Tetraoctylammonium cation forms a room-temperature molten salt (RTMS) with 2,4,6-trinitrophenolate anion. The RTMS is immiscible with water (W) and forms a stable RTMS | W interface. It has been shown that the RTMS | W interface can be electrochemically polarized. A well-defined voltammetric wave due to the transfer of thiocyanate ion across the RTMS | W interface was observed within the potential window. This is the first example of a polarized RTMS | W interface.

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DNA and gold nanoparticles are co-immobilized at a gold electrode through elaborate self-assembly processes. This configuration has proven to be useful as a sensor for phenothiazine drugs, taking advantage of the well-known, relatively large surface area of gold nanoparticles and the strong intercalation between dsDNA and phenothiazine drugs. This modified electrode has demonstrated good sensitivity and stability towards the oxidation of two model phenorthiazine drugs: promethazine and chlorpromazine. A linear dependence between the concentration of phenothiazine drugs and the peak current is observed, with a concentration range of 2.0 × 10^-5 - 1.6 × 10^-4 M and 1.0 × 10^-5 - 1.2 × 10^-4 M, and a detection limit of 1.0 × 10^-5 M and 7.0 × 10^-6 M, for promethazine and chlorpromazine, respectively.

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A method for the spectrophotometric assay of yeast vitality was developed using 2,3,5,6-tetramethyl-1,4-benzoquinone and tetrazolium salts. The metabolic efficiency of 2,3,5,6-tetramethyl-1,4-benzoquinone by yeast cells was used as an index of yeast vitality. 2,3,5,6-Tetramethyl-1,4-benzoquinone was reduced to 2,3,5,6-tetramethyl-1,4-hydroquinone by yeast cells. Then, the superoxide anion radicals generated from O₂ by reduction with 2,3,5,6-tetramethyl-1,4-hydroquinone under alkaline conditions reduced tetrazolium salts to formazan, which exhibited absorbance maxima at 440 nm. A linear relationship between the absorbance and viable cell density was obtained in the range of 1.0 × 10⁵ - 2.0 × 10⁷ cells/ml for a sample solution. During the cultivation of yeast cells, the absorbance showed almost an anti-parallel change with that of glucose in yeast growth and fermentation, suggesting that the absorbance change reflected the vitality of yeast cells.

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Hydrogen peroxide sensors where horseradish peroxidase (HRP) is incorporated into pyrrole/3-alkylsulfonate pyrrole copolymer films deposited on an SnO₂ electrode (HRP/Py-PS electrode) were investigated with regard to the effects of the fabrication parameters (electropolymerization charge, deposition current density, and electrodeposition solution pH) on the amount of surface-immobilized enzyme and the sensor response. The amount of incorporated enzyme was determined with a method recently developed by ourselves. The results suggest that the amount of entrapped enzyme increases almost linearly with the total charge passed, and strongly depends on the polymer film growth rate and the electropolymerization pH. These findings open up a way to control the amount of enzyme and the resultant response of the biosensor by modifying the preparation conditions.

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A method for activating ISE is proposed that can allow determination of the fluoride concentration at ng mL^-1 level with good precision and accuracy. Fluoride ISE is activated in 0.5 mol L^-1 HClO₄ medium and then fluoride is determined in the same medium. The linear range for the determination of fluoride is between 1.00 × 10^-2 - 1.00 × 10^-7 mol L^-1, and the detection limit of the method is 1.0 ng mL^-1. The advantage of this method is that it is free from the use of TISAB solution while being, time-saving and labor-saving. A mechanism study of the activation of FISE in HClO₄ medium is explained. The method has been used for the determination of trace fluoride in milk and flour with satisfactory results.

