Luminescent lanthanide (III) ions have been exploited for circularly polarized luminescence (CPL) for decades. However, very few of these studies have involved chiral samarium (III) complexes. Complexes are prepared by mixing axial chiral ligands (R/S))-2,2'-bis(diphenylphosphoryl)-1,1′-binaphthyl (BINAPO) with europium and samarium Tris (trifluoromethane sulfonate) (Eu (OTf) 3 and Sm (OTf) 3 ). Luminescence-based titration shows that the complex formed is Ln((R/S)-BINAPO) 2 (OTf) 3 , where Ln = Eu or Sm. The CPL spectra are reported for Eu((R/S)-BINAPO) 2 (OTf) 3 and Sm((R/S)-BINAPO) 2 (OTf) 3 .The sign of the dissymmetry factors, g em , was dependent upon the chirality of the BINAPO ligand, and the magnitudes were relatively large. Of all of the complexes in this study, Sm((S)-BINAPO) 2 (OTf) 3 has the largest g em = 0.272, which is one of the largest recorded for a chiral Sm 3+ complex. A theoretical three-dimensional structural model of the complex that is consistent with the experimental observations is developed and refined. This report also shows that (R/S)-BINAPO are the only reported ligands where g em (Sm 3+ ) > g em (Eu 3+ ).

Metabolic G-protein Coupled Receptors (GPCRs). (A) Intramembrane access to the binding pocket of GPR40 (also known as free fatty acid receptor 1; PDB code: 4PHU). The binding pocket of GPR40 (grey) is covered by extracellular loop 2 (ECL2; cyan) preventing entry from the extracellular space. Instead the allosteric regulator, TAK-875 (pink), accesses the binding pocket through the plasma membrane. (B) Structural determination of the lysophosphatidic acid receptor (LPA 1 ; PDB code: 4Z34). LPA 1 was crystallized with a stabilizing Cytochrome b 562 RIL subunit (circled in orange) inserted into the third intracellular loop and with membrane lipids bound to help orient LPA 1 in the plasma membrane. (C) Pharmacological regulation of metabotropic glutamate receptor 5 (mGlu5; PDB code: 4OO9). Slab view of the allosteric binding site (allosteric regulator mavoglurant (red)) within the 7-transmembrane helices of mGlu5 (green).