Vibrational Circular Dichroism Spectroscopy toward Intercalation Compounds of Sodium Montmorillonite: Evidences for Molecular Packing of Enantiopure Monovalent Ir(III) Complexes within Interlayer Spaces

Solid state vibrational circular dichroism (SD-VCD) spectra were recorded on the intercalation compounds of sodium montmorillonite with a chiral iridium(III) complex. The complex used was Δ- (or Λ-)[Ir(bzq) ₂(phen)] ⁺ (bzqH = benzo[ h ]quinoline; phen = 1,10-phenanthroline). The complex formed mono- or bi-molecular layers in interlayer spaces, depending on the adsorption amount to 50% or 100% cation exchange capacity (CEC), respectively. Notably, the VCD signals were sensitive enough to reveal the detailed molecular interactions in adsorption layers. Signal enhancement was achieved by the coherent delocalization of vibrational motions over tightly bound associates. Models of molecular packing were proposed with the help of theoretical simulations.