Smartphone-integrated dual fluorescent–colorimetric chemosensor for Cu2+detection in aqueous–organic media: RGB/test kit approach, X-ray crystal structure, computational, and biological studies

چکیده مقاله

In this study, the ligand N-(2-phenoxyphenyl)pyrazine-2-carboxamide (LPhen) was synthesized and evaluated as a dual-mode colorimetric and fluorescent sensor for the selective and sensitive detection of Cu2+ ions in organic/aqueous media. Upon interaction with copper ions, the ligand exhibited a distinct color change and significant fluorescence quenching, allowing for both naked-eye detection and spectral monitoring. The practical applicability of the sensor was demonstrated through the fabrication of paper-based test strips and subsequent analysis using an RGB model, facilitating rapid and portable visual and digital detection of Cu2+ ions across various sample matrices. The sensor exhibited a fast response, high selectivity towards Cu2+ ions in the presence of competing metal ions, a low detection limit, a favorable binding constant, excellent reversibility, and remarkable stability, with its optical and spectral features remaining consistent for at least one week under ambient conditions. Additionally, the sensor's performance was validated over a broad pH range. The corresponding Cu2+ complex was successfully synthesized and structurally characterized by single-crystal X-ray diffraction, revealing a six-coordinate distorted octahedral geometry elongated along the z-axis. DFT and Hirshfeld surface analyses were performed on the free ligand to explore its electronic properties and intermolecular interactions. Antimicrobial assays demonstrated that the Cu2+ complex exhibited significantly enhanced and broader-spectrum antimicrobial activity compared to the free ligand. These results highlight the multifunctional potential of the ligand–metal system as a highly responsive and stable optical sensor for Cu2+ ions, as well as an effective antimicrobial agent, combining structural robustness, analytical performance, and biological relevance. © 2026 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.