Stability and electronic properties of aromatic and heteroaromatic molecules for Guest@MOF complexes

A set of Guest@Host complexes formed by aromatic and heteroaromatic guest molecules encapsulated into the [Zn2(SDC)2(An2Py)] as host structure was computationally investigated. The stability of these complexes was characterized by energy decomposition and intermolecular interaction analysis, demonstrating the strong effect of dispersion forces and electrostatic interactions on the adsorption and interaction energy, being more stable the heteroaromatic cases. The electronic structure and semiconductor properties of Guest@MOF complexes have proved that heteroaromatic guest molecules allow band-gap tuning, depending on the electron donor and acceptor character of the guest molecules. Simulated absorption spectra of Guest@MOF complexes preserved the same profile because of the higher contribution of MOF, but heteroaromatic complexes displayed interesting cases of Charge−Transfer excitations, generating new bands at lower energy. The Charge−Transfer spectra have exhibited the active participation of the Guest molecule in Charge−Transfer excitations, but the electronic Redistribution has played the key role in the global spectrum of Guest@MOF complexes. Incorporating heteroaromatic guest molecules appeared as an outstanding strategy to tune-up the MOF electronic properties.