Polychromatic Electrochemiluminescence Imaging of Single Heteroligand Metal-Organic Crystals

Conventional polychromatic electrochemiluminescence (ECL) imaging is realized with the several separated luminophores at the different potentials. In this study, an emerging polychromatic ECL imaging system was constructed based on single heteroligand metal-organic framework (MOF) crystals as nanoemitters through an intrareticular energy transfer process. The heteroligand MOF crystals, named h-NJU-241, were coassembled of meso-tetrakis(4-carboxyphenyl)porphyrin (TCPP) with 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy) ligand using benzoic acid catalyst with coordination ability, leading to the conjugated spacing of 0.624 nm between two ligands. Remarkably, an energy transfer efficiency of 92.2% was achieved when the coordination weight ratio of TCPP acceptor and TBAPy donor was only 1.87‰. Different from monoligand MOFs, the heteroligand h-NJU-241 exhibits dual ECL emissions in both blue and red regions at one step applied potential, which is first example of polychromatic ECL imaging for single MOF crystals. Furthermore, by adjusting the reaction conditions, the morphology distribution of porphyrin within the crystal can be dynamically controlled, providing a tailored crystal platform for decoding fundamentals in polychromatic ECL imaging.