Abstract <p>This paper focuses on the preparation, structural characterization, and property investigation of the copper(I) complex [Cu(dppe)(phon)]I based on 1,2-bis(diphenylphosphino)ethane. The target complex was synthesized via a solution method, using 1,2-bis(diphenylphosphino)ethane, cuprous iodide, and 1,10-phenanthroline-5,6-dione as raw materials and acetonitrile as the solvent. It was then characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV–Vis), and fluorescence spectroscopy. Methylene blue was used to simulate dyeing wastewater, and the single-factor method was employed to study the effects of the initial concentration of methylene blue, illumination time, complex dosage, and temperature on the- efficiency. The results indicated that the optimal photocatalytic degradation performance was achieved at a relatively low initial concentration of methylene blue, an appropriate complex dosage (25 mg), and a temperature of 40°C. Additionally, the copper(I) complex was utilized as a phosphorescent probe for the detection of tetracycline hydrochloride, doxycycline hydrochloride, and chlortetracycline hydrochloride. It was found that the addition of tetracycline antibiotics led to a decrease in the fluorescence intensity of the complex, and the higher the concentration of the antibiotics, the stronger the quenching effect. The detection limit of the phosphorescent probe for tetracycline hydrochloride antibiotics was 3.0 × 10^–9 mol/L. This study provides a theoretical basis and practical reference for the application of copper(I) complexes in photocatalytic degradation and tetracycline detection.</p>