Structures, electronic states, and electroluminescent properties of a zinc(II) 2-(2-hydroxyphenyl)benzothiazolate complex

Bis(2-(2-hydroxyphenyl)benzothiazolate)zinc (Zn(BTZ)(2)) is one of the best white electroluminescent materials used in organic light-emitting diodes (LEDs). Despite a large number of studies devoted to this complex, very little is known about its basic molecular and electronic structures and electron transport properties in LEDs. Therefore, we investigate the structures and electroluminescent properties. The unsolvated single crystal of Zn(BTZ)(2) was grown and its crystalline structure was determined from X-ray diffraction data. The crystal is triclinic, space group P-1, a = 9.4890(19) A, b = 9.5687(19) A, c = 11.685(2) A, alpha = 84.38(3) degrees, beta = 78.94(3) degrees, gamma = 83.32(3) degrees. The structure of the chelate is dimeric [Zn(BTZ)(2)](2) with two isotropic Zn(2+) ion centers having five-coordinate geometry. The present study provides direct evidence for the sole existence of dimeric structure in the powder and the thin film. The dimer is energetically more stable than the monomer. Analysis of the electronic structure of [Zn(BTZ)(2)](2) calculated by density functional theory reveals a localization of orbital and the distribution of four orbital "tetrads". The structural stabilities of both anion and cation and the distribution of the hole in the cation and that of the excess electron in the anion are discussed in terms of theoretical calculations. Strong intermolecular interaction may be expected to enable good electron transport properties as compared with tris(8-hydroxyquinolinato)aluminum.     

Correlation between structure and thermal properties in 2-hydroxy-benzophenone Co(II) complexes

In this study, simultaneous TG/DTG–DTA technique was used for the simple cobalt(II) complex [Co(dpamH)₃]Br₂ (1) (dpamH = 2,2′-dipyridylamine) and the novel mixed-ligand complexes [Co(dpamH)₂(bpo)]Br (2) and [Co(dpamH)₂(opo)]Br (3), (bpo = the anion of 2-hydroxybenzophenone and opo = the anion of 2-hydroxy-4-methoxybenzophenone), in order to determine their thermal degradation in static air and dynamic nitrogen atmospheres. The cationic complexes were characterized by physicochemical methods, spectroscopy (FT-IR, UV–Vis), and single-crystal X-ray analysis, revealing octahedral coordination around cobalt(II) with chromophore CoN₄O₂, being chelated by one anionic 2-hydroxy-benzophenone ligand and two neutral dpamH molecules. The compounds crystallize as ethanol or ethanol/water solvates, with solvent molecules involved, to a different extent, in hydrogen bonding giving quite different packing modes and thus influencing their stability. The differences in crystal structures are reflected in thermal stabilities of the compounds. Thus, in the crystals of 3 ethanol is more weakly bound than in 2 and anticipate that the former one exhibit lower thermal stability, which is in agreement with the results found by TG–DTA. The thermal decomposition of the title complexes was found to be a multi-step decomposition related to the release of the solvent and ligand molecules, leading at 1,000 °C to pure metallic cobalt in nitrogen atmosphere, while in air atmosphere to the expected cobalt oxides.     

Synthesis,molecular structure and biological activity of Niii complexes based on substituted 2-(2-hydroxyphenyl)benzoxazole

New Niⁱⁱ complexes based on the substituted 2-(2-hydroxy-phenyl)benzoxazole have been synthesized from the corresponding ligands and nickel acetate. The crystal structure of bis[2-(1,3-benzoxazol-2-yl-κN)-4,5-dichloro-3-(methoxycarbonyl)phenolate-κO]nickel(ii) has been determined by X-ray diffraction. The new Niⁱⁱ complexes have been screened for their antibacterial, protistocidal and fungistatic activities     

Phenylarsenic(III) complexes of 2-(2-hydroxyphenyl)benzothiazolines

Equimolar reactions of PhAs(OMe)₂ (prepared in situ) and 2-(2-hydroxyphenyl)benzothiazolines LH₂ give the addition products PhAs(OMe)₂LH₂, while equimolar reactions of PhAsCl₂ with Na₂L yield substitution products PhAsL. All these derivatives have been characterized by elemental analyses and their plausible structures have been established on the basis of physico-chemical, IR, and NMR (¹H and ¹³C) spectral studies. © 2003 Wiley Periodicals, Inc. 15:92–96, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/.10220     

