Ancillary ligand modulated stereoselective self-assembly of triple-stranded Eu(iii) helicate featuring circularly polarized luminescence.

Creating optically pure metal assemblies is a hot research topic in the realms of chiral supramolecules. Here, three new triple-stranded europium(iii) helicates Eu 2 L 3 (L') 2 [L = 4,4'-bis(4,4,4-trifluoro-1,3-dioxobutyl)diphenyl sulphide; L' = 1,10-phenanthroline (Phen) or R / S -2,2'-bis(diphenylphosphinyl)-1,1'-binaphthyl ( R / S -BINAPO)] were synthesized in order to investigate the effects of ancillary ligands on controlling the stereoselective self-assembly of lanthanide helicates. X-ray single crystal structure analysis showed that Eu 2 L 3 (Phen) 2 crystalized in an achiral space group P 1̄ with the equivalent amount of P and M helicates in one single cell. The isolated Eu 2 L 3 ( S -BINAPO) 2 and Eu 2 L 3 ( R -BINAPO) 2 were verified to be enantiopure by 1 H, 19 F, 31 P NMR and DOSY NMR analyses. Additionally, the mirror-image CD spectra also demonstrated the successful syntheses of the enantiomers and the presence of an effective chirality transformation from BINAPO to achiral L. Furthermore, the perfect mirror-image circularly polarized luminescence (CPL) spectra of Eu 2 L 3 ( S -BINAPO) 2 and Eu 2 L 3 ( R -BINAPO) 2 indicated the existence of the excited state chirality of the Eu 3+ center associated with | g lum | values reaching 0.112. In addition, the photophysical properties of three helicates were also discussed.