[(Cu-Radical)₂‑Ln]: Structure and Magnetic Properties of a Hetero-tri-spin Chain of Rings (Ln = Y^III, Gd^III, Tb^III, Dy^III)

Novel hetero-tri-spin coordination polymers formed of ring-shaped Cu-nitronyl nitroxide spin clusters and Ln^III linkers are reported. These mixed 2p-3d-4f compounds of formula {[Ln­(hfac)₃]­[Cu­(hfac)₂(NIT-3Py)]₂·C₆H₁₄}_<i>n</i> [Ln^III = Y (<b>1</b>), Gd (<b>2</b>), Tb (<b>3</b>), and Dy (<b>4</b>); NIT-3Py = 2-(3-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; hfac = hexa-fluoroacetylacetonate], exhibit a 1D chain structure consisting of [Cu­(NIT-3Py)]₂ rings linked by Ln­(hfac)₃ units. Their magnetic behavior is characteristic for ferromagnetic interactions between the metal centers and the coordinated radical units. The Tb derivative was found to exhibit slow relaxation of its magnetization

Lanthanide–Nitronyl Nitroxide Chains Derived from Multidentate Nitronyl Nitroxides

Unprecedented lanthanide (Ln)-radical loop-chain coordination polymers were achieved using multidentate pyridyl- or triazole- substituted nitronyl nitroxide ligands. Their magnetic units consist of ferromagnetic [Ln₂Radical] moieties, leading for the dysprosium­(III) derivatives to slow relaxation of magnetization, which was found to be dependent on the heterocyclic ligands

Pentagonal-Bipyramid Ln(III) Complexes Exhibiting Single-Ion-Magnet Behavior: A Rational Synthetic Approach for a Rigid Equatorial Plane

A pentadentate chelating ligand is employed for the facile synthesis of air-stable pentagonal-bipyramid Ln­(III) complexes with a rigid equatorial plane. The Dy­(III) analogue exhibits single-ion-magnet behavior with <i>U</i>_eff/<i>k</i>_B = 70 K under <i>H</i>_dc = 500 Oe

Heptacoordinated Nickel(II) as an Ising-Type Anisotropic Building Unit: Illustration with a Pentanuclear [(NiL)₃{W(CN)₈}₂] Complex

Heptacoordinated nickel­(II) complexes characterized by substantial Ising-type single-ion anisotropy have been involved in the construction of two pentanuclear [Ni₃W₂] compounds by association with [W­(CN)₈]^3–. For one of them, slow relaxation of magnetization was observed to occur concomitantly with antiferromagnetic ordering

Heptacoordinated Nickel(II) as an Ising-Type Anisotropic Building Unit: Illustration with a Pentanuclear [(NiL)₃{W(CN)₈}₂] Complex

Heptacoordinated nickel­(II) complexes characterized by substantial Ising-type single-ion anisotropy have been involved in the construction of two pentanuclear [Ni₃W₂] compounds by association with [W­(CN)₈]^3–. For one of them, slow relaxation of magnetization was observed to occur concomitantly with antiferromagnetic ordering

Tuning of the Emission Efficiency and HOMO–LUMO Band Gap for Ester-Functionalized {Al(salophen)(H₂O)₂}⁺ Blue Luminophors

A series of [Al<b>L</b>(H₂O)₂(NO₃)] complexes, with <b>L</b> standing for an ester substituted salophen-type ligand, has been synthesized, and the luminescence properties have been investigated. These derivatives differ by the nature of the ester-R group introduced at the C5 position of their salicylidene rings (i.e., phenyl, <b>7a,a</b>′; naphthyl, <b>7b,b</b>′; pentafluorophenyl, <b>7c,c</b>′; and <i>p</i>-nitrophenyl, <b>7d</b>) and by the bis-imino bridge (i.e., 1,2- phenylene, <b>7a</b>–<b>d</b>; and 1,2-naphthalene, <b>7a</b>′<b>–c</b>′). All the complexes are characterized by luminescence in the blue range, the chemical diversity having no effect on the emission wavelength (480–485 nm). However, the emission efficiency was found to be strongly dependent on the Schiff-base ligand with quantum yields ranging from ϕ = 22% to 44%, the highest values being for the salophen derivatives with the electron-withdrawing ester-R groups (<b>7a</b>, 34%; <b>7a</b>′, 23%; <b>7b</b>, 31%; <b>7b</b>′, 22%; <b>7c</b>, 40%; <b>7c</b>′, 29%, and <b>7d</b>, 44%). Both the electrochemical data and DFT calculations show that the HOMO–LUMO band gap is modified as a function of the ester R group (from 2.92 to 3.16 eV, based on the redox potentials). The crystal structures for the <i>N,N</i>′-bis­(5-(phenoxycarbonyl)­salicylidene)-1,2-phenylenediamine and the <i>N,N</i>′-bis­(5-(<i>p</i>-nitrophenoxycarbonyl)­salicylidene)-1,2-phenylenediamine aluminum complexes (<b>7a</b> and <b>7d</b>) are reported

Tuning of the Emission Efficiency and HOMO–LUMO Band Gap for Ester-Functionalized {Al(salophen)(H₂O)₂}⁺ Blue Luminophors

