Development of high refractive index UiO-66 framework derivatives via ligand halogenation

UiO-66 is a Zr-based metal-organic framework (MOF) with exceptional chemical and thermal stability. The modular design of a MOF allows the tuning of its electronic and optical properties to obtain tailored materials for optical applications. Making use of the halogenation of the 1,4-benzenedicarboxylate (bdc) linker, the well-known monohalogenated UiO-66 derivatives were examined. In addition, a novel diiodo bdc based UiO-66 analogue is introduced. The novel UiO-66-I-2 MOF is fully characterized experimentally. By applying density functional theory (DFT), fully relaxed periodic structures of the halogenated UiO-66 derivatives are generated. Subsequently, the HSE06 hybrid DFT functional is used to calculate the electronic structures and optical properties. The obtained band gap energies are validated with UV-Vis measurements to assure a precise description of the optical properties. Finally, the calculated refractive index dispersion curves are evaluated underlining the capabilities to tailor the optical properties of MOFs by linker functionalization.

Automated summary

UiO-66 is a Zr-based metal-organic framework (MOF) with exceptional stability. By halogenating the linker, UiO-66 derivatives with tailored optical properties are examined, and a novel UiO-66 analogue is introduced. Experimental characterization and density functional theory (DFT) calculations are performed to analyze the electronic and optical properties. The results demonstrate the potential of linker functionalization to tailor the optical properties of MOFs.