Electronic singlet-singlet absorption spectra of α-naphtol in pure and mixed crystals

Polarized S-S absorption spectra of α-naphtol single crystals show that the first two electronic absorption systems are respectively long-axis and short-axis polarized (A′←A′) transitions. The polarized absorption spectra of α-naphtol in a diphenyl host crystal, however, show that the electronic transition of the α-naphtol molecule is not exactly along the long axis, but slightly bent towards the short axis of the molecule.     

Halogen substitution reaction in bromonaphtol and iodophenol photoinitiated by aromatic amines

An increase in quantum yield in the halogen photosubstitution reaction upon the photolysis of 1-bromo-2-naphtol and o-iodophenol by the sulfo group in aqueous sodium sulfite solution or by the hydrogen in organic solvents in the presence of aromatic amines (diphenylamine, carbazole) was observed. Quenching of the triplet 1-bromo-2-naphtol by diphenylamine with the rate constant 7 × 10⁷ M¹ s¹ was discovered with the help of flash photolysis. The photoinitiation mechanism of the substitution reaction is due to electron transfer.     

Use of an on-line imprinted polymer pre-column, for the liquid chromatographic-UV absorbance determination of carbaryl and its metabolite in complex matrices

A carbaryl and 1-naphtol molecular imprinted polymers (MIP1 and MIP 2, respectively) were prepared using suspension polymerization and tested for selective and reversible binding to carbaryl and 1-naphtol, respectively. In the suspension polymerization technique used, polymers of methacrylic acid (MAA), highly cross-linked with ethylene dimethacrylate, provide a specific binding sites for the carbaryl molecule and its metabolite when using it as a template to be removed after polymerization. The molecular imprinted polymer with a particle size of approximately 5 microm were isolated and packed into a pre-column (50 mm x 4.6 mm id) that was used to isolate carbaryl and its metabolite from complex matrices injected on a high performance liquid chromatography system using ultra-violet detection without extensive sample preparation and clean up. The HPLC method had a detection limit of 1.00 ng/mL and a linear response (r2 > 0.98) over the concentration range of 1.00-10.0 ng/mL.     

Determination of uranium by XRF analysis following its preconcentration with some organic precipitants

The determination of uranium in natural waters by XRF analysis after its preconcentration with some organic precipitants is described.¹⁰⁹Cd source is used for the excitation of L-series X-rays of uranium. Separation yield, kinetics of coprecipitation and the possibility of preparing thin-layer samples for XRF analysis were studied in detail for uranium concentration with α-nitroso-β-naphtol, methylene blue with ammonium thiocyanate, tannin with urotropine and other precipitants. A procedure using coprecipitation of uranium with α-nitroso-β-naphtol from 500 ml samples of surface or waste, waters is proposed.     

Possible mediators of the "living" radical polymerization

The stable radicals derived from different compounds were detected in process of styrene autopolymerization. The nitroxide radicals are produced from nitrosocompound, hindered hydroxylamine, nitrophenols and nitroanisoles. The phenoxyl radicals are formed from quinine methides, and naphtoxyl radicals are generated from 2-nitro-1-naphtol. The radicals are identified, the kinetics of their formation and follow-up evolution are studied. These radicals can participate in process of living radical polymerization as the mediators and can effect significantly on kinetics of polymerization and structure of the resulting polymer.     

Ab initio simulation of the sum-frequency generation response of optically active liquids in the presence of a dc electric field —determination of the absolute molecular configuration

Quantum chemical computations have been performed to evaluate the first and second hyperpolarizability quantities of the interference term, linear in the external static electric field, that appear in the electric field-induced sum-frequency generation signal of chiral liquids. These are performed at the time-dependent Hartree-Fock level on the prototypical 1,1′-bi-2-naphtol chiral species.     