Polycarbonates of bis(4-hydroxyphenyl)phenylmethane and bis(4-hydroxyphenyl)diphenylmethane

The polycarbonates prepared by phosgenation of bis(4-hydroxyphenyl)phenylmethane (BHPM) or bis(4-hydroxyphenyl)diphenylmethane (BHDM) were characterized by inherent viscosity measurements, infra-red spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The polycarbonate of BHDM showed a significantly higher glass transition temperature as well as polymer decomposition temperature than the BHPM polycarbonate. Several physical and thermal characteristics of these polymers were correlated with their chemical structure.     

Crystal and molecular structure of bis(2-isotropyliminomethinylphenyl) telluride

Scientific-Research Institute of Physical and Organic Chemistry, Rostov State University. A. N. Nesmeyanov Institute of Heteroorganic Compounds, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 3, pp. 104–106, May–June, 1991.     

Bridged bis(amidinate) lanthanide complexes: Synthesis,molecular structure and reactivity

The yttrium chloride with the bridged bis(amidinate) L (L = Me₃SiNC(Ph)N(CH₂)₃NC(Ph)NSiMe₃) LYCl(DME) (2) was synthesized and structurally characterized. Treatment of LLnCl(sol)_x (Ln = Yb, sol = THF, x = 2 1; Ln = Y, sol = DME, x = 1 2) with the dilithium salt Li₂L(THF)_0.5 afforded the novel bimetallic lanthanide complexes supported by three ligands, Ln₂(μ₂-L)₃ · DME (Ln = Yb 3, Y 4; DME = dimethylether), instead of the designed complex LLn(μ₂-L)LnL via the ligand redistribution reaction. Complexes 3 and 4 were fully characterized including X-ray analysis and ¹H NMR spectrum for 4. Reaction of LnCl₃ (Ln = Yb, Y) with 2 equiv. of Li₂L(THF)_0.5 gave the anionic complexes [Li(DME)₃][L₂Ln] (Ln = Yb 5, Y 6), which were confirmed by a crystal structure determination. The further study indicated that complexes 3 and 4 can also be synthesized by reaction of LnCl₃ (Ln = Yb, Y) with 1.5 equiv. of Li₂L(THF)_0.5 or reaction of 1 and 2 with anionic complexes 5 and 6. Complexes 3, 4, 5 and 6 were found to be high active catalysts for ring-opening polymerization of ε-caprolactone (CL).     

Relationship between the ligand structure and the luminescent properties of water-soluble lanthanide complexes containing bis(bipyridine) anionic arms

A series of six new ligands (L(1)-L(6)) suitable for the formation of luminescent lanthanide complexes in water is described. Ligands L(1)-L(4) are constructed from two 6'-carboxy-6-methylene-2,2'-bipyridine chromophoric arms bonded to the amino function of a 2-aminomethylene-6-carboxy-pyridine (L(1)), an N,N-diacetate-ethylene diamine (L(2)), a serine (L(3)), or an aminomalonic acid (L(4)). For ligands L(5) and L(6), the linking amino function is provided by a glutamic acid, and the anionic functions at the 6'-position of the bipyridyl arms are made of the sodium salts of monoethylphosphonic ester (L(5)) and phosphonic acid (L(6)). The synthesis and characterisation of the ligands are described, together with the study of the formation of lanthanide complexes with europium and terbium. In the case of L(3), the europium complex obtained in acidic conditions was crystallised and the X-ray crystal structure is depicted. Photophysical properties of the complexes were studied by means of UV-visible absorption, and steady-state and time-resolved luminescence spectroscopy. Excited-state luminescence lifetimes of the complexes were determined in water and deuterated water to gain insight into the number of water molecules directly coordinated in the first coordination sphere of the complexes. The coordination behaviour of the series of ligands is questioned in the light of the spectroscopic data and discussed in terms of protection of the cation towards water molecules and their impact on the luminescence efficiency.     

