Synthesis,crystal structure,and luminescent properties of a new modification of the zinc(II) dichloride complex with phthalazine

The coordination compound [ZnCl₂(Phtz)₂] has been synthesized by the reaction of ZnCl₂ with phthalazine (Phtz, L, C₈H₆N₂) in an ethanol solution. Its crystal structure has been determined: crystals are triclinic, space group P 0000000, a = 7.346(1) Å, b = 8.095(1) Å, c = 14.275(1) Å, α = 85.63(1)°, β = 75.75(1)°, γ = 88.43(1)°, V = 820.4(2) ų, ρ_calc = 1.605 g/cm³, Z = 2. The zinc atom is tetrahedrally coordinated to two crystallographically nonequivalent chlorine atoms and two nitrogen atoms of the ligands L (Zn(1)–N(1), 2.036(4) Å; Zn(1)–N(3), 2.043(4) Å; Zn(1)–Cl(1), 2.225(2) Å; Zn(1)–Cl(2), 2.220(2) Å; angles NZnN, 106.1(2)°; ClZnCl, 116.47(7)°). The complexes are combined into a 1D supramolecular structure by nonclassical hydrogen bonds C–H···Cl and π–π-stacking interaction between centrosymmetric pairs of aromatic rings of one of the independent ligands. The compounds [CdI₂(Phtz)] and [HgBr₂(Phtz)] have also been synthesized, and their luminescent properties have been studied.     

Iron complex redox system as a mediator for a dye-sensitized solar cell

Photoelectric parameters of a dye-sensitized solar cell (DSSC) based on nanocrystalline titania with an adsorbed commercial sensitizer Ruthenizer 505 and a redox system based on the [FeL₂] · 2Otf complex (where L = 4′-(4-bipyridyl)-2,2′:6′,2″-tert-pyridine and Otf^? =CF₃SO ₃ ^? ) as the mediator are studied. When illuminated with a power of 100 mW/cm2, the DSSC voltage with the mediator under study and the iodide/triiodide redox pair have close values of 470 and 480 mV, respectively. The current-voltage characteristics of the DSSC with the iron complex mediator are far lower than for the iodide/triiodide redox pair. Our data indicate the slower reduction kinetics of the oxidized sensitizer species for the iron complex. The reason for this may be associated with the shift of the redox potential toward positive values in going from the iodide/triiodide redox pair to the iron complex, and thereby a reduced driving force for the reduction of the oxidized sensitizer species. We also cannot rule out that the DSSC characteristics are affected by the reduction on the photoanode of the oxidized mediator species as a result of the high reversibility of the iron complex mediator redox system.     

Coordination Polymeric Ensemble of Silver with Nitrate and 4-(Aminomethyl)benzoate: Synthesis,Crystal Structure,and Luminescence Properties

Russian Journal of Coordination Chemistry - Prismatic crystals of Ag3(4-Amba)2(NO3)2 (I) and Ag(4-AmbaH)NO3 (II) are isolated from the reaction mixture of aqueous solutions of 4-aminomethylbenzoic...     

Bimetallic 3d—4f-molecules [MEu(Bu<Superscript>t</Superscript>COO)<Subscript>5</Subscript>(1,10-phen)] (M = Zn<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, phen is phenanthroline): synthesis,structure, luminescent and magnetic properties

New heterometallic complexes [MEu(Piv)₅(1,10-phen)]?MeCN (M = Zn²⁺ (1), Co²⁺ (2), Piv^– = Bu^tCOO^–, 1,10-phen is 1,10-phenanthroline) were obtained. Luminescence spectra of compound 1 reveal a metal-centered Eu³⁺ luminescence, the luminescence lifetime is about 1 ms. Using TGA and DSC methods, it was shown that [ZnEu(Piv)₅(1,10-phen)] is a stable binuclear molecule undergoing a structural transformation in the 210—230 °C temperature range, which leads to a partial transition of the sample into the glass state. Complex 2 does not exhibit luminescence due to the presence of high-spin cobalt(II) ions. The magnetic behavior of 2 according to calculations based on the molecular field model is determined by spin-orbit interactions of cobalt(II) and europium(III) ions.     

Coordination Compounds of Silver Methanesulfonate with Triphenylphosphine and 1,2-Bis(4-Pyridyl)ethane

The reaction of Ag(CH₃SO₃) with PPh₃ gave the compound [Ag(CH₃SO₃)(PPh₃)₂] (I) and the reaction of Ag(CH₃SO₃) with PPh₃ and 1,2-bis(4-pyridyl)ethane (Dpe) affords the mixed complex [Ag(CH₃SO₃)(PPh₃)(Dpe)] (II). The crystal structures of I and II were determined by X-ray diffraction (CIF file CCDC no. 1563357 (for I)). In I, the centrosymmetric binuclear complex [Ag(CH₃SO₃)-(PPh₃)₂]₂ is formed. The Ag atom has a distorted tetrahedral coordination composed of two bidentate bridging O atoms of the sulfonate anion and two P atoms of two PPh₃ ligands. The structure of II is based on the centrosymmetric binuclear molecule with two bridging Dpe ligands between two [Ag(CH₃SO₃)(PPh₃)] complexes. The O atoms of the methanesulfonate ion are statistically disordered, which induces a considerable distortion of the silver polyhedron with C.N. 5. Both compounds tend to emit in the blue and green regions of the PL spectra.     

