Near Infrared–CircularlyPolarized Luminescence/CircularDichroism Active Yb(III) Complexes Bearing Both Central and AxialChirality

In this contribution, we present new NIR-CPL/CD active Yb­(III) complexes, which are synthesized by combining two ligands characterized by different types of chirality: central and axial chirality. The ligand bearing central chirality is represented by the neutral <i>trans</i>-<i>N</i>,<i>N</i>′-bis­(2-pyridylmethylidene)-1,2-(<i>R</i>,<i>R</i> or <i>S</i>,<i>S</i>) cyclohexanediamine (<b>L</b>), whereas the axial ligand is 1,1′-binaphthyl-2,2′-diol (BINOL-H₂). A combined ¹H NMR, thermodynamic (spectrophotometric titrations), and theoretical (DFT structural calculations) study is presented, revealing the high stability in the methanol solution of the homochiral <i>C</i>_<i>2</i>-symmetric anionic [Yb<b>L</b>(BINOL)₂]⁻ complexes, in which the two labile BINOLate molecules exhibit the same stereochemistry (<i>R</i> or <i>S</i>). The metal ion-related optical and chiroptical properties of the complexes in the near-infrared spectral region are here presented and discussed: while the axial chirality dominates the circularly polarized luminescence features, the NIR-CD signal is affected by both chiral elements.