Transmembrane ion transport by arachidonic acid (AA) through bilayer lipid membranes (BLMs) was investigated by means of electrochemical measurements to provide a basis for designing a sensor membrane. We found that AA induces a channel-type current, in addition to a carrier-type current, across planar BLMs. A linear relation between the logarithmic value of the AA concentration and the current responses (given as integrated currents) was observed for a carrier-type current, while a sigmoid relation was found for a channel-type current. Although AA transports NA⁺, Ca²⁺ and Mg²⁺ and exhibits ion selectivity between Na⁺ and Mg²⁺ for the carrier-type current, ion transport for the channel-type current was non-selective. It was found that ion transport via the channel mechanism occurs frequently for AA, while channel-type currents were only occasionally observed for γ-linolenic acid and prostaglandin D₂. No channel-type currents were induced by other fatty acids (oleic, linoleic, stearic, myristic, eicosapentanoic and docosahexanoic acids) and metabolites of AA (12-HETE and 5-HETE). The carrier-type ion transport occurs selectively to these compounds if the concentration is below 1.0 μM. These results suggest that AA selectively facilitates an ion flux through the BLMs, generating channel-type and/or carrier-type currents, which can be used as a measure of the AA concentration.

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Slab optical waveguide (SOWG) spectroscopy was used to observe the adsorption behavior of three important heme proteins, namely cytochrome c, myoglobin and hemoglobin, in a quartz surface. Using prism-coupled polychromatic visible light propagated into a quartz waveguide by internal total reflection, the real-time monitoring of evanescent wave absorption revealed a strong dependence of the protein-surface interaction on the protein concentration, the solution pH and the ionic strength. For the three proteins studied, the absorbance-bulk concentration ratio was higher at low bulk concentrations, and decreased at higher concentrations. For cytochrome c and myoglobin, the absorbance approached a limiting value, but buffered hemoglobin surprisingly did not show any indication of forming a signal plateau. Moreover, the slow introduction of protein into the solution lessened the total adsorbed amount per unit area. These observations suggested a possible conformational transition of the protein molecules at the quartz surface after adsorption. For a bulkier protein, hemoglobin, adsorption onto the quartz surface was enhanced in the presence of a phosphate buffer, while the opposite effect was observed for the smaller cytochrome c and myoglobin molecules. The results of pH studies concurred with the electrostatic interactions predicted from the isoelectric data of proteins and the quartz surface.

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Urinary level of type IV collagen is an important indicator for early renal dysfunction, but there has been no practical system to measure mouse type IV collagen adaptable to extremely small amounts of urine samples. We developed a highly sensitive time-resolved fluoroimmunoassay (TR-FIA) to measure mouse urinary type IV collagen. Based on the structural features of type IV collagen molecule, dithiothreitol (DTT) was used for pretreatment of the samples. This assay permits measurement of 100 pg/ml type IV collagen in 5 μl urine samples. Urinary levels of type IV collagen derived from 12 samples of two different mouse strains (KK/Ta and BALB/c) were measured using this assay. The results demonstrated very clearly the difference in values of urinary type IV collagen between diabetic mice and non-diabetic mice. Compared with the conventional enzyme-linked immunosorbent assay (ELISA), this method requires far smaller volumes of samples, and is best suited to mouse models in future experiments.

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A simple corrected resonance light-scattering (CRLS) technique was established to correct for any distortion of the resonance light scattering (RLS) spectra resulting from molecular absorption. By using an absorption cell holder to change the propagation direction of the incident light beam of a common spectrofluorometer, the molecular absorption was directly measured through a spectrofluorometer. With measurements of the CRLS signals of the interaction of Fast Red VR (FRV) and proteins, we proved that the present correction for the RLS spectra in terms of the molecular absorption of excitation and scattering radiation can improve the detection sensitivity by about two fold.

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A hydrogen ion-selective poly(vinyl chloride) membrane electrode was constructed using 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetracyanomethoxycalix[4]arene as a neutral carrier. The electrode showed an apparent Nernstian response in the 2 - 11.5 pH range with a slope of 54.0±0.2 mV/pH at 20±1°C. This electrode showed a rapid response of the emf to changes in the pH, high ion selectivity with respect to lithium, sodium and potassium, and characteristics similar to those reported for the conventional pH glass membrane electrode. It can be used as a potentiometric indicator electrode in hydrofluoric acid solutions. The effects of iodide, thiocyanate, perchlorate and bromide on the characteristics of the electrode were also considered.

