Corrosion behaviour of mechanically polished AA7075‐T6 aluminium alloy

In the present study, the effects of mechanical polishing on the microstructure and corrosion behaviour of AA7075 aluminium alloy are investigated. It was found that a nano‐grained, near‐surface deformed layer, up to 400 nm thickness, is developed due to significant surface shear stress during mechanically polishing. Within the near‐surface deformed layer, the alloying elements have been redistributed and the microstructure of the alloy is modified; in particular, the normal MgZn₂ particles for T6 are absent. However, segregation bands, approximately 10‐nm thick, containing mainly zinc, are found at the grain boundaries within the near‐surface deformed layer. The presence of such segregation bands promoted localised corrosion along the grain boundaries within the near‐surface deformed layer due to microgalvanic action. During anodic polarisation of mechanically polished alloy in sodium chloride solution, two breakdown potentials were observed at ?750 mV and ?700 mV, respectively. The first breakdown potential is associated with an increased electrochemical activity of the near‐surface deformed layer, and the second breakdown potential is associated with typical pitting of the bulk alloy. Copyright © 2009 John Wiley & Sons, Ltd.     

Development of cerium‐based conversion coatings on 2024‐T3 Al alloy after rare‐earth desmutting

The deposition of Ce‐based conversion coatings onto 2024‐T3 Al alloy sheet was studied using Rutherford backscattering spectroscopy, scanning electron microscopy, Auger electron spectroscopy, x‐ray photoelectron spectroscopy and atomic force microscopy. The Al sheet was pretreated with an alkaline clean followed by treatment in a Ce(IV) and H₂SO₄‐based desmutter. The Ce(IV)‐based conversion coating solution contained 0.1 M CeCl₃·7H₂O and 3% H₂O₂ and was acidified to pH 1.9 with HCl. Upon immersion, there was an induction period that included activation followed by aluminium oxide growth over the matrix and cerium oxide deposition onto cathodic intermetallic particles and along rolling marks on the surface. After the induction period cerium oxide deposited generally across the whole surface and thickened. The strongest anodic sites initially were adjacent to the intermetallic cathodes and resulted in aluminium dissolution but also oxide thickening. Copyright © 2004 John Wiley & Sons, Ltd.     

Electrochemical Behavior of the Li+/Li Couple and Stability of Lithium Deposits in Tri‐1‐Butylmethylammonium Bis((Trifluoromethyl)Sulfonyl)Imide Room Temperature Ionic Liquid

The electrochemical behavior of the Li⁺/Li couple was studied at polycrystalline tungsten, platinum, copper and aluminum electrodes in tri‐1‐butylmethylammonium bis((trifluoromethyl)sulfonyl)imide ionic liquid mixed with a little propylene carbonate at 30 °C. Lithium cations were introduced into the ionic liquid by dissolution of lithium bis((trifluoromethyl)sulfonyl)imide which is highly soluble in ionic liquid. Propylene carbonate was used to reduce the viscosity of this ionic liquid in order to enhance the mass transfer and to additionally improve the stability of lithium deposits. At the tungsten and copper electrodes, the cyclic voltammetric behavior of a Li⁺/Li couple is a quasi‐reversible reaction. At the platinum electrode, the behavior becomes very complicated because of the alloy formation. Coulombic efficiency was used to evaluate the stability of lithium deposits at each electrode. The aluminum electrode showed the best efficiency due to the formation of Li‐Al alloy. However, lowest efficiency was obtained at the platinum electrode because of the low redox reversibility of the lithium in the Li‐Pt alloy. The diffusion coefficient of lithium cation in this solution was 1.0 ± 0.1 × 10^?;7 cm² s^?;1 as determined by chronopotentiometry. The best coulombic efficiency obtained at the Al electrode is 97% but dropped to about 90% after 12 hours. The self‐discharge current of the lithium deposits at the Al electrode was 0.4 μA/cm² during the experimental period.     

