An Azole-Based Metal–Organic Framework toward Direct White-Light Emissions by the Synergism of Ligand-Centered Charge Transfer and Interligand π–π Interactions

An azole-based metal–organic framework [Cd(tzphtpy)2]n·6.5nH2O, hydrothermally synthesized from the reaction mixture of a π-electron rich azole ligand 4-(tetrazol-5-yl)phenyl-2,2′:6′,2″-terpyridine (Htzphtpy) and CdBr2·4H2O, displays direct white-light emissions at a wide range of excitation wavelengths (286–386 nm) through modulating the relative intensity of complementary yellow and blue colors. Photoluminescence experiments and density of states and the calculations of time-dependent density functional theory demonstrate that the higher-energy blue emission is attributed to intraligand charge transfer, and the lower-energy yellow emission is related to interligand π–π interactions. The synergism of ligand-centered charge transfer and interligand π–π interactions is first found in white-light emitting azole-based metal–organic frameworks. Our work provides a new synthetic strategy for azole-based or other system white-light emitting materials.