Six tetranuclear complexes $\left[\text{Fe}{\left(\text{III}\right)}_3\text{Ln}{\left({\mu }_3\text{-O}\right)}_2{\left({\text{CCl}}_3\text{COO}\right)}_8\left({\text{H}}_2\text{O}\right){\left(\text{THF}\right)}_3\right]\cdot \text{THF}\cdot {\text{C}}_7{\text{H}}_{16}$ [$\text{Ln}=\text{Gd}\left(\text{III}\right)$ (1), Tb(III) (2), Dy(III) (3), Ho(III) (4), Y(III) (5), and Lu(III) (6)] have been studied by magnetic susceptibility and Mössbauer spectroscopy. These isostructural molecules have a “butterfly” structure core consisting of two ${\text{Fe}}_2\text{Ln}\left({\mu }_3\text{-O}\right)$ triangular “wings” which share a common Ln-Fe “body”; the dihedral angle between the wings is ca. $148°$. The coordination spheres of the iron ions are essentially distorted octahedral. The lanthanides are eight-coordinate with coordination polyhedra that may be described as distorted tetragonal bipyramids. Variable-temperature solid-state magnetic susceptibility in the temperature range 1.8–300 K and magnetization at 1.8 K for compounds 1–6 were measured. The spin state of Fe is $S=5/2$ in all cases. In compounds 5 and 6, where Ln(III) (Y and Lu, respectively) is diamagnetic, the three Fe atoms form an obtuse isosceles triangle with antiferromagnetic interactions $J_{\text{Fe-Fe}}=-50\text{K}$ between the wing-tip ${\text{Fe}}_w$ and body ${\text{Fe}}_b$ atoms, and negligible interaction between the ${\text{Fe}}_w$’s, resulting in a ground state of effective spin $S=5/2$ per cluster. In the complexes with paramagnetic lanthanide ions, the interaction between the ${\text{Fe}}_3$ triangle and the Ln(III) center is described by an effective exchange constant which is antiferromagnetic and 1 order of magnitude weaker. Besides, at 3 K incipient spin blocking, characteristic of single molecule magnets, was found to occur in the out-of-phase component of the ac susceptibility in $\left\{{\text{Fe}}_3{\text{TbO}}_2\right\}$, $\left\{{\text{Fe}}_3{\text{DyO}}_2\right\}$, and $\left\{{\text{Fe}}_3{\text{HoO}}_2\right\}$. The activation energy of a Debye process describing the magnetization reversal has been determined to be, $E_a\approx 8$, 9, and 10 K for the $\text{Ln}=\text{Tb}$, Dy, and Ho, respectively, and the prefactor ${\tau }_0\approx {10}^{-7}\text{s}$. The high spin states of the Fe(III) centers were confirmed by the Mössbauer spectra, in which two distinguishable Fe sites could be resolved above 80 K, corresponding to the ${\text{Fe}}_w$ and ${\text{Fe}}_b$ sites, respectively. Relatively larger values of the quadrupole splitting of the Mössbauer spectra were observed for the ${\text{Fe}}_w$ pair as compared with that for the ${\text{Fe}}_b$, and both quadrupole splittings diminished with increasing temperature. At 3 K the Mössbauer spectra showed a state with blocked spins (sextets) for the $\left\{{\text{Fe}}_3{\text{TbO}}_2\right\}$ and $\left\{{\text{Fe}}_3{\text{DyO}}_2\right\}$ cases. From the $E_a$ and ${\tau }_0$, determined in the ac susceptibility, the relaxation time at 3 K is estimated as $\tau \approx {10}^{-5}–{10}^{-6}\text{s}$ much longer than the time window of Mössbauer spectroscopy and compatible with the single molecule magnet behavior. In the presence of a strong magnetic field the moments of the Ln(III) cation and the ${\text{Fe}}_3$ triangle are polarized. For some compounds at low temperature a magnetic pattern (sextet) for each of the three Fe sites appeared, and the antiferromagnetic coupling within the ${\text{Fe}}_3$ cluster was directly proved by the opposite trend of the field dependence of the two ${\text{Fe}}_w$ sextets as compared with the ${\text{Fe}}_b$ third one.

Synthesis and characterization of iron oxide nanoparticles coated with a large molar weight dextran for environmental applications are reported. The first experiments involved the synthesis of iron oxide nanoparticles which were coated with dextran at different concentrations. The synthesis was performed by a co-precipitation technique, while the coating of iron oxide nanoparticles was carried out in solution. The obtained nanoparticles were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectrometry, Fourier transform infrared spectroscopy and superconducting quantum interference device magnetometry. The results demonstrated a successful coating of iron oxide nanoparticles with large molar weight dextran, of which agglomeration tendency depended on the amount of dextran in the coating solution. SEM and TEM observations have shown that the iron oxide nanoparticles are of about 7 nm in size.

Dopamine-based attachment chemistry was used to form trifunctional magnetic particles.

Ru(III)/functionalized silica-coated magnetic nanoparticles (Ru(III)-MNP) were proven to be a highly active, selective and easily recoverable catalyst for the oxidation of levulinic acid to succinic acid under green conditions.