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A copper(II) ion-selective PVC membrane sensor based on 2-(1′-(4′-(1″-hydroxy-2″-naphthyl)methyleneamino)butyl iminomethyl)-1-naphthol (BHNB) as a novel Schiff base containing a sensing material has been successfully developed. The sensor exhibits a good linear response of 29mV per decade within the concentration range of 10^-1-10^-6 M of Cu²⁺. The sensor shows good selectivity for copper(II) ion in comparison with alkali, alkaline earth, transition and heavy metal ions. The BHNB-based sensor is suitable for use with aqueous solutions of pH 3.5-7.0 and displays minimal interference by Sr(II), Cd(II), Hg(II), Zn(II) and Pb(II), which are known to interfere with other previously suggested electrodes. The proposed membrane electrode was used as a sensor for determining the Cu(II) content in black tea samples. It was also applied as an indicator electrode in the potentiometric titration of Cu²⁺ ions with EDTA.

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A new carbon paste electrode (CPE) for the determination of iodide ion based on a cetyltrimetylammonium iodide (CTMAI) ion pair as an electroactive material is described. The electrode shows a linear response for iodide ion over the concentration range of 4×10^-5 M to 1×10^-1 M with a lower detection limit of 4×10^-5 M at 25°C. The electrode has a Nernstian slope of −55.0±0.4 mV/decade and a fast potential response of 45 s, which is almost constant over a pH range of 5.0-9.0. Selectivity coefficient data of the CTMAI-CPE for some common ions show negligible interference, and the electrode has high selectivity towards the iodide ion. An average recovery of 101.83% with a relative standard deviation of 1.53% has been achieved for the determination of iodide in Flaxedil (gallamine triethiodide) ampoules, a muscle relaxant drug. The electrode has been examined for the determination of iodide in saline water; the results were found to compare favorably with those obtained using Metrohm iodide ISE. The electrode has been utilized as an end-point indicator electrode for the determination of Hg(II) and phenylmercury(I) in their aqueous solutions using potentiometric titration with a potassium iodide standard solution.

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A plasticized Cr³⁺ ion sensor by incorporating 2,3,8,9-tetraphenyl-1,4,7,10-tetraazacyclododeca-1,3,7,9-tetraene (TTCT) ionophore exhibits a good potentiometric response for Cr³⁺ over a wide concentration range (1.0×10^-6-1.0×10^-1 M) with a slope of 19.5 mV per decade. The sensor response is stable for at least three months. Good selectivity for Cr³⁺ in comparison with alkali, alkaline earth, transition and heavy metal ions, and minimal interference are caused by Li⁺, Na⁺, K⁺, Co²⁺, Hg²⁺, Ca²⁺, Pb²⁺ and Zn²⁺ ions, which are known to interfere with other chromium membrane sensors. The TTCT-based electrode shows a fast response time (15 s), and can be used in aqueous solutions of pH 3 - 5.5. The proposed sensor was used for the potentiometric titration of Cr³⁺ with EDTA and for a direct potentiometric determination of Cr³⁺ content in environmental samples.

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A micro-phase sorbent in situ formation from an aqueous solution was proposed for the sensitive spectrophotometric determination of nitrite in environmental waters. Nitrite in a 10 mL sample solution was converted into a cationic azo dye by the reaction with 4-trifluoromethylanilinium ion and N-1-naphthylethylenediammonium ion in an acidic medium. Addition of dodecylbenzenesulfonate ion caused the formation of a suspension of ion associate in the solution. Centrifugation of the solution led to the isolation of a liquid organic phase that extracted the azo dye at the bottom of the centrifuge tube. The volume of the new phase was ca. 5 μL. After the aqueous phase was discarded, the organic phase was dissolved with 1 mL of 2-methoxyethanol to measure the absorbance. Nitrogen as NO₂^- at concentrations from 1.5 to 30 μg L^-1 was determined with sufficient precision. When 0.2 mL of 2-methoxyethanol was applied to dissolve the organic phase, 0.3 - 4.8 μg NO₂^--N L^-1 was determined. The recovery tests for nitrite added to some river water and seawater were satisfactory. This method is very simple and rapid. It takes only 30 min from the dye formation to the measurement of the absorbance.

