Circularly Polarized Luminescence from an Eu(III) Complex Based on 2‑Thenoyltrifluoroacetyl-acetonate and a Tetradentate Chiral Ligand

A new chiral complex {[Eu<b>L</b>(tta)₂(H₂O)]­CF₃SO₃; <b>L</b> = <i>N</i>,<i>N</i>′-bis­(2-pyridylmethylidene)-1,2-(<i>R</i>,<i>R</i> + <i>S</i>,<i>S</i>)-cyclohexanediamine; tta = 2-thenoyltrifluoroacetyl-acetonate} has been synthesized and characterized from a structural and spectroscopic point of view. The molecular structure in the solid state shows the presence of one chiral <b>L</b>, two tta, and one water molecules bound to the metal center. <b>L</b> and tta molecules can efficiently harvest and transfer to Eu­(III) the UV light absorbed in the 250–400 nm range. The forced electric-dipole ⁵D₀ → ⁷F₂ emission band dominates the Eu­(III) emission spectra recorded in the solid state and in solution of acetonitrile or methanol and the calculated intrinsic quantum yield of the metal ion is around 40–50%. The light emitted by the enantiopure complex shows a sizable degree of polarization with a maximum value of the emission dissymmetry factor (<i>g</i>_lum) equal to 0.2 in methanol solution. If compared with the complex in the solid state or in acetonitrile solution, then the first coordination sphere of Eu­(III) when the complex is dissolved in methanol is characterized by the presence of one CH₃OH molecule instead of water. This fact is related to different Eu­(III) CPL signatures in the two solvents

Boron Functionalization and Unusual B–C Bond Activation in Rhodium(III) and Iridium(III) Complexes with Diphenylbis(pyrazolylborate) Ligands (Ph₂Bp)

The Rh­(III) and Ir­(III) pentamethylcyclopentadienyl compounds [M­(Cp*)­(κ²-Ph₂Bp)­Cl] (M = Rh, <b>1</b>; M = Ir, <b>4</b>) were readily prepared from interaction of the salt K­[Ph₂Bp] (Ph₂Bp = diphenylbis­(pyrazolyl)­borate) and the [M­(Cp*)­Cl₂]₂ dimer precursors in dichloromethane under anhydrous conditions. When the same reactions were carried out in non-anhydrous conditions by using acetonitrile as solvent, we observed, in the case of Rh, both B–N bond hydrolysis and Rh–C­(Ph) bond activation with the formation of the hydroxy­(pyrazolyl)­borate complex [Rh­(Cp*)­(Ph)­{κ²-(pz)­(OH)­BPh₂}] (<b>2</b>). In contrast, in the case of Ir only B–N hydrolysis was observed and the ionic species [Ir­(Cp*)­(Hpz)­{κ²-(pz)­(OH)­BPh₂}]Cl (<b>5</b>) was obtained, upon coordination of the liberated Hpz. Additionally, by reaction of <b>1</b> with AgClO₄ in acetonitrile, the ionic [Rh­(Cp*)­(Ph)­{κ²-(pz)­(OH)­B­(OH)}]­ClO₄ (<b>3</b>) was isolated. Complexes <b>1</b>–<b>3</b> and <b>5</b> have been structurally characterized by X-ray crystallography. Spectral studies have been performed for all species, together with a computational DFT modeling investigation. A decomposition mechanism for the diphenylbis­(pyrazolyl)­borate ligand in the different complexes is proposed

Boron Functionalization and Unusual B–C Bond Activation in Rhodium(III) and Iridium(III) Complexes with Diphenylbis(pyrazolylborate) Ligands (Ph₂Bp)

The Rh­(III) and Ir­(III) pentamethylcyclopentadienyl compounds [M­(Cp*)­(κ²-Ph₂Bp)­Cl] (M = Rh, <b>1</b>; M = Ir, <b>4</b>) were readily prepared from interaction of the salt K­[Ph₂Bp] (Ph₂Bp = diphenylbis­(pyrazolyl)­borate) and the [M­(Cp*)­Cl₂]₂ dimer precursors in dichloromethane under anhydrous conditions. When the same reactions were carried out in non-anhydrous conditions by using acetonitrile as solvent, we observed, in the case of Rh, both B–N bond hydrolysis and Rh–C­(Ph) bond activation with the formation of the hydroxy­(pyrazolyl)­borate complex [Rh­(Cp*)­(Ph)­{κ²-(pz)­(OH)­BPh₂}] (<b>2</b>). In contrast, in the case of Ir only B–N hydrolysis was observed and the ionic species [Ir­(Cp*)­(Hpz)­{κ²-(pz)­(OH)­BPh₂}]Cl (<b>5</b>) was obtained, upon coordination of the liberated Hpz. Additionally, by reaction of <b>1</b> with AgClO₄ in acetonitrile, the ionic [Rh­(Cp*)­(Ph)­{κ²-(pz)­(OH)­B­(OH)}]­ClO₄ (<b>3</b>) was isolated. Complexes <b>1</b>–<b>3</b> and <b>5</b> have been structurally characterized by X-ray crystallography. Spectral studies have been performed for all species, together with a computational DFT modeling investigation. A decomposition mechanism for the diphenylbis­(pyrazolyl)­borate ligand in the different complexes is proposed

