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

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 (¹⁹F 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 ¹⁹F chemical shift, we developed a stepwise tuning strategy to precisely modulate ¹⁹F chemical shift via nuclear shielding. Through a simple one-step synthesis, we constructed a demonstrating platform of 64 FArs with distinct ¹⁹F chemical shifts, enabling the quick generation of binary Farcodes capable of 64-bit encoding and their facile reading and decoding with ¹⁹F NMR. Moreover, by leveraging the solvent-dependent ¹⁹F 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.