A series of [Al<b>L</b>(H₂O)₂(NO₃)] complexes, with <b>L</b> standing for an ester substituted salophen-type ligand, has been synthesized, and the luminescence properties have been investigated. These derivatives differ by the nature of the ester-R group introduced at the C5 position of their salicylidene rings (i.e., phenyl, <b>7a,a</b>′; naphthyl, <b>7b,b</b>′; pentafluorophenyl, <b>7c,c</b>′; and <i>p</i>-nitrophenyl, <b>7d</b>) and by the bis-imino bridge (i.e., 1,2- phenylene, <b>7a</b>–<b>d</b>; and 1,2-naphthalene, <b>7a</b>′<b>–c</b>′). All the complexes are characterized by luminescence in the blue range, the chemical diversity having no effect on the emission wavelength (480–485 nm). However, the emission efficiency was found to be strongly dependent on the Schiff-base ligand with quantum yields ranging from ϕ = 22% to 44%, the highest values being for the salophen derivatives with the electron-withdrawing ester-R groups (<b>7a</b>, 34%; <b>7a</b>′, 23%; <b>7b</b>, 31%; <b>7b</b>′, 22%; <b>7c</b>, 40%; <b>7c</b>′, 29%, and <b>7d</b>, 44%). Both the electrochemical data and DFT calculations show that the HOMO–LUMO band gap is modified as a function of the ester R group (from 2.92 to 3.16 eV, based on the redox potentials). The crystal structures for the <i>N,N</i>′-bis­(5-(phenoxycarbonyl)­salicylidene)-1,2-phenylenediamine and the <i>N,N</i>′-bis­(5-(<i>p</i>-nitrophenoxycarbonyl)­salicylidene)-1,2-phenylenediamine aluminum complexes (<b>7a</b> and <b>7d</b>) are reported

Tuning of the Emission Efficiency and HOMO–LUMO Band Gap for Ester-Functionalized {Al(salophen)(H₂O)₂}⁺ Blue Luminophors

A series of [Al<b>L</b>(H₂O)₂(NO₃)] complexes, with <b>L</b> standing for an ester substituted salophen-type ligand, has been synthesized, and the luminescence properties have been investigated. These derivatives differ by the nature of the ester-R group introduced at the C5 position of their salicylidene rings (i.e., phenyl, <b>7a,a</b>′; naphthyl, <b>7b,b</b>′; pentafluorophenyl, <b>7c,c</b>′; and <i>p</i>-nitrophenyl, <b>7d</b>) and by the bis-imino bridge (i.e., 1,2- phenylene, <b>7a</b>–<b>d</b>; and 1,2-naphthalene, <b>7a</b>′<b>–c</b>′). All the complexes are characterized by luminescence in the blue range, the chemical diversity having no effect on the emission wavelength (480–485 nm). However, the emission efficiency was found to be strongly dependent on the Schiff-base ligand with quantum yields ranging from ϕ = 22% to 44%, the highest values being for the salophen derivatives with the electron-withdrawing ester-R groups (<b>7a</b>, 34%; <b>7a</b>′, 23%; <b>7b</b>, 31%; <b>7b</b>′, 22%; <b>7c</b>, 40%; <b>7c</b>′, 29%, and <b>7d</b>, 44%). Both the electrochemical data and DFT calculations show that the HOMO–LUMO band gap is modified as a function of the ester R group (from 2.92 to 3.16 eV, based on the redox potentials). The crystal structures for the <i>N,N</i>′-bis­(5-(phenoxycarbonyl)­salicylidene)-1,2-phenylenediamine and the <i>N,N</i>′-bis­(5-(<i>p</i>-nitrophenoxycarbonyl)­salicylidene)-1,2-phenylenediamine aluminum complexes (<b>7a</b> and <b>7d</b>) are reported

Cyano-Bridged Fe(II)–Cr(III) Single-Chain Magnet Based on Pentagonal Bipyramid Units: On the Added Value of Aligned Axial Anisotropy

A cyano-bridged Fe­(II)–Cr­(III) single-chain magnet designed to ensure a parallel orientation of the axial anisotropy of the building units is reported. This ferromagnetic chain compound consists of a pentagonal bipyramid Fe­(II) complex with Ising-type anisotropy and a dicyanide Cr­(III) complex interlinked through their apical positions. It is characterized by an energy gap for the magnetization reversal of Δ_eff/<i>k</i>_B = 113 K and exhibits magnetic hysteresis with a coercive field of 1400 Oe at 2 K which positions this compound among the very few examples of SCMs with spin reversal barriers above 100 K. The quite remarkable performances of this single-strand SCM are attributed to the alignment of the local anisotropy axes, which is supported by <i>ab initio</i> modeling. A discrete Cr₂Fe complex based on the same building units and behaving as a SMM in zero field is also reported

Tetradihydrobenzoquinonate and Tetrachloranilate Zr(IV) Complexes: Single-Crystal-to-Single-Crystal Phase Transition and Open-Framework Behavior for K₄Zr(DBQ)₄

The molecular complexes K₄[Zr­(DBQ)₄] and K₄[Zr­(CA)₄], where DBQ^2– and CA^2– stand respectively for deprotonated dihydroxybenzoquinone and chloranilic acid, are reported. The anionic metal complexes consist of Zr­(IV) surrounded by four O,O-chelating ligands. Besides the preparation and crystal structures for the two complexes, we show that in the solid state the DBQ complex forms a 3-D open framework (with 22% accessible volume) that undergoes a crystal-to-crystal phase transition to a compact structure upon guest molecule release. This process is reversible. In the presence of H₂O, CO₂, and other small molecules, the framework opens and accommodates guest molecules. CO₂ adsorption isotherms show that the framework breathing occurs only when a slight gas pressure is applied. Crystal structures for both the hydrated and guest free phases of K₄[Zr­(DBQ)₄] have been investigated