White Electroluminescence from a Star-Like Polymer with an Orange Emissive Core and Four Blue Emissive Arms

A star-like white light-emitting polymer with an orange emissive core and four blue emissive arms is designed and synthesized. White electroluminescence is observed with simultaneous orange emission from the core and blue emission from the arms. A single-layer device based on this polymer emits white light with CIE coordinates of (0.35, 0.39) and a luminous efficiency of 7.06 cd A(-1).

The Reasons for Ligand-Dependent Quantum Yields and Absorption Spectrum of Four Polypyridylruthenium(II) Complexes with a Tetrazolate-Based Ligand: TDDFT Study

The quantum yield, lifetime, and absorption spectrum of four [Ru(bpy)(2)L](+) [where bpy is 2,2'-bipyridyl; L is represented by the deprotonated form of 2-(1H-tetrazol-5-yl)pyridine (L1) or 2-(1H-tetrazol-5-yl)pyrazine (L2)], as well as their methylated complexes [Ru(bpy)(2)LMe](2+) (RuL1Me and RuL2Me) are closely ligand dependent. In this paper, density functional theory (DFT) and time-dependent DFT (TDDFT) were performed to compare the above properties among these complexes. The calculated results reveal that the replacement of pyridine by pyrazine or the attachment of a CH3 group to the tetrazolate ring greatly increases the pi-accepting ability of the ancillary ligands.

Self-Assembly from Two-Dimensional Layered Networks to Tetranuclear Structures: Syntheses, Structures, and Properties of Four Copper-Thiacalix[4]arene Compounds

Two new copper-thiacalix[4]arene compounds, [Cu-2(1)-Cl-2(H(4)TC4A)](CH3OH) (1) and [Cu(I)2Cl(2)(H(4)PTC4A)](CH3OH)(CHCl3)(0.5) (2) (where H(4)TC4A = p-tert-butylthiacalix[4]arene and H(4)PTC4A = p-phenylthiacalix[4]arene), were synthesized by the solvothermal method in the mixed CH3OH/CHCl3 (1: 1) solvent and reassembled in air at room temperature to two other structures, [(Cu4Cl3)-Cl-II(HCO2)(TC4A)(CH3-OH)(2)(H2O)](CHCl3)(CH3OH)(2.7) (3) and [(Cu4Cl4)-Cl-II(PTC4A)(CH3OH)(4)] (4), respectively. All these four compounds were characterized by TG analyses, FTIR spectroscopy, and singlecrystal X-ray diffraction analyses. Compounds 1 and 2 feature two-dimensional layered networks, while compounds 3 and 4 are assembled by some tetranuclear units.

Four New Lanthanide-Nitronyl Nitroxide (Ln(III)=Pr-III, Sm-III, Eu-III, Tm-III) Complexes and a Tb-III Complex Exhibiting Single-Molecule Magnet Behavior

Five new complexes based on rare-earth-radical [Ln(hfac)(3)(NIT-5-Br-3py)](2) (Ln=Pr (1), Sm (2), Eu (3), Tb (4), Tm (5); hfac = hexafluoroacetylacetonate; NIT-5-Br-3py = 2-(4,4,5,5-tetramethyl-3-oxylimidazoline-1-oxide)-5-bromo-3-pyridine) have been synthesized and characterized by X-ray crystal diffraction. The single-crystal structures show that these complexes have similar structures, in which a NIT-5-Br-3py molecule acts as a bridging ligand linking two Ln(III) ions through the oxygen atom of the N-O group and nitrogen atom from the pyridine ring to form a four-spin system. Both static and dynamic magnetic properties were measured for complex 4, which exhibits single-molecule magnetism behavior.

Synthesis of four-armed poly(epsilon-caprolactone)-block-poly(ethylene oxide) by diethylzinc catalyst

Biodegradable, amphiphilic, four-armed poly(epsilon-caprolactone)-block-poly(ethylene oxide) (PCL-b-PEO) copolymers were synthesized by ring-opening polymerization of ethylene oxide in the presence of four-armed poly(epsilon-caprolactone) (PCL) with terminal OH groups with diethylzinc (ZnEt2) as a catalyst. The chemical structure of PCL-b-PEO copolymer was confirmed by H-1 NMR and C-13 NMR. The hydroxyl end groups of the four-armed PC L were successfully substituted by PEO blocks in the copolymer. The monomodal profile of molecular weight distribution by gel permeation chromatography provided further evidence for the four-armed architecture of the copolymer. Physicochemical properties of the four-armed block copolymers differed from their starting four-armed PCL precursor. The melting points were between those of PCL precursor and linear poly(ethylene glycol). The length of the outer PEO blocks exhibited an obvious effect on the crystallizability of the block copolymer. The degree of swelling of the four-armed block copolymer increased with PEO length and PEO content.