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The strength and the character of the binding of 12 organic solvents to the corn protein zein was determined by preparing zein-coated carbon stationary phase and by measuring the retention of solvents on a high-performance liquid chromatographic column filled with this stationary phase. The relationship between the physicochemical parameters and binding characteristics of solvents was elucidated by principal component analysis. Various interactive forces are involved in the binding of solvent to the protein. The strength of the binding is dominantly influenced by the molecular hydrophobicity while the Gaussian or non-Gaussian distribution of the adsorption strength is markedly dependent on the polarity parameters of the solvent. Sterical correspondences exerted considerable influence on each binding parameter.

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An automatic HPLC system for analyzing nitropolycyclic aromatic hydrocarbons (NPAHs, nitroarenes) in airborne particulates was previously described (Anal. Chim. Acta, 2001, 445, 20). Some problems with this system were that in generated a peak originating from an ascorbic acid solution that elutes at a retention time close to that of 1,6-dinitropyrene (DNP), and that it was able to analyze only 1,3-, 1,6-, 1,8-DNPs and 1-nitropyrene (1-NP). Here, we describe an improved system that effectively removes the interfering peak by introducing an ODS column just after the pump for the ascorbic acid solution, and which is capable of analyzing several additional compounds (2-, 4-NPs, 2-nitrofluorene, 6-nitrochrysene, 7-nitrobenz[a]anthracene, 3-nitroperylene and 6-nitrobenzo[a]pyrene etc.). The improved sensitivities were achieved by concentrating the compounds in a benzene-ethanol extract from airborne particulates, by increasing the loading time of the sample solution from 20 to 38 min, and by increasing the flow rate of an ascorbic acid solution from 1.3 to 1.8 mL/min.

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A new method for the simultaneous determination of lead, cadmium and mercury ions in microwave-digested foodstuffs by reversed-phase high-performance liquid chromatography combined with on-line enrichment technique has been developed. The foodstuff samples were digested by microwave digestion. The lead, cadmium and mercury ions can be precolumn derivatized with 5,10,15,20-tetrakis(3-aminophenyl)porphine (T₃APP) to form color chelates; then, the Hg-T₃APP, Cd-T₃APP and Pb-T₃APP chelates can be enriched and separated on a valve switching HPLC system combined with on-line enrichment technique. The linearity ranges are 0.01 - 120 μg/l for each metal ion. The detection limits (S/N = 3) of lead, cadmium and mercury are 1.2 ng/l, 0.5 ng/l and 0.8 ng/l, respectively. This method was applied to the determination of lead, cadmium and mercury in foodstuffs with good results.

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The selective retention of the Sb(III) chelate with ammonium pyrrolidine dithiocarbamate (APDC) on a column of Chromosorb 102 resin from a buffered sample solution including Sb(V) was used for the determination of Sb(III). The retained antimony was eluted with acetone. The retention of the Sb(III)-iodide compounds with sodium iodide on the Chromosorb 102 resin column from the same solution after reducing Sb(V) to Sb(III) by iodide in acidic solution was used to preconcentrate the total antimony. The retained antimony was eluted with 0.25 mol l^-1 HNO₃. The antimony in the effluent was determined by flame atomic-absorption spectrometry. Also, the total antimony was determined directly by graphite-furnace atomic absorption spectrometry. The Sb(V) concentration could be calculated by the difference. The recoveries were ≥95%. The detection limits of a combination of the column procedure and flame AAS for antimony were 6 - 61 μg l^-1 and comparable to 4 μg l^-1 for a direct GFAAS measurement. The relative standard deviations were <6%. The procedure was applied to the determination of Sb(III) and Sb(V) in spiked tap water, waste-water samples and a certified copper metal with the satisfactory results.

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A membrane filtration method was examined concerning the effective collection of iron(III) from a homogeneous aqueous solution with Chromazurol B (CAB), one of the triphenylmethane dyes, as a precipitating reagent in the presence of a non-ionic surfactant, polyethylene glycol mono[4-(1,1,3,3-tetramethylbutyl)phenyl]ether (Triton X-100). A formed blue Fe(III)-CAB complex was collected as a precipitate on a membrane filter by filtration under suction from a homogeneous aqueous solution in the pH range over about 2. The original solution was prepared at a concentration ratio of CAB of Fe(III) of to 10, and that of Triton X-100 to CAB of 10 to 100. It was then adjusted to a pH value of between 1.0 and 6.5. A linear relationship (r = 0.999) was obtained between the initial concentration and the found one of Fe(III) in the range of 2.0×10^-5 to 4.0×10^-4 mol dm^-3 at a fixed concentration ratio of CAB to Fe(III) of 3 and that of Triton X-100 to CAB of 20. This membrane filtration with CAB and Triton X-100 may be utilized for the separation of Fe(III) as a background species.