Photophysical Evidence of Charge‐Transfer‐Complex Pairs in Mixed‐Linker 5‐Amino/5‐Nitroisophthalate CAU‐10

The photochemistry of two isostructural metal–organic frameworks based on 5‐amino/5‐formamidoisophthalate (CAU‐10‐NH₂/NHCHO) or mixed‐linker 5‐amino/5‐formamido‐ and 5‐nitroisophthalate (CAU‐10‐NO₂/NH₂/NHCHO) has been studied using laser flash photolysis. 355 nm excitation of CAU‐10‐NH₂/NHCHO leads to a transient absorption spectrum characterized by a broad continuous absorption from 380 to 800 nm that was attributed to the presence of holes (440 nm) and electrons (600 nm) based on iPrOH and N₂O quenching, respectively. In contrast, no transients were observed for the isostructural mixed‐linker CAU‐10‐NO₂/NH₂/NHCHO, data that is compatible with the uniform distribution of linkers 5‐amino/5‐formamido/5‐nitroisophthalate as charge‐transfer complex pairs. The same effect of quenching of 5‐aminoisophthalate transients by 5‐nitroisophthalate was also observed in aqueous solution (pH 9) but with much lower strength. Using a simple Stern–Volmer formalism allowed the estimation of the interaction of 5‐aminoisophthalate with 5‐nitroisophthalate in MOF to be 5.2×10⁴ times stronger than in the aqueous phase.     

“Coordination‐insertion” ring‐opening polymerization of 1,4‐dioxan‐2‐one and controlled synthesis of diblock copolymers with ε‐caprolactone

This communication deals with the coordination‐insertion ring‐opening polymerization of 1,4‐dioxan‐2‐one (DX) as initiated by aluminium triisopropoxide (Al(OⁱPr)₃) either in bulk or in solution. First, polymerization of DX has been carried out in bulk at 100°C and compared to the ring‐opening polymerization promoted by tin(II)octoate. Block copolymers of ε‐caprolactone (CL) and DX have been then selectively obtained by first initiating CL polymerization with Al(OⁱPr)₃ in toluene and then adding DX to the living PCL macroinitiator solution at room temperature. In spite of the inherent poor solubility of poly(1,4‐dioxan‐2‐one) in most organic solvents, DX polymerization has proven to proceed through a “living” mechanism. Interestingly enough, the semi‐crystalline P[CL‐b‐DX] block copolymers displayed two well separated melting endotherms at ca. 55 and 102°C for PCL and PDX sequences, respectively.     

Investigation of the Anodic Behavior of Al in Room Temperature Ionic Liquid Electrolytes: BMI‐BF4, PP14‐BF4 and BMI‐BF4·PC

The anodic polarization behavior of Al, Ta and Nb foil was investigated in 1‐butyl‐3‐methylimidazolium tetrafluoroborate ionic liquid (BMI‐BF₄). Compared with that of Ta and Nb foil, it showed that a better passive film was formed on Al foil surface after the anodic polarization in BMI‐BF₄, which could resist the potential up to 94.58 V vs. Ag⁺/Ag. Besides, similar anodic behavior of Al foil was observed in N‐methyl‐N‐butylpiperidinium tetrafluoroborate ionic liquid (PP14‐BF₄), which indicated that the anodic polarization behavior of Al foil was independent of the cations of RTIL. In addition, the investigation of anodic polarization behavior of Al foil was carried out in the mixture electrolytes composed of BMI‐BF₄·PC. Differently, two breakdown potential processes of Al foil were presented compared to pure BMI‐BF₄. Further research showed that the passive film on Al foil was mainly composed of AlF₃ and Al₂O₃ after the first breakdown potential process, while the fluoride film increased with continual anodic polarization, which improved the anodic stability of Al foil and resisted higher breakdown potential. The high breakdown potential properties of Al foil in BMI‐BF₄, PP14‐BF₄ and the mixture of BMI‐BF₄·PC during the anodic polarization can be favored for R&D of the high performance electrochemical devices.     

