Zinc oxide nanonail based chemical sensor for hydrazine detection

Using ZnO nanonails, a hydrazine electrochemical sensor has been fabricated, for the first time, which showed a high and reproducible sensitivity of 8.56 microA cm(-2) microM(-1) with a response time less than 5 s, a linear range from 0.1 to 1.2 microM and a correlation coefficient of R = 0.999. The limit of detection (LOD), based on the S/N ratio, was estimated to be 0.2 microM.     

Improved method for the diimide reduction of multiple bonds on solid-supported substrates

A mild and improved method for reducing multiple bonds on various resins with diimide is described. The simple procedure readily generates diimide from 2-nitrobenzenesulfonohydrazide and triethylamine at room temperature. A number of representative multiple bonds in various steric and electronic environments were examined, including polar double bonds such as carbonyl and azo, for ease and selectivity of reduction. A general trend of reactivity was identified which revealed, inter alia, that terminal olefins, 1,2-disubstituted olefins, electron-poor olefins, and terminal alkynes were the most easily reduced.     

A coumarin based chemodosimetric probe for ratiometric detection of hydrazine

A coumarin-based sensor containing trifluoroacetyl acetonate moiety was designed, synthesized, and applied for hydrazine detection. Hydrazinolysis of the chemodosimeter results in a prominent chromogenic and fluorescence ratiometric response toward hydrazine within 3 min. The probe is highly selective toward hydrazine over other important amines and other biologically and environmentally abundant analytes. The limit of detection (LOD) of the probe is in 10⁻⁶ M range. The sensing mechanism was supported by NMR and HRMS analysis. The experimentally observed change in structure and electronic properties of the sensor after reaction with hydrazine was modeled by Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TDDFT) computational calculations, respectively.     

Solvent effect on the self-assembled structure of an amphiphilic perylene diimide derivative

An amphiphilic electron-deficient (n-type) perylene diimide has been synthesized and characterized. The diimide contains a hydrophobic long chain on one end and a hydrophilic ethoxy chain on the other. The self-assembly of this molecule in polar and nonpolar solvents has been demonstrated by concentration- and temperature-dependent absorption and fluorescence spectroscopies. Analysis of the spectral change for the aggregates shows typical J-aggregates for structures precipitated from polar solvents and H-aggregates for structures precipitated from nonpolar solvents. SEM and TEM micrographs and a suggested packing scheme, compatible with the formation of nanostrips in nonpolar solvents and nanofibers in polar solvents, are presented.     

Utilization of flow injection with hydrazine reduction and photometric detection for the determination of nitrate in rain-water

The hydrazine reduction method for determination of nitrate at the parts per million level is adapted to flow injection sample processing of rain-water. Reagent composition and physical variables were evaluated and optimized. Forty samples per hour can be processed. A precision of better than 3% is possible in the range of 1.0–10.0 ppm nitrate. Results for nitrate obtained from 9 rain-water samples agreed favorably with those determined by ion chromatography.     

Copper oxide nanoarray based on the substrate of Cu applied for the chemical sensor of hydrazine detection

This communication reports on a novel amperometric hydrazine sensor of CuO nanoarray based on a Cu substrate. Copper oxide nanoarray was directly grown on Cu substrates using a one-step facile hydrothermal method and was characterized using scanning electron microscopy and X-ray powder diffraction. The electrochemical study has shown that the CuO nanoarray exhibits higher catalytic effect on the hydrazine than the normal CuO nanoparticles. This may be attributed to the special structure of the nanomaterials esp. the substrate of the electric Cu. And the amperometric response showed that the CuO nanoarray modified glassy carbon electrode has a low detection and a high sensitivity for hydrazine.     

Cu triggered fluorescence sensor based on fluorescein derivative for Pd detection

This Letter describes the synthesis of a novel fluorescein-based derivative used as the fluorescence sensor for Pd²⁺ detection. The sensor can show highly selective and sensitive ‘off-on’ fluorescence response only in the presence of Cu²⁺ as a synergic trigger, which presents a new strategy for Pd²⁺ detection method.     