Synthesis and Structural Characterizations of New Coordination Polymers Generated by the Interaction Between the Trinuclear Triangular SBU [Cu₃(μ₃‑OH)(μ-pz)₃]²⁺ and 4,4′-Bipyridine. 3°

The reactions of 4,4′-bipyridine with selected trinuclear triangular copper­(II) complexes, [Cu₃(μ₃-OH)­(μ-pz)₃(RCOO)₂L_<i>x</i>], [pz = pyrazolate anion, R = CH₃(CH₂)_<i>n</i> (2 ≤ <i>n</i> ≤ 5); L = H₂O, MeOH, EtOH] yielded a series of 1D coordination polymers (CPs) based on the repetition of [Cu₃(μ₃-OH)­(μ-pz)₃] secondary building units joined by bipyridine. The CPs were characterized by conventional analytical methods (elemental analyses, ESI-MS, IR spectra) and single crystal XRD determinations. An unprecedented 1D CP, generated through the bipyridine bridging hexanuclear copper clusters moieties, two 1D CPs presenting structural analogies, and two monodimensional tapes having almost exactly superimposable structures, were obtained. In one case, the crystal packing makes evident the presence of small, not-connected pores, accounting for ca. 6% of free cell volume

Interaction of the Trinuclear Triangular Secondary Building Unit [Cu₃(μ₃‑OH)(μ-pz)₃]²⁺ with 4,4′-Bipyridine. Structural Characterizations of New Coordination Polymers and Hexanuclear Cu^II Clusters. 2°

By reacting 4,4′-bipyridine (bpy) with selected trinuclear triangular Cu^II complexes, [Cu₃(μ₃-OH)­(μ-pz)₃­(RCOO)₂­(LL′)] [pz = pyrazolate anion; R = CH₃, CH₃CH₂, CH₂CH, CH₂C­(CH₃); L, L′ = Hpz, H₂O, MeOH] in MeOH, the substitution of monotopic ligands by ditopic bpy was observed. Depending on the stoichiometric reaction ratios, different compounds were isolated and structurally characterized. One- and two-dimensional coordination polymers (CPs), as well as two hexanuclear Cu^II clusters were identified. One of the hexanuclear clusters self-assembles into a supramolecular three-dimensional structure, and its crystal packing shows the presence of two intersecting channels, one of which is almost completely occupied by guest bpy, while in the second one guest water molecules are present. This compound also shows a reversible, thermally induced, single-crystal-to-single-crystal transition

A new copper(I) coordination polymer from 2,6-bis(1<i>H</i>-benzotriazol-1-ylmethyl)pyridine: Synthesis, characterization, and use as additive in transparent submicron UV filters

<p>The use of a new copper(I) coordination polymer (CP) as additive in transparent composite films of 190 nm of thickness for ultraviolet (UV) shielding is presented. The luminescent 1-D Cu(I) CP was easily synthesized through a self-assembly process between Cu(I) iodide and 2,6-bis(1<i>H</i>-benzotriazol-1-ylmethyl)pyridine (L). The CP, [Cu₂(<i>μ</i> − I)₂(<i>μ</i> − <b>L</b>)₂]_<i>n</i>, was structurally characterized by infrared, UV–visible diffuse reflectance and photoluminescence spectroscopy, elemental and thermogravimetric analyses, single-crystal and powder X-ray diffraction, and relativistic density functional theory calculations. The CP was dispersed and immobilized into a polymeric matrix in the presence of Sudan I, yielding a composite material that exhibits a reduction of 49% of the UV transmittance at 350 nm. Thus, the use of a new Cu(I) CP in polymeric composite films appears as a novel approach toward ultrathin and transparent UV shielding films, which have potential applications as protection layers of paints and coatings that tend to degrade when exposed to UV radiation.</p

