Computational Details. Theoretical calculations were performed under the density functional theory (DFT) framework by means of the Gaussian-16.A03 suite of programs. Minimum-energy geometry structures were obtained upon atom relaxation at the B3LYP/6-31G(d,p) level of theory including dispersion corrections by means of the Grimme's D3 (Becke-Johnson damping function) protocol. To maintain the topology of the cluster models as in the corresponding MOF, the terminal hydrogen atoms were frozen during the optimization procedure. Non-covalent interaction (NCI) surfaces were obtained under the NCIPLOT-3.0 program 37 and visualized through the VMD software 38 with standard thresholds of 0.3 and 0.04 a.u. for the reduced density gradient and density, respectively. Time-dependent DFT calculations were performed on the lowest-lying singlet excited states at the B3LYP/6-31G(d,p) level.