Dimerized -Semiquinone Radical Anions Stabilized by a Pair of Rare-Earth Metal Ions.

Here we report stable -quinone-radical-bridged rare-earth complexes involving the ligand tetramethylquinone (QMe). The complexes, {Y[(QMe)Cl(THF)]} () and {Gd[(QMe)Cl(THF)]} (), where THF = tetrahydrofuran, are sufficiently stable that we can measure the single-crystal structures and perform magnetic and electron paramagnetic resonance measurements. These studies show the presence of a semiquinone form and that the magnetic interaction between the radicals in the dimer is strong and antiferromagnetic.

Engineering electronic structure to prolong relaxation times in molecular qubits by minimising orbital angular momentum.

The proposal that paramagnetic transition metal complexes could be used as qubits for quantum information processing (QIP) requires that the molecules retain the spin information for a sufficient length of time to allow computation and error correction. Therefore, understanding how the electron spin-lattice relaxation time (T) and phase memory time (T) relate to structure is important. Previous studies have focused on the ligand shell surrounding the paramagnetic centre, seeking to increase rigidity or remove elements with nuclear spins or both.

A large barrier single-molecule magnet without magnetic memory.

We report a six coordinate Dy single-molecule magnet (SMM) with an energy barrier of 1110 K for thermal relaxation of magnetization. The pure compound shows no retention of magnetization even at 2 K.

Correlating blocking temperatures with relaxation mechanisms in monometallic single-molecule magnets with high energy barriers (U > 600 K).

We report an empirical correlation between the blocking temperature of large energy barrier SMMs and the relaxation time at the point where the Raman and Orbach relaxation mechanisms have the same rate; this supports the idea that the ability to retain magnetisation is controlled by the Raman relaxation process in these materials.

Hybrid Organic-Inorganic Rotaxanes, Including a Hetero-Hybrid [3]Rotaxane Featuring Two Distinct Heterometallic Rings and a Molecular Shuttle.

[2] and [3] hybrid rotaxanes are reported based on {Ti M} rings (M is a trivalent metal such as Fe or Ga ). NMR studies show that [2]rotaxanes can act as molecular shuttles, while EPR studies of [3]rotaxanes show weak interactions between the paramagnetic components of the supramolecular assemblies.

Chromium chains as polydentate fluoride ligands for actinides and group IV metals.

The reactions of {Cr6} horseshoe chains {[nPr2NH2]3[Cr6F11(O2CtBu)10]}2, 1 and precursors of actinides and group IV metals led to a series of ring complexes [nPr2NH2][Cr7TiF6O2(O2CtBu)16], 2, [nPr2NH2][Cr6Ti2F5O3(O2CtBu)16], 3, [Cr6ThF7(O2CtBu)15 (Me2SO)], 4, [(nPr2NH2)2(Cr6Th2F12(O2CtBu)16)], 5 and [nPr2NH2][Cr6U2O2F8(O2CtBu)16(Me2SO)], 6. X-ray structure studies indicate that the {Cr6} chains maintain their structures in these complexes, acting as polydentate fluoride ligands. Their static magnetic properties were measured and fitted by isotropic exchange Hamiltonian.

An Extensive Family of Heterometallic Titanium(IV)-Metal(III) Rings with Structure Control through Templates.

A family of heterometallic [Cat][Ti MO )(O C Bu) ] rings is reported where Cat=a secondary or tertiary alkyl ammonium ion, x=7, 8 or 9, and M=Fe , Ga , Cr , In and Al . The structures are regular polygons with eight, nine or ten vertices with each edge bridged by an oxide and two pivalates. The size of the ring formed is controlled by the alkylammonium cation present.

Use of Supramolecular Assemblies as Lithographic Resists.

A new resist material for electron beam lithography has been created that is based on a supramolecular assembly. Initial studies revealed that with this supramolecular approach, high-resolution structures can be written that show unprecedented selectivity when exposed to etching conditions involving plasmas.

Novel mononuclear and 1D-polymeric derivatives of lanthanides and (η-benzoic acid)tricarbonylchromium: synthesis, structure and magnetism.

Two series of novel heteroleptic derivatives of lanthanides and (η-benzoic acid)tricarbonylchromium (benchrotrenecarboxylic acid) were synthesized and characterized: mononuclear complexes [Ln(BcrCOO)(acac)(HO)] (Ln = Eu (1), Gd (2), Tb (3a), Dy (4a), Ho (5a)) and 1D-polymeric ones [Ln(BcrCOO)(acac)(HO)] (Ln = Tb (3b), Dy (4b), Ho (5b), Er (6), Tm (7), Yb (8) and Y (9)), Bcr = (η-CH)Cr(CO). The molecular and crystal structures of the obtained compounds were determined. Complexes 3a, 4a, 4b, 6 and 8 were found to exhibit SMM properties.

A pseudo-icosahedral cage {Gd12} based on aminomethylphosphonate.

Reaction of (aminomethyl)phosphonic acid (ampH2) with a mixture of gadolinium and cobalt pivalates under solvothermal conditions, led to a pseudo-icosahedral cage {Gd12}, which shows a large magnetocaloric effect (MCE).

Circular serendipity: in situ ligand transformation for the self-assembly of an hexadecametallic [Cu(II)16] wheel.

A [Cu(II)16] wheel was isolated serendipitously from the reaction of acetylacetone dioxime with copper(ii) chloride and lanthanide ions in a reaction initially designed to produce heterometallic 3d-4f cages. The ligand has been transformed in situ to three different forms, all found within the [Cu16] wheel, with the original ligand completely absent.