The {FeIII[FeIII(L1)2]3} star-type single-molecule magnet

Assessing the effect of regularization on the molecular properties predicted by SCAN and self-interaction corrected SCAN meta-GGA

Recent regularization of the SCAN meta-GGA functional (rSCAN) has simplified the numerical complexities of the SCAN functional, alleviating SCAN's stringent demand on the numerical integration grids to some extent. The regularization of rSCAN, however, results in the breaking of some constraints such as the uniform electron gas limit, the slowly varying density limit, and coordinate scaling of the iso-orbital indicator. Here, we assess the effects of regularization on the electronic, structural, vibrational, and magnetic properties of molecules by comparing the SCAN and rSCAN predictions. The properties studied include atomic energies, atomization energies, ionization potentials, electron affinities, barrier heights, infrared intensities, dissociation and reaction energies, spin moments of molecular magnets, and isomer ordering of water clusters. Our results show that rSCAN requires less dense numerical grids and gives very similar results to those of SCAN for all properties examined with the exception of atomization energies, which are worsened in rSCAN. We also examine the performance of self-interaction-corrected (SIC) rSCAN with respect to SIC-SCAN using the Perdew-Zunger (PZ) SIC method. The PZSIC method uses orbital densities to compute one-electron self-interaction errors and places an even more stringent demand on numerical grids. Our results show that SIC-rSCAN gives marginally better performance than SIC-SCAN for almost all properties studied in this work with numerical grids that are on average half or less as dense as that needed for SIC-SCAN.

Molecular Engineering of Metal Alkoxides for Solution Phase Synthesis of High-Tech Metal Oxide Nanomaterials

The 'bottom-up' synthesis of inorganic nanomaterials with precision at the atomic/molecular level offers many opportunities for the design and improvement of the nanomaterials for various applications. Molecular engineering during soft chemical processing for the synthesis of functional nanomaterials enables the desired chemical and physical properties of the precursors, such as solubility or volatility, clean decomposition, control of stoichiometry for multimetallic species to name a few, and leads to easy control of uniform particle size distribution, stoichiometry…. This Minireview illustrates some important aspects of the molecular engineering in light of some recent developments from the molecular synthesis of nanomaterials involving non-silicon metal alkoxide systems for high-tech applications.

Element specific determination of the magnetic properties of two macrocyclic tetranuclear 3d-4f complexes with a Cu3Tb core by means of X-ray magnetic circular dichroism (XMCD)

We apply X-ray magnetic circular dichroism to study the internal magnetic structure of two very promising star shaped macrocyclic complexes with a CuII3TbIII core. These complexes are rare examples prepared with a macrocyclic ligand that show indications of SMM (Single Molecule Magnet) behavior, and they differ only in ring size: one has a propylene linked macrocycle, [CuII3TbIII(LPr)(NO3)2(MeOH)(H2O)2](NO3)·3H2O (nickname: Cu3Tb(LPr)), and the other has the butylene linked analogue, [CuII3TbIII(LBu)(NO3)2(MeOH)(H2O)](NO3)·3H2O (nickname: Cu3Tb(LBu)). We analyze the orbital and spin contributions to the Cu and Tb ions quantitatively by applying the spin and orbital sum rules concerning the L2 (M4)/L3 (M5) edges. In combination with appropriate ligand field simulations, we demonstrate that the Tb(iii) ions contribute with high orbital magnetic moments to the magnetic anisotropy, whereas the ligand field determines the easy axis of magnetization. Furthermore, we confirm that the Cu(ii) ions in both molecules are in a divalent valence state, the magnetic moments of the three Cu ions appear to be canted due to 3d-3d intramolecular magnetic interactions. For Cu3Tb(LPr), the corresponding element specific magnetization loops reflect that the Cu(ii) contribution to the overall magnetic picture becomes more important as the temperature is lowered. This implies a low value for the 3d-4f coupling.

Chiroptical and magnetic properties of star-shaped Fe complexes from chiral Schiff bases. Structural and magnetic correlations based on continuous shape measures

New chiral FeIII4 star-shaped complexes have been synthesized starting from enantiomerically pure Schiff bases and chiroptically and magnetically characterized. The structural and magnetic properties of the complete family of 40 Fe4 complexes reported in the literature have been analyzed in the search for synthetic and magnetostructural correlations.

Uniaxial magnetic anisotropy energy of bimetallic Co-Ni clusters from a first-principles perspective

