A supramolecular species composed of a pair nonequivalent Dy(III)–radical complexes exhibits single-molecule magnet (SMM) properties. The weak effective antiferromagnetic coupling between the Dy(III) ions can be compensated by application small (700 Oe) dc field, revealing relaxation mode two distinct SMMs. These unique results illustrate how dynamics [Dy-Radical]2 SMM fine-tuned exchange-bias and an applied magnetic field.

The thermodynamics of amino acid systems are key to the understanding protein chemistry. We have found that many previous studies apparent molar volumes and heat capacities aqueous solutions acids were conducted at standard temperature 298.15 K. This does not allow for fact most biological processes occur temperatures removed from this condition.In an attempt address imbalance we measured densities glycine, L-alanine, L-serine, L-threonine 288.15, 298.15, 313.15, 328.15 K using a Picker flow...

Densities and heat capacities have been measured for aqueous solutions of L-aspartic acid, L-glutamic acid α-aminobutyric at 288.15, 298.15, 313.15 328.15 K. These data used to calculate apparent molar volumes, V2, ϕ, capacities, Cp, 2, which in turn standard-state text-decoration:overlineV°2, text-decoration:overlineC°p, 2. Helgeson, Kirkham Flowers equations, neutral organic species water, model the calculated volumes amino acids as a function temperature constant pressure. data,...

A diverse variety of thiazyl radicals is known. Intense study these heterocycles continues in the pursuit molecule-based materials with novel, academically interesting, and technologically relevant properties. Coordination species to metal atoms ions has focused primarily on 1,2,3,5-dithiadiazolyl 2 1,3,2-dithiazolyl 6. The potential two as ligand building-blocks has, by no means, been fully exploited. From structural electronic similarities between verdazyl nitronyl nitroxide radicals, it...

Encapsulation of unstable guests is a powerful way to enhance their stability. The lifetimes organic anions and radicals produced by reduction are typically short on account reactivity with oxygen while larger sizes preclude use traditional anion receptors. Here we demonstrate the encapsulation noncovalent stabilization radical C-H hydrogen bonding in π-stacked pairs cyanostar macrocycles having large cavities. Using electrogenerated tetrazine anions, observe significant extension lifetimes,...

Complexes of the 4-(2'-pyridyl)-1,2,3,5-dithiadiazolyl radical bidentate ligand with bis(hexafluoroacetylacetonato)manganese(II) and bis(hexafluoroacetylacetonato)copper(II) have been prepared. Unlike previously reported cobalt(II) complex, these complexes form dimers via intermolecular S···S contacts in solid state. The spectroscopic magnetic properties species state solution are compared to Co(II) emphasis on elucidation a monomer/dimer equilibrium solution. electrochemical also presented...

The neutral radical 4-(2'-benzimidazolyl)-1,2,3,5-dithiadiazolyl (HbimDTDA) exhibits a first order phase transition around 270 K without symmetry breaking, preserving its orthorhombic Pbca space group between 340 and 100 K. Associated with this reversible single-crystal-to-single-crystal transition, thermal hysteresis of the magnetic susceptibility is observed. low temperature (LT) diamagnetic owing to pancake bonding π-radicals. In paramagnetic high (HT) phase, bonds are broken, new...

Densities and volumetric heat capacities have been measured for aqueous solutions of L-valine, L-leucine, L-isoleucine at 288.15, 298.15, 313.15, 328.15 K. These data used to calculate apparent molar volumes, [Formula: see text] capacities, which in turn obtain standard state each amino acid system. Helgeson, Kirkham, Flowers equations, neutral organics water, model the calculated volumes acids as a function temperature constant pressure. The results our fitting procedures may be predict...

The 4-(2'-pyridyl)-1,2,3,5-dithiadiazolyl neutral radical 1 has been prepared for use as a spin-bearing bidentate ligand. coordination of this ligand to bis(hexafluoroacetylacetonato)cobalt affords thermally stable complex 2. Magnetic susceptibility measurements the crystalline indicate ferromagnetic coupling between ligand-centered spin and unpaired electrons high-spin Co(II).

A spin-bearing bis-bidentate ligand, designed from a pyrimidyl-substituted R-CN2S2 neutral radical, is used to co-ordinate two Mn(II) metal centres yielding thermally stable complex with antiferromagnetic coupling between the ligand-centred spin and metal-centred spins, thus an overall ferrimagnetic scheme ground state S = 9/2.

Relative densities, (ρ − ρ°1), and heat capacity ratios, cpρ/cp°1ρ°1 1, for l-arginine, l-proline, d,l-methionine in water have been measured at 288.15, 298.15, 313.15 328.15 K. These data used to calculate apparent molar volumes capacities. Calculated standard state capacities compared available literature data. Standard expansibilities calculated from the temperature dependences of volume

T. M. Barclay, A. Wallace Cordes, L. Beer, R. Oakley, K. E. Preuss, N. J. Taylor and W. Reed, Chem. Commun., 1999, 531 DOI: 10.1039/A809951K

Two structurally characterized dinuclear valence tautomers are described. Cobalt ions bridged by p- and m-phenylene units connected to 2,2'-bipyridines. X-ray crystal structures show that the molecules in [(Co(III))(Co(III))] forms at ca. 125 K, while spectroscopic studies both can achieve [(Co(II))(Co(II))] form above 400 K confirm below 10 K. Magnetic susceptibility also included. Our results highlight necessity of studying crystalline amorphous samples distinguish effects intrinsic...

