An undecanuclear ferrimagnetic Cu9Dy2 SMM achieved through ligand fine-tuning

We describe the concept of increasing the nuclearity of a previously reported high-spin Cu5Gd2 core using a “fine tuning” ligand approach. Thus two Cu9Ln2 coordination clusters, with Ln = Dy (1), Gd(2) were synthesized with the Gd compound having a ground spin state of 17/2 and the Dy analogue showing SMM behavior in zero field

Twists to the spin structure of the Ln9-diabolo motif exemplified in two {Zn2Ln2}[Ln9]{Zn2} coordination clusters

Two pentadecanuclear Zn4Ln11 [with Ln = Gd(1) or Dy(2)] coordination clusters, best formulated as {Zn2Ln2}[Ln9]{Zn2}, are presented. The central {Ln9} diabolo core has a {Zn2Ln2} handle motif pulling at two outer Ln ions of the central core via two {ZnLn} units, which also invest the system with C2 point symmetry. The resulting cluster motif is supported on two Zn “feet”, corresponding to the {Zn2} unit in the formula. A thorough investigation of the magnetic properties in the light of the properties of previously reported {Ln9} diabolo compounds was undertaken. Up to now, the spin structure of such diabolo motifs usually proves ambiguous. Our magnetic studies show that the orientation of the central spin in the {Gd9} diabolo plays a decisive role. In stabilizing the core by attachment of the {Zn}2+ “feet” and using the C2 symmetry related {ZnGd}5+ handles to influence the spin direction of the central Gd of the {Gd9} diabolo we can understand why the “naked” {Gd9} diabolo shows ambiguous spin structure. This then allowed us to elucidate the single molecule magnetic (SMM) properties of the Dy based compound 2 through disentangling the magnetic properties of the isostructural Gd based compound 1

Varying the dimensionality of Cu(II)-based coordination polymers through solvent influence

This work reports the synthesis and structure of a large porous zeotype network observed within compound (1) using {Cu2(piv)4} as the linking unit (piv = pivalate). The slow in-situ formation of the hmt ligand (hexamethylenetetramine) appears to be key in generating a µ4-briding mode of the hmt-node. Attempts to improve the low yield of compound (1) using different solvent layer diffusion methods resulted in the µ3-hmt complexes (2) and (3). Both compounds exhibit a 3D network of two intertwined chiral networks. Strong hydrogen bonding present in (3) leads to the formation of intertwined DNA-like double-helix structures. The use of bulky solvents in the synthesis of compound (4) leads to the structure crystallizing solvent-free. The packing of (4) is dominated by energy minimization which is achieved when the 1D-“cylinders” pack into the closest possible arrangement. This work highlights the potential for solvent controlled synthesis of extended copper-hmt systems

Progesterone Inhibits Epithelial-to-Mesenchymal Transition in Endometrial Cancer

Background: Every year approximately 74,000 women die of endometrial cancer, mainly due to recurrent or metastatic disease. The presence of tumor infiltrating lymphocytes (TILs) as well as progesterone receptor (PR) positivity has been correlated with improved prognosis. This study describes two mechanisms by which

A magnetically highly frustrated CuII27 coordination cluster containing a Cu18 folded-sheet motif

[CuII27(μ4-O)2(OH)13(OMe)7(vanox)10(NO3)8(OH2)2(MeOH)7](NO3)2·2H2O·11MeOH (1) was synthesised from Cu(NO3)2·3H2O and o-vanillin-oxime. Structural analysis shows a molecule composed of a Cu18 “folded-sheet” motif linked to a Cu9 bridging unit. The cluster is highly frustrated and has an S = 1/2 spin ground state

Layered Ln(III) complexes from a sulfonate-based 1,8-naphthalimide: structures, magnetism and photophysics

Five lanthanide(III) complexes of N-(4-phenylsulfonate)-1,8-naphthalimide (L 1 ) are described {[Ln(L1)(DMSO)5(H2O)2](L1)2 ⋅3H2O where Ln(III)=Eu(III) (1), Tb(III) (2), Dy(III) (3), Ho(III) (4) and Er(III) (5)}. A structural, magnetic and photophysical study is reported for these complexes. The complexes feature a 1,8-naphthalimide based anionic ligand, which is known for extending structure directing properties through π-based interactions. Within these complexes L1 acts as both a coordinating ligand as well as a non-coordinating counter-ion and overall the solid-state structures adopt layered topologies that are achieved through π-π interactions between L1 molecules. Complexes of 1 and 2 display the characteristic line-like emission profiles expected for Eu(III) and Tb(III) whilst the magnetic properties of the Dy(III) containing complex 3 were investigated. </p

Modulation of Mn³⁺ Spin State by Guest Molecule Inclusion

Spin state preferences for a cationic Mn3+ chelate complex in four different crystal lattices are investigated by crystallography and SQUID magnetometry. The [MnL1]+ complex cation was prepared by complexation of Mn3+ to the Schiff base chelate formed from condensation of 4-methoxysalicylaldehyde and 1,2-bis(3-aminopropylamino)ethane. The cation was crystallized separately with three polyatomic counterions and in one case was found to cocrystallize with a percentage of unreacted 4-methoxysalicylaldehyde starting material. The spin state preferences of the four resultant complexes [MnL1]CF3SO3&middot;xH2O, (1), [MnL1]PF6&middot;xH2O, (2), [MnL1]PF6&middot;xsal&middot;xH2O, (2b), and [MnL1]BPh4, (3), were dependent on their ability to form strong intermolecular interactions. Complexes (1) and (2), which formed hydrogen bonds between [MnL1]+, lattice water and in one case also with counterion, showed an incomplete thermal spin crossover over the temperature range 5&ndash;300 K. In contrast, complex (3) with the BPh4&minus;, counterion and no lattice water, was locked into the high spin state over the same temperature range, as was complex (2b), where inclusion of the 4-methoxysalicylaldehyde guest blocked the H-bonding interaction

The first use of a ReX₅ synthon to modulate Fe^III spin crossover via supramolecular halogen⋅⋅⋅halogen interactions

We have added the {ReIVX5}− (X=Br, Cl) synthon to a pocket-based ligand to provide supramolecular design using halogen⋅⋅⋅halogen interactions within an FeIII system that has the potential to undergo spin crossover (SCO). By removing the solvent from the crystal lattice, we “switch on” halogen⋅⋅⋅halogen interactions between neighboring molecules, providing a supramolecular cooperative pathway for SCO. Furthermore, changes to the halogen-based interaction allow us to modify the temperature and nature of the SCO event.</p

Anion Influence on Spin State in Two Novel Fe(III) Compounds: [Fe(5F-sal2333)]X

Structural and magnetic data on two iron (III) complexes with a hexadentate Schiff base chelating ligand and Cl&minus; or BPh4&minus; counterions are reported. In the solid state, the Cl&minus; complex [Fe(5F-sal2333)]Cl, 1, is high spin between 5&ndash;300 K while the BPh4&minus; analogue [Fe(5F-sal2333)]BPh4, 2, is low spin between 5&ndash;250 K, with onset of a gradual and incomplete spin crossover on warming to room temperature. Structural investigation reveals different orientations of the hydrogen atoms on the secondary amine donors in the two salts of the [Fe(5F-sal2333)]+ cation: high spin complex [Fe(5F-sal2333)]Cl, 1, crystallizes with non-meso orientations while the spin crossover complex [Fe(5F-sal2333)]BPh4, 2, crystallizes with a combination of meso and non-meso orientations disordered over one crystallographic site. Variable temperature electronic absorption spectroscopy of methanolic solutions of 1 and 2 suggests that both are capable of spin state switching in the solution