Syntheses, structures, and characterizations of four new silver(I) sulfonate coordination polymers with neutral ligands

In this paper, four novel silver(I) sulfonate coordination polymers containing neutral ligands, namely, [Ag(2)Ll (biim)(2)]center dot 2H(2)O (1). AgL2(biim) (2), [Ag(HL3)(Pic)(2)]center dot H2O (3), and [Ag-3(L3)(HL3)(4,4'-bipy)(3)(H2O)(2)]center dot 4H(2)O (4), have been synthesized [L1 = 3-carboxy-4-hydroxybenzenesulfonate, L2 = p-aminobenzenesulfonate, H(2)L3 = p-hydroxybenzenesulfonic acid, biim = 1,1'-(1.4-butanediyl)-bis(imidazole), Pic = beta-picoline, 4,4'-bipy = 4,4'-bipyridine]. For compounds 1 and 2, Ag(I) cations are bridged by biim ligands to form a one-dimensional (1D) "zigzag" chain, and L1 and L2 sulfonate ligands are not coordinated to the silver cation. Compound 3 has a dimeric structure in which two silver cations are bridged by two HL3 ligands. For compound 4, L3 ligand coordinates to a silver cation as a monodentate ligand, and Ag(l) cations are bridged by 4,4'-bipy ligands to form a ID chain. Compound 1 contains water dimers, while compound 4 contains water trimers. Compounds 1-3 display room-temperature photoluminescence.

Syntheses and crystal structures of four new organotin complexes with Schiff bases containing triazole

Four new organotin complexes, namely [(Bu2Sn)(2)O(EtO)(L1)](2) (1), [(Bu2Sn)(2)O(EtO)(L2)](2) (2), [(Bu2Sn)(2)O(EtO)(L-3)](2) (3) and [Ph3Sn(L4)]center dot 0.5H(2)O (4), were obtained by reactions of Bu2SnO and Ph3SnOH with 4-phenylideneamino-3-methyl-1,2,4-triazole-5-thione (HL1), 4-furfuralideneamino-3-methyl-1,2,4-triazole-5-thione (HL2), 4-(2-thienylideneamino)-3-ethyl-1,2,4-triazole-5-thione (HL3) and 4-(3,5-di-t-butylsalicylideneamino)-3-ethyl-1,2,4-triazole-5-thione (HL4). Compounds 1-4 were characterized by elemental analysis, IR spectra and their structures were determined by single-crystal X-ray diffraction methods. Complexes 1-3 show similar structures containing a Sn4O4 ladder skeleton in which each of the exo tin atoms is bonded to the N atom of a corresponding thione-form deprotonated ligand. Complex 4 shows a mononuclear structure in which the tin atom of triphenyltin group is coordinated by the S atom of a thiol-form L4(-) anion.

A new alpha-Keggin type polyoxometalate coordinated to four silver complex moieties: {PW9V3O40[Ag(2,2 '-bipy)](2)[Ag-2(2,2 '-bipy)(3)](2)}

A new polyoxometalate derivative {PW9V3O40[Ag(2,2'-bipy)](2)[Ag-2(2,2'-bipy)(3)](2)} 1 has been hydrothermally synthesized and structurally characterized by the single crystal X-ray diffraction. X-Ray analysis showed that both [Ag(2,2'-bipy)](+) and [Ag-2(2,2'-bipy)(3)](2+) units are supported on the alpha-Keggin polyoxoanion [PW9V3O40](6-) via the surface bridging oxygen atoms. 1 represents the first alpha-Keggin type polyoxoanion coordinated with four transition metal complex moieties, which further acts as a neutral molecular units for the construction of an interesting three-dimensional supramolecular framework.