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Two novel potentiometric membrane sensors responsive to the ibuprofen drug have been developed. These incorporate poly(vinyl chloride) and polyurethane matrix membranes containing 5,10,15,20-tetraphenylporphrinato (TPP) indium (III) ionophore plasticized with dibutylsebacate. The sensors show a near-Nernstian response with anionic slopes of −53 and −55 mV decade^-1, over the concentration range of 4.2 × 10^-6 - 1.0 × 10^-2 and 3.3 × 10^-6 - 1.0 × 10^-2 M ibuprofen within pH ranges of 4 - 9 and 5 - 9 for PVC and PU matrix membranes, respectively. A sensor based on a polyurethane membrane displays a lower detection limit and a wider linear working range, and a sensor based on a PVC membrane exhibits a better overall selectivity, especially in the presence of lipophilic organic anions. Both sensors are used for the quantification and quality-control assessment of ibuprofen in pharmaceutical preparations. The average recoveries are 99.1±0.3% and 99.3±0.3% for TPP In(III)-PVC and TPP In(III)-PU based membrane sensors, respectively. High selectivities towards ibuprofen in the presence of many anions, drug excipients and diluents are offered by both sensors, which exhibit a non-Hofmeister selectivity pattern.

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Carbon-paste electrodes (CPEs) were studied to elucidate the cathodic stripping voltammetric determination of iodine. At an accumulation potential of 1.0 V (vs. SCE), iodide was preconcentrated on CPEs via an ion-pairing reaction, followed by oxidation to iodine. Then a linear scan voltammogram was recorded after 10 s of quiescent time by a cathodic potential scan from 0.7 V to 0.1 V at a scan rate of 100 mV s^-1. A cathodic peak current was obtained at about 0.38 V. Various experiment parameters such as the acidity, chloride concentration, accumulation potential, accumulation time, concentration of cetyltrimethylammonium bromide (CTAB) and scan rate, were optimized to analyze the iodide by employing linear-scan stripping voltammetry. Under the optimal conditions, calibration curves were obtained over a wide concentration range of the iodide ion from 8 × 10^-9 mol L^-1 to 5 × 10^-6 mol L^-1 with a detection limit of 2 × 10^-9 mol L^-1 at an accumulation time of 3 min. The effect of interfering species was evaluated and the procedure was applied to an iodide analysis in table salt, with good results.

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A new lead(II)-selective electrode has been developed based on bis(acetylacetone)-p-phenylenediamine-lead(II) [LPb(NO₃)₂]H₂O complex ionophore as a sensing material, dioctylphthalate (DOP) as a solvent mediator and PVC as a matrix. This electrode exhibits a linear Nernstian response over the concentration range of 1 × 10^-5 - 1 × 10^-1 mol l^-1 of Pb(II) cation, with a cationic calibration slope of 30.0 ± 0.2 mV/concentration decade and a detection limit of 2 × 10^-6 mol l^-1 (0.40 ppm). It has a fast response time and can be used for a period of 2 months without any divergence in potentials. The proposed electrode reveals a good selectivity for Pb(II) over a wide variety of other tested cations and could be used in the pH range of 4 - 8. It was successfully used for direct determination of Pb(II) concentration in some samples. The obtained results show a good agreement with those obtained by an atomic absorption spectrometric method. The average recovery obtained is 96.5 ± 0.5% with standard deviation of 1.2% (n = 8).

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This work describes an FIA potentiometric procedure for the quantification of dipyrone in pharmaceutical products. For the detector, a tubular electrode comprising a polymeric membrane containing tetraoctylammonium as an electroactive material (5% w/w), dibutylphtalate as a mediator solvent (65% w/w) and PVC (30% w/w) directly applied above a graphite conductor support was used. This unit was incorporated into a monochannel FI-system with a 0.1 mol/L phosphate buffer solution (pH = 5.2) as the carrier solution. The electrode showed a linear response from 8.0 × 10^-4 to 10^-1 mol/L dipyrone, a slope of 62.1 ± 0.2 mV/dec in pH 5.2 units, an injection volume of 500 μL and a carrier flow-rate of 6 mL/min. This procedure was applied to the analysis of pharmaceutical formulations (oral and injectable) containing dipyrone; the obtained results gave a relative error of less than 3.9% and coefficients of variation less than 1% and 5%, respectively, for the FIA and classical iodometric methods.