[OSSO]-Type Iron(III) Complexes for the Low-Pressure Reaction of Carbon Dioxide with Epoxides: Catalytic Activity, Reaction Kinetics, and Computational Study

The selective conversion of variously substituted epoxides into the corresponding cyclic carbonates under mild reaction conditions was achieved with mononuclear Fe­(III) complexes bearing bis-thioether-diphenolate [OSSO]-type ligands, in combination with tetrabutylammonium bromide (TBAB). For example, propylene carbonate was obtained in 1 h at 35 °C (turnover frequency, TOF = 290 h^–1), from propylene oxide and 1 bar of CO₂ pressure, using 0.1 mol % of the Fe­(III) complex and 0.5 mol % of TBAB. Product divergence is observed only for cyclohexene oxide toward the exclusive formation of the aliphatic polycarbonate (TOF = 165 h^–1 at 80 °C and 1 bar of CO₂ pressure, using 0.1 mol % of the Fe­(III) complex and 0.1 mol % of tetrabutylammonium chloride). Kinetic investigations indicated reaction orders of two and one, with respect to the Fe­(III) complex, for the production of propylene carbonate and the poly­(cyclohexene carbonate), respectively. The enthalpy and entropy of activation were determined using the Eyring equation [for propylene carbonate: Δ<i>H</i>^‡ = 8.4 ± 0.7 kcal/mol and Δ<i>S</i>^‡ = −33 ± 3 cal/(mol·K); for poly­(cyclohexene carbonate): Δ<i>H</i>^‡ = 11.9 ± 0.3 kal/mol and Δ<i>S</i>^‡ = −36 ± 2.2 cal/(mol·K)]. Supported by density functional theory based investigations, we propose a mechanistic scenario in which the rate-limiting step is the bimetallic ring opening of the epoxide, in the case of propylene carbonate, and the monometallic insertion of the epoxide in the growing polymer chain, in the case of poly­(cyclohexene carbonate)

Coordination Polymers Based on the Trinuclear Triangular Secondary Building Unit [Cu₃(μ₃‑OH)(μ-pz)₃]²⁺ (pz = pyrazolate) and Succinate Anion

Reaction conditions (solvent, temperature, pressure) and reagents ratios control the formation of different products from the reactions involving Cu^II, pyrazole (Hpz), and succinate ion (Suc). Three different coordination polymers (CPs) (one of which porous) based on the trinuclear triangular Cu₃(μ₃-OH)­(μ-pz)₃ secondary building unit (SBU), as well as a 1D CP based on the Cu­(Hpz)₂ SBU were obtained. Moreover, a 3D supramolecular network, formed through quite strong H-bonding interactions involving the mononuclear Cu­(HSuc)₂(Hpz)₄ complex, was also synthesized when an excess of H₂Suc was added

Coordination Polymers Based on the Trinuclear Triangular Secondary Building Unit [Cu₃(μ₃‑OH)(μ-pz)₃]²⁺ (pz = pyrazolate) and Succinate Anion

Reaction conditions (solvent, temperature, pressure) and reagents ratios control the formation of different products from the reactions involving Cu^II, pyrazole (Hpz), and succinate ion (Suc). Three different coordination polymers (CPs) (one of which porous) based on the trinuclear triangular Cu₃(μ₃-OH)­(μ-pz)₃ secondary building unit (SBU), as well as a 1D CP based on the Cu­(Hpz)₂ SBU were obtained. Moreover, a 3D supramolecular network, formed through quite strong H-bonding interactions involving the mononuclear Cu­(HSuc)₂(Hpz)₄ complex, was also synthesized when an excess of H₂Suc was added

Coordination Polymers Based on the Trinuclear Triangular Secondary Building Unit [Cu₃(μ₃‑OH)(μ-pz)₃]²⁺ (pz = pyrazolate) and Succinate Anion

Reaction conditions (solvent, temperature, pressure) and reagents ratios control the formation of different products from the reactions involving Cu^II, pyrazole (Hpz), and succinate ion (Suc). Three different coordination polymers (CPs) (one of which porous) based on the trinuclear triangular Cu₃(μ₃-OH)­(μ-pz)₃ secondary building unit (SBU), as well as a 1D CP based on the Cu­(Hpz)₂ SBU were obtained. Moreover, a 3D supramolecular network, formed through quite strong H-bonding interactions involving the mononuclear Cu­(HSuc)₂(Hpz)₄ complex, was also synthesized when an excess of H₂Suc was added