[N‐(6‐Amino‐3,4‐di­hydro‐3‐methyl‐5‐nitroso‐4‐oxopyrimidin‐2‐yl)glycylglycinato]aquapotassium,a three‐dimensional coordination polymer

In the title compound, polymeric potassium N‐(6‐amino‐3,4‐di­hydro‐3‐methyl‐5‐nitro­so‐4‐oxopyrimidin‐2‐yl)­glycyl­gly­cinate hydrate, (K⁺·C₉H₁₁N₆O₅^?·H₂O)_n, the hexacoordinate K⁺ cation is linked to five different anions as well as to the water mol­ecule, with K—O distances in the range 2.617 (2)–2.850 (2) Å. Four of the O atoms in each anion coordinate to K centres, one of them acting as a bridging ligand, leading to the formation of nearly square centrosymmetric K₂O₂ rings. The structure is analysed in terms of (010) metal–ligand sheets linked by [010] chains of fused rings.     

Halogen,hydrogen and electrostatic interactions in 2‐amino‐5‐chloro‐1,3‐benzoxazol‐3‐ium nitrate and 2‐amino‐5‐chloro‐1,3‐benzoxazol‐3‐ium perchlorate

In the title compounds, C₇H₆ClN₂O⁺·NO₃⁻ and C₇H₆ClN₂O⁺·ClO₄⁻, the ions are connected by N—H...O hydrogen bonds and halogen interactions. Additionally, in the first compound, co‐operative π–π stacking and halogen...π interactions are observed. The energies of the observed interactions range from a value typical for very weak interactions (1.80 kJ mol⁻¹) to one typical for mildly strong interactions (53.01 kJ mol⁻¹). The iminium cations exist in an equilibrium form intermediate between exo‐ and endocyclic. This study provides structural insights relevant to the biochemical activity of 2‐amino‐5‐chloro‐1,3‐benzoxazole compounds.     

Preparation and Characterization of Aluminum Alkoxides and their Application to Ring‐Opening Polymerization of ϵ‐Caprolactones

The reaction of 2‐methoxybenzyl alcohol with one molar equiv of R₂AIX in diethyl ether at 0°C gives [(2‐MeOC₆H₄CH₂‐μ‐O)AlRX]₂ ( 1 : R = Et, X = Cl, 2 : R = X = Et). In addition, 2,4‐di‐tert‐butylphenol reacts with ⁱBu₃Al affording a four‐coordinated aluminum compound [(μ‐2,4‐^tBu₂‐C₆H₄O)Al(ⁱBu)₂]₂ ( 4 ). Single crystal X‐ray structure analysis of 4 shows a C_2h‐symmetry with a planar Al₂O₂ core. Ring‐opening polymerization (ROP) of caprolactones initiated by 1, 4 and [(μ‐OCH₂C₆H₄OMe)Al(ⁱBu)₂]₂ ( 3 ) is performed and polyesters with narrow molecular weight distributions were obtained from the “living” ROP of caprolactones. ¹H NMR spectroscopic studies of PCL reveal that the initiator of 1 and 3 is through the Al‐OAr function, but the initiator of 4 is through the Al‐ ⁱBu group.     

7‐Iodo‐8‐aza‐7‐deaza‐2′‐deoxy­adenosine and 7‐bromo‐8‐aza‐7‐deaza‐2′‐deoxyadenosine

The isomorphous structures of the title molecules, 4‐amino‐1‐(2‐deoxy‐β‐d ‐erythro‐pento­furan­osyl)‐3‐iodo‐1H‐pyrazolo‐[3,4‐d]pyrimidine, (I), C₁₀H₁₂IN₅O₃, and 4‐amino‐3‐bromo‐1‐(2‐deoxy‐β‐d ‐erythro‐pento­furan­osyl)‐1H‐pyrazolo[3,4‐d]­pyrimidine, (II), C₁₀H₁₂BrN₅O₃, have been determined. The sugar puckering of both compounds is C1′‐endo (^1′E). The N‐­glycosidic bond torsion angle χ¹ is in the high‐anti range [?73.2 (4)° for (I) and ?74.1 (4)° for (II)] and the crystal structure is stabilized by hydrogen bonds.     