Metal complexes of the 4-(2′-pyrimidyl)-1,2,3,5-dithiadiazolyl (pymDTDA) neutral radical ligand and its selenium analogue (pymDSDA) are presented. The following series metal ions has been studied using M(hfac)2 as coordination fragment choice (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato): MnII, CoII, NiII, ZnII. binuclear cobalt nickel pymDTDA both exhibit ferromagnetic (FM) coupling between unpaired electrons on ion, while zinc complex is presented a comparative example incorporating...

A binuclear metal coordination complex of the first thiazyl-based biradical ligand 1 is reported (1 = 4,6-bis(1,2,3,5-dithiadiazolyl)pyrimidine; hfac =1,1,1,5,5,5,-hexafluoroacetylacetonato-). The Mn(hfac)2-biradical-Mn(hfac)2 2 a rare example discrete, molecular species employing neutral bridging ligand. It soluble in common organic solvents and can be easily sublimed as crystalline solid. Complex has spin ground state S(T) 4 resulting from antiferromagnetic coupling between S(birad) two...

The condensation of diaminobenzenedithiol with sulfur monochloride leads to the chloride salt radical cation 3,6-dichlorobenzo[1,2-d:4,5-d']bis(1,2,3-dithiazole), dichloro-[BB-123-DTA][Cl], which can be reduced neutral dichloro-[BB-123-DTA] triphenylantimony. A similar selenium tetrachloride leads, upon reduction, corresponding bis(1,2,3-thiaselenazole) dichloro-[BB-123-TSA]. crystal and molecular structures both compounds have been determined by X-ray diffraction. Both compounds, are...

Synthesis and structural, magnetic electrochemical characterization of the Ni(hfac) 2(pyDTDA) Fe(hfac) complexes are reported (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato-; pyDTDA 4-(2'-pyridyl)-1,2,3,5-dithiadiazolyl). Unlike previously Mn(II) Cu(II) complexes, but similar to Co(II) complex, Ni(II) Fe(II) not dimerized in solid state, allowing for coupling between metal ion paramagnetic ligand be readily obtained from state measurements: Ni J/k B +132(1) K, using H -2 J{ S Ni. Rad} g...

The crystal structures of a broad series anhydrous Ln(hfac)3(monoglyme) complexes, prepared in moderate to high yield, are presented: hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato-; Ln La, Ce, Pr, Sm, Eu, Gd, Tb, Dy, Er, Tm. This study contradicts the general assumption that monoglyme is too small polyether act as partitioning agent displacing coordinated water on larger lanthanide(III) ions. an intermediate La(hfac)3(monoglyme)2 species and hydrated Ce(hfac)3(monoglyme)(H2O) also included....

π–π radical interactions have exacting geometry requirements, significantly more stringent than those of a hydrogen bond or van der Waals interaction. Here, supramolecular synthons based on such radical–radical recognition are employed to generate switchable structural and magnetic properties. Interactions between neighboring paramagnetic ligands the La(hfac)3(pyDTDA)2 coordination complex cause rare re-entrant phase transition (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato-; pyDTDA...

4,6-Di-2'-pyridylpyrimidine is employed as a bis(diimine) ligand bridging two cobalt bis(dioxolene) centers. The thermally induced valence tautomeric transitions of these metal centers are coupled through the ligand. result that sequential switching from high-spin Co(II) to low-spin Co(III) one center, followed by onset other center at lower temperature, observed in solid amorphous thin film IR absorption spectroscopy.

The synthesis of 4′-CN, 5′-CN and 5′-Br substituted pyDTDA neutral radical bidentate ligands is reported (pyDTDA = 4-(2′-pyridyl)-1,2,3,5-dithiadiazolyl). Ni(hfac)2 Mn(hfac)2 coordination complexes both cyano ligands, the complex bromo ligand, have been prepared crystal packing these compared (hfac 1,1,1,5,5,5-hexafluoroacetylacetonato-). Unlike previously Mn(hfac)2(pyDTDA), Mn(hfac)2(4′-CN-pyDTDA) does not form dimers in solid-state making it possible to measure magnetic coupling between...

The Mn(hfac)(2) complex of the paramagnetic 4-(benzoxazol-2'-yl)-1,2,3,5-dithiadiazolyl ligand is reported (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato-). Mn(ii) and radical spins are coupled antiferromagnetically (AF) in coordination complex. Short sulfur-oxygen contacts between molecules provide an efficient pathway for AF coupling one molecule a neighbouring molecule, resulting large total spin ground state (S(T) 4) pair molecules.

A structurally characterized lanthanide-radical coordination polymer exhibits ferromagnetic ordering. Superexchange and McConnel I mechanisms are implicated.