Near-Infrared-II Photothermal Conversion and Magnetic Dynamic Synchronous Control in [Ln3Rad2] Aggregate by Rigidity Modification of Nitronyl Nitroxide

Abstract

Radical-metal compounds as functional materials could apply to multiple fields such as solar-thermal conversion and ultra-high density data storage. However, reactivity and instability of organic radicals usually hamper the development and application of radical-metal compounds. Herein, we utilized persistent nitronyl nitroxide to construct two categories of nitronyl nitroxide-Ln compounds involving a rare [4f-2p-4f-2p-4f] multi-spin motif with electron donor-acceptor pattern. Significantly, the introduction of nitronyl nitroxide effectively recedes radiative transition process and facilitates bathochromic shift of absorption spectrum to endow Dy compounds with precious NIR-II photothermal conversion function. Furthermore, synergistic action of rad-Dy/rad magnetic interactions and strong magnetic anisotropy of DyIII ions bestows single-molecule magnets (SMMs) behavior upon the system. Notably, thanks to rigidity modification of nitronyl nitroxide, prominent enhancement of photothermal conversion efficiency from 56.9% to 74.0% and magnetic switching phenomenon have been observed with molecular structure transformation from flexibility to stiffness, offering an avenue in synchronous control of photothermal effect and magnetic dynamic for the first time.