Two Pairs of Homochiral Parallelogram-like Dy 4 Cluster Complexes with Strong Magneto-Optical Properties.

Two pairs of homochiral Dy(III) tetranuclear cluster complexes derived from (+)/(-)-3-trifluoroacetyl camphor ( D -Htfc/ L -Htfc), [Dy 4 (OH) 2 (L1) 4 ( D -tfc) 2 (DMF) 2 ]·4DMF ( D - 1 ) [H 2 L1 = ( E )-2-(2-hydroxy-3-methoxybenzylideneamino)phenol)]/[Dy 4 (OH) 2 (L1) 4 ( L -tfc) 2 (DMF) 2 ]·4DMF ( L - 1 ) and [Dy 4 (OH) 2 (L2) 4 ( D -tfc) 2 (DMF) 2 ]·2H 2 O·3MeCN ( D - 2 ) [H 2 L2 = ( E )-3-(2-hydroxy-3-methoxybenzylideneamino)naphthalen-2-ol]/[Dy 4 (OH) 2 (L2) 4 ( L -tfc) 2 (DMF) 2 ]·2H 2 O·3MeCN ( L - 2 ), were synthesized at room temperature, which have a Dy 4 parallelogram-like core. The magnetic studies revealed that D - 1 exhibits single-molecule magnet (SMM) behavior under zero dc magnetic field, and its magnetic relaxation has a distinct Raman process in addition to the Orbach process, with the U eff / k value of 57.5 K and the C value of 28.27 s -1 K -2.14 ; while D - 2 displays dual magnetic relaxation behavior at 0 Oe field, with the U eff / k value 114.8 K for the slow relaxation process (SR) and the C value of 10.656 s -1 K -5.80 for the fast relaxation process (FR), respectively. Theoretical calculations indicated that the conjugated groups (phenyl vs naphthyl) of the Schiff base bridging ligands (H 2 L1 and H 2 L2) significantly affect the intramolecular magnetic interactions between the Dy 3+ ions and ultimately lead to different relaxations. Furthermore, magnetic circular dichroism (MCD) measurements showed that these two pairs of Dy 4 enantiomers exhibit strong room temperature magneto-optical Faraday effects; notably, increasing the conjugated group on the Schiff base bridging ligand is beneficial to enhancing the magneto-optical Faraday effects.