Promoting photoswitching in mismatching mixed-linker multivariate Zr₆ MOFs

Multivariate metal-organic frameworks (MTV MOFs) have emerged as promising materials due to their ability to combine properties that enhance features beyond those of their pristine counterparts. Despite the potential for tailoring electronic properties through structural distortions and defects introduced by linkers of variable lengths, examples remain scarce, and information on the electronic structure is limited. Here, we present the multivariate mismatching linker approach to generate photoswitching nanoparticulated MOFs with variable lattice parameters and porosity features controlled by mixed-linker composition. Structural defects, such as dangling linkers, are generated due to mismatching crystal lattices, tuning the electronic structure. Combining biphenyl and azobenzene ditopic linkers promotes cis-trans photoswitching of dangling azobenzene linkers, which is constrained in Zr₆-azobenzene MOFs. Moreover, introducing low quantities of azobenzene drastically reduces the bandgap of the materials due to the contribution of the azo group, which is supported by first-principles calculations. This paves the way for new photo-responsive materials for photo-switching applications.