The electrochemically induced conformational transition of disulfides in bovine serum albumin studied by thin layer circular dichroism spectroelectrochemistry

The conformational transition of disulfides in bovine serum albumin (BSA) induced by electrochemical redox reaction of disulfides were monitored by in-situ circular dichroism (CD) spectroelectrochemistry, with a long optical path thin layer cell and analyzed by a singular value decomposition least square (SVDLS) method. Electrochemical reduction of disulfides drives the left-handed conformation of disulfides changed into the right-handed. At open circuit, eight of the 17 disulfides were of left-handed conformation. Four of the 17 disulfides took part in the electrochemical reduction with an EC mechanism. Only one-fourth of the reduced disulfides returned to left-handed conformation in the re-oxidation process. Some parameters of the electrochemical reduction process, i.e. the number of electrons transferred and electron transfer coefficient, n=8, alphan=0.15, apparent formal potential, E-1(0') = -0.65(+/-0.01) V, standard heterogeneous electron transfer rate constant, k(1)(0) = (2.84 +/- 0.14)x 10(-5) cm s(-1) and chemical reaction equilibrium constant, K-c=(5.13 +/- 0.12) x 10(-2), were also obtained by double logarithmic analysis based on the near-UV absorption spectra with applied potentials. (C) 2001 Elsevier Science B.V. All rights reserved.

Four-level decay model of P-6(7/2) excited state of Eu2+ ion in KMgF3

A four-level model of P-6(7/2) excited state of Eu2+ ion in KMgF3: Eu2+ has been proposed. The decay profiles of the P-6(7/2) excited sstate of Eu2+ are two exponential and the physical implication of each term in the fit equation responsible for the model is interpreted. The data obtained spectroscopically are in good agreement with the fit results.

Estimation of individual phases from the four-phase structure invariants in the single isomorphous replacement case

The probability distribution of the four-phase invariants in the case of single isomorphous replacement has been developed to estimate some individual phases. An example of its application to obtain the phases having special values of 0, pi or +/-pi /2 is given for a known protein structure in space group P2(1)2(1)2(1). The phasing procedure includes the determination of starting phases and an iterative calculation. The initial values of starting phases, which are required by the formula, can be obtained from the estimate of one-phase seminvariants and by specifying the origin and enantiomorph. In addition, the calculations lead to two sets of possible phases for each type of reflection by assigning arbitrarily an initial phase value. The present method provides a possibility for the multisolution technique to increase greatly the number of known phases while keeping the number of the trials quite small.

Synthesis, electrochemistry and fluorescence of four new Ru(phen)(3)(2+) derivatives

Four typical LB monolayer film materials, Ru(phen)(3)(2+) complexes with one ligand attached to different long chain alkyl amides, were designed and synthesized. Their chemical structures were identified by the techniques of FT-IR, H-1 NMR and ESI-MS. Also, UV-Vis, electrochemistry and fluorescence of these complexes are reported.

Four novel screw-like tris(1,10-phenanthroline) ruthenium(II) bishexafluorophosphate derivatives

Four novel screw-like Ru(II) complexes, tris(5-lauramide-1,10-phenanthroline)Ru(II) bishexafluorophosphate, tris(5-myristamide-1,10-phenanthroline)Ru(II) bishexafluorophosphate, tris(5-palmitamide-1,10-phenanthroline)Ru(II) bishexafluorophosphate and tris (5-stearamide-1,10-phenanthroline)Ru(II) bishexafluorophosphate have been efficiently synthesized. They are confirmed by the techniques of IR, H-1 NMR, H-1-H-1 COSY and ES-MS. Also, their electrochemistry, fluorescence and electrochemiluminescence are reported.

Probability distribution of the four-phase structure invariants of isomorphously related structure factors and its applications

The probability distribution of the four-phase structure invariants (4PSIs) involving four pairs of structure factors is derived by integrating the direct methods with isomorphous replacement (IR). A simple expression of the reliability parameter for 16 types of invariant is given in the case of a native protein and a heavy-atom derivative. Test calculations on a protein and its heavy-atom derivative using experimental diffraction data show that the reliability for 4PSI estimates is comparable with that for the three-phase structure invariants (3PSIs), and that a large-modulus invariants method can be used to improve the accuracy.

Impedance spectrum measurement in liquid liquid interface electrochemistry .1. Analysis of various kinds of interfacial impedance in the four-electrode system

Applying impedance spectrum technique to liquid/liquid interfacial electrochemistry, we present the theoretical expression of the liquid/liquid interfacial impedance in the four - electrode electrolytic cell measured by alternating current impedance method. The influence of the electrolytic cell parameters and input passage parameters of the impedance apparatus on impedance spectrum curves are theoretically studied.