Decolorization and partial degradation of selected azo dyes by methanogenic sludge

The toxicity potential and decolorization of three acid azo dyes (Acid Orange 6, Acid Orange 7, and Acid Orange 52) by methanogenic granular sludge from an anaerobic expanded granular sludge bed reactor was assayed. Complete bioreduction was found for all three azo dyes. Sulfanilic acid and 4-aminoresorcinol were detected from the decolorization of Acid Orange 6, sulfanilic acid and 1-amino-2-naphtol were detected from the reduction of Acid Orange 7, and sulfanilic acid and N,N-dimethyl-1,4-phenylenediamine (DMP) were found to be intermediates of Acid Orange 52 degradation. Sulfanilic acid and 1-amino-2-naphtol were persistent in the anaerobic conditions, whereas 4-aminoresorcinol was completely mineralized by anaerobic sludge and DMP was transformed into 1,4-phenylenediamine. Enrichment cultures obtained via consecutive passages on basal medium with only azo dye as a carbon and an energy source seemed to be morphologically heterogeneous. Baculiform and coccus cells were found when viewed under a light microscope. Cocci were joined in chains. Because anaerobic sludge contains sulfate-reducing bacteria and therefore may generate sulfide, azo dyes were tested for chemical decolorization by sulfide to compare rates of chemical and biologic reduction.     

Kinetic methods for the determination of cadmium(II) based on a flow-through bulk optode

Three kinetic methods based on flow injection, flow, and stopped-flow injection were applied for the determination of Cd(II) using a flow-through bulk optode membrane that incorporates 1-(2-pyridylazo)-2-naphtol (PAN) in a plasticized poly(vinyl) chloride membrane entrapped in a cellulose support. The calibration graphs plotting the reflectance at 560 nm versus [Cd(II)](1/2) for the first two methods and versus [Cd(II)] for the third were linear up to 56.2 mg l(-1). The detection limits of the methods were 0.01, 0.06 and 0.8 mg l(-1), respectively. The FI method was selected for application purposes. The variation coefficient of the sensor response for 11.2 mg l(-1) of Cd(II) was +/-0.31 and +/-0.65% between different membranes. The sensor can be readily regenerated with a carrier (acetic-acetate) buffer of pH 4. The FI method was applied to the determination of cadmium in an alloy and in water.     

HPLC Assay of 6-Methoxy-2-Naphthylacetic Acid,a Major Metabolite of Nabumetone,in Human Serum

Abstract

A modified high-performance liquid chromatographic method for the quantitative determination of 6-methoxy-2-naphthylacetic acid (6-MNA), a major metabolite of nabumetone, in human serum was developed and validated. The composition of the mobile phase in Daigneault & Ferslew's method was changed in this study to improve the separation of 6-MNA from serum components. The volume ratio of acetonitrile to 1.5% acetic acid solution was changed from 60: 40 to 25: 75 in this study. As a result of the modification, the separation of 6-MNA from 2-naphtol (internal standard) and serum components was greatly improved. At a flow rate of 3.0 ml/min of the mobile phase, retention times of 6-MNA and 2-naphtol were 13 and 9 min, respectively. The detection limit was 1 μg/ml. Intra- and interday variations of the assay were <10.0 and <7.28%, respectively. Intra- and interday relative errors were <7.82 and <6.76%, respectively. 6-MNA in human serum could be determined successfully after oral administration of nabumetone (1g). Thus, the modified UV-HPLC method was confirmed to be applicable to the pharmacokinetic study of 6-MNA after oral administration of nabumetone to human subjects.     

The uses of 1-(2-pyridylazo) 2-naphtol (PAN) impregnated Ambersorb 563 resin on the solid phase extraction of traces heavy metal ions and their determinations by atomic absorption spectrometry

1-(2-pyridylazo) 2-naphtol (PAN) impregnated Ambersorb 563 resin was used as solid phase extractor of copper, nickel, cadmium, lead, chromium and cobalt ions in aqueous solutions prior to their atomic absorption spectrometric determinations. The parameters including pH, sample volume, matrix effects were also investigated. The relative standard deviation (R.S.D.) of the combined method of sample treatment, preconcentration and determination with atomic absorption spectrometry is generally lower than 10%. The limit of detection was between 0.21 and 1.4 μg l⁻¹. The results were used for preconcentration of analyte ions from natural water samples. The method was also applied to a stream sediment standard reference material (GBW7309) for the determination of Cu, Ni, Cd, Pb, Cr and Co.     

