Effect of solvents on multifunctional Dy2 complexes with axial chiral ligands (R)/(S)-1,1′-binaphthyl-2,2′-diyl phosphate

Abstract

It is still a major challenge to construct multifunctional complexes using axial chiral ligands. Herein, the axial chiral ligands (R)/(S)-1,1′-binaphthyl-2,2′-diyl hydrogen phosphate (R-HL/S-HL) were used as bridging ligands, and together with the Schiff base bridging ligand {H₂L_Schiff = [2-[(E)-(5-fluoro-2-hydroxyphenyl)methylidene]diazanyl](4-chloropyridin-2-yl)methanone}, two pairs of homochiral Dy₂ complexes [Dy₂(R-L/S-L)₂(L_Schiff)₂(DMA)₂]·3DMA·4H₂O (R-1/S-1) and [Dy₂(R-L/S-L)₂(L_Schiff)₂(DMF)₂]·3DMF (R-2/S-2) were successfully constructed at room temperature in different solvents (DMA vs. DMF). Interestingly, although their coordination modes as terminal ligands are very similar, the subtle differences between DMA and DMF molecules cause changes in the space groups: R-1 and S-1 crystallize in the P1 chiral space group, whereas R-2 and S-2 crystallize in the P2₁2₁2₁ chiral space group, which may affect their nonlinear optical properties: R-1/S-1 exhibits both SHG and THG responses, while R-2 and S-2 only display a THG response. Notably, R-1/S-1 and R-2/S-2 are ferromagnetically coupled and behave as single-molecule magnets (SMMs) at 0 Oe, and their magnetic properties were further studied using ab initio calculations. Moreover, the magneto-optical effects of R-1/S-1 and R-2/S-2 were investigated using their magnetic circular dichroism (MCD) spectra.