CPL Study Of Chiral Rare Earth Spirochetes Based On Dipicolinic Acid

In the past 20 years,due to the characteristics of circularly polarized luminescence(CPL),chiral lanthanide helicates had potential application value in the fields of optical storage,OLEDs,chiral recognition and biological probes,which has aroused great research enthusiasm among scientists.However,because lanthanide ions have variable coordination numbers and unclear coordination geometry,it is still a difficult problem to synthesize high |glum|,high luminescence quantum yield and enantiomerically pure chiral lanthanide helicates by self-assembly.This paper designed a C2-symmetric chiral bitridentate ligand based on two 2,6-pyridine dicarboxamide moieties,constructed two series of binuclear triple helicates,and studied their photophysical properties and CPL properties.The specific work was as follows:(1)A chiral bi-tridentate ligands L1RR/SS with ethylenediamine as spacer and two 2,6pyridine dicarboxamide as coordination units was designed and synthesized.And a series of enantiomerically pure chiral dinuclear triple-stranded helicates[Ln2(L1RR/SS)3](OTf)6(Ln=Eu,Y,Gd)was synthesized with the ligands and Ln(?)by self-assembly in a 3:2 ratio.Spectral characterization and semi-empirical structure optimization model showed that the point chirality of the ligand successfully induced the helicates[Eu2(L1RR/SS)3](OTf)6 to tend to a single helicates twist direction during the self-assembly process.The results of photophysical properties and CPL properties exhibited that the quantum yield of[Eu2(L1RR/SS)3](OTf)6 was 19%,and |glum| was 0.083.(2)A chiral bi-tridentate ligands L2RR/SS with 4,4'-diaminodiphenyl ether as the spacer and two 2,6-pyridine dicarboxamide as the coordination units was designed and synthesized.And a series of enantiomerically pure chiral dinuclear triple-stranded helicates[Ln2(L1RR/SS)3](OTf)6(Ln=Eu,Y,Gd)was synthesized with the ligands and Ln(?)by self-assembly in a 3:2 ratio.Spectral characterization and semi-empirical structure optimization model exhibited that the point chirality of the ligand successfully induced the helicates[Eu2(L2RR/SS)3](OTf)6 to tend to a single helicates twist direction during the self-assembly process.The results of photophysical properties and CPL properties showed that the quantum yield of[Eu2(L2RR/SS)3](OTf)6 was 16%,and |glum|was 0.061.