Different mechanisms for lanthanide(III) sensitization and Yb-field-induced single-molecule magnet behaviour in a series of pentagonal bipyramidal and octahedral lanthanide complexes with axial phosphine oxide ligands.

Seven mononuclear lanthanide complexes have been isolated and structurally characterised. Four of them are cationic, whose charges are balanced by chloride counteranions, and exhibit pentagonal bipyramidal coordination geometry, whereas the rest of them are neutral and display octahedral coordination environment. In all cases, the coordination sphere of the Ln ions consists of two di(1-adamantyl)benzylphosphine oxide ligands in axial positions, whereas in the equatorial plane the former contains a chloride and four water molecules and the latter a solvent molecule and three chloride ligands.

Magneto-Structural Correlations, Substitution Effects and Slow Relaxation of the Magnetization on Trinuclear Linear Ni(II) Complexes: An Experimental and Theoretical Study.

We report the preparation of three neutral linear trinuclear Ni(II) complexes [Ni(LX)] (1-3) by self-assembly of Ni(II) ions and NO-tripodal Schiff base ligands, LX, which were obtained by condensation between the triamine tris(methylhydrazine)phosphorylsulfide and salicylaldehyde derivatives with substituents X=H (L1) (1), Br (L2) (2) and NO (L3) (3) in para position to the phenoxo group. Experimental magneto-structural studies carried out on these complexes indicate that the magnetic exchange interactions between the neighboring Ni(II) ions are ferromagnetic in nature, moderate in magnitude and clearly dependent of the electronic properties of the substituent in para position. Thus, the electron-withdrawing NO group decreases the ferromagnetic coupling, whereas the Br substituent, with small electronic effects, does not significantly vary the exchange coupling observed for the unsubstituted complex.

Control of the geometry and anisotropy driven by the combination of steric and anion coordination effects in Co complexes with N-tripodal ligands: the impact of the size of the ligand on the magnetization relaxation time.

Four mononuclear Co complexes of formula [Co(L)(SCN)(CHOH)(HO)]·1.5HO·0.75CHOH (1), [Co(L1)Cl]·HO·2CHCN (2), [Co(L1)(SCN)]·1.

Synthesis, structures and magnetic studies of hexanuclear lanthanide complexes: SMM behavior of the Dy analogue and MCE properties of the Gd analogue.

The synthesis, structure and magnetic properties of homometallic hexanuclear lanthanide complexes [Ln(HL)(tfa)(S)]·2NO· HO·MeOH (1, Ln = Gd, S = MeOH, = 0, = 0; 2, Ln = Tb, S = HO, = 2, = 2; 3, Ln = Dy, S = MeOH, = 0, = 2; 4, Ln = Er, S = MeOH, = 0, = 2). [(HL) = 6-((bis(2-hydroxyethyl)amino)-'-(2-hydroxybenzylidene)picolinohydrazide) (tfa = trifloroacetylacetone)] are reported. These hexanuclear assemblies are made up of two trinuclear triangular sub-units linked through the oxygen atoms of two phenoxide bridging groups in a corner sharing arrangement.

Pushing up the easy-axis magnetic anisotropy and relaxation times in trigonal prismatic Co mononuclear SMMs by molecular structure design.

The replacement of pyridine by 1-methyl-imidazol in the arms of a N-tripodal ligand allows preparing two new Co complexes with quasi-ideal triangular prismatic geometry, which behave as SIMs (Single Ion Magnets) at zero dc field with enhanced axial magnetic anisotropy, magnetic relaxation times and magnetic hysteresis.

Magneto-thermal properties and slow magnetic relaxation in Mn(II)Ln(III) complexes: influence of magnetic coupling on the magneto-caloric effect.

A family of Mn(II)Ln(III) dinuclear and tetranuclear complexes (Ln = Gd and Dy) has been prepared from the compartmental ligands ,'-dimethyl-,'-bis(2-hydroxy-3-formyl-5-bromobenzyl)ethylenediamine (HL) and ,',''-trimethyl-,''-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (HL). The Mn(II)Gd(III) complexes exhibit antiferromagnetic interactions between Mn(II) and Gd(III) ions in most cases, which are supported by Density Functional Theory (DFT) calculations. Experimental magneto-structural correlations carried out for the reported complexes and other related complexes found in bibliography show that the highest ferromagnetic coupling constants are observed in di-μ-phenoxido bridged complexes, which is due to the planarity of the Mn-(μ-O)-Gd bridging fragment and to the high Mn-O-Gd angles.

Dinuclear CoYvs. tetranuclear CoY complexes: the effect of increasing molecular size on magnetic anisotropy and relaxation dynamics.