Fe(HSO4)3: An efficient, heterogeneous and reusable catalyst for the synthesis of 14-aryl- or alkyi-14H-dibenzo[a.j]xanthenes

Fe(HSO4)3 has been used as an efficient and reeyclable catalyst for the one-pot synthesis of 14-aryl- or alkyl-14H-dibenzo[a,j]xanthene derivatives by the reaction of 2-naphtol and aldehydes. Different types of aromatic and aliphatic aldehydes are used in the reaction and in all cases the products were obtained in good to excellent yields.     

Alkyl 2-(2-benzoyl-2-ethoxycarbonyl-1-ethenyl)amino-3-dimethylaminopropenoates in the synthesis of heterocyclic systems

Alkyl 2-(2-benzoyl-2-ethoxycarbonyl-1-ethenyl)amino-3-dimethylaminopropenoates 4a,b were prepared. They react with C-nucleophiles such a 2-pyridinylacetonitrile 5 and methyl-2-quinolinylacetate 8, cyclohexane-1,3-dione 10 and its derivatives 12 and 14, resorcinol derivative 16 , 2-naphtol 18, 2-pyranone derivatives 20 and 22, and 4-hydroxypyridin-2(1H)-one 24, to form substituted amino derivatives of quinolizine 6, benzo[c]quinolizine 9, tetrahydrobenzopyran-2-one 11, 13, 15 , naphto[2,1-b]pyran-3-one 19 , pyranopyranones 21, 23, and pyrano[3,2-c]pyridine 25.     

A disposable electrochemical immunosensor for prolactin involving affinity reaction on streptavidin-functionalized magnetic particles

A novel electrochemical immunosensor was developed for the determination of the hormone prolactin. The design involved the use of screen-printed carbon electrodes and streptavidin-functionalized magnetic particles. Biotinylated anti-prolactin antibodies were immobilized onto the functionalized magnetic particles and a sandwich-type immunoassay involving prolactin and anti-prolactin antibody labelled with alkaline phosphatase was employed. The resulting bio-conjugate was trapped on the surface of the screen-printed electrode with a small magnet and prolactin quantification was accomplished by differential pulse voltammetry of 1-naphtol formed in the enzyme reaction using 1-naphtyl phosphate as alkaline phosphatase substrate. All variables involved in the preparation of the immunosensor and in the electrochemical detection step were optimized. The calibration plot for prolactin exhibited a linear range between 10 and 2000 ng mL(-1) with a slope value of 7.0 nA mL ng(-1). The limit of detection was 3.74 ng mL(-1). Furthermore, the modified magnetic beads-antiprolactin conjugates showed an excellent stability. The immunosensor exhibited also a high selectivity with respect to other hormones. The analytical usefulness of the immnunosensor was demonstrated by analyzing human sera spiked with prolactin at three different concentration levels.     

Kinetic Studies upon the Influence of Cyclodextrin on the Polymerization of Methacrylamides in Homogenous Aqueous Solution

Summary: N‐methacryloyl‐1‐aminopropane ( 1 ), N‐methacryloyl‐1‐aminobutane ( 2 ), N‐methacryloyl‐1‐aminopentane ( 3 ), and N‐methacryloyl‐1‐aminohexane ( 4 ) are synthesized and treated with an aqueous solution of randomly methylated β‐cyclodextrin (Me‐β‐CD) to form the water‐soluble host‐guest complexes 1a – 4a . In case of the aqueous polymerization of the free monomers 1 – 4 the initial polymerization rate increases with increasing water solubility. The opposite effect is observed in the case of the polymerizations of the Me‐β‐CD‐complexed methacrylamide monomers 1a – 4a . The polymerization rates are increased with increasing alkyl chain length of the complexed monomers 1a – 4a and decreasing water solubility of the free monomers 1 – 4 .

