’t Hoff plot, and a negative ΔG indicated that the acidification reac-tion is spontaneous. The λmax sequence demonstrated that para-substituted chromophores on the aromatic ring possess stronger conjugation and higher reactivity than their meta-substituted counter-parts. In the aggregated state, SA and SB2 displayed aggregation-induced emission (AIE) effects due to restricted intramolecular rotation, while SB1 exhibited aggregation-caused quenching (ACQ) attributed to π–π stacking. X-ray crystallographic analysis confirmed the presence of intramolecular hydrogen bonding, accounting for the opposite fluorescence emissions of SB1 and SB2. The com-plexes Ca-L1 and Zn-L1 exhibited distinct color variations under different pH conditions, enabling the development of a self-fabricated fluorescent pH test paper. Furthermore, an improved multistep synthetic strategy for Ca-L1 was developed to replace the conventional one-pot method, effectively reducing the reaction time from 12 h to 3 h with an increased yield, attributed to the purification pro-cess that ensured the purity of SB1 and minimized side reactions, thereby achieving higher yield and energy efficiency.