Synthesis and properties of 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-5-nitroindazole

N-(2-Azido-5-nitrobenzylidene)-3,5-di-tert-butyl-4-hydroxyaniline (3a) and N-(2-azido-5-nitrobenzilidene) aniline (3b), when heated in dimethylformamide yielded 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-5-nitroindazole (4a) and 2-phenyl-5-nitroindazole (4b), respectively. The structure of4b was confirmed by X-ray analysis. A stable phenoxyl radical was shown to originate from the oxidation of4a with lead (IV) dioxide.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1095–1097, June, 1994.     

Synthesis and optical properties of bis(oligophenyleneethynylenes)

Bis(oligophenyleneethynylenes) 1-4 were prepared as representative members of a new class of potential nonlinear optical materials. The optical properties of 1-4 were examined for evidence of restricted rotation of the aryl rings when compared to their single-strand precursors, which could potentially increase their nonlinear response through more effective conjugation. The effect of altering the electron density of the terminating functional group of these compounds on their properties was also investigated.     

Redox properties of bis(1,10-phenanthroline)-(pyridine)ruthenium(II) complexes

The redox properties of a series of [Ru(phen)₂(py)X]ⁿ⁺ cations (X = pyridine, NH₃, Cl, Br, I, CN, SCN, N₃ and NO₂) have been investigated in acctonitrile. Two reversible reduction steps are seen at ? 1.35 and ? 1.6 V vs Ag/AgCl; the invariance of these processes with X-group is indicative of electron addition to molecular orbitals mainly of phenanthroline ligand π^* origin. Irreversible multi-electron reductions follow below ? 2.20 V. The Ru(II)/Ru(III) couple is seen as a reversible wave near + 0.8 V vs the normal hydrogen electrode, from calibration with ferrocene, except in the cases of the NO₂ and SCN complexes, where rapid reactions involving these ligands occur.     

Correlation between magnetic properties and molecular structure of some metallo-mesogens

The behaviour of a large number of paramagnetic metallo-mesogenic molecules with Cu and VO in different mesophases in a magnetic field was investigated by EPR techniques and magnetic susceptibility measurements. The investigation of the angular dependence of the EPR spectra enabled conclusions to be reached concerning the molecular orientation in the external magnetic field. Temperature dependence magnetic susceptibility measurements were carried out in order to obtain information about the overall susceptibility anisotropy. The good agreement between experimental results and calculated data based on the known increment scheme is obvious. It is shown that the direction of orientation of the molecules in a magnetic field is predetermined by the sum of the anisotropy of the phenyl ring and the chelate core in the molecular structure.     

Crystal structure and luminescence properties of 4-(4-benzoyloxy-2-hydroxyphenyl)-2,2-difluoro-6-phenyl-1,3,2-dioxaborine

The crystal structure of 4-(4-benzoyloxy-2-hydroxyphenyl)-2,2-difluoro-6-phenyl-1,3,2-dioxaborine (1) was determined by X-ray diffraction analysis. π-π-Stacking interaction between the molecules results in joining the molecules into a three-dimensional layered framework. Luminescence of the aggregates is observed in concentrated solutions of compound 1. Two routes of excimer formation in crystal were revealed by steady-state and time-resolved luminescence spectroscopy: via excitation of single molecules and via excitation of aggregates.     

Crystal structure,optical and magnetic properties of the bis(perchlorate) of 3,4-diaminopyridine

3,4-diaminopyridinium bis(perchlorate) has been synthesized and its crystal structure has been solved by single crystal X-ray diffraction. The optical and magnetic properties of the N1, N4 protonated 3,4-diaminopyridinium dication have been elucidated in solution and in the solid-state by means of linear-polarized solid state IR-spectroscopy (IR-LD), UV-spectroscopy, TGA, DSC, and positive and negative ESI MS. Quantum chemical calculations were used to obtain the electronic structure, vibrational data, and electronic spectra of the dication. The studied compound crystallizes in the noncentrosymmetric space group Cc and exhibits infinite molecular chains formed by 3,4-diaminopyridinium dications and ClO ₄ ^? anions along the c-axis by moderate intermolecular NH ₃ ⁺ ···OClO ₃ ^? interactions with bond lengths of 3.031, 3.024, 2.825, and 2.875 Å. The NH group participates in intermolecular NH···OClO ₃ ^? contacts with bond lengths of 3.220 and 3.172 Å, respectively. The effect of N1, N4 diprotonation on the optical and magnetic properties of the 3,4-diaminopyridinium dication is discussed.     