Synthesis and characterization of indenofluorene‐based copolymers containing 2,5‐bis(2‐thienyl)‐N‐arylpyrrole for bulk heterojunction solar cells and polymer light‐emitting diodes

Two novel alternating π‐conjugated copolymers, poly[2,8‐(6,6′,12,12′‐tetraoctyl‐6,12‐dihydroindeno‐[1,2b]fluorene‐ alt‐5(1‐(2,6‐diisopropylphenyl)‐2,5‐di(2‐thienyl)pyrrole) ( P1 ) and poly[2,8‐(6,6′,12,12′‐tetraoctyl‐6,12‐dihydroindeno‐[1,2b]fluorene‐ alt‐5(1‐(p‐octylphenyl)‐2,5‐di(2‐thienyl)pyrrole) ( P2 ), were synthesized via the Suzuki coupling method and their optoelectronic properties were investigated. The resulting polymers P1 and P2 were completely soluble in various common organic solvents and their weight‐average molecular weights (M_w) were 5.66 × 10⁴ (polydispersity: 1.97) and 2.13× 10⁴ (polydispersity: 1.54), respectively. Bulk heterojunction (BHJ) solar cells were fabricated in ITO/PEDOT:PSS/polymer:PC₇₀BM(1:5)/TiO_x/Al configurations. The BHJ solar cell with P1 :PC₇₀BM (1:5) has a power conversion efficiency (PCE) of 1.12% (J_sc= 3.39 mA/cm², V_oc= 0.67 V, FF = 49.31%), measured using AM 1.5 G solar simulator at 100 mW/cm² light illumination. We fabricated polymer light‐emitting diodes (PLEDs) in ITO/PEDOT:PSS/emitting polymer:polyethylene glycol (PEG)/Ba/Al configurations. The electroluminescence (EL) maxima of the fabricated PLEDs varied from 526 nm to 556 nm depending on the ratio of the polymer to PEG. The turn‐on voltages of the PLEDs were in the range of 3–8 V depending on the ratio of the polymer to PEG, and the maximum brightness and luminance efficiency were 2103 cd/m² and 0.37 cd/A at 12 V, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3169–3177, 2010     

Electrochemical Determination of 2‐Nitrophenol in Water Samples Using Mg‐Al‐SDS Hydrotalcite‐Like Clay Modified Glassy Carbon Electrode

A glassy carbon electrode (GCE) modified with Mg‐Al‐SDS hydrotalcite‐like clay (SDS‐HTLC) was used for the sensitive voltammetric determination of 2‐nitrophenol (2‐NP) utilizing the oxidation process. The results indicate the prepared modified electrode has an excellent electrocatalytic activity toward 2‐NP oxidation, lowering the oxidation overpotential and increasing the oxidation current. Under optimal conditions, the oxidation current was proportional to 2‐NP concentration in the range from 1.0×10^?6 to 6.0×10^?4 M with the detection limit of 5.0×10^?7 M by DPV (S/N=3). The fabricated electrode was applied for 2‐NP determination in water samples and the recovery for these samples was from 95.6 to 103.5%.     

Preferential anodic oxidation of second‐phase constituents during anodising of AA2024‐T3 and AA7075‐T6 alloys

Model analogues of the metallurgical phases found in 2xxx and 7xxx series aluminium alloys were produced by magnetron sputtering and employed to investigate the local and general anodising behaviour of the alloys. Electrochemical tests, allied with scanning and transmission electron microscopy, enabled insight into the local anodising behaviour of the constituents and related effects on the overall porous oxide morphology. Under potentiodynamic conditions, the observed anodic current peaks of the commercial alloys were related with the anodic oxidation of specific second‐phase particles. At 0 V, magnesium‐containing particles, including S‐phase, were preferentially removed from the alloy surface; at 5–6 V_SCE, the copper‐ and/or iron‐containing particles, such as θ phase and Al₇Cu₂Fe particles were anodically oxidised. The initial voltage transient revealed for the commercial alloys during galvanostatic anodising was related to the previous findings and reproduced by the use of coupled alloy analogues. Transmission electron microscopy revealed that the voltage transient associated with oxidation of second‐phase material influence the morphology of the anodic film formed on the aluminium matrix. Copyright © 2010 John Wiley & Sons, Ltd.     