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A flow-injection analysis method for the determination of nitrite and nitrate in natural water samples has been developed that consists of two systems based on their reduction to NO with hydrazine and/or ascorbic acid, followed by chemiluminescence detection. The procedure of sweeping the generated NO into an NO_x monitor, by means of a gas-liquid separating coil consisting of microporous polytetrafluoroethylene (PTFE) tubing, offers practical advantages. The adjustment of the carrier gas-flow rates could yield the same calibration graphs for the two measurement systems, and the accumulation sweeping mode provides a higher sensitivity. Chemiluminescence detection allows a wide linear calibration range of 5 × 10^-8 to 5 × 10^-5 M. The detection limits for nitrate and nitrite, defined as three-times the standard deviation of measurement blanks, are 2 × 10^-8 M and 1 × 10^-8 M, respectively, and the average precision was 3.2% at ambient natural concentration levels. Recovery tests were between 94% and 106% for a variety of natural water samples. The method is relatively free from interferences from the substances normally found in natural water, and only ferric ion has an effect for the nitrite determination.

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A new analytical method has been validated for determining the insecticide acetamiprid in vegetables using gas chromatography (GC) and different mass spectrometric detection techniques, such as full-scan mass spectrometry (MS), and tandem mass spectrometry (MS/MS). For this purpose, a previous extraction of the vegetable sample was carried out with ethyl acetate. In GC-MS/MS, the lowest detectable concentration was 0.001 mg kg^-1, the average recovery rates at various fortification levels (0.015 and 0.030 mg kg^-1) ranged between 82.4 and 85.7% and the relative standard deviations were lower than 12.2% in all cases.

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A very specific, selective, simple and inexpensive procedure was developed for the speciation of Cr^VI and Cr^III. This method is based on the quantitative extraction of chromate and Cr^III (previously oxidized to Cr^VI) as a tetrabutylammonium-chromate ion-pair in methyl isobutyl ketone (MIBK), and then back extraction and preconcentration with an acidic diphenylcarbazide (DPC) solution. Back extraction was applied to achieve further preconcentration by a final factor of 20. The Cr^VI-DPC complex was determined in back-extract by a spectrophotometer at 548 nm. Under these extraction conditions, most of the probable concomitant cations and anions remained in the first inorganic phase. The calibration curve was linear up to 0.14 μg L^-1 of Cr^VI with a detection limit of 2.22 ng L^-1. The developed procedure was found to be suitable for the determination of the Cr^VI and Cr^III species in various natural water samples with a relative standard deviation of better than 1.6%. The method was successfully applied to the speciation of chromium in spiked natural water samples, and also samples of effluent from a leather treatment plant.

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A β-cyclodextrin bonded silica was synthesized by using a convenient method, and was evaluated as a selective sorbent for the solid-phase extraction of 4-nitrophenol and 2,4-dinitrophenol. When double-distilled water was used as the sample matrix, the sorbent showed a strong capacity to adsorb 4-nitrophenol and 2,4-dinitrophenol; the recoveries were found to be 96% and 99%, respectively, with a 1 L water sample. The selectivity of the sorbent was investigated by using a washing step with methanol. Most of the phenols were washed out with 5 mL of methanol, while 4-nitrophenol and 2,4-dinitrophenol still gave recoveries of 94% and 90%. The solution for efficiently eluting the analytes was optimized and the effect of the inorganic salt on the extraction was examined. In order to investigate the potentiality of the sorbent in dealing with real water samples, water from Donghu lake (Wuhan, China) spiked with nine phenolic compounds at microgram per liter levels were preconcentrated on this cartridge.

