Here we report photodynamic therapy (PDT) photosensitizer of N^C^N-coordinated Pt(II) complexes: [Pt(L1)(MeOH)]⁺ (HL1 = 1,3-(2-dipyridyl)benzene, MeOH = methanol) and [Pt(L1)]@HSA which is the Pt(II) complex encapsulated in human serum albumin (HSA). Quantum yield of singlet oxygen production for [Pt(L1)(MeOH)]⁺ is more than 50 % while that for the encapsulated Pt(II) complex is much lower. Photo-images of human umbilical vein endothelial cell (HUVEC) treated with the Pt(II) complexes suggest that [Pt(L1)(MeOH)]⁺ is delocalized in entire cell after the fast uptake by diffusion and [Pt(L1)]@HSA is taken up by the endocytosis and localized on organelles and cell membrane. [Pt(L1)(MeOH)]⁺ shows high photocytotoxicity for HUVEC while [Pt(L1)]@HSA doesn’t show photocytotoxicity.

　Metal–organic cages (MOCs) with luminophores have significant advantages for the facile detection of specific molecules based on turn-on or turn-off luminescence changes induced by host–guest complexation. One important challenge is the development of turn-on-type near-infrared (NIR)-luminescent MOCs. In this study, we synthesized a novel MOC consisting of two porphyrin dyes linked by four Yb(III) complexes, which exhibit bimodal red and NIR fluorescence signals upon photoexcitation of the porphyrin π system. Single-crystal X-ray structural analysis and computational molecular modeling revealed that planar aromatic perfluorocarbons were intercalated into the MOC. The tight packing between the MOC and guests enhanced the NIR fluorescence of Yb(III) by suppressing energy transfer from the photoexcited porphyrin to oxygen molecules. Guest-responsive turn-on NIR fluorescence changes in an MOC were successfully demonstrated.

　Oxygen quantification using luminescence has attracted considerable attention in various fields, including environmental monitoring and clinical analysis. Among the reported luminophores, trivalent lanthanide complexes have displayed characteristic narrow emission bands with high brightness. This bright emission is based on photo-sensitized energy transfer via organic triplet states. The organic triplet states in lanthanide complexes effectively react with the triplet oxygen, enabling oxygen quantification by lanthanide luminescence. Some Tb^III and Eu^III complexes with slow deactivation processes have also formed the excited state equilibrium, thus resulting in the emission-lifetime based oxygen sensing property. The combination of Tb^III/Eu^III emission, Eu^III/Sm^III emission, Eu^III/ligand phosphorescence, and ligand fluorescence/ligand phosphorescence provide the ratiometric oxygen-sensing properties. Moreover, the reaction generates singlet oxygen species which exhibit numerous applications in the photo-medical field. The ligands with large π-conjugated aromatic systems, such as porphyrin, phthalocyanine, and polyaromatic compounds, induces highly efficient oxygen generation. The combination of effective luminescence with singlet-oxygen generation by the lanthanide complexes render them suitable for photo-driven theranostics. This review summarizes the research progress of lanthanide complexes with efficient oxygen-sensing and singlet-oxygen generation properties.