Tautomeric properties, conformations and structure of N-(2-hydroxyphenyl)-4-amino-3-penten-2-on

N-(2-hydroxyphenyl)-4-amino-3-penten-2-on (C₁₁H₁₃NO₂) has been studied by X-ray analysis. It crystallizes the orthorhombic space group P2₁2₁2₁ with a=8.834(1), b=10.508(2), c=11.212(2) Å, V=1040.8(3) Å³, Z=4, D_c=1.22 g cm⁻³ and μ(MoK)=0.084 mm⁻¹. The structure was solved by direct methods and refined to R=0.038 for 1373 reflections (I>2σ(I)). The title compound is photochromic and the molecule is not planar. Intramolecular hydrogen bonds occur between the pairs of atoms N(1) and O(1) [2.631(2) Å], and N(1) and O(2) [2.641(2) Å], the H atom essentially being bonded to the N atom. There is also a strong intermolecular O–HO hydrogen bonding [2.647(2) Å] between neighbouring molecules. Tautomeric properties and conformations of the title compound were investigated by semi-empirical quantum mechanical AM1 calculations and the results are compared with the X-ray results.     

Structure and DNA-binding properties of bis(quinolonato)bis(pyridine)zinc(II) complexes

The novel neutral mononuclear zinc complexes with the quinolone antibacterial drugs enrofloxacin and oxolinic acid in the presence of the nitrogen donor heterocyclic ligand pyridine have been synthesized and characterized. The experimental data suggest that the quinolone ligands are on the deprotonated mode acting as bidentate ligands coordinated to the zinc(II) ion through the ketone oxygen and a carboxylato oxygen. The crystal structure of the complex bis(enrofloxacinato)bis(pyridine)zinc(II), 1, has been determined with X-ray crystallography. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT-DNA) with UV and fluorescence spectroscopies. UV spectroscopic titration studies of the interaction of the complexes with DNA have shown that they can bind to CT-DNA and the DNA binding constants have been calculated. Competitive studies with ethidium bromide (EB) have shown that the complexes exhibit the ability to displace the DNA-bound EB indicating that they can bind to DNA in strong competition with EB for the intercalative binding site.     

Crystal and molecular structure of the ethanol solvate of 2-[bis(diphenylphosphoryl)methyl]phenol

Crystal and molecular structure of the ethanol solvate of 2-[bis(diphenylphosphoryl)methyl]phenol, C₃₁H₂₆O₃P₂·3/4 C₂H₅OH (I), was determined by X-ray diffraction analysis. Crystals I are monoclinic: a=11.896(3), b=17.207(3), c=28.421(6) Å, β=90.75(2)°, Z=8, space group P2₁/c. The structure of I was solved by direct methods and refined anisotropically by large-block least-squares analysis to R=0.066 (CAD-4 automatic diffractometer, λMoK_α radiation, 3650 independent reflections with I≥3σ). The crystal structure of I contains two independent molecules, Ia and Ib, of the basic substance and two independent solvate molecules of ethanol. The P atoms in molecules Ia and Ib have distorted tetrahedral environments; the average bond lengths are: P=O 1.476(3), P-C(sp³)=1.833(4) and P-C(Ar)=1.809(4) Å. Molecule Ia has an approximate symmetry plane C_s. The conformation of molecule Ib differs from that of Ia in rotation of one diphenylphosphoryl substituent around the P-C(sp³) bond by an angle of ≈34°. In molecule Ia, the O=P-C-P=O fragment has the form of a chela with two nearly parallel P=O bonds. In the crystal structure of I there are O-H...O=P intermolecular H-bonds; in molecules Ia and Ib there is an intramolecular H-bond of C-H...OH type.