Effects of Counterions, Coordination Anions, and Coordination Solvent Molecules on Single-Molecule Magnetic Behaviors and Nonlinear Optical Properties of Chiral Zn 2 Dy Schiff Base Complexes.

By changing the counterions (ClO 4 - and CF 3 SO 3 - ) and the coordination anions (Cl - and Br - ), we investigated their influences on the structures and performances of a class of Zn 2 Dy chiral single-molecule magnets (SMMs), which are based on a pair of chiral Schiff bases R , R -H 2 L Schiff and S , S -H 2 L Schiff { R , R -H 2 L Schiff = 2-(( E )-((1 R ,2 R )-2-(( E )-2-hydroxy-3-methoxybenzylideneamino)cyclohexylimino)methyl)-6-methoxyphenol and S , S -H 2 L Schiff = 2-(( E )-((1 S ,2 S )-2-(( E )-2-hydroxy-3-methoxybenzylideneamino)cyclohexylimino)methyl)-6-methoxyphenol}. Three pairs of chiral Zn 2 Dy Schiff base complexes were obtained by directed synthesis, which are [DyZn 2 ( R , R - L Schiff )Cl 2 (H 2 O)](ClO 4 )·0.5MeOH·0.25H 2 O ( R - 1 ) and [DyZn 2 ( S , S - L Schiff )Cl 2 (H 2 O)][DyZn 2 ( S , S - L Schiff )Cl 2 (MeOH)](ClO 4 ) 2 ·MeOH·0.5H 2 O ( S - 1 ), [DyZn 2 ( R , R - L Schiff )Cl 2 (H 2 O)](CF 3 SO 3 )·0.5MeOH ( R - 2 ) and [DyZn 2 ( S , S - L Schiff )Cl 2 (H 2 O)][DyZn 2 ( S , S - L Schiff )Cl 2 (MeOH)](CF 3 SO 3 ) 2 ·MeOH ( S - 2 ), and [DyZn 2 ( R , R - L Schiff )Br 2 (H 2 O)](CF 3 SO 3 )·0.25MeOH ( R - 3 ) and [DyZn 2 ( S , S - L Schiff )Br 2 (H 2 O)][DyZn 2 ( S , S - L Schiff )Br 2 (MeOH)](CF 3 SO 3 ) 2 ( S - 3 ). They all exhibit good SMM behaviors, and their magnet relaxation is regulated by not only the counterions (ClO 4 - and CF 3 SO 3 - ) but also the coordination anions (Cl - and Br - ); these anions also have important effects on the second-harmonic generation (SHG) and third harmonic generation (THG) nonlinear optical properties. Interestingly, in the S -configuration complexes, the coordination solvent molecule of the Dy 3+ ion on half of the molecules is the methanol molecule instead of the water molecule. This change in the coordinating solvent molecule can also significantly affect the SMM behaviors and the SHG and THG nonlinear optical properties. Moreover, ab initio calculations were applied to rationally explain the SMM properties.