Molecular Design Guidelines for Large Magnetic Circular Dichroism Intensities in Lanthanide Complexes

Abstract

Magneto optical devices based on the Faraday effects of lanthanide ion have attracted much attention. Recently, large Faraday effects were found in nano-sized multinuclear lanthanide complexes. In this study, the Faraday rotation intensities were estimated for lanthanide nitrates [Ln(III) (NO3 )3 ⋅n H2 O: Ln=Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm) and Eu(III) complexes with β-diketone ligands, using magnetic circular dichroism. Eu ions exhibit the largest Faraday rotation intensity for (7) F0 →(5) D1 transitions, and high-symmetry fields around the Eu ions induce larger Faraday effects. The molecular design for the enhancement of Faraday effects in lanthanide complexes is discussed.

Homochiral Ferromagnetic Coupling Dy2 Single-Molecule Magnets with Strong Magneto-Optical Faraday Effects at Room Temperature

“…Another feature is that the magnetic field parallel to and antiparallel to the light propagation direction have completely opposite effects on the CD signal: the positive direction magnetic field (+1.6 T) has a negative effect on the CD signal; on the contrary, the negative direction magnetic 45 and 4f complexes (≤0.24 T −1 ). 93 The large absolute value of g max(MCD) for the chiral Dy 2 enantiomers D-1 and L-1 indicates a very strong magneto-optical Faraday effect. Recent studies have shown that, for lanthanide (III) compounds, the strength of MCD can be enhanced by increasing the magnetic dipole moment of the ground states and the excited states.…”

“…The anisotropy factor of MCD, g MCD = 2­(ε + ( B ) – ε + (− B ))/(ε + ( B ) + ε + (− B )), was calculated for both l - 1 and d - 1 (Figure ), which have a roughly mirror symmetry in the 250–350 nm range. Notably, the values of g max(MCD) for l - 1 and d - 1 at room temperature are 1.27 and −1.72 T –1 , respectively, whose absolute values are remarkably large values, much larger than those of 3d–4f complexes [Co 2 Ln­[( R )/( S )-L] 4 ]·Cl 5 ·2H 2 O·MeOH·EtOH (Ln = Gd, Dy) (0.02 T –1 ) and 4f complexes (≤0.24 T –1 ) . The large absolute value of g max(MCD) for the chiral Dy 2 enantiomers d - 1 and l - 1 indicates a very strong magneto-optical Faraday effect.…”

“…The large absolute value of g max(MCD) for the chiral Dy 2 enantiomers d - 1 and l - 1 indicates a very strong magneto-optical Faraday effect. Recent studies have shown that, for lanthanide (III) compounds, the strength of MCD can be enhanced by increasing the magnetic dipole moment of the ground states and the excited states . The Dy­(III) ion itself has a large magnetic moment ( S = 7/2), and the ferromagnetic interaction between the two Dy­(III) ions corresponds to large magnetic dipole moments of the ground state and the excited states; therefore, a strong magneto-optical Faraday effect for d - 1 and l - 1 appears as expected.…”

“…Recent studies have shown that, for lanthanide (III) compounds, the strength of MCD can be enhanced by increasing the magnetic dipole moment of the ground states and the excited states. 93 The Dy(III) ion itself has a large magnetic moment (S = 7/2), and the ferromagnetic interaction between the two Dy(III) ions corresponds to large magnetic dipole moments of the ground state and the excited states; therefore, a strong magneto-optical Faraday effect for D-1 and L-1 appears as expected. This implies that they have potential application prospects in magnetooptical devices.…”

An Estimation Method of Metal‐Ligand Orbital Mixing in Lanthanide(III) Complexes Using Magnetic Circular Dichroism

“…In Figure b, we observed that the 4 f–5d transition bands of TbCl 3 ⋅6H 2 O and PrCl 3 ⋅ n H 2 O in the MCD spectra exhibit a similar same shape as those in the absorption spectra. According to the general theory, the MCD signals are classified into three terms using the existence or nonexistence of degenerate ground states and excited states as follows , …”