Tailoring of the electronic property of Zn-BTC metal–organic framework via ligand functionalization: an ab initio investigation

Metal–organic frameworks (MOFs) are porous materials of recent interest due to their promising properties for technological applications. In this paper, the structure–property relationships of pristine and functionalized Zn-BTC (Zn(3)(BTC)(2)) MOFs are investigated. The results based on density functional theory (DFT) find that MOFs with coordinatively saturated secondary building units (SBU) are metallic, and MOFs with coordinatively unsaturated SBU are semi-conducting. The ligand functionalization with electron acceptor (cyano-) and electron donor (amino-) groups appears to tailor the electronic properties of Zn-BTC MOFs; amino-functionalization led to a significant upward shift of the band-edges whereas cyano-functionalization yields shifting of band-edges in the opposite direction, which led to a narrowing of the band gap. Modifying the electronic properties through such ligand functionalization design principles can be useful in engineering MOFs for gas sensing and device applications.