Near Infrared–Circularly Polarized Luminescence/Circular Dichroism Active Yb(III) Complexes Bearing Both Central and Axial Chirality

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 trans-N,N′-bis­(2-pyridylmethylidene)-1,2-(R,R or S,S) cyclohexanediamine (L), 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 C₂-symmetric anionic [YbL(BINOL)₂]⁻ complexes, in which the two labile BINOLate molecules exhibit the same stereochemistry (R or S). 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.