Covalent　organic　frameworks　(COFs)　are　crystalline,　porous　semiconductors　that　have　attracted　significant　interest　in　photocatalysis.　The　double　chain　edge　structure　of　one-dimensional　(1D)　COFs　enhances　stability　and　minimizes　energy　loss,　while　varying　linkage　orientations　create　diverse　optical　band　gaps　and　charge　transfer　properties.　However,　dimensional　and　isomeric　COFs　are　rarely　explored　in　photoinduced　electron　transfer-reversible　addition-fragmentation　chain　transfer　(PET-RAFT)　polymerization,　leaving　their　structure-activity　relationships　unclear.　Herein,　we　synthesized　1D　TA-COF,　1D　TF-COF,　2D　TA-COF,　and　2D　TF-COF　to　evaluate　their　behavior　in　oxygen-tolerant　PET-RAFT　polymerization.　Notably,　1D　TA-COF　demonstrated　optimal　photocatalytic　performance　(79.4%,　16　h)　owing　to　efficient　charge　separation,　while　isomeric　1D　TF-COF　exhibited　lower　productivity　(41.5%)　due　to　hindered　electron　transfer.　Additionally,　2D　TF-COF　outperformed　2D　TA-COF　(51.0%　vs.　36.7%,　16　h),　highlighting　the　considerable　impacts　of　dimension　and　isomerism　on　performance,　with　dimension　playing　a　more　dominant　role　due　to　the　electron　delocalization　characteristics　determined　by　topological　structure.　©　2025　Elsevier　Ltd