Thermally Stable Naphthalenediimide Alkali-MOFs Exhibiting Photo-Thermochromism for Cefuroxime Detection and Information Encryption

Most of the nonalkali MOFs containing NDI only turn darken after photoresponse, with a narrow color change range. To expand the color response range of photochromic materials, this work designs two novel metal-organic frameworks (Na/Cs-CMNDI) constructed by alkali metals (Na⁺, Cs⁺) and the photoresponsive linker N, N'-bis(carboxymethyl)-1,4,5,8-naphthalenedicarboximide (H₂CMNDI). It was found that the thermally stable Cs-CMNDI exhibits a remarkable four-color transformation from yellow, gray to black and finally red under photothermal costimulation, surpassing the limitation of single-color change in traditional NDI-based MOFs. Based on this, a dynamic information encryption system was successfully established, which can generate specific passwords within a certain period of time, and a color-based encryption strategy was developed by using an 8888-type mold to brush the powder to encrypt specific four-digit numbers. Moreover, both AMOFs can be used as fluorescent sensors for the detection of the antibiotic cefuroxime, demonstrating good application potential in the fields of medicine and ecological protection.