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Uniformly sized molecularly imprinted polymers, which can recognize bisphenol A (BPA), have been prepared by a multi-step swelling and polymerization method using BPA or a structurally related analogue of BPA [p-t-octylphenol (OP) or p-t-butylphenol (BP)] as the template molecule, 4-vinylpyridine as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The BP-imprinted polymer showed higher molecular recognition ability for BPA than the OP-imprinted polymer. The BPA- and BP-imprinted polymers were applied for the assay of a trace amount of BPA in river water using column-switching HPLC with fluorescence detection: A BPA-imprinted polymer was used for removal of BPA from the pretreatment eluent as the trap column, and a BP-imprinted polymer was used for selective pretreatment and enrichment of BPA in river water as the pretreatment column. The calibration graph, constructed from peak area data plotted versus BPA concentration, was linear with a correlation coefficient of >0.999 in the concentration ranges of 25 - 1000 ppt. The limit of quantitation was 25 ppt with a 5-ml injection. The column-switching HPLC system was successfully applied for the assay of BPA in river water.

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A colloidal powder was prepared by fixing polyaniline (PANI, conducting polymer), poly(vinyl alcohol)(PVA, surfactant stabilizer) and a suitable dopant anion to silica-gel powder. This hydrophilic composite colloidal particle incorporates anions with the protonation of PANI in an acidic solution. The anion can be exchanged with other anions when the colloid is immersed in an acidic solution. Thus, the PANI colloid works as an ion exchanger. The ion-exchange properties on the composite colloidal powder were investigated. Anions were successfully and easily exchanged in the order Br^- < Cl^- < NO₃^- < ClO₄^- < SCN^-. This ion-exchange selectivity corresponds largely to the ion-exchange equilibrium constants, which are based on a hydrophobic interaction between the anion and colloid. However, this ion-exchange selectivity does not agree simply with the lipophilic order, but is instead explainable by a gap in the effective ion-exchange capacity due to a size effect between the micropore on the colloidal particle formed by the dopant anion in polymerization and anion sizes in the hydrophobic environment.

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A serially coupled column system for capillary supercritical fluid chromatography was constructed by connecting two capillary columns of different polarities using or without using a coupling restrictor. The influence of the column sequence, the size of the coupling restrictor and the column temperature on the polarity of the system were studied. The system without a coupling restrictor (the directly coupled system) provided an intermediate polarity between two columns, depending on the column geometry, such as the film thickness and column length, although it slightly shifted to that of the first column. In the system with a coupling restrictor, the contribution of the second column to the overall retention increased with its resistance. The use of a coupling restrictor allowed to control the polarity of the coupled system virtually over the whole range between two columns. The temperature was an additional effective parameter for tuning the polarity of the system.

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A kinetic-catalytic spectrophotometric flow-injection method was developed for the rapid and sensitive determination of trace amounts of copper(II). The method is based on the catalytic effect of copper(II) on the redox reaction of cysteine with iron(III). Iron(II) produced by the catalytic reaction reacts with 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ) to form the iron(II)-TPTZ complex (λ_max = 593 nm). By measuring an absorbance of the complex, one could determine 0.05 - 8 ppb copper(II) with the relative standard deviations (n = 10) of 1.6%, 1.3%, and 0.8% for 0.5 ppb, 1 ppb, and 2 ppb copper(II), respectively. The limit of detection (S/N = 3) was 0.005 ppb. The sample throughput was 30 h^-1. The proposed method was successfully applied to the determination of copper in natural water and serum samples.

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A simple sequential injection (SI) method is reported for the determination of the non-ionic surfactant polyoxyethylene sorbitan monoleate (Tween-80). The proposed method is based on a fluorescence enhancement of the probe 4′,5′-dibromo-2′,7′-dinitro fluorescein, disodium salt (Eosin B) in the presence of a surfactant. The procedure is optimized using the univariate method of optimization. The optimum operating conditions are as follows: reagent concentration, 40 ppm; pH, 4.5; aspirated volumes of sample and reagent, 120 μL and 100 μL, respectively. With the optimum conditions described, linear calibration curves were obtained from 10 - 200 ppm. The detection limit was 1.7 ppm and the maximum relative standard deviation of the method was 2.7% (n = 5). The fluorescence excitation and emission were fixed at λ_ex = 545 nm and λ_em = 585 nm. The method was successfully applied to the determination of (TW-80) in natural water samples.

