The influence of nuclear spin on the magnetic hysteresis of a single-molecule is evidenced. Isotopically enriched Dy(III) complexes are synthesized and an isotopic dependence of their magnetic relaxation is observed. This approach is coupled with tuning of the molecular environment through dilution in an amorphous or an isomorphous diamagnetic matrix. The combination of these approaches leads to a dramatic enhancement of the magnetic memory of the molecule. This general recipe can be efficient for rational optimization of single-molecule magnets (SMMs), and provides an important step for their integration into molecule-based devices.

We report persistent chiral organic mono-and diradical cations based on bicarbazole molecular design with an unprecedented stability dependence on the type of chirality, namely axial versus helical. An unusual chemical stability was observed for sterically unprotected axial bicarbazole radical, in comparison with monocarbazole and helical bicarbazole ones. Such results were experimentally and theoretically investigated, revealing an inversion in energy of the singly occupied molecular orbital (SOMO) and the doubly highest occupied molecular orbital (HOMO) in both axial and helical bicarbazole monoradicals, along with a subtle difference of electronic coupling between the two carbazole units, which is modulated by their relative dihedral angle and related to the type of chirality. Such findings allowed us to explore in-depth the SOMO-HOMO inversion (SHI) in chiral radical molecular systems and provide new insights regarding its impact on the stability of organic radicals. Finally, these specific electronic properties allowed us to prepare a persistent, intrinsically chiral, diradical which notably displayed near infrared electronic circular dichroism responses up to 1100 nm and almost degenerate singlet-triplet ground states with weak antiferromagnetic interactions evaluated by magnetometry experiments.

Racemic and optically pure [Dy(hfac)(L)] complexes with L = 3-(2-pyridyl)-4-aza[6]-helicene have been synthesized and characterized. Both the racemic and enantiopure forms behave as single molecule magnets in their crystalline phase, while electronic circular dichroism activity is evidenced. Ab initio calculations on isolated complexes followed by the determination of intermolecular dipolar couplings allowed the rationalization of the different low-temperature magnetic behaviours. The enantiopure SMM differs from the racemic one by the presence of a hysteresis loop in the former system.

Stable bulk glasses from the quaternary system Cu-As-Te-Se are investigated for thermoelectric applications. These materials exhibit a low thermal conductivity k $ 0.3 W K À1 m À1 which is appealing for raising the thermoelectric figure of merit ZT. The addition of small amounts of selenium within the telluride amorphous matrix plays two fundamental roles. First, the increased disorder associated with the size mismatch improves glass-formation and widens the glass-formation domain, and second, it increases phonon scattering and slightly decreases the thermal conductivity. Furthermore, the addition of copper up to 32% dramatically increases the electrical conductivity without notably affecting the thermal conductivity. This permits us to obtain bulk glass samples with promising thermoelectric properties, which could be manufactured through conventional low-cost glass casting methods. While addition of copper permits the increase of electrical conductivity by more than six orders of magnitude, another three orders of magnitude are required to obtain thermoelectric materials with competitive ZT.Nevertheless, predicted values of ZT > 1.2 are estimated which would constitute some of the highest reported figure of merit for a bulk solid at room temperature. The effect of glass annealing on thermoelectric properties is also discussed.

We report a single‐chain magnet (SCM) made of a terbium(III) building block and a nitronyl‐nitroxide radical (NIT) functionalized with an aliphatic chain. This substitution is targeted to induce a long‐range distortion of the polymeric chain and accordingly it gives rise to chains that are curled with almost 20 nm helical pitch. They self‐organize as a chiral tubular superstructure made of 11 chains wound around each other. The supramolecular tubes have a 4.5 nm internal diameter. Overall, this forms a porous chiral network with almost 44 % porosity. Ab initio calculations highlight that each TbIII ion possesses high magnetic anisotropy. Indeed, notwithstanding the supramolecular arrangement each chain behaves as a SCM. Magnetic relaxation with both finite and infinite‐size regimes is observed and confirms the validity of the Ising approximation. This is associated with quite strong coercive field and magnetic remanence (Hc=2400 Oe MR=2.09 μB at 0.5 K) for this class of compounds.

We report the study of a Dy-based metal-organic framework (MOF) with unprecedented magnetic properties. The compound is made of nine-coordinated Dy magnetic building blocks (MBBs) with poor intrinsic single-molecule magnet behavior. However, the MOF architecture constrains the MBBs in a one-dimensional structure that induces a ferromagnetic coupling between them. Overall, the material shows a magnetic slow relaxation in absence of external static field and a hysteretic behavior at 0.5 K. Low-temperature magnetic studies, diamagnetic doping, and ab initio calculations highlight the crucial role played by the Dy-Dy ferromagnetic interaction. Overall, we report an original magnetic object at the frontier between single-chain magnets and single-molecule magnets that host intrachain couplings that cancel quantum tunneling between the MBBs. This compound is evidence that a bottom-up approach through MOF design can induce spontaneous organization of MBBs able to produce remarkable molecular magnetic materials.

A novel radical gold dithiolene complex exhibits a hexagonal columnar mesophase, as confirmed by optical microscopy, DSC analysis and X-ray diffraction. The extent of delocalization of the spin density in such a complex was analyzed by EPR. Temperature dependent magnetization measurements reveal that the global magnetic moment is remarkably affected at the liquid-crystalline phase transition with a marked hysteresis signature, rare behavior among the few described paramagnetic discotic phases. In addition, these molecules were found to strongly aggregate in solution into one-dimensional fibers with a mean diameter of 60 nm extending over micrometres, leading to the formation of gel-like structures. These fibers are stable and can be isolated on surfaces. The gelation of the system can also be detected by temperature-dependent magnetic measurements.

A ruthenium carbon-rich-based ligand that brings redox reversibility to a dysprosium-based single-molecule magnet is reported. Long-distance perturbation of the 4f ion is achieved upon oxidation, resulting in an overall enhancement of the magnetic slow relaxation.