Multifunctional Dy Enantiomeric Pairs Showing Enhanced Photoluminescences and Third-Harmonic Generation Responses through the Coordination Role of Homochiral Tridentate -Pincer Ligands.

By utilizing Dy(hfac)(HO) to react with enantiomerically pure tridentate -pincer ligands, namely (-)/(+)-2,6-bis(4',5'-pinene-2'-pyridyl)pyridine (L and L), respectively, homochiral Dy enantiomeric pairs formulated as Dy(hfac)L/Dy(hfac)L (/) (hfac = hexafluoroacetylacetonate) were achieved and structurally characterized. Meanwhile, their magnetic, photoluminescent (PL), and chiroptical properties were probed. The PL test results indicate that the precursor Dy(hfac)(HO) only shows very weak emission, while exhibits characteristic Dy f-f transition emission bands at room temperature. Furthermore, the nonlinear optical responses of Dy(hfac)(HO), L/L, and / were investigated in detail based on crystalline samples. The results reveal that L and L present the coexistence of second- and third-harmonic generation (SHG and THG) responses with more intense signals for SHG responses; and Dy(hfac)(HO) merely displays weak THG responses, while and also only exhibit THG responses. However, the THG intensities of and are more than six times larger than that of Dy(hfac)(HO) under the identical measurement conditions. These results demonstrate that introducing homochiral -pincer ligands to replace two HO molecules of Dy(hfac)(HO) results in significant improvements of both PL performances and THG responses of resultant / enantiomers. and integrate PL, THG, and chiral optical activity in one molecule, suggesting their multifunctional merits. In particular, a convenient method is introduced to simultaneously test THG and SHG responses of molecular materials based on crystalline samples in this work.