A Bis-Aromatic MOF System Constructed by a Copper Iodine Cluster and Porphyrinic Ligand for Enhancing Near-Infrared Photothermal Conversion

Abstract

Near-infrared (NIR) photothermal materials efficiently convert low-energy near-infrared light into heat and have a significant role across various domains. Herein, a copper iodine cluster node (Cu14I14) featuring inorganic aromaticity was assembled with porphyrinic ligands characterized by classical π-aromaticity to create a dual-aromatic crystalline MOF (denoted as Cu14I14-CuTPyP). Cu14I14-CuTPyP with extensive electron delocalization exhibited a broad NIR absorption and achieved a high NIR photothermal conversion efficiency of 63.77% under 1064 nm laser irradiation; this efficiency surpassed those of most reported porphyrin assembly materials. By combining in situ Raman spectroscopy, transient absorption spectroscopy, and control experiments, we revealed that the cooperation between aromatic Cu14I14 and porphyrin led to an active electron transfer pathway in Cu14I14-CuTPyP, which consumed a considerable portion of excited-state molecules (71.4%) through ultrafast nonradiative relaxation channels (2.1 ps). In this study, our thorough investigation of the photothermal properties of bis-aromatic MOFs could aid in the creation of set a new standard for material design.