Defect　engineering　in　metal　organic　frameworks　(MOFs)　has　captured　significant　attention　in　the　field　of　photocatalysis.　A　series　of　UiO-66(Ce)　(UiO　=　University　of　Oslo)　MOFs　with　different　contents　of　missing-linker　defects　have　been　developed　for　the　photocatalytic　selective　oxidation　of　benzylamine　(BA)　and　thioanisole　(TA)　under　visible　light.　The　introduction　of　missing-linker　defects　promotes　the　formation　of　unsaturated　Ce　sites　with　a　high　Ce3+　content.　It　also　generates　a　high　concentration　of　oxygen　vacancies.　In　situ　Fourier　transform　infrared　spectroscopy　(FTIR)　results　revealed　that　BA　and　TA　molecules　were　activated　on　coordinatively　unsaturated　Ce　sites　via　the　H–N···Ce　and　the　C–S···Ce　interactions,　respectively.　Simulated　in　situ　electron　paramagnetic　resonance　(EPR)　data　indicate　that　O2　activation　and　reduction　occur　at　coordinatively　unsaturated　Ce3+　sites　to　form　·O2–.　This　is　accelerated　by　the　Ce3+/Ce4+　redox　cycle　associated　with　the　photogenerated　electrons.　The　corresponding　photogenerated　holes　are　involved　in　the　deprotonation　of　the　activated　BA　and　TA.　The　most　active　sample　exhibits　98.4%　and　95.5%　conversion　rates　for　BA　and　TA　oxidation.　Mechanisms　for　the　molecular　activation　are　proposed　at　the　molecular　level.　Graphical　abstract:　(Figure　presented.).　©　Youke　Publishing　Co.,Ltd　2024.