Homochiral Cu6Dy3 single-molecule magnets displaying proton conduction and a strong magneto-optical Faraday effect

Abstract

Using the new Schiff base ligands condensed from 2-hydroxy-1-naphthalenecarboxaldehyde and (1R,2R)/(1S,2S)-2-aminocyclohexanol (R-H₃L/S-H₃L), a pair of homochiral Cu₆Dy₃ heterometallic cluster complexes [Cu₆Dy₃(R-L)₆(OH)₆(H₂O)₆](ClO₄)(NO₃)₂·4.75H₂O·8.5MeOH (R-1) and [Cu₆Dy₃(S-L)₆(OH)₆(H₂O)₆](ClO₄)(NO₃)₂·5.5H₂O·8MeOH (S-1) were synthesized at room temperature, which exhibit an interesting topology of triangular corner-sharing cubanes. Magnetic measurements revealed that they are zero-field single-molecule magnets (SMMs), with different U_eff/k values of 19.5(0.6) K for R-1 and 21.4(0.4) K for S-1, owing to solvent magnetic effects. Meanwhile, the chiral enantiomers show proton conductivity caused by hydrogen bonding networks. Furthermore, the circular dichroism (CD) spectra of R-1 and S-1 confirmed their enantiomeric nature, and the magnetic circular dichroism (MCD) study indicated that both R-1 and S-1 have strong magneto-optical Faraday effects at room temperature, with a large |g_max(MCD)| value of 0.58 T⁻¹.