Extraction-chromatographic determination of hydrazine in natural water as a 5,7-Dinitrobenzofurazan derivative using diode-array detection

The conditions for the derivatization of hydrazine withp-dimethylaminobenzaldehyde and 4-chloro-5,7-dinitrobenzofurazan, extraction preconcentration of derivatives from natural water, and HPLC determination of the toxicant with diode-array detection were studied. The 5,7-dinitrobenzofurazan derivative was quantitatively extracted from water with isoamyl alcohol and a mixture of isoamyl alcohol with methylene chloride at pH 3–4. A procedure was developed for the extraction-chromatographic determination of hydrazine in water with c_min = 0.05 Μg/L and the analytical range 0.12-60 Μg/L. The concentration of hydrazine in lake Kaban water was determined.     

FRET-induced nanomolar detection of Fe based on cinnamaldehyde-rhodamine derivative

A new dimethylaminocinnamaldehyde linked rhodamine based fluorescence receptor 3 is synthesized which shows fluorescence resonance energy transfer in the presence of Fe²⁺ ions, thus enhancing rational partition in between donor and acceptor emissions and permitting separated measurement of emissions of both fluorophores.     

Hydroboration and diimide reduction of caryophyllene and isocaryophyllene

The monohydroboration of caryophyllene with dicyclohexylborane followed by oxidation brought about the participation of the (E)-trisubstituted double bond in preference to the exocyclic double bond during hydroboration to the corresponding unsaturated alcohol. This alcohol gave the corresponding ketone by oxidation. Isocaryophyllene under similar conditions provided the unsaturated alcohol as the major product, wherein the participation of the exocyclic double bond took place during hydroboration. Our attempts to achieve cyclic hydroboration with caryophyllene or isocaryophyllene using thexylborane resulted in the formation of the corresponding unsaturated alcohol. We achieved partial regioselective reduction of caryophyllene and isocaryphyllene with diimide to produce the corresponding dihydroderivative.     

Ultrasensitive sensing of hydrazine vapor at sub-ppm level with pyrimidine-substituted perylene diimide film device

A pyrimidine-substituted perylene diimide (Pyrimidine-PDI), in which the electron-deficient N-heterocyclic pyrimidine rings were introduced into the core positions, were synthesized to produce a conductometric film device for the sensitive detection of hydrazine (NH₂NH₂) vapor at room temperature under ambient conditions. The Pyrimidine-PDI film device exhibited ultrafast response, excellent reproducibility, excellent selectivity and good long-term stability towards hydrazine vapor. The response and recovery time of the device was calculated to be very low as 0.4?s and 0.6?s for hydrazine vapor at sub-ppm level (0.1?ppm). Moreover, the effect of the film thickness, relative humidity and temperature on the sensing performance were also studied. To understand the sensing mechanism, the core-benzene group perylene diimide (Ph-PDI) was also designed as a comparison. The film devices of Pyrimidine-PDI and Ph-PDI to hydrazine vapor were investigated with UV–vis spectra and cyclic voltammetry, which indicated that the redox of PDIs played a critical role in the sensing process. The electrochemical properties also indicated that electron-deficient N-heterocyclic pyrimidine rings could effectively lower the LUMO energy level and improve the response of the device.     

