Highly Photosensitive Metal-Organic Cage Based on 2,4,6-Tri(4-pyridyl)-1,3,5-triazine Ligand

In recent years, 2,4,6-tris(4-pyridyl)-1,3,5-triazine has attracted significant attention for the development of photochromic materials owing to its capacity to facilitate intramolecular charge separation under light irradiation. However, it remains a significant challenge to enhance photosensitivity by stabilizing the intramolecular charge-separated state. Based on our research foundation, the strategy of introducing strong electron acceptors and donors to construct electron donor-acceptor systems is highly effective for enhancing photosensitivity and stabilizing charge-separated states. Therefore, we utilized the ligand [H₃m-Batpt]Cl₃ to construct a metal-organic cage compound, namely, Zn₃Cl₆·(m-Batpt)₂, with an inner diameter of 13.417 Å. It exhibits remarkable photosensitivity under room light conditions; it turns olive green within 20 min and can maintain its colored state for at least two months in the dark. This work reports the first observation of pronounced photochromism in the 2,4,6-tris(4-pyridyl)-1,3,5-triazine system under room light. This is the first time that the 2,4,6-tris(4-pyridyl)-1,3,5-triazine system has been found to undergo significant color change under room light. In addition, we applied 1 to the adsorption of solid iodide, and the adsorption amount of iodide can reach 1.0 g·g^-1. These findings present a novel photosensitive ligand with the potential to advance optical material design through radical-mediated mechanisms in photochromic, catalytic, and electrical applications.