A Host–Guest Approach to Generate a Zr-Based MOF with Photothermal Conversion Properties

In this work, we report on how the judicious selection of the guest, the tetrathiafulvalene molecule (TTF), and the host, a zirconium-based metal–organic framework (MOFL7), enables the creation of a metal–organic framework with a supramolecular charge-transfer (CT) complex, TTF@MOFL7. The crystalline material exhibits broad absorption extending into the near-infrared region, demonstrating good thermal stability and low photoluminescence, which are all essential characteristics for the photothermal conversion (PTC) effect. Upon irradiation, TTF@MOFL7 shows a PTC efficiency of 11.7%. The observed PTC property results from the charge-transfer interactions between the benzothiadiazole core of the host and the guest molecules, as evidenced by EPR analyses and supported by computational studies. The approach presented here represents an effective supramolecular strategy to prepare MOFs with good photothermal conversion efficiency, while it provides insights into the design of crystalline materials with interesting PTC properties for several applications.