Integrating Cu _x I _y ( <i>L</i> ) Emission Center into Metal–organic Frameworks to Achieve Solvatochromic Luminescence

Abstract Stimuli‐induced fluorescence in metal–organic frameworks is typically achieved by stimulating emissive organic centers in their frameworks. In this work, a {Cu 2 I 2 } cluster is incorporated in a Gd‐based metal–organic framework as part of a fluorescence center to yield [Gd 2 (Cu 2 I 2 )(L) 3 (DMF) 4 ]·(DMF) 0.5 (CH 3 CN) (Gd‐CuI‐MOF, H 2 L = 3, 5‐pyridinedicarboxylic acid). The Gd‐CuI‐MOF exhibits sensitive and reversible solvatochromic fluorescence between green and orange color, triggered by solvent molecules. Gd‐CuI‐MOF, as a colorimetric fluorescence sensor, shows considerable promise for applications in qualitative monitoring of organic reactions for specific industrial synthesis. It can also be used as an intriguing dual‐stimuli‐responsive (solvent and temperature) luminescent material in multiple information encryption, offering a sophisticated and accurate information protection system.