Xanthate-Based Customizable Fluorescent/Non-Fluorescent Macrocycles: Design, Synthesis, Photophysical Modulation, and Tailoring Silver Nanoparticle

Macrocycles, with tunable ring sizes and versatile functional groups, are garnering significant interest for their extensive applications in material and biomedical science. Herein, an effort was made to synthesize metal-free, xanthate-based tunable macrocycles. The mild reaction conditions, along with the versatile tunability of functional groups, render this synthetic strategy highly efficient. Subsequent to the synthesis, the macrocycles were comprehensively characterized by liquid chromatography-mass spectrometry (LC-MS), 1H NMR, 1H–1H correlation spectroscopy (COSY) NMR, and 13C NMR. The synthesis of macrocycles yields between 40 and 50%. The macrocycles were tailored in terms of hydrophilicity–hydrophobicity and fluorescence properties by varying the backbone and fluorophore side chains. As a proof of concept, the macrocycles were employed as capping agents for silver nanoparticles, where they effectively stabilized the nanoparticles, tuned their properties, and significantly enhanced their catalytic activity. These findings demonstrate that this class of macrocycles can be readily integrated with various secondary systems to tune and optimize their physicochemical and functional properties.