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A method for the superheated water chromatography of phenols was developed using a poly(styrene-divinylbenzene) (PSDVB) stationary phase. The stationary phase of superheated water chromatography must be stable against the attack of water. A durability test for PSDVB packings and octadecylsilyl (ODS)-silica gels indicated that PSDVB packings were stable in superheated water in the temperature range of 100 - 150°C, whereas octadecylsilyl groups of ODS-silica gels cleaved even at 100°C. The retention of phenols on the PSDVB stationary phase decreased with an elevation of the column themperature. The retention mechanism was characterized using a thermodynamic theory that has been used for describing retention in conventional RP-HPLC. The application of the present method to an environmental analysis was also demonstrated, in which a suitable separation with good peak shape was obtained for p-chlorophenol in river-water samples.

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It has recently been reported that aluminum plays a very important role in reducing the activity of Krebs-cycle enzymes and glutamate dehydrogenase in rat brain homogenate. Therefore, it is necessary to identify the aluminum binding ability with the pivotal substrate α-ketoglutarate in biological systems. The interactions of aluminum with α-ketoglutarate were studied with pH-potentiometry, cyclic voltammetry, UV-vis, ¹H, ²⁷Al-NMR and Raman spectra multi-analytical techniques in acidic aqueous solution to measure the stoichiometries and stability constants of the complexes and its ketoenol tautomerism. The α-ketoglutarate was found to bind Al in a bidentate manner at the carboxylate and carbonyl moieties. The mononuclear 1:1 (AlLH_-1, AlL⁺, AlHL²⁺) and 2:1 (AlL₂^-, AlL₂H_-2^3-) species, and dinuclear 2:1 (Al₂L⁴⁺) species were found in acidic aqueous solution. Meanwhile, Al can promote α-KG tautomerize to its enolic-structure compounds in solutions. These findings may help to further understand the influence of Al on GDH enzyme reactions in biological systems.

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Studies were carried out to develop a simple, rapid and accurate spectrophotometric method for the analysis of fifteen cephalosporins. The method depends on the charge-transfer complexation reaction between any of these drugs as an n-electron donor and p-chloranilic acid (p-CA) as a π-acceptor to form a violet chromogen measured at 520 nm. Different variables affecting the reaction were studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9986 - 0.9996) were found between the absorbances and the concentrations of the studied drugs in the range of 4 - 1200 μg ml^-1. The limits of assay detection ranged from 2.54 to 42.83 μg ml^-1. The accuracy and precision of the method were satisfactory. The method was successfully applied to an analysis of the studied drugs in their pharmaceutical formulations; the recovery percentages ranged from 96.76 ± 0.87% to 100.50 ± 1.30%. The interaction sites were confirmed by UV/VIS, IR, ¹H-NMR techniques. Molecular modeling for the interaction was used for deriving an equation for calculating the ε value for a particular drug. This equation gave a perfect prediction for the degree of interaction of the investigated drugs with the p-CA reagent.

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Fluorometric determination of thiamine requires the conversion of the analyte to fluorescent thiochrome by hexacyanoferrate(III) oxidation in alkaline solution and the isolation of the produced thiochrome from the reaction medium by solvent extraction. It was observed that thiochrome could be concentrated and separated from the reaction medium by solid-phase extraction. The thiochrome sorpted on the surface of octadecyl-alkylated poly-[styrene/divinylbenzene] (C18-PS/DP) microbeads emitted strong fluorescence upon excitation, the maximum excitation and emission wavelengths being 385 nm and 433 nm, respectively. Based on this observation, a sequential injection renewable surface solid-phase spectrofluorometry was developed for the determination of thiamine. A sequential injection system on-line coupled to a chip-based flow-through cell was employed to handle the chemical reaction, bead injection and discharging, and adsorption of thiochrome. Solid-phase fluorometric detection was realized by coupling the chip-based flow-through cell to a spectrofluorometer with a multistrand bifurcated optical fiber. Under the optimized condition, a detection limit of 0.03 μg ml^-1 was achieved at the sample throughput of 30 h^-1 and consumption of 1 mg C18-PS/DP microbeads for each run. Eleven runs of a 2 μg ml^-1 thiamine standard solution gave a relative standard deviation of 1.0%. The developed approach was successfully applied for the determination of thiamine contents in pharmaceutical preparations.