MAO‐free polymerization of propylene by rac‐ Me2Si(1‐C5H2‐2‐Me‐4‐tBu)2Zr(NMe2)2 compound

Ansa‐zirconocene diamide complex rac‐Me₂Si(CMB)₂Zr(NMe₂)₂ (rac‐1, CMB = 1‐C₅H₂‐2‐Me‐4‐^tBu) reacts with AlR₃ (R = Me, Et, i‐Bu) and then with [CPh₃]⁺[B(C₆F₅)₄]⁻ (2) in toluene in order to in situ generate cationic alkylzirconium species. In the sequential NMR‐scale reactions of rac‐1 with various amount of AlMe₃ and 2, rac‐1 transforms first to rac‐Me₂Si(CMB)₂Zr(Me)(NMe₂) (rac‐3) and rac‐Me₂Si(CMB)₂ZrMe₂ (rac‐4) by the reaction with AlMe₃, and then to [rac‐Me₂Si(CMB)₂ZrMe]⁺ (5⁺) cation by the reaction of the resulting mixtures with 2. The activities of propylene polymerizations by rac‐1/Al(i‐Bu)₃/2 system are dependent on the type and concentration of AlR₃, resulting in the order of activity: rac‐1/Al(i‐Bu)₃/2 > rac‐1/AlEt₃/2 > rac‐1/MAO ≫ rac‐1/AlMe₃/2 system. The bulkier isobutyl substituents make inactive catalytic species sterically unfavorable and give rise to more separated ion pairs so that the monomers can easily access to the active sites. The dependence of the maximum rate (R_{p, max}) on polymerization temperature (T_p) obtained by rac‐1/Al(i‐Bu)₃/2 system follows Arrhenius relation, and the overall activation energy corresponds to 0.34 kcal/mol. The molecular weight (MW) of the resulting isotactic polypropylene (iPP) is not sensitive to Al(i‐Bu)₃ concentration. The analysis of regiochemical errors of iPP shows that the chain transfer to Al(i‐Bu)₃ is a minor chain termination. The 1,3‐addition of propylene monomer is the main source of regiochemical sequence and the [mr] sequence is negligible, as a result the meso pentad ([mmmm]) values of iPPs are very high ([mmmm] > 94%). These results can explain the fact that rac‐1/Al(i‐Bu)₃/2 system keeps high activity over a wide range of [Al(i‐Bu)₃]/[Zr] ratio between 32 and 3,260. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1071–1082, 1999     

2,4‐Diamino‐5‐(1‐naphthyl)‐3,5‐diaza‐1‐azoniaspiro[5.5]undeca‐1,3‐diene chloride

The title salt, C₁₈H₂₂N₅⁺·Cl^?, is a member of a new series of lipophilic 4,6‐di­amino spiro‐s‐triazines which are potent in­hib­itors of di­hydro­folate reductase. The protonated triazine ring deviates from planarity, whereas the cyclo­hexane ring adopts a chair conformation. A rather unusual hydrogen‐bonding scheme exists in the crystal. There is a centrosymmetric arrangement involving two amino groups and two triazine ring N atoms, with graph‐set R(8) and an N?N distance of 3.098 (3) Å, flanked by two additional R(8) systems, involving two amino groups, a triazine ring N atom and a Cl^? anion, with N?Cl distances in the range 3.179 (2)–3.278 (2) Å. Furthermore, the Cl^? anion, the protonated triazine ring N atom and an amino group form a hydrogen‐bonding system with graph‐set R(6).     