A new CoII2YIII2 complex with the formula [{Co(μ-L)Y(NO3)}2(μ-CO3)2]·2CH3OH·2H2O (where H2L = N,N',N''-trimethyl-N,N''-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine) has been prepared and its structure solved by single-crystal X-ray diffraction. The tetranuclear structure is formed by the connection of two [Co(μ-L)Y(NO3)] dinuclear units through two carbonate bridging ligands, which exhibit a μ3-κ2-O,O':κ-O:κ-O'' tetradentate coordination mode. The CoII ion exhibits a slightly distorted octahedral CoN3O3 coordination environment.

Gold@Prussian blue analogue core-shell nanoheterostructures: their optical and magnetic properties.

Au@Prussian-Blue Analogue (PBA) shell nanoheterostructures are multifunctional nano-objects combining optical properties (surface plasmon resonance) of the Au core and magnetic properties of the PBA shell. We report in this article a series of new Au core@PBA shell nano-objects with different PBA shells: Au@K/Co/[FeII(CN)6] (2) and Au@K/Ni/[CrIII(CN)6]:[FeII(CN)6] (3) single PBA shell, as well as Au@K/Ni/[FeII(CN)6]@K/Ni/[FeIII(CN)6] (4) double PBA shell and Au@K/Ni/[FeII(CN)6]@K/Ni/[FeIII(CN)6]@K/Ni/[CrIII(CN)6] (5) triple PBA shell systems. The position and intensity of the Au SPR band, as well as the magnetic behaviour of the nanoheterostructures, are strongly affected by the shell composition and its thickness.

On the Magnetic Coupling and Spin Crossover Behavior in Complexes Containing the Head-to-Tail [Fe(μ-SCN)] Bridging Unit: A Magnetostructural Experimental and Theoretical Study.

A new dinuclear complex [{Fe(tpc-OBn)(NCS)(μ-NCS)}] (1) based on the tripodal tpc-OBn ligand (tpc-OBn = tris(2-pyridyl)benzyloxymethane), containing bridging μ-κN:κS-SCN and terminal κN-SCN thiocyanate ligands, has been prepared and characterized by single crystal X-ray diffraction, magnetic studies, and DFT theoretical calculations. This complex represents the first example of dinuclear Fe complex with double μ-κN:κS-SCN bridges in a head-to-tail configuration that exhibits ferromagnetic coupling between metal ions (J = +1.08 cm).

Unprecedented tetranuclear complexes with "weighing balance shaped" topology: single crystal structures, unusual EPR spectra, magnetic properties and antioxidant activity.

Using the 2-hydroxy-N'-[(E)-phenyl(pyridin-2-yl)methylidene]benzohydrazide ligand and dicarboxylate anions (succinate and malonate), two new copper(ii) complexes of formula [Cu(μ-L)(μ-CH(COO))(HO)](NO)·4HO (1) and [Cu(μ-L)(μ-CH-CH(COO))(HO)](NO)] (2) have been synthesized and characterized by single crystal X-ray diffraction. Complexes 1 and 2 contain a dicarboxylate bridged tetranuclear Cu(ii) cationic unit with "weighing balance shaped" topology. These compounds have also been studied by variable temperature magnetic susceptibility measurements, X-band EPR spectroscopy and electrochemistry.

Importance of Steric Influences in the Construction of Multicomponent Hybrid Polymetallic Clusters.

The straightforward room temperature synthesis of hybrid polymetallic manganese clusters is investigated, exploiting complementary ligand combinations of p-tert-butylcalix[4]arene and salicylaldoximes. Eight new [MnMn] clusters have been prepared wherein the simple substitution of alkyl or aryl groups at well-defined positions of the salicylaldoxime scaffold leads to two distinct structure types that, while exhibiting the same general topology, contain the unique Mn ion in different positions. Incorporation of a methyl, ethyl, or isopropyl group at the 3-position of the aromatic skeleton or a phenyl group at the oximic carbon gives structure type A that displays competing weak ferromagnetic and antiferromagnetic interactions.

Synthetic ability of dinuclear mesocates containing 1,3-bis(diazinecarboxamide)benzene bridging ligands to form complexes of increased nuclearity. Crystal structures, magnetic properties and theoretical studies.

Triple stranded Ni-metallacyclic complexes Na[Ni(bpcb)]·0.5OH·18.5HO (1) and Na[Ni(bpzcb)]·16HO (2), and double stranded Cu-metallacyclic complexes [Cu(bpcb)(HO)]·8HO (3) and [Cu(bpzcb)(HO)]·4HO (4) have been assembled from the tailored bisbidentate bridging ligands, 1,3-bis(pyrimidine-2-carboxamide)benzene (Hbpcb) and 1,3-bis(pyrazine-2-carboxamide)benzene (Hbpzcb), and the corresponding nitrate salts of the metal ions.

