Optical Phenomena in Molecule-Based Magnetic Materials

Since the last century, we have witnessed the development of molecular magnetism which deals with magnetic materials based on molecular species, i.e., organic radicals and metal complexes. Among them, the broadest attention was devoted to molecule-based ferro-/ferrimagnets, spin transition materials, including those exploring electron transfer, molecular nanomagnets, such as single-molecule magnets (SMMs), molecular qubits, and stimuli-responsive magnetic materials. Their physical properties open the application horizons in sensors, data storage, spintronics, and quantum computation. It was found that various optical phenomena, such as thermochromism, photoswitching of magnetic and optical characteristics, luminescence, nonlinear optical and chiroptical effects, as well as optical responsivity to external stimuli, can be implemented into molecule-based magnetic materials. Moreover, the fruitful interactions of these optical effects with magnetism in molecule-based materials can provide new physical cross-effects and multifunctionality, enriching the applications in optical, electronic, and magnetic devices. This Review aims to show the scope of optical phenomena generated in molecule-based magnetic materials, including the recent advances in such areas as high-temperature photomagnetism, optical thermometry utilizing SMMs, optical addressability of molecular qubits, magneto-chiral dichroism, and opto-magneto-electric multifunctionality. These findings are discussed in the context of the types of optical phenomena accessible for various classes of molecule-based magnetic materials.

Rare-earth based tetrapyrrolic sandwiches: chemistry, materials and applications

This review summarises advances in chemistry of tetrapyrrole sandwiches with rare earth elements and highlights the current state of their use in single-molecule magnetism, organic field-effect transistors, conducting materials and nonlinear optics.

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

By the bridging action of the 6-chloro-2-hydroxypyridine (Hchp) ligand and the terminal coordination role of the homochiral ligand, (-)/(+)-3-trifluoroacetyl camphor (l-Htfc/d-Htfc), a pair of enantiomerically pure dysprosium(III) dinuclear complexes, [Dy₂(l-tfc)₄(chp)₂(MeOH)₂] (l-1) and [Dy₂(d-tfc)₄(chp)₂(MeOH)₂] (d-1), was obtained. Their circular dichroism (CD) spectra verified their enantiomeric nature. Magnetic investigation indicated that they exhibit ferromagnetic interaction and good zero field single-molecule magnet (SMM) properties. The U_eff/k values of l-1 and d-1 at 0 Oe are 180.5 and 181.3 K, respectively, which are large values for homochiral Dy(III) SMMs. A reasonable explanation for the magnetic properties of l-1 and d-1 was supplied by ab initio calculations. Remarkably, magnetic circular dichroism (MCD) investigation revealed that the chiral Dy₂ enantiomers show a strong magneto-optical Faraday effect at room temperature, suggesting potential applications in magneto-optical devices.

Assembly of chiral 3d–4f wheel-like cluster complexes with achiral ligands: single-molecule magnetic behavior and magnetocaloric effect

With the help of perchlorate ions, chiral M₃Ln₃ wheel-like cluster complexes were constructed from achiral ligands, and showed single-molecule magnetic behavior and magnetocaloric effect.

Bis[1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninato]terbium Double-Decker Single-Ion Magnets

For the purpose of further exploring the effect of nonperipherally attached substituents on single-ion magnet (SIMs) performance, tetrasubstituted bis[1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninato]terbium double-deckers, in both the reduced form TbH[Pc(α-OC₅H₁₁)₄]₂ (1) and the neutral form Tb[Pc(α-OC₅H₁₁)₄]₂ (2), were prepared. Single-crystal X-ray diffraction analysis for 2 unambiguously demonstrates the pinwheellike molecular structure with C₄ symmetry. Magnetic investigations of the two bis(phthalocyaninato)terbium double-deckers reveal their characteristic SIM nature. 2 exhibits SIM performance superior to that of 1, as revealed by the larger energy barrier of 466 K for the former species and 431 K for the latter species due to the presence of organic radical-f (radical-Tb) interactions. The enhanced SIM performance of 2 in comparison to 1 actually stems from the presence of radical-f interactions and an enhanced ligand field strength. The latter positive factor is indicated by the electrostatic potential around the terbium ion on the basis of density functional theory (DFT) calculations.

A rare chloride-bridged dysprosium chain with slow magnetic relaxation: a thermally activated mechanism via a second-excited state promoted by magnetic interactions

Magnetic interactions induced by chloride bridges promote the slow magnetic relaxation in a dysprosium chain to pass through the second-excited state.