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A technique for determination of mercury is described; it is based on electrolytic reduction of Hg(II) ion on a graphite cathode, the trapping of mercury vapor and its volatilization into a quartz tube aligned in the optical path of an atomic absorption spectrometer. The electrochemical cell consisted of a graphite cathode and an anode operating with constant direct current for the production of mercury atoms. A pre-activated graphite rod was used as the cathode material. The optimum conditions for electrochemical generation of mercury cold vapor (the electrolysis time and current, the flow rate, the type of electrode and electrolyte) were investigated. The characteristic electrochemical data with chemical cold vapor using NaBH₄-acid were compared. The presence of cadmium(II), arsenic(III), antimony(III), selenium(IV), bismuth(III), silver(I), lead(II), lithium(I), sodium(I) and potassium(I) showed interference effects which were eliminated by suitable separation techniques. The calibration curve is linear over the range of 5 - 90 ng ml^-1 mercury(II). The detection limit is 2 ng ml^-1 of Hg(II) and the RSD is 2.5% (n = 10) for 40 ng ml^-1. The accuracy and recovery of the method were investigated by analyzing spiked tap water and river water.

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Four rapid, simple, reproducible and sensitive methods (A-D) for assaying domperidone (I) and metoclopramide (II) in a bulk sample and in dosage forms were investigated. The first and second methods, A and B, are based on the oxidation of I and/or II by Fe³⁺ in the presence of o-phenanthroline (o-phen) or bipyridyl (bipy). The formation of tris-complex upon reactions with Fe³⁺-o-phen and/or Fe³⁺-bipy mixture in an acetate buffer solution of the optimum pH-values was demonstrated. Methods C and D involve the addition of excess Ce⁴⁺ and the determination of unreacted oxidant by a decrease of the red color of chromotrope 2R (C2R) at a suitable λ_max of 528 nm for method C, or a decrease in the orange pink color of Rhodamine 6G (Rh6G) at a suitable λ_max value of 525 nm for method D. A regression analysis of Beer-Lambert plots showed a good correlation in the concentration range of 0.2 - 5.8 μg ml^-1. The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits were calculated. For a more accurate analysis, the Ringbom optimum concentration ranges are 0.35 - 5.6 μg ml^-1. The developed methods were successfully applied to the determination of domperidone and metoclopramide in bulk and pharmaceutical preparations without any interference from common excipients.

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A novel algorithm, alternatively minimizing coupled vector (COV) resolution error and PARAFAC error algorithm, is proposed in this paper. This algorithm can overcome the problem of slow convergence and is insensitive to the estimation of component number, such problems are unavoidable while using the traditional parallel factors analysis (PARAFAC) algorithm. In other words, this algorithm is capable of improving the computing speed and providing accurate resolutions provided that the number of factors used in the computation is no less than that of the actual underlying ones. The characteristic performances were demonstrated with a novel fluorescence data array.

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High-frequency spectroscopy has been applied to monitoring the stability of oil-in-water emulsions. It was found that stable emulsions showed absorption peaks at around 550 MHz; further, they shifted from lower to higher frequencies with time. The rate of increase of the frequencies was dependent on the amount of emulsifier added. These results show that the stability of emulsions can be monitored by the amount of the frequency shift.

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Seven useful mixed-ligand complexes in the form of [Ir(terpy)(L)Cl]²⁺ were prepared and their spectroscopic and electrochemical properties were investigated. The ligands used were terpy = 2,2′:6′,2″-terpyridine, L = 2,2′-bipyridine, 4,4′-dimethyl-2,2′-bipyridine, 4,4′-diphenyl-2,2′-bipyridine, 1,10-phenanthroline, 5-phenyl-1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline, 2,3-bis(2-pyridyl)pyrazine. Synthetic methods were developed by a sequential ligand-replacement which occurred in the reaction vessel using a microwave oven. All complexes showed that LUMOs are based on the π-system contribution of the terpyridine ligand for [Ir(terpy)(bpy)Cl]²⁺, [Ir(terpy)(dmbpy)Cl]²⁺, [Ir(terpy)(dpbpy)Cl]²⁺, [Ir(terpy)(phen)Cl]²⁺, [Ir(terpy)(dpphen)Cl]²⁺ and [Ir(terpy)(phphen)Cl]²⁺. On the other hand, the LUMO in the [Ir(terpy)(bppz)Cl]²⁺ complex is localized on the π-system of the bppz ligand, whereas the HOMOs in the iridium complexes are localized on the terpyridine ligand. It was found that Ir(terpy)(L)Cl emits in a fluid solution at room temperature. The ancillary ligands, such as terpy and bpy, have been explored to extend the lifetime of the triplet ³(π-π^*) excited states of Ir(III) terpyridine complexes. Ir(III) terpyridine units with an electron donor (dmbpy) or electron acceptor substituents (terpy, dpbpy, phphen, dpphen and bppz) are found to decrease the energy of the ³LC states for use as photosensitizer molecular components in supramolecular devices. The spectroscopic and electrochemical details are also reported herein.

