Semiquantitative Studies on the Correlations Between the Electrostatic Potential of Single DyIII Ion and its Energy Barriers in the Containing Dy Single Molecule Magnets†

Abstract

Although design of the containing Dy(III) single molecule magnets (SMMs) based on electrostatic potential has been employed for several years, the reasonable studies on the correlations between the electrostatic potential of single DyIII ion and its energy barriers was not reported previously. In this work, a novel “Y”-shaped MnIII5DyIII3 complex, [MnIII5DyIII3(NO3)(OCH3)(L)4(L')2(tea)(teaH)4]OH·3CH3OH·2H2O (1, H2L = 2-methoxy-6-[(Z)-(1H-1,2,4-triazol-3-ylimino)methyl]phenol, H3tea = triethanolamine and HL'= 2-hydroxy-3-methoxybenzaldehyde) was obtained by the reaction of H2L ligand, teaH3, Dy(NO3)3·6H2O and MnCl2·4H2O in CH3OH and DMF. Structural analysis revealed that the coordination geometry of Dy1 in 1 is muffin (MFF-9, Cs), while the geometries of Dy2 and Dy3 are located among spherical capped square antiprism (CSAPR-9, C4v), spherical tricapped trigonal prism (TCTPR-9, D3h) and muffin (MFF-9, Cs). Magnetic studies indicated that 1 exhibits slow magnetic relaxation behavior under a zero dc field. More importantly, we first proposed two parameters Req and Rax to describe the relationship. The two parameters were employed for three DyIII in 1, and one Zn2Dy complex as well as one mononuclear Dy complex reported by others. The results indicate that the calculated energy barrier (Ucal) continuously increase upon decreasing the Rax absolute values. However, the Rax absolute values are larger, the Ucal are smaller. This indicates that when the electrostatic potentials from two sides of the equatorial plane of DyIII are completely equivalent with each other, the Ucal is the largest. Moreover, POLY_ANISO and DFT calculations for 1 indicated that except for J4 showing ferromagnetic coupling, all magnetic couplings are antiferromagnetic, which were interpreted by the magneto-structural correlation.