Toward tuning the bandgap in meta-substituted Fe-MOFs

Abstract

Semiconductor materials are crucial components in current and upcoming green industrial sectors, such as electric vehicles. As supply chain issues loom with sources of semiconductor materials, there is an emerging need for alternative and environmentally friendly semiconducting materials. One of the potential candidates is iron metal–organic frameworks (Fe-MOFs) which have been used as photocatalysts. Studying the bandgap modulation trends in Fe-MOFs thus will be beneficial for future applications in semiconductor technologies. With a response surface method, here we examine the bandgap, HOMO, and LUMO energy level trends in MOF-5 fully transmetalated with iron (i.e., Fe-MOF-5), as a function of the substituent effect (in the term of Hammett constant σ_m) and solvent effect (in the term of dielectric constant ε). The bandgap, HOMO, and LUMO energy levels all decrease with decreasing ε and increasing σ_m. However, the dominating influence for the bandgap switches from σ_m and ε to just ε as the value of ε increases. This result along with the polynomial equations of fit from statistical analysis suggest that the bandgap in these transmetalated models is significantly influenced by the dipole–induced dipole interactions. These results provide insight into the impact of shifting interactions of σ_m and ε on the bandgap of Fe-MOF-5.