Oxime based manganese molecular magnets

The synthesis and characterisation of a large family of hexametallic [MnIII 6] Single-Molecule Magnets with general formula [MnIII 6O2(R-sao)6(X)2(L)4-6] (where sao2- = dianion of salicylaldoxime; R = H, Me, Et, Ph; X = O2CR' (R' = H, Me, Ph etc), Hal , O2PHPh or O2P(Ph)2; L = solvent) are presented. Deliberate structural distortions of the [Mn3O] trinuclear moieties within the complexes are used to tune the observed magnetic properties. These findings highlight a qualitative magnetostructural correlation whereby the type (anti- or ferromagentic) of each Mn2 pairwise magnetic exchange is dominated by the magnitude of each individual Mn-N-O-Mn torsion angle. To shed further light on this intriguing family of nanomagnets, a large family of the analogous “half” molecules has been synthesised and fully characterised. These trimetallic [MnIII 3] complexes can be divided into three categories with general formulae (type 1) [MnIII 3O(R-sao)3(X)(sol)3-4] (where R = H, Me, tBu; X = O2CR (R = H, Me, Ph etc); sol = py and / or H2O), (type 2) [MnIII 3O(R-sao)3(X)(sol)3-5] (where R = Me, Et, Ph, tBu; X = O2CR (R = H, Me, Ph etc); sol = MeOH, EtOH and / or H2O), and (type 3) [MnIII 3O(R-sao)3(sol)3](XO4) (where R = H, Et, Ph, Naphth; sol = py, MeOH, -pic, Et-py, tBu-py; X = Cl, Re). In the crystals the ferromagnetic triangles are involved in extensive inter-molecular H-bonding which is clearly manifested in the magnetic behaviour, producing exchange-biased SMMs. These interactions can be removed by ligand replacement to give “simpler” SMMs. The [MnIII 6] and [MnIII 3] molecular nanomagnets are then exploited as building blocks to construct supramolecular architectures by means of host-guest interactions and coordination driven self-assembly. A number of discrete and infinite architectures based on the molecular triangle [Mn3] and various pyridyl-type ligands were obtained and structurally and magnetically characterised

Electroskip Auditory Biofeedback in a Patient with Parkinson Disease: A Case Report

The purpose of this case study was to observe the effects of a rehabilitation program with an audio-biofeedback technology device called Electroskip in a patient with Parkinson disease. The patient was a 61-year-old man with moderate Parkinson disease (Hoehn and Yahr Parkinson’s scale stage III) and dementia who had progressive episodes of freezing of gait. The patient also had a history of recent falls. The patient completed a 6-week rehabilitation program focused on functional tasks, balance and gait training while using Electroskip technology, which is a wireless, wearable device that sends a discrete real-time generative audio-biofeedback signal when the user steps on either the heel or toe force sensors positioned under the innersoles. The outcome measures included the Timed Up and Go test, the modified Gait Abnormality Rating Scale, the modified Parkinson’s Activity Scale, and the Freezing of Gait Questionnaire. The patient completed 17 of the 18 scheduled training sessions and all testing sessions; no adverse events occurred during the rehabilitation program and high satisfaction levels were reported by the patient and family after completion of the 6-week rehabilitation program. Clinically significant improvements were seen in all measures at 6 weeks. The results of this report suggest that a rehabilitation program focused on functional tasks, balance, and gait training using the Electroskip technology may be beneficial for improving gait and balance in a patient with moderate Parkinson disease. Future work is needed to determine the effectiveness of Electroskip technology by means of randomized controlled trials

Magnetic Quantum Tunneling: Insights from Simple Molecule-Based Magnets

This article takes a broad view of the understanding of magnetic bistability and magnetic quantum tunneling in single-molecule magnets (SMMs), focusing on three families of relatively simple, low-nuclearity transition metal clusters: spin S = 4 Ni4, Mn(III)3 (S = 2 and 6) and Mn(III)6 (S = 4 and 12). The Mn(III) complexes are related by the fact that they contain triangular Mn3 units in which the exchange may be switched from antiferromagnetic to ferromagnetic without significantly altering the coordination around the Mn(III) centers, thereby leaving the single-ion physics more-or-less unaltered. This allows for a detailed and systematic study of the way in which the individual-ion anisotropies project onto the molecular spin ground state in otherwise identical low- and high-spin molecules, thus providing unique insights into the key factors that control the quantum dynamics of SMMs, namely: (i) the height of the kinetic barrier to magnetization relaxation; and (ii) the transverse interactions that cause tunneling through this barrier. Numerical calculations are supported by an unprecedented experimental data set (17 different compounds), including very detailed spectroscopic information obtained from high-frequency electron paramagnetic resonance and low-temperature hysteresis measurements. Diagonalization of the multi-spin Hamiltonian matrix is necessary in order to fully capture the interplay between exchange and local anisotropy, and the resultant spin-state mixing which ultimately gives rise to the tunneling matrix elements in the high symmetry SMMs (ferromagnetic Mn3 and Ni4). The simplicity (low-nuclearity, high-symmetry, weak disorder, etc..) of the molecules highlighted in this study proves to be of crucial importance.Comment: 32 pages, incl. 6 figure

Two unique star-like [MnIVMnIII2LnIII] clusters: magnetic relaxation phenomena

Synthesis and magnetic properties of two tetrametallic star-like [MnIVMnIII2Ln] (Ln: Gd, Dy) clusters.</p

A hexameric [MnIII18Na6] wheel based on [MnIII3O]7+ sub-units

International audienc

Addressing the magnetic properties of sub-monolayers of single-molecule magnets by X-ray magnetic circular dichroism

We report on a comparative study of electronic and magnetic properties of Mn6 single-molecule magnets (SMMs) grafted on gold surface. Two derivatives with spin-ground states S ¼ 4 andhave been functionalized with 3-tp-CO2 (3-thiophene carboxylate, tpc) ligands and characterized thick films (TFs) as well as sub-monolayers (sMLs) by synchrotron based techniques. X-ray absorption spectroscopy at the Mn L2,3 edges shows the modification of the spectral lineshape in the sMLs respect to the TFs suggesting that the local symmetry at the Mn sites changes once the molecules deposited on gold surface. In spite of this, the expected MnIII oxidation state is preserved. X-ray magnetic circular dichroism (XMCD) spectra show that the total magnetic moment is only spin part because of the quenched orbital moment. Moreover, variable temperature and variable XMCD spectra reveal an effective decrease of the Mn spin moment for both derivatives

CO2 as a reaction ingredient for the construction of metal cages:a carbonate-panelled [Gd6Cu3] tridiminished icosahedron

A CO32--panelled [(Gd6Cu3II)-Cu-III] cage conforming to a tridiminished icosahedron is synthesised by bubbling CO2 through a solution of Gd-III and Cu-II ions