Small Fluorinated Aromatic Molecule‐Based Radiofrequency Identification Tags Enabled by Stepwise Tuning of Nuclear Shielding

Abstract In the Internet of Things (IoT) network, radiofrequency identification (RFID) is a key enabler for wireless communication, facilitating real‐time monitoring and control. A primary goal of enhancing IoT infrastructure is the development of versatile RFID tags that are of compact size, high capacity, and robust security with seamless read‐write operations. Here, we report a fluorine‐19 nuclear magnetic resonance ( 19 F NMR)‐based molecular encoding strategy using a fluorinated aromatics (FArs) library, termed “FArsEER” (fluorinated aromatics‐empowered encoding and reading), to generate small molecule‐based ID tags (Farcodes). By leveraging the structure‐sensitive nature of 19 F chemical shift, we developed a stepwise tuning strategy to precisely modulate 19 F chemical shift via nuclear shielding. Through a simple one‐step synthesis, we constructed a demonstrating platform of 64 FArs with distinct 19 F chemical shifts, enabling the quick generation of binary Farcodes capable of 64‐bit encoding and their facile reading and decoding with 19 F NMR. Moreover, by leveraging the solvent‐dependent 19 F chemical shifts and hydrolysis‐sensitive property, reversible encryption and irreversible erasure were further achieved with Farcodes for information security applications. With further advancements, Farcode may serve as a promising small molecule‐based RFID tag for secure information storage and communication in IoT networks.