Analysis of Magnetic Anisotropy and the Role of Magnetic Dilution in Triggering Single-Molecule Magnet (SMM) Behavior in a Family of Co Y Dinuclear Complexes with Easy-Plane Anisotropy.

Three new closely related Co Y complexes of general formula [Co(μ-L)(μ-X)Y(NO ) ] (X =NO 1, benzoate 2, or 9-anthracenecarboxylato 3) have been prepared with the compartmental ligand N,N',N''-trimethyl-N,N''-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H L). In these complexes, Co and Y are triply bridged by two phenoxide groups belonging to the di-deprotonated ligand (L ) and one ancillary anion X . The change of the ancillary bridging group connecting Co and Y ions induces small differences in the trigonally distorted CoN O coordination sphere with a concomitant tuning of the magnetic anisotropy and intermolecular interactions.

Engineered Au Core@Prussian Blue Analogous Shell Nanoheterostructures: Their Magnetic and Optical Properties.

We report a new approach for the synthesis of multifunctional Au core@Prussian Blue analogous (PBA) shell nanoheterostructures that involves PBA shell growth on the surface of cyanide-stabilized gold nanoparticles. It permits the assembly of Au@KNi [Fe (CN) ] core@shell and Au@KNi [Fe (CN) ]@KNi [Cr (CN) ] core@shell@shell heterostructures with well-defined and size-controlled gold cores and PBA shells. These heterostructures exhibit tunable size- and shape-dependent magnetic and optical properties: (i) the surface plasmon resonance band position and intensity mainly depend on the PBA shell thickness, and (ii) the magnetic properties (the transition temperature, the coercivity, and magnetic regime) depend in a complex manner on the thickness as well as the particular morphology of the magnetic shell.

Copper Keplerates: High-Symmetry Magnetic Molecules.

Keplerates are molecules that contain metal polyhedra that describe both Platonic and Archimedean solids; new copper keplerates are reported, with physical studies indicating that even where very high molecular symmetry is found, the low-temperature physics does not necessarily reflect this symmetry.

Facile interchange of 3d and 4f ions in single-molecule magnets: stepwise assembly of [Mn4 ], [Mn3Ln] and [Mn2Ln2 ] cages within calix[4]arene scaffolds.

The central Mn(II) ions in a series of calix[4]arene-stabilised butterflies can be sequentially replaced with Ln(III) ions, maintaining the structural integrity of the molecule but transforming its magnetic properties. The replacement of Mn(II) for Gd(III) allows for the examination of the transferability of spin-Hamiltonian parameters within the family as well as permitting their reliable determination. The introduction of the 4f ions results in weaker intramolecular magnetic exchange, an increase in the number of low-lying excited states, and an increase in magnetisation relaxation, highlighting the importance of exchange over single-ion anisotropy for the observation of SMM behaviour in this family of complexes.

Linked supramolecular building blocks for enhanced cluster formation.

Methylene-bridged calix[4]arenes have emerged as extremely versatile ligand supports in the formation of new polymetallic clusters possessing fascinating magnetic properties. Metal ion binding rules established for this building block allow one to partially rationalise the complex assembly process. The ability to covalently link calix[4]arenes at the methylene bridge provides significantly improved control over the introduction of different metal centres to resulting cluster motifs.

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

A CO3(2-)-panelled [Gd(III)6Cu(II)3] cage conforming to a tridiminished icosahedron is synthesised by bubbling CO2 through a solution of Gd(III) and Cu(II) ions.

Bifunctional Zn(II)Ln(III) dinuclear complexes combining field induced SMM behavior and luminescence: enhanced NIR lanthanide emission by 9-anthracene carboxylate bridging ligands.

There were new dinuclear Zn(II)-Ln(III) complexes of general formulas [Zn(μ-L)(μ-OAc)Ln(NO3)2] (Ln(III) = Tb (1), Dy (2), Er (3), and Yb (4)), [Zn(μ-L)(μ-NO3)Er(NO3)2] (5), [Zn(H2O)(μ-L)Nd(NO3)3]·2CH3OH (6), [Zn(μ-L)(μ-9-An)Ln(NO3)2]·2CH3CN (Ln(III) = Tb (7), Dy (8), Er (9), Yb(10)), [Zn(μ-L)(μ-9-An)Yb(9-An)(NO3)3]·3CH3CN (11), [Zn(μ-L)(μ-9-An)Nd(9-An)(NO3)3]·2CH3CN·3H2O (12), and [Zn(μ-L)(μ-9-An)Nd(CH3OH)2(NO3)]ClO4·2CH3OH (13) prepared from the reaction of the compartmental ligand N,N',N″-trimethyl-N,N″-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H2L), with ZnX2·nH2O (X = NO3(-) or OAc(-)) salts, Ln(NO3)3·nH2O, and, in some instances, 9-anthracenecarboxylate anion (9-An). In all these complexes, the Zn(II) ions invariably occupy the internal N3O2 site whereas the Ln(III) ions show preference for the O4 external site, giving rise to a Zn(μ-diphenoxo)Ln bridging fragment. Depending on the Zn(II) salt and solvent used in the reaction, a third bridge can connect the Zn(II) and Ln(III) metal ions, giving rise to triple-bridged diphenoxoacetate in complexes 1-4, diphenoxonitrate in complex 5, and diphenoxo(9-anthracenecarboxylate) in complexes 8-13.