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Aldehyde biosensors were constructed by cross-linking formaldehyde dehydrogenase (FDH) or aldehyde dehydrogenase (ADH) and bovine serum albumin on the surface of a redox Os-polymer-coated electrode. The prepared aldehyde biosensors responded rapidly (within 30 s) to aldehydes without the addition of a soluble mediator, because the inner redox Os-polymer film effectively mediated the electron transfer from NADH generated enzymatically into the outer enzyme film to a glassy carbon electrode. An FDH/Os-polymer electrode responded linearly over the concentration range of 2 × 10^-6 - 5 × 10^-4 M for formaldehyde, while an ADH/Os-polymer electrode, though responding similarly to long chain aldehydes, such as propionaldehyde and butylaldehyde, responded linearly over the concentration range of 4 × 10^-6 - 2 × 10^-4 M for acetaldehyde.

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p-tert-Butylcalix[8]arene-octaacetic acid octaethyl ester and calix[8]arene-octaacetic acid octaethyl ester well recognized 2-phenylethylamine and phenylalanine methyl ester compared with the corresponding calix[6]arene derivatives. Moreover, the calix[8]arene derivatives, especially one having tert-butyl groups, gave better selectivity against biologically active amines having a complicated structure, such as norephedrine. We considered the interaction between calixarenes and organic ammonium ions from the viewpoint of molecular symmetries.

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The dissociation of t-butyl methacrylate-methacrylic acid copolymers in dimethyl sulfoxide was analyzed by a nonaqueous potentiometric titration technique. The negative logarithm of the dissociation constant of the monomer unit of a methacrylic acid (MAA) monotonously increased with the increasing degree of dissociation corresponding to the titrant/MAA amount ratio, and was highly influenced by the copolymerization ratio. The results are discussed in terms of the suppression of the dissociation of MAA by a neighboring charged methacrylate anion unit.

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One titrimetric and two spectrophotometric procedures have been reported for the determination of albendazole and its tablets. Using titrimetry, the drug was titrated directly with Chloramine-T under acidic conditions using a Methyl Orange indicator. The spectrophotometric procedures involve treating the sample solution with a measured excess of Chloramine-T in an acid medium, followed by an estimation of unreacted Chloramine-T by reacting with a fixed amount of either Methyl Orange or Indigo Carmine dye solution and measuring the absorbance at 510 nm or 610 nm. The stoichiometric ratio, which forms the basis for the calculations in titrimetry as well as the range of the applicability, are reported. The Beer’s law range and sensitivity values for spectrophotometric procedures are included. The methods were applied to the determination of albendazole in tablets with satisfactory results.

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A column-switching high-performance liquid chromatographic method with fluorescence detection was developed for the simultaneous determination of four benzamide-type anti-psychotic drugs: sulpiride, tiapride, sultopride and metoclopramide in human serum. In this method, a TSKgel Super-ODS column was used as an analytical column, and a TSKgel G 2000SW was prepared as a pretreatment column. Under the optimized analytical conditions, four benzamide-type anti-psychotic drugs were eluted within 18 min. The detection limits (S/N = 3) for sulpiride, tiapride, sultopride and metoclopramide are 1 ng/ml, 4 ng/ml, 2 ng/ml and 0.5 ng/ml, respectively. Finally, the method was applied to the determination of sulpiride in human serum samples obtained after a single oral dose of sulpiride.