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Carbazole is a promising pharmaceutical species. A novel optical sensor for determining doxycycline based on the fluorescence quenching of N-allylcarbazole immobilized on an quartz glass plate surface by covalent bonding has been described. The sensor shows satisfactory virtues in reversibility, repeatability, selectivity and sufficient lifetime resulting from its excellent optode membrane. Its response time is less than 60 s. The determination range and detection limit of the sensor are 6.0×10^-7-2.0×10^-3 M and 2.0×10^-7 M, respectively. The lifetime of each sensor is at least three to four months. The sensor can be used for direct determination of doxycycline in pharmaceutical preparations and urine samples.

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A new chromogenic reagent, 2-(2-quinolylazo)-5-diethylaminophenol (QADEAP), was synthesized. A sensitive, selective and rapid method has been developed for the determination of μg/L level silver ion based on the rapid reaction of silver(I) with QADEAP and the solid phase extraction of the colored chelate with C₁₈ cartridge. The QADEAP reacts with Ag(I) to form a violet chelate of a molar ratio 1:2 (silver to QADEAP) in pH 3.5 - 8.0. This chelate was preconcentrated by solid phase extraction with C₁₈ cartridge. An enrichment factor of 100 was achieved. The molar absorptivity of the chelate is 1.30×10⁵ L mol^-1 cm^-1 at 590 nm in measured solution. Beer’s law is obeyed in the range of 0.01 - 0.6 μg/ml. The relative standard deviation for eleven replicate samples of 0.01 μg/ml is 1.15%. The detection limit is 0.02 μg/L in the original samples. This method was applied to the determination of μg/L level silver ion in water with good results.

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A flow injection system for the simultaneous determination of uranium and thorium has been developed by using selective masking and a spectrophotometric detector with two flow cells aligned with the same optical path. The injected sample solution was first mixed with a reagent solution containing Chromazurol S (CAS) and cetyltrimethylammonium chloride (CTMAC), and the total absorbance of uranium- and thorium-CAS complexes was measured in the first flow cell at 620 nm. The sample stream was then mixed with an EDTA solution in order to convert the thorium-CAS complex to a thorium-EDTA complex, and the absorbance of the uranium-CAS complex was measured in the second flow cell. The detection limits were 10 μg dm^-3 for uranium and 7 μg dm^-3 for thorium. The calibration graphs were linear (r < 0.9998) at least over the ranges of 0.1 to 10 mg dm^-3 for uranium and 0.08 to 8 mg dm^-3 for thorium. The RSDs were less than 1.5% (n = 3) in the calibration range. Uranium and thorium of up to the 6-fold concentration to each other could be determined in admixtures with relative errors of less than 3.3%. The sample throughput was 24 per hour. The proposed system was successfully applied to the analysis of a uranium-thorium ore mock solution by coupling with anion-exchange in a magnesium nitrate medium to eliminate interference from coexisting elements.

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In the recycling of poly(vinyl chloride)(PVC), it is required to discriminate every plasticizer for quality control. For this purpose, the near-infrared spectra were measured for 41 kinds of PVC samples with different plasticizers (DINP, DOP, DOA, TOTM and Polyester) and different plasticizer contents (0 - 49%). A neural-network analysis was applied to the near-infrared spectra pretreated by second-derivative processing. They were discriminated from one another. The neural-network analysis also allowed us to propose a calibration model which predicts the contents of plasticizers in PVC. The correlation coefficient (R) and the root-mean-square error of prediction (RMSEP) for the DINP calibration model were found to be 0.999 and 0.41 wt%, respectively. In comparison, a partial least-squares regression analysis was carried out. The R and RMSEP of the DINP calibration model were calculated to be 0.993 and 1.27 wt%, respectively. It is found that a near-infrared spectra measurement combined with a neural-network analysis is useful for plastic recycling.

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Trace amounts of cobalt and nickel in a water sample were quantitatively coprecipitated with scandium hydroxide at pH 8.0 - 10.5. Because the coprecipitant could be easily dissolved with 1 mol dm^-3 nitric acid, and te presence of up to 10 mg cm^-3 of scandium did not interfere with the graphite-furnace atomic absorption spectrometric determination of cobalt and nickel, the volume of the final solution prepared for the determination could be minimized down to 0.5 cm³. The concentration factor was 400-fold and the detection limits (signal to noise = 2) were 5.0 pg cm^-3 of cobalt and 10.0 pg cm^-3 of nickel in 200 cm³ of the initial sample solution. The 27 diverse ions investigated did not interfere with the determination in at least a 500-fold mass ratio to cobalt or nickel. The proposed method was successfully applied to the determination of trace amounts of cobalt and nickel in river-water samples.