Initial polymerization rate v₀ of CD‐complexed monomers 1a – 4a (○) vs. water solubilities of monomers 1 – 4 (▪).     

Preparation and Characterization of Chromophor Group Containing Cyclotriphosphazenes: III Bis-Azo Chromophor Carrying Some Cyclotriphosphazenes

Some new substituted cyclotriphosphazenes were prepared by reaction of hexachlorocyclotriphosphazene and phenylazophenylazophenol compounds such as p -[ p -phenylazo-phenylazo]phenol, p -[ p -( o -chlorophenylazo)phenylazo]phenol, p -[ p -( p -chlorophenylazo)phenylazo]phenol, p -[ p -( p -methylphenylazo)phenylazo]phenol, and tetrazobenzene- g -naphtol. They are characterized by UV-Vis, FT IR, elemental analysis, and TG, DTG, and DTA.     

Synthesis and Bioactivity of New Chalcone Derivatives as Potential Tyrosinase Activator Based on the Click Chemistry

A new series of (E)‐1‐(4‐((1‐benzyl‐1H‐1,2,3‐triazol‐4‐yl)methoxy)phenyl)‐3‐phenylprop‐2‐en‐1‐one 1a (4‐((1‐benzyl‐1H‐1,2,3‐triazol‐4‐yl) methoxy)phenyl)‐1‐phenylprop‐2‐en‐1‐one 1b – 15b were designed, synthesized based on click chemistry, and biologically evaluated for their activity on tyrosinase. The result showed that most of prepared compounds 1a – 15a have potent activating effect on tyrosinase, especially for 3a , 8a – 10a and 14a – 15a . Among them, compounds 10a and 14a demonstrated the best activity with EC₅₀=1.71 and 5.60 µmol·L^?1 respectively, even better than the positive control 8‐MOP (EC₅₀=14.8 µmol·L^?1). Conversely, compounds 3b , 5b – 6b , 9b – 10b , and 15b induced enzymatic inhibition on tyrosinase.     

Fe（HSO4）3： An efficient,heterogeneous and reusable catalyst for the synthesis of 14-aryl- or alkyl- 14H-dibenzo[a,j]xanthenes

Fe（HSO4）3 has been used as an efficient and recyclable catalyst for the one-pot synthesis of 14-aryl- or alkyl-14Hdibenzo[aj]xanthene derivatives by the reaction of 2-naphtol and aldehydes. Different types of aromatic and aliphatic aldehydes are used in the reaction and in all cases the products were obtained in good to excellent yields.     

β-Naphthol as a Chromophore and Fluorophore Forming Reagent in the HPLC Determination of Alkyl Halides

Abstract

A suitable chromophore- and fluorophore- forming reagent for the detection of alkyl halide water contaminants is β-naphtol. The ether derivatives are separated from each other and excess β-naphthol reagent by reverse, phase HPLC and are detected by ultraviolet absorption or fluorescence. A method for the determination of alkyl halides is presented. The method is applicable to concentration levels in the ppm range for UV detection and in the ppb concentration range using fluorescence detection.     

Effect of Temperature on the Retention of Aromatic Hydrocarbons with Polar Groups in Binary Reversed-Phase TLC

JPC – Journal of Planar Chromatography – Modern TLC - RM (log[(1 - RF)/RF]) values at different temperatures have been compared for aromatic hydrocarbons with different functional...     

Effects of Addition of Ion-Pair Reagent to the Mobile Phase on Electroosmotic Flow Velocity in Pressurized Planar Electrochromatography

JPC – Journal of Planar Chromatography – Modern TLC - In the paper, the influence of the addition of different ion-pair reagents — sodium-1-heptane sulfonate (HS),...