Direct and simultaneous determination of arsenic, manganese, cobalt and nickel in urine with a multielement graphite furnace atomic absorption spectrometer

A simple method was developed for the direct and simultaneous determination of arsenic (As), manganese (Mn), cobalt (Co), and nickel (Ni) in urine by a multi-element graphite furnace atomic absorption spectrometer (Perkin-Elmer SIMAA 6000) equipped with the transversely heated graphite atomizer and longitudinal Zeeman-effect background correction. Pd was used as the chemical modifier along with either the internal furnace gas or a internal furnace gas containing hydrogen and a double stage pyrolysis process. A standard reference material (SRM) of Seronorm™ Trace Elements in urine was used to confirm the accuracy of the method. The optimum conditions for the analysis of urine samples are pyrolysis at 1350 °C (using 5% H₂ v/v in Ar as the inter furnace gas during the first pyrolysis stage and pure Ar during the second pyrolysis stage) and atomization at 2100 °C. The use of Ar and matrix-free standards resulted in concentrations for all the analytes within 85% (As) to 110% (Ni) of the certified values. The recovery for As was improved when mixture of 5% H₂ and 95% Ar (v/v) internal furnace gas was applied during the first step of a two-stage pyrolysis at 1350 °C, and the found values of the analytes were within 91-110% of the certified value. The recoveries for real urine samples were in the range 88-95% for these four elements. The detection limits were 0.78 μg l⁻¹ for As, 0.054 μg l⁻¹ for Mn, 0.22 μg l⁻¹ for Co, and 0.35 μg l⁻¹ for Ni. The upper limits of the linear calibration curve are 60 μg l⁻¹ (As); 12 μg l⁻¹ (Mn); 12 μg l⁻¹ (Co) and 25 μg l⁻¹ (Ni), respectively. The relative standard deviations (R.S.D.s) for the analysis of SRM were 2% or less. The R.S.D.s of a real urine sample are 1.6% (As), 6.3% (Mn), 7.0% (Ni) and 8.0% (Co), respectively.     

Halocyclization of Methyl 2‐Alkynylbenzoates to Isocoumarins Using Cupric Halides

Treatment of methyl 2‐alkynylbenzoates with two to three equivalents of CuX₂ (X = Cl or Br) in refluxing acetonitrile gave isocoumarins 2 in good to excellent chemical yields.     

Preparation and characterization of chiral polyacrylates end‐capped with bornyl groups in the side chains

Chiral polyacrylates with bornyl end‐capped side chains with four kinds of mesogenic moieties (azobenzene, biphenyl, benzoyloxy biphenyl, and phenyl benzoate) were prepared. The phase properties of the polymers were investigated with X‐ray diffraction, differential scanning calorimetry, and polarizing optical microscopy. The thermogravimetric characteristics, the glass‐transition temperatures and weight‐average molecular weights, of the homopolymers were evaluated. The optical properties of the synthesized polymers in diluted solutions and in the thin‐film state were also evaluated. The optical behavior of the composite films upon photoirradiation was investigated through the change in the transmittance of the probe light triggered by ultraviolet (365‐nm) irradiation. Ultraviolet irradiation and heat treatment caused a reversible intensity change of the probe light at λ = 400 nm. The shrinkage of the photoisomerization of the composite films was also investigated with atomic force microscopy. A spot contraction appeared on the surface when it was irradiated with a laser light spot. The contraction was recovered by heat treatment at 80 °C for 10 min. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1075–1092, 2004     

Chirality Control of Quadruple Helixes of Metal Strings by Peripheral Chiral Ligands

Chirality control of helixes with the Δ (P) or Λ (M) form is interesting in various fields such as extended metal atom chains (EMACs), in which the metal backbones are helically wrapped by four ligands. Herein, we report two EMACs, Δ‐[Ni₅((?)camnpda)₄] and Λ‐[Ni₅((+)camnpda)₄], whose chiralities are controlled by chiral ligands with naphthyridine and camphorsulfonyl groups. There is a large energy difference (108 kcal mol^?1) between the two helical structures with one chiral ligand. Furthermore, the electron communication between [Ni₂]³⁺ units is more pronounced than in [Ni₅(bna)₄Cl₂]²⁺ (bna=binaphthyridylamido). The results demonstrate control of small‐scale helical structure and set the stage for future development of chiral controlled base and nanoelectronic devices.     

