Asymmetric Eu(III) Coordination Polymers Featuring Coexisting Δ/Λ Chirality and Diverse Coordination Geometries.

Chiral Eu(III) coordination polymers incorporating three types of aromatic bridging ligands ([Eu(+tfc)3(dpb)]n, [Eu(+tfc)3(dpf)]n, and [Eu(+tfc)3(dpt)]n) were successfully synthesized (+tfc: (+)-3-(trifluoroacetyl)camphor; dpb: 1,4-bis(diphenylphosphoryl)benzene; dpf: 2,5-bis(diphenylphosphoryl)furan; dpt: 2,5-bis(diphenylphosphoryl)thiophene). The chain arrangement appears to depend on the bridging ligand: [Eu(+tfc)3(dpb)]n and [Eu(+tfc)3(dpf)]n adopt Type-A structures, each comprising two distinct homochiral polymer chains in a spiral arrangement: one with a Λ configuration and the other with a Δconfiguration. In contrast, [Eu(+tfc)3(dpt)]n forms a Type-B structure featuring heterochiral chains with alternating Λ and Δconfigurations in a zigzag pattern. Notably, these asymmetric Eu(III) coordination polymers represent the first example combining dual chiral configurations (Δ-form and Λ-form) with different coordination geometries (8-SAP or 8-TDH). The photophysical properties and circularly polarized luminescence (CPL) spectra were investigated.