Kinetics of propylene polymerization initiated by rac‐Me2Si(1‐C5H2‐2‐Me‐4‐tBu)2Zr(NME2)2/MAO catalyst

The kinetics of propylene polymerization initiated by ansa‐metallocene diamide compound rac‐Me₂Si(CMB)₂Zr(NMe₂)₂ (rac‐1, CMB = 1‐C₅H₂‐2‐Me‐4‐^tBu)/methylaluminoxane (MAO) catalyst were investigated. The formation of cationic active species has been studied by the sequential NMR‐scale reactions of rac‐1 with MAO. The rac‐1 is first transformed to rac‐Me₂Si(CMB)₂ZrMe₂ (rac‐2) through the alkylation mainly by free AlMe₃ contained in MAO. The methylzirconium cations are then formed by the reaction of rac‐2 and MAO. Small amount of MAO ([Al]/[Zr] = 40) is enough to completely activate rac‐1 to afford methylzirconium cations that can polymerize propylene. In the lab‐scale polymerizations carried out at 30°C in toluene, the rate of polymerization (R_p) shows maximum at [Al]/[Zr] = 6,250. The R_p increases as the polymerization temperature (T_p) increases in the range of T_p between 10 and 70°C and as the catalyst concentration increases in the range between 21.9 and 109.6 μM. The activation energies evaluated by simple kinetic scheme are 4.7 kcal/mol during the acceleration period of polymerization and 12.2 kcal/mol for an overall reaction. The introduction of additional free AlMe₃ before activating rac‐1 with MAO during polymerization deeply influences the polymerization behavior. The iPPs obtained at various conditions are characterized by high melting point (approximately 155°C), high stereoregularity (almost 100% [mmmm] pentad), low molecular weight (MW), and narrow molecular weight distribution (below 2.0). The fractionation results by various solvents show that iPPs produced at T_p below 30°C are compositionally homogeneous, but those obtained at T_p above 40°C are separated into many fractions. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 737–750, 1999     

Higher α‐olefin polymerizations catalyzed by rac‐Me2Si(1‐C5H2‐2‐CH3‐4‐tBu)2Zr(NMe2)2/Al(iBu)3/[Ph3C][B(C6F5)4]

Polymerizations of higher α‐olefins, 1‐pentene, 1‐hexene, 1‐octene, and 1‐decene were carried out at 30 °C in toluene by using highly isospecific rac‐Me₂Si(1‐C₅H₂‐2‐CH₃‐4‐^t Bu)₂Zr(NMe₂)₂ (rac‐1) compound in the presence of Al(iBu)₃/[CPh₃][B(C₆F₅)₄] as a cocatalyst formulation. Both the bulkiness of monomer and the lateral size of polymer influenced the activity of polymerization. The larger lateral of polymer chain opens the π‐ligand of active site wide and favors the insertion of monomer, while the large size of monomer inserts itself into polymer chain more difficultly due to the steric hindrance. Highly isotactic poly(α‐olefin)s of high molecular weight (MW) were produced. The MW decreased from polypropylene to poly(1‐hexene), and then increased from poly(1‐hexene) to poly(1‐decene). The isotacticity (as [mm] triad) of the polymer decreased with the increased lateral size in the order: poly(1‐pentene) > poly(1‐hexene) > poly(1‐octene) > poly(1‐decene). The similar dependence of the lateral size on the melting point of polymer was recorded by differential scanning calorimetry (DSC). ¹H NMR analysis showed that vinylidene group resulting from β‐H elimination and saturated methyl groups resulting from chain transfer to cocatalyst are the main end groups of polymer chain. The vinylidene and internal double bonds are also identified by Raman spectroscopy. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1687–1697, 2000     

Design,Synthesis and Biological Evaluation of Novel N‐(4‐([2,2′:5′,2′′‐Terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) Benzamide Derivatives

On the basis of the principle of combination of active groups, a series of novel N‐(4‐([2,2′:5′,2′′‐terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) benzamide derivatives were designed, synthesized and systematically evaluated for their antiviral activity against tobacco mosaic virus (TMV). The bioassay results showed that most of these compounds displayed good anti‐TMV activity, and some of them exhibited higher antiviral activity than commercial Ningnanmycin. Especially, compound 8e with excellent anti‐TMV activity (inactivation activity, 92.3%/500 µg·mL^?1; curative activity, 85.7%/500 µg·mL^?1 and protection activity, 64.7%/500 µg·mL^?1) emerged as a potential inhibitor of plant virus TMV. Quantitative structure‐activity relationship studies proved that the van der Waals volume (V) and electronic parameter (∑(∑σ_o+σ_p) and ∑σ_m) for the substituent R¹ were very important for antiviral activities in this class of compounds.     