Kinetically Enhanced Approach for Rapid and Tunable Self‐Assembly of Rod–Coil Block Copolymers

A facile approach is reported to process rod–coil block copolymers (BCPs) into highly ordered nanostructures in a rapid, low‐energy process. By introducing a selective plasticizer into the rod–coil BCPs during annealing, both the annealing temperature and time to achieve thermodynamic equilibrium and highly ordered structures can be decreased. This process improvement is attributed to enhanced chain mobility, reduced rod–rod interaction, and decreased rod–coil interaction from the additive. The novel method is based on kinetically facilitating thermodynamic equilibrium. The process requires no modification of polymer structure, indicating that a wide variety of desired polymer functionalities can be designed into BCPs for specific applications.

     

Synthesis and properties of novel aromatic polyhydrazides and poly(amide–hydrazide)s based on the bis(ether benzoic acid)s from hydroquinone and substituted hydroquinones

4,4′‐(1,4‐Phenylenedioxy)dibenzoic acid as well as the 2‐methyl‐, 2‐tert‐butyl‐, or 2‐phenyl‐substituted derivatives of this dicarboxylic acid were synthesized in two main steps from p‐fluorobenzonitrile and hydroquinone or its methyl‐, tert‐butyl‐, or phenyl‐substituted derivatives. Polyhydrazides and poly(amide–hydrazide)s were prepared from these bis(ether benzoic acid)s or their diacyl chlorides with terephthalic dihydrazide, isophthalic dihydrazide, or p‐aminobenzoyl hydrazide by means of the phosphorylation reaction or low‐temperature solution polycondensation. Most of the hydrazide polymers and copolymers are amorphous and readily soluble in various polar solvents such as N‐methyl‐2‐pyrrolidone (NMP) and dimethyl sulfoxide. They could be solution‐cast into transparent, flexible, and tough films. These polyhydrazides and poly(amide–hydrazide)s had T_gs in the range of 167–237°C and could be thermally cyclodehydrated into the corresponding poly(1,3,4‐oxadiazole)s and poly(amide–1,3,4‐oxadiazole)s approximately in the region of 250–350°C, as evidenced by the DSC thermograms. All the tert‐butyl‐substituted oxadiazole polymers and those derived from isophthalic dihydrazide were organic soluble. The thermally converted oxadiazole polymers exhibited T_gs in the range of 208–243°C and did not show significant weight loss before 450°C either in nitrogen or in air. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1169–1181, 1999     

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.     

Enhanced lithium intercalation and conduction in LiαFeTaxOyCz films by the addition of lithium oxides with an atmospheric pressure plasma jet

Journal of Solid State Electrochemistry - An enhancement of lithium ionic intercalation and conduction performance of lithiated-organo-iron-tantalum oxide (LiαFeTaxOyCz) films has been...     

An Efficient Synthetic Method and Single Crystal Structure of a 2:3 Adduct of Cyclohexyl Isocyanide and Dimethyl Acetylenedicarboxylate

An efficient synthetic method and single crystal structure of a 2:3 adduct of cyclohexyl isocyanide and dimethyl acetylenedicarboxylate are described.     

Synthesis and Characterization of the First Doubly‐bridged N,N‐dimethylthiocarbamoyl Metal Complex: Crystal Structure of [Mo(Cl)(CO)2(PPh3)]2(η1:η2:μ‐SCNMe2)2

The first doubly‐bridged thiocarbamoyl metal complex [Mo(Cl)(CO)₂(PPh₃)]₂(η¹:η²:μ‐SCNMe₂)₂ ( 2 ) was formed from stirring [Mo(CO)₂(η²‐SCNMe₂)(PPh₃)₂Cl] ( 1 ) in dichloromethane at room temperature. Complex 2 is a dimer with each thiocarbamoyl unit coordinating through sulfur and carbon to one metal center and bridging both metals through sulfur. Complex 2 is characterized by X‐ray diffraction analysis.