Oxahelicene-Based Pd ₂ L ₄ Cages: Synthesis, Optical Properties, and Guest Encapsulation

7-Oxa[5]- and 9-oxa[7]helicene-based ligands L1 and L2 bearing two pyridyl coordination sites were synthesized, and their self-assembly with Pd(II) ions into a Pd₂L₄ cages was demonstrated. The self-assembled cages retained high fluorescence quantum yields (ΦF = 0.50 for Pd2L1₄), exhibited significant circular dichroism (CD)/circularly polarized luminescence (CPL) activity for Pd2L2₄, and displayed guest-encapsulating behavior owing to the inherent oxahelicene ligands. Structural analysis via NMR, MS, and DFT calculations supported cage formation.