Modulating Two Pairs of Chiral Dy^III Enantiomers by Distinct β-Diketone Ligands to Show Giant Differences in Single-Ion Magnet Performance and Nonlinear Optical Response

Abstract

Using Dy(dbm)3(H2O) and Dy(btfa)3(H2O)2 to react with enantiopure N-donors, (−)/(+)-4,5-pinenepyridyl-2-pyrazine (LR/LS), respectively, two pairs of chiral DyIII enantiomers, Dy(dbm)3LR/Dy(dbm)3LS (R-1-Dy/S-1-Dy) and Dy(btfa)3LR/Dy(btfa)3LS (R-2-Dy/S-2-Dy) were obtained, wherein one of the benzene rings of dbm– (dibenzoylmethanate) in R-1-Dy/S-1-Dy is displaced by the −CF3 group of btfa– (4,4,4-trifluoro-1-phenyl-1,3-butanedionate) in R-2-Dy/S-2-Dy. Interestingly, this substitution results not only in giant differences in their single-ion magnetic (SIM) performances but also in their completely different nonlinear optical (NLO) responses. R-1-Dy presents a large effective energy barrier (Ueff = 265.47 K) under zero applied field, being more than 4 × R-2-Dy (61.40 K). The discrepancy on their magnetic performances has been further elucidated by ab initio calculations. Meanwhile, R-1-Dy/S-1-Dy display the strongest third-harmonic generation responses (35/33 × α-SiO2) among the known lanthanide NLO-active coordination compounds (CCs). On the contrary, R-2-Dy/S-2-Dy exhibit moderate second-harmonic generation responses (0.65/0.70 × KDP). These results not only give the first example of the CCs with both SMM/SIM behavior and a THG response but also provide an efficient strategy for achieving the function regulation and switch in multifunctional CCs.