The dielectric properties and flow of electrorheological fluids based on polymer-coated nanodispersed barium tetraacetate titanyl particles upon a dynamic shear in electric fields

The shear stress in flowing electrorheological fluids consisting of PMS-20 poly(dimethylsiloxane) filled with nanodispersed barium tetraacetate titanyl particles coated with polymers (polyethyleneimine, poly(ethylene glycol), and polyethyloxazoline) has been studied as depending on the strengths of direct- and alternating-current (f = 50 Hz) electric fields. Results of analyzing the dielectric spectra of electrorheological fluids in a frequency range of 25–10⁶ Hz have been presented. The values of the shear stress in the flowing fluids as depending on the nature of a polymer adsorbed on the particle surface decrease in a series corresponding to a reduction in the Maxwell–Wagner relaxation times of the suspensions. The current-voltage characteristics of the electrorheological fluids at high voltages (up to 5 kV) indicate the realization of the mechanism of currents limited by the space charge. The influence of an adsorbed polymer on the magnitude of the electrorheological effect is reduced to blocking polar groups on the particle surface and variations in the conductivity, effective dielectric permittivity, and loss tangents of filler materials. An increase in the contribution from these factors leads to a gradual decrease in the magnitude of the electrorheological effect.     

2D-layered structure of coordination polymer,zinc trifluoroacetate-1,3-bis(4-pyridyl)propane

Compound [Zn(CF₃CO₂)₂(Bpp)₂], where Bpp is 1,3-bis(4-pyridyl)propane, was synthesized and its structure and luminescent properties were determined. Crystals are monoclinic, space group C2/c, a = 21.261(1) Å, b = 17.642(1) Å, c = 18.632(1) Å, β = 115.85(1)°, V = 6289.3(6) ų, ρ_calcd = 1.453 g/cm³, Z = 8. The structure comprises 2D neutral layers of conjugated multiunit rings composed of four Zn²⁺ ions united by four bridging Bpp ligands. Each of two crystallographically nonequivalent Zn atoms is coordinated at the octahedra apices to four nitrogen atoms of two Bpp ligands and two O(CF₃CO₂) atoms. Trifluoroacetate anions are coordinated to Zn²⁺ ions in monodentate manner. The compound exhibits photoluminescence in solid state.     

Thermal Stability of the Structure and Optical Properties of Nanostructured TIO2 Films

Russian Physics Journal - The structure and optical properties of titanium dioxide films have been studied during annealing from 100 to 400°C. The films were obtained by ion-plasma...     

Four- and five-coordinate metal atoms in a supramolecular polymeric assembly of silver(I) with (4-methyl-2-quinolylthio)acetate

The coordination compound [Ag₂L₂(H₂O)₂] · ₂H₂O (I), L = C₁₂H₁₀NO₂S has been synthesized by the reaction of AgNO₃ with 4-methyl-2-quinolylthioacetic acid (HL) preliminarily neutralized with an equimolar amount of NBu₄OH. Its crystal structure has been determined, and luminescence properties have been studied. Crystals of I are monoclinic, space group C2/_c, _a = 31.239(6) Å, _b = 12.056(2) Å, _c = 16.846(3) Å, β = 122.17(3)°, V = 5370.4(2) ų, ρ_calc = 1.861 g/cm³, Z = 16. The structure is formed by two crystallographically nonequivalent silver atoms Ag(1) and Ag(2) and two tridentate bridging ligands L coordinated through the S, N, and O atoms. These atoms, together with water molecules, form the coordination environments of the metal atoms with CN = 5 and 4, respectively. The Ag⁺ ions and the tridentate ligands form infinite [Ag₄L₄]_n bands extended in the [001] direction. The presence of outer-sphere water molecules involved in O–H···O hydrogen bonding is responsible for the formation of a supramolecular framework structure. The photoluminescence spectrum of compound I shows two bands at ~450 and ~485 nm corresponding to the blue spectral range.     

Synthesis,crystal structure,and luminescent properties of silver complexes with 2-methylquinoline

The complexes [AgL₂(NO₃)] (I) and [AgL₂(CH₃SO₃)] · H₂O (II) (L is 2-methylquinoline, C₁₀H₉N) have been synthesized and structurally characterized by single-crystal X-ray diffraction. Crystals of I are monoclinic, space group P2₁/n, a = 9.296(1) Å, b = 13.495(1) Å, c = 14.931(1) Å, β = 95.06(1)°, V = 1865.8(3) ų, ρ_calc = 1.624 g/cm³, Z = 4. Crystals of II are monoclinic, space group P2₁/n, a = 13.147(1) Å, b = 11.767(1) Å, c = 13.814(1) Å, β = 96.06(1)°, V = 2124.3(3) ų, ρ_calc = 1.599 g/cm³, Z = 4. Compounds I and II are composed of discrete complexes of similar structure but with different orientation of the methyl groups of ligand L (trans and cis arrangement, respectively). Both anions, NO ₃ ^- and CH₃SO ₃ ^- function as a chelating weakly bound ligand for the Ag⁺ ion. The presence of water molecules in II is favorable for the formation of dimeric supramolecular moieties between the centrosymmetrically arranged Ag⁺ complexes with 2-methylquinoline. The luminescence spectra of solid complexes I and II showed a bathochromic shift as compared to the spectrum of L in acetonitrile. Complexes I and II have been characterized by ¹H and ¹³C{H} NMR spectra in CD₃CN.