Stimuli-responsive materials that exhibit chiroptical properties are critical to developing complex responsivity in next generation security, biological sensing, 3-D display and data storage materials.[1] Current chiral materials are, however, limited in their device application due to their low chiroptical responses and a lack of specific control over the response. The achievement of supramolecular chirality, particularly through the combination of metal ions and chiral ligands as coordination polymers, is known to not only increase chiroptical responsivity, but also generate properties additional or different to those of their component parts.[2] Lanthanoid (Ln) based materials have efficient chiroptical responses due to their magnetic anisotropy and their fluorescent properties make Ln-based chiral materials effective circularly polarised luminescence (CPL) emitters.[2] We aim to develop stimuli responsive chiral coordination polymers through the combination of Ln3+ ions and chiral ligands with an outlook for their applications as sensing materials.
We report a series of Ln-based assemblies comprised of either Pr3+, Eu3+ or Eu3+ and a chiral naphthalene-based ligand. X-ray diffraction studies showed material structure was dependent on both the identity of the metal ion and the amount of water present during synthesis. Fluorescence, circular dichroism and magnetic circular dichroism studies reflect the observed differences in the materials’ structure. Water responsivity studies within the Pr3+ based materials showed chiroptical modulation based on the relative hydration levels of the materials. Findings will support the development of sustainable materials with complex detection functionality for use in next generation devices.