Near-infrared phosphorescence emission of three-fold interpenetrated MOF based on 1,4-bis(imidazole-1-ylmethyl)benzene: Syntheses, structure and photoelectron performance

One new Zn(II) based 3D metal-organic framework (MOF) [Zn(IPA) (TBMIM)] (1) (IPA = isophthalic acid, TBMIM = 1,4-bis(imidazole-1-ylmethyl)benzene) has been synthesized under hydrothermal conditions. X-ray single-crystal diffraction analysis indicates that the title MOF exhibits a 3-fold interpenetrated diamond network with new type of molecular braid. Time-resolved measurements reveal that 1 emissions rare example of near-infrared phosphorescence at room temperature. The density functional theoretical (DFT) calculations indicate complete separation of molecular orbits between IPA and TBMIM ligands, which is in favor of the generation of triplet state excitons. This MOF also shows well photoelectron responds performance owing to the abundant pi center dot center dot center dot pi stacking in the entanglement molecular braids, which afford long-range pi electrons delocalization for efficient electron transport.