High electroluminescent properties of conjugated copolymers from poly[9,9‐dioctylfluorenyl‐2,7‐vinylene]‐co‐(2‐(3‐dimethyldodecylsilylphenyl)‐1,4‐phenylene vinylene)] for light‐emitting diode applications

A new series of copolymers with high brightness and luminance efficiency were synthesized using the Gilch polymerization method, and their electro‐optical properties were investigated. The weight‐average molecular weights (M_w) and polydispersities of the synthesized poly(9,9‐dioctylfluorenyl‐2,7‐vinylene) [poly(FV)], poly[2‐(3‐dimethyldodecylsilylphenyl)‐1,4‐phenylenevinylene] [poly(m‐SiPhPV)], and poly[9,9‐di‐n‐octylfluorenyl‐2,7‐vinylene]‐co‐(2‐(3‐dimethyldodecylsilylphenyl)‐1,4‐phenylene vinylene)] [poly(FV‐co‐m‐SiPhPV)] were found to be in the ranges of (8.7–32.6) × 10⁴ and 2.3–5.4, respectively. It was found that the electro‐optical properties of the copolymers could be adjusted by controlling the feed ratios of the comonomers. Thin films of poly(FV), poly(m‐SiPhPV), and poly(FV‐co‐m‐SiPhPV) were found to exhibit photoluminescence quantum yields between 21% and 42%, which are higher than those of MEH‐PPV. Light‐emitting diodes were fabricated in ITO/PEDOT/light‐emitting polymer/cathode configurations using either double layer (LiF/Al) or triple layer (Alq₃/LiF/Al) cathode structures. The performance of the polymer light‐emitting diodes (PLEDs) with triple layer cathodes was found to be better than that of the PLEDs with double layer cathodes in poly(FV) and poly(FV‐co‐m‐SiPhPV). The turn‐on voltages of the PLEDs were in the range of 4.5–6.0 V, with maximum brightness and luminance efficiency up to 9691 cd/m² at 16 V and 3.27 cd/A at 13 V, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5062–5071, 2005     

Synthesis,Bioactivities and Structure Activity Relationship of N‐4‐Methyl‐1,2,3‐thiadiazole‐5‐carbonyl‐N′‐phenyl Ureas

Twenty nine novel N‐4‐methyl‐1,2,3‐thiadiazole‐5‐carbonyl‐N′‐phenyl ureas were designed and synthesized, and their structures were confirmed by proton nuclear magnetic resonance (¹H NMR), infra red spectroscopy (IR) and high‐resolution mass spectroscopy (HRMS). Compounds V‐9 , V‐11 , V‐12 , V‐15 , V‐19 , V‐21 , V‐22 and V‐24 exhibit excellent activity against Culex pipiens pallens. Compounds V‐12 and V‐22 present good insecticidal activity against Plutella xylostella L. Their median lethal concentrations (LC₅₀) are 164.15 and 89.69 mg·L^?1, respectively. Compound V‐11 also has potential wide spectrum of fungicide activity. Its median effective concentrations (EC₅₀) detected from 3.82 µg·mL^?1 against Physalospora piricola to 31.60 µg·mL^?1 against Cercospora arachidicola. Compounds V‐15 and V‐24 show outstanding induction activities as same as positive controls TDL and ningnanmycin, furthermore V‐24 has the highest induction activity of 41.85%±4.43%. To elucidate the structure activity relationship in these compounds, a 3D‐QSAR model has been built. The established model showed a reliable predicting ability with q² values of 0.643 and r² values of 0.982.