Pollution caused by antibiotics, bacteria, and organic dyes presents global public health challenges, posing serious risks to human health. Consequently, new, efficient, fast, and simple photocatalytic systems are urgently required. To this end, 2,7-di(pyridin-4-yl)benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone (NDI)-an electron acceptor-is introduced as a connecting column into a porphyrin-based metal-organic layer (2DTcpp) with excellent photocatalytic activity
this modification yields a three-dimensional pillar-layered metal-organic framework (MOF, 3DNDITcpp) with superior photocatalytic reactive oxygen species (ROS) generation capability. Introducing NDI enlarges the pore cavity of 3DNDITcpp creating active sites and boosting type II ROS production. The orderly arrangement of the electron donor (porphyrin layer) and acceptor (NDI) within 3DNDITcpp promotes photo-induced electron transfer (PET) interactions-as confirmed by density functional theory calculations-substantially boosting type I ROS production. Specifically, the energy levels of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of the porphyrin derivative ligand are -0.122252 and -0.185307 eV, respectively. The energy levels of the LUMO and HOMO of the NDI ligand are -0.15977 and -0.221199 eV, respectively. The HOMO energy level of the porphyrin ligand is between the HOMO and LUMO of NDI, and higher than the HOMO orbital energy level of NDI, proving that the porphyrin derivative ligand can act as an electron donor and carry out an efficient PET process with the electron acceptor NDI. Various ROS indicators demonstrate the superior ROS generation ability of 3DNDITcpp under light irradiation. Using activated 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) as an indicator of total ROS, the fluorescence enhancement factors of 2DTcpp, 3DPyTcpp, and 3DNDITcpp were 42.13, 48.24 and 94.21 times, respectively. Both the degradation curve and degradation rate of 9,10-anthracenediyl-bis(methylene)dimalonic acid (ABDA) demonstrated that the order of