Intrachain chromophore interactions in silanylene‐spaced divinylbenzene copolymers

A range of silanylene‐spaced divinylbenzene copolymers ( 1 ) and the corresponding monomers ( 2 ) have been synthesized by the rhodium‐catalyzed hydrosilylation of the corresponding bisalkynes with bissilyl hydrides, and the photophysical properties of 1 and 2 have been investigated. The silicon moiety in 1 serves as an insulating tetrahedral spacer that makes 1 highly folded. The two chromophores may be in close proximity such that a ground‐state intrachain interaction between two conjugated moieties through space might occur. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2218–2231, 2003     

Conjugated and partially conjugated 2,5‐diphenylthiophene‐containing light‐emitting copolymers in polymeric light‐emitting diode (PLED) device fabrications

To study the effect of nonconjugation on polymeric and photophysical properties of thiophene‐containing polymers, new light‐emitting copolymers comprising either alternate 2,5‐diphenylthiophene and vinylene or alternate 2,5‐diphenylthiophene and aliphatic ether segments were synthesized. Both copolymers contained 2,5‐diphenylthiophene as the major chromophore and emitted a sky bluish fluorescence in dilute solution (10^?2 mg/mL). With a rigid and planarity structure and the concomitant crystallinity, the former copolymer (fully conjugated) possessed a higher quantum efficiency, a higher glass‐transition temperature, and a better thermal stability. In contrast, the latter copolymer (conjugated–nonconjugated) had better solubility and provided enhanced photophysical properties for the fabricated polymeric light‐emitting diode (PLED) device: at 15 V, the maximum current and brightness were 110 mA/cm² and 4289 cd/m², respectively, and the electroluminescence efficiency remained constant at approximately 4.9 cd/A in a voltage range of 8 to 14 V. The existence of intramolecular/intermolecular aggregates in the latter copolymer was corroborated from the the UV–vis and photoluminescence spectra of its solutions. With an increase in solution concentration, the shape and λ_max of the photoluminescence spectrum were redshifted. In a solution with a concentration as high as 10 mg/mL, the redshift was so drastic that the photoluminescence spectrum was nearly identical to that of a solid‐film. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6061–6070, 2004     

Highly Efficient Dye‐Sensitized Solar Cells Based on Panchromatic Ruthenium Sensitizers with Quinolinylbipyridine Anchors

Panchromatic Ru^II sensitizers TF‐30–TF‐33 bearing a new class of 6‐quinolin‐8‐yl‐2,2′‐bipyridine anchor were synthesized and tested under AM1.5 G simulated solar irradiation. Their increased π conjugation relative to that of the traditional 2,2′:6′,2′′‐terpyridine‐based anchor led to a remarkable improvement in absorptivity across the whole UV–Vis–NIR spectral regime. Furthermore, the introduction of a bulky tert‐butyl substituent on the quinolinyl fragment not only led to an increase in the J_SC value owing to the suppression of dye aggregation, but remarkably also resulted in no loss in V_OC in comparison with the reference sensitizer containing a tricarboxyterpyridine anchor. The champion sensitizer in DSC devices was found to be TF‐32 with a performance of J_SC=19.2 mA cm^?2, V_OC=740 mV, FF=0.72, and η=10.19 %. This 6‐quinolin‐8‐yl‐2,2′‐bipyridine anchor thus serves as a prototype for the next generation of Ru^II sensitizers with any tridentate ancillary.     

A Tetravalent Cerium Complex Containing a CeO Bond

Whereas terminal oxo complexes of transition and actinide elements are well documented, analogous lanthanide complexes have not been reported to date. Herein, we report the synthesis and structure of a cerium(IV) oxo complex, [Ce?O(L_OEt)₂(H₂O)]?MeC(O)NH₂ ( 1 ; L_OEt^?=[Co(η⁵‐C₅H₅){P(O)(OEt)₂}₃]^?), featuring a short Ce?O bond (1.857(3) Å). DFT calculations indicate that the hydrogen bond to cocrystallized acetamide plays a key role in stabilizing the Ce?O moiety of 1 in the solid state. Complex 1 exhibits oxidizing and nucleophilic reactivity.     

Synthesis of the Heparin‐Based Anticoagulant Drug Fondaparinux

Fondaparinux, a synthetic pentasaccharide based on the heparin antithrombin‐binding domain, is an approved clinical anticoagulant. Although it is a better and safer alternative to pharmaceutical heparins in many cases, its high cost, which results from the difficult and tedious synthesis, is a deterrent for its widespread use. The chemical synthesis of fondaparinux was achieved in an efficient and concise manner from commercially available D ‐glucosamine, diacetone α‐D ‐glucose, and penta‐O‐acetyl‐D ‐glucose. The method involves suitably functionalized building blocks that are readily accessible and employs shared intermediates and a series of one‐pot reactions that considerably reduce the synthetic effort and improve the yield.     

Bornological Coderivative and Subdifferential Calculus in Smooth Banach Spaces

Set-Valued and Variational Analysis - In this paper, we study bornological generalized differential properties of sets with nonsmooth boundaries, nonsmooth functions, and set-valued mappings in...     

Determination of in situ speciation of manganese in treated acid mine drainage water by using multiple diffusive gradients in thin films devices

Acid mine drainage (AMD) is a serious environmental problem that creates acidic solution with high Mn concentrations. The speciation of residual Mn from AMD after an active treatment involving the addition of a neutralizing agent can reliably evaluate the treatment efficiency and provide knowledge of the Mn species being inputted into the environment. The aim of this study was to evaluate the in situ lability and speciation of Mn using the diffusive gradients in thin films (DGT) technique with treated drainage water from a uranium mine (TAMD). DGT devices with different binding phases (Chelex-100 and P81 and DE81membranes) were used to perform the in situ speciation of Mn.     

Analysis of Calix[4]arenes Using Nonaqueous Capillary Electrophoresis

In nonaqueous capillary electrophoresis (NACE), an organic solvent is used in place of an aqueous medium as the background solution to improve the solubility and selectivity for hydrophobic analytes. In this study, we employed NACE with UV detection for the analysis of eight calix[4]arenes. We examined the influence of several parameters—the buffer composition, the nonaqueous solvent‘s composition and proportion, and the concentration of the electrolyte of the nonaqueous buffer—on the efficiency of the electrophoretic separation. The separation was achieved through the analyte's different effective mobility via different degrees of deprotonation on the phenolic OH groups of the calix[4]arene. This deprotonation can further affect the analyte's ability to form a complex with the metal ion. The optimized background electrolyte (BGE), comprising a mixture of N‐methylformamide/acetonitrile (30:70, v/v) and 100 mM AcOH/20 mM NH₄OAc, provided rapid (<11 min) separation of the calix[4]arenes with good resolution. The relative standard deviations of the migration times for the eight analytes were all less than 1%. Within the calibration concentration range, the coefficients of determination (R²) were all greater than 0.9914. Thus, the present study demonstrated NACE can provide adequate separation for the analysis of calix[4]arenes.