Along with the growing precision in the control of matter at increasingly smaller size scales, a field of research, based onto magnetic materials of technical interest, such as bimetallic clusters, has been developed in very recent years. Thereby, here, we report on a complete study of bimetallic clusters composed of cobalt and nickel with up to 7 atoms using ab initio methods in the GGA approach. We applied an unrestricted search method based on the tensor of inertia eigenvalues to find the most stable configurations of the clusters, obtaining a diverse set of structures with different geometric properties. We explored the effect of composition on the structural properties, the chemical stability, the magnetization and the magnetic anisotropy energy (MAE) of the so-obtained systems. Our results indicate that the behavior of the clusters is mainly governed by the Co-Co interaction and to a lesser extent by the Co-Ni and Ni-Ni interactions. Furthermore, for a given cluster size the magnetic moment increases by 2 μB/Co-substitution plus 1 μB/Ni-substitution coming from the cobalt and nickel core d-states, while in some cases unpaired hybrid s-electrons can also give rise to itinerant magnetism. These features have been analyzed with the help of a Jellium model and have important consequences for the magnetism and the magnetic anisotropy of the clusters. The magnetic behavior and MAE present complex and intriguing landscapes, which suggests the possibility of finely controlling the magnetic states, by tuning the cluster composition, aiming at technical implementation in fields such as molecular magnetism or quantum computation. In particular, cases such as Co6Ni, Co4Ni3, CoNi6 Co2Ni5 and Co3Ni3 present high relative stability and enhanced magnetic moments (around 10 μB), what makes them promising candidates for applications such as subnanometer magnetic information storage.

Self-assembly of a mixed-valence FeII–FeIII tetranuclear star

A self-assembled mixed-valence Fe^II–Fe^III tetranuclear star is reported that shows ferromagnetic coupling, field-induced single molecule magnetism and strong magnetic anisotropy at the peripheral Fe^II centres.

Aminoalcohols and benzoates-friends or foes? Tuning nuclearity of Cu(ii) complexes, studies of their structures, magnetism, and catecholase-like activities as well as performing DFT and TDDFT studies

The Cu(ii) complexes of varying nuclearity are synthesized, characterized and assessed for catecholase activities.

First heterometallic GaIII–DyIII single-molecule magnets: implication of GaIII in extracting Fe–Dy interaction

First heterometallic Ga^III–Dy^III single-molecule magnets have been synthesized and the role of the Ga^III in extracting Fe^III–Dy^III interaction has been assessed.

Magnetic and transport properties of Fe4single-molecule magnets: a theoretical insight

DFT methods have been employed to analyse the magnetic and transport properties of a family of Fe₄complexes showing single-molecule magnet behaviour deposited on gold surfaces.

Structural isomers of iron(iii) N-methyl diethanolaminate as sol–gel precursors for iron-based oxide nanomaterials

New aminoalkoxides of Fe(iii) were synthesized, evaluated for different sol–gel parameters to stabilize nano-sized colloidal suspensions, and employed for the elaboration of magnetic Fe₂O₃ and BiFeO₃ NPs and thin films.

A single molecule magnet to single molecule magnet transformation via a solvothermal process: Fe4Dy2 → Fe6Dy3

Under ambient and solvothermal conditions four new compounds [FeIII4LnIII2(μ₃-OH)₂(mdea)₄(m-NO₂C₆H₄COO)₈]·3MeCN and [FeIII6LnIII3(μ₄-O)₃(μ₃-O)(mdea)₅(m-NO₂C₆H₄COO)₉]·3MeCN (Ln = Y and Dy) have been synthesised and their magnetic properties investigated.

Enforcement of a high-spin ground state for the first 3d heterometallic 12-metallacrown-4 complex

Applying a novel magnetic director approach, we have realized Cu(ii)(DMF)₂Cl₂[12-MC_{Fe(III)N(Shi)}-4](DMF)₄·2DMF as the first heterometallic transition metal 12-MC-4 complex in order to provide this type of compound with a high-spin ground state.

Syntheses, structures and magnetic properties of a family of heterometallic [Mn(II)2Mn(III)2Ln(III)2] clusters

A new family of isostructural Mn-Ln heterometallic clusters, [Mn(II)(2)Mn(III)(2)Ln(III)(2)(Piv)(8)(thme)(2)(H(2)tea)(2)] (H(3)thme = 1,1,1-tris(hydroxymethyl)ethane, Hpiv = pivalic acid, H(3)tea = triethanolamine, and Ln = Pr, Nd, Sm, Eu, Gd, Tb, and Dy) have been prepared by reaction of the hexanuclear manganese precursor, [Mn(6)O(2)(Piv)(10)(4-Me-Py)(2.5)(Hpiv)(1.5)], with H(3)thme, H(3)tea, and Ln(NO(3))(3)·6H(2)O under the solvothermal conditions. Complexes 1Pr-7Dy were characterized by single-crystal X-ray diffraction and their core [Mn(2)(III)Mn(2)(II)Ln(2)(III)(μ(3)-OR)(4)(μ(2)-OR)(6)](6+) composed of four face-sharing defected cubane units. Antiferromagnetic (AF) exchange interactions were suggested for all of the complexes by solid-state dc magnetic susceptibility measurements. Complexes 6Tb and 7Dy, show frequency-dependent ac susceptibility signals suggestive of slow magnetic relaxation.

Effects of frustration on magnetic molecules: a survey from Olivier Kahn until today

In magnetism, of which molecular magnetism is a part, the term frustration is used rather sloppily. Sometimes one gains the impression that if the reason for some phenomenon is not quite clear then it is attributed to frustration. In this paper a discussion of the effects of frustration that are relevant for the field of molecular magnetism is presented. As will become clear later these effects indeed lead to a variety of unusual magnetic properties.