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Electrothermal vaporization with two filaments was studied for low-pressure helium-ICP-MS. A 10-μl volume of sample was dried and vaporized, and then introduced to the ICP. With this technique, four elements were simultaneously determined with the acceptable precisions (RSD ca. 10%). The detection limit based on 3σ of background signals approached the fractional ppb range. The proposed method was successfully applied to the analysis of the certified reference material for human hair.

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A novel diffractive optical element was constructed by means of gel electrophoresis. Five capillaries were filled with a methylene blue solution and inserted into a slab gel. An electrical potential was then applied to the slab gel. Methylene Blue in the capillaries underwent electrophoretic migration, forming clear blue bands in the gel. The bands functioned as a transmission grating, and diffracted a laser beam. The intensity of the diffracted light increased with increasing the concentration of methylene blue.

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The title compound is a double oxygen-bridged dimeric heteronuclear metal complex. The coordination around the Cu atom is distorted square-planar involving two O and two N atoms from the bis(salicylidene)-1,3-propanediamine ligand. The Zn atom in the molecule has a distorted tetrahedral coordination sphere consisting of the two O atoms of the ligand and the two Br atoms. The bridging plane between the metal atoms is not planar.

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C₁₅H₁₈O₅ is orthorhombic, P2₁2₁2₁. The unit-cell dimensions at 293 K are a = 6.526(3), b = 10.247(4), c = 21.008(13)Å, V = 1404.8(12)ų, D_x = 1.316 g/cm³, and Z = 4. The R value is 0.044 for 1288 observed reflections. The A, B and C rings adopt chair, twist, and half-chair conformations. The absolute configuration is inferred from the C6 stereochemistry of (+)-cedrol. The crystal structure is stabilized by an O-H…O hydrogen bond and van der Waals forces.

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A polymeric self-assembled complex {[Pb(pydc)(pydc·H₂)(H₂O)₂]₂}_n is prepared from the complexation of a novel pyridine containing self-assembling system, LH₂, [pyda·H₂]²⁺[pydc]^2- (pyda = 2,6-pyridindiamine and pydc·H₂ = 2,6-pyridinedicarboxilic acid) and lead(II) nitrate in 84% yield. The characterization was performed using X-ray crystallography. The crystal system is triclinic with space group P_1¯ and two molecules per unit cell. The unit cell dimensions are a = 6.913(2)Å, b = 10.687(4)Å and c = 11.182(4)Å with α = 92.805(6)°, β = 101.821(6)° and γ = 95.688(6)°. The final R value is 0.0373 for 4633 reflections measured. This compound is a nine-coordinate binuclear complex with two metal fragments linked via the central four-membered Pb₂O₂ ring. The crystal also contains a neutral [pydc·H₂] molecule, that form hydrogen and coordination bonds that dominate the crystal packing, by forming layers of molecules.

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Crystal structure of zwitterionic trimethylammoniopropane sulfonate (Z1-Methyl) was determined by single-crystal X-ray diffractometry. Z1-Methyl crystallized in the monoclinic system, space group P2₁, with a = 6.3639(2), b = 10.9237(4), c = 8.1505(4)Å, β = 111.078(2)°, V = 528.69(4)ų, Z = 2. An inter-molecular ionic association was observed in the crystal. The shortest distance between the methyl protons of the trimethylammonium group and the oxygens of the sulfonate group was 2.51(2)Å.

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In the crystal structure of TBM-trihydrate three waters of crystallization were found to locate dissymmetrically. Thus, one of them forms a chelated ring with the neighboring C=O and N-H of TBM. Two other ones bind each other through hydrogen bonding and two sets of which form a cyclic dimer by hydrogen bonding (namely, water-tetramer). A C=O group binds by hydrogen bonding to each of the tetrameric water. The spatial volume occupied by water-teramer appears to be sufficient for complexation with organic molecules.

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