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A simple and sensitive fluorometric high-performance liquid chromatographic method was developed for the determination of midodrine in human plasma. After liquid-liquid extraction from plasma, the drug and 2-phenylglycinol (internal standard) were converted into the corresponding fluorescent derivatives by reaction with 3,4-dihydro-6,7-dimethoxy-4-methyl-3-oxoquinoxaline-2-carbonyl chloride, a fluorescence derivatization reagent for amines. The derivatives were separated within 30 min on a reversed-phase column using isocratic elution with acetonitrile-methanol-water (10:30:60, v/v) and were detected spectrofluorometrically at 485 nm with excitation at 400 nm. The detection limit for midodrine was 0.3 pmol (76 pg) per mL plasma at a signal-to-noise ratio of 3.

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“Substituent on benzenesulfonyl group” effect of 8-benzenesulfonamidoquinoline [N-(8-quinolyl)benzenesulfonamide, Hbsq] as bidentate chelate extractant for divalent metal cations was investigated with using Hbsq and its eight derivatives. Introduction of electron-withdrawing substituent on the benzenesulfonyl group in Hbsq enhanced the extractability that originated from its inductive effect. Furthermore, a bulky substituent on an ortho-position of the benzenesulfonyl group resulted in no steric effect in extraction, whereas the existence of two substituents on each ortho-position caused lower extraction performance due to steric hindrance.

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In glow discharge optical emission spectrometry, an argon-helium mixed gas plasma was investigated to improve the detection sensitivity of arsenic in steel samples. The emission line of arsenic was enhanced and the background intensity was simultaneously reduced when an Ar-He plasma was employed instead of an Ar plasma, which is effective for the sensitive determination of arsenic. The detection limits were calculated to be 0.009 mass% for a 700-V Ar plasma, 0.004 mass% for a 700-V Ar-He plasma, and 0.001 mass% for a 900-V Ar-He plasma.

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Ciprofloxacin belongs to a family of quinolone antibacterial agents. The crystal structure of ciprofloxacin hydrochloride 1.34-hydrate was determined. Most of the bond lengths and angles of the ciprofloxacin cation are very similar to those of ciprofloxacin hexahydrate, which appears in the zwitterionic form. The exceptions are the carbon-oxygen bond distances in the carboxylic group, since in the title compound this group is not deprotonated. Various inter- and intramolecular hydrogen bonds were found in the molecule and are described.

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The crystal structure of the title compound has been determined. The coordination geometry about the iron(II) center is a tetrahedrally distorted square plane formed by the four-coordinate N₂O₂ donor set of the Schiff-base imine-phenol ligand. Molecules of the title compound are not planar. The two Schiff-base moieties, which themselves are reasonably planar, are inclined at an angle of 31.5(1)°.

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The adduct of piperazine, o-phthalic acid and water (1:2:2), C₂₀H₂₆N₂O₁₀, crystallizes in the monoclinic space group P2₁/c with a = 6.129(1), b = 12.810(2), c = 13.137(2)Å, β = 95.87(1)°, V = 1026.0(3)ų, Z = 2. The piperazinium adopts a chair comformer, and is tied with the hydrogen orthophthalate via a hydrogen bond of the N-H…O type. Because of bifurcated hydrogen bonding of C(sp³)H-O [3.0801(17) and 3.1408(18)Å] and the shortest hydrogen bond of C(sp³)H-O [2.9758(17)Å], C(sp³)H-O hydrogen bonds play important roles in stablizing the title adduct.

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In the title compound, the coordination around the Cu atom is a distorted square-pyramid involving three N atoms from the ligand and one N atom from the azido group at the basal plane. The Cl atom is located at the apical position. The Cu atom is 0.32(5)Å above the basal plane. There are three intramolecular and four weak intermolecular hydrogen bonds in the structure. IR spectra confirm the asymmetric N₃ stretching vibrations of the terminal azide group.

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Tetracarbonyl(2,2′-dipyridylamine)tungsten was prepared from W(CO)₆ and 2,2′-dipyridylamine in toluene. The structure was determined by an X-ray diffraction analysis. Crystal data: triclinic; space group, P-1 (No.2); a = 8.454(1)Å, b = 13.369(2)Å, c = 6.9452(9)Å, α = 85.88(1)°, β = 68.28(1)°, γ = 80.93(1)°, V = 720.0(1)ų; Z = 2.

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