Oxacalix[4]arene-supported di-, tetra- and undecanuclear copper(II) clusters.

Oxacalix[4]arenes containing either one or two oxa-bridges afford di and undecanuclear Cu(II) clusters respectively upon reaction with cupric nitrate under facile conditions. Variation in reaction conditions results in formation of a tetranuclear Cu(II) cluster with mono-oxacalix[4]arene, representing a structural expansion of the dinuclear assembly.

A bis-phenolate for the construction of linear lanthanide trimers.

The ligand bis(5-tert-butyl-2-hydroxy-3-hydroxymethyl-phenyl)methane, a flexible calix[n]arene analogue, is employed to construct an unusual linear [Ln3] trimer.

Increasing the dimensionality of cryogenic molecular coolers: Gd-based polymers and metal-organic frameworks.

The magnetothermal properties of a coordination polymer and a metal-organic framework (MOF) based on Gd(3+) ions are reported. An equally large cryogenic magnetocaloric effect (MCE) is found, irrespective of the dimensionality. This combined with their robustness makes them appealing for widespread magnetic refrigeration applications.

Diphenoxo-bridged Ni(II)Ln(III) dinuclear complexes as platforms for heterotrimetallic (Ln(III)Ni(II))2Ru(III) systems with a high-magnetic-moment ground state: synthesis, structure, and magnetic properties.

The first examples of pentanuclear heterotrimetallic [(LnNi)(2)Ru] [Ln(3+) = Gd (1) and Dy (2)] complexes were prepared and magnetostructurally characterized. They exhibit ferromagnetic interactions, leading to a high-magnetic-moment ground state.

Family of carboxylate- and nitrate-diphenoxo triply bridged dinuclear Ni(II)Ln(III) complexes (Ln = Eu, Gd, Tb, Ho, Er, Y): synthesis, experimental and theoretical magneto-structural studies, and single-molecule magnet behavior.

Seven acetate-diphenoxo triply bridged M(II)-Ln(III) complexes (M(II) = Ni(II) and Ln(III) = Gd, Tb, Ho, Er, and Y; M(II) = Zn(II) and Ln(III) = Ho(III) and Er(III)) of formula [M(μ-L)(μ-OAc)Ln(NO(3))(2)], one nitrate-diphenoxo triply bridged Ni(II)-Tb(III) complex, [Ni(μ-L)(μ-NO(3))Tb(NO(3))(2)]·2CH(3)OH, and two diphenoxo doubly bridged Ni(II)-Ln(III) complexes (Ln(III) = Eu, Gd) of formula [Ni(H(2)O)(μ-L)Ln(NO(3))(3)]·2CH(3)OH have been prepared in one pot reaction from the compartmental ligand N,N',N"-trimethyl-N,N"-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H(2)L). Moreover, Ni(II)-Ln(III) complexes bearing benzoate or 9-anthracenecarboxylate bridging groups of formula [Ni(μ-L)(μ-BzO)Dy(NO(3))(2)] and [Ni(μ-L)(μ-9-An)Dy(9-An)(NO(3))(2)]·3CH(3)CN have also been successfully synthesized. In acetate-diphenoxo triply bridged complexes, the acetate bridging group forces the structure to be folded with an average hinge angle in the M(μ-O(2))Ln bridging fragment of ~22°, whereas nitrate-diphenoxo doubly bridged complexes and diphenoxo-doubly bridged complexes exhibit more planar structures with hinge angles of ~13° and ~2°, respectively.

Characterization of Pt-protein complexes by nHPLC-ESI-LTQ MS/MS using a gel-based bottom-up approach.

The suitability of in-gel digestion for the characterization of Pt-binding proteins by gel-based bottom-up MS approaches has been evaluated regarding the preservation of Pt-protein bonds during the process. Standard proteins (albumin, transferrin, carbonic anhydrase, myoglobin and cytochome c) incubated with cisplatin were separated by nrSDS-PAGE and in-gel trypsin-digested. The whole in-gel digestion protocol included treatment with reagents such as: ammonium bicarbonate, acetonitrile, formic acid, trypsin as enzyme and alternatively, dithiotreitol and iodoacetamide as reducing and alkylating agents.