Chemiluminescence detection of hydrazine vapor

An efficient, real-time chemiluminescence detector for hydrazine vapor, N(2)H(4)(g), is described, capable of monitoring sub part-per-billion levels of hydrazine in air. The catalytic oxidation of hydrazine by colloidal platinum forms an intermediate, oxidizing agent (e.g. OH or OOH) which subsequently oxidizes luminol, generating a chemiluminescence signal that is proportional to the hydrazine concentration. Major components of the instrument include a photomultiplier tube (PMT), a short length of glass tubing coiled directly in front of the PMT cathode surface, a vacuum pump for sampling the air, and a peristaltic pump for circulating the liquid reagent. The liquid reagent, a basic solution (pH 13) of luminol and colloidal platinum, is continuously recycled. The detection sequence is initiated by pumping the hydrazine vapor through a short length of teflon tubing that is concurrently transporting the liquid reagent. The liquid is separated from the gas stream in an impinger and quickly pumped to the PMT. We have evaluated the effect of solution pH, luminol and platinum concentrations, and air and liquid flow rates on the analytical characteristics of this system. A linear, dynamic detection range for hydrazine has been obtained from 1 to 2000 ppb in air, with an instrument response that is fully reversible and achieves plateau response in less than 2 min.     

Photoelectrochemical oxidation of hydrazine on TiO2 modified titanium electrode: its application for detection of hydrazine

Despite extensive investigations on the photoelectrochemical properties of TiO₂-based electrodes, it is surprising that no photoelectrochemical investigation has been done for the case of hydrazine oxidation. In this paper, TiO₂ modified titanium (Ti/TiO₂) electrode was fabricated by anodization process under a constant applied potential. The morphological and microstructural characterization of the Ti/TiO₂ electrode was performed by scanning electron microscopy (SEM). The electrochemical and photoelectrochemical behavior of Ti/TiO₂ electrode in the absence and presence of hydrazine was examined by cyclic voltammetry and linear sweep voltammetry. Experimental results indicated that the photocurrent response of photoelectrode was highly increased in the presence of hydrazine especially at lower potentials. It can be due to hole scavenging effect of hydrazine which decreases the recombination of photogenerated electrons and holes. Based on these perceptions, a simple photoelectrochemical sensor for detection of hydrazine was obtained. The sensor showed high reproducibility, stability, and selectivity properties. This photoelectrode was successfully applied for direct determination of hydrazine in tap water.     

Perylene diimide based ‘turn-on’ fluorescence sensor for detection of Pd in mixed aqueous media

A perylene diimide (PDI) based fluorescence chemosensor (PDI-1) for Pd²⁺ was prepared. PDI-1 showed a remarkable fluorescence enhancement (over 120-fold) in the presence of Pd²⁺ in mixed aqueous media with high selectivity and sensitivity. Moreover, the dramatically ‘off–on’ fluorescence response concomitantly induced the obvious color change from dark purple to brilliant pink, which could also be identified by naked eyes easily. The low limit for Pd²⁺ detection was found to be as small as 10⁻⁹ mol/L. Hence, PDI-1 is a highly promising fluorescent chemosensor for the direct determination of residual Pd²⁺ in chemical medicines and environment samples.     

Iron-mediated hydrazine reduction and the formation of iron-arylimide heterocubanes

The reaction of Fe(N{SiMe(3)}(2))(2) (1) with 1 equiv of arylthiol (ArSH) results in material of notional composition Fe(SAr)(N{SiMe(3)}(2)) (2), from which crystalline Fe(2)(μ-SAr)(2)(N{SiMe(3)}(2))(2)(THF)(2) (Ar = Mes) can be isolated from tetrahydrofuran (THF) solvent. Treatment of 2 with 0.5 equiv of 1,2-diarylhydrazine (Ar'NH-NHAr', Ar' = Ph, p-Tol) yields ferric-imide-thiolate cubanes Fe(4)(μ(3)-NAr')(4)(SAr)(4) (3). The site-differentiated, 1-electron reduced iron-imide cubane derivative [Fe(THF)(6)][Fe(4)(μ(3)-N-p-Tol)(4)(SDMP)(3)(N{SiMe(3)}(2))](2) ([Fe(THF)(6)][4](2); DMP = 2,6-dimethylphenyl) can be isolated by adjusting the reaction stoichiometry of 1/ArSH/Ar'NHNHAr' to 9:6:5. The isolated compounds were characterized by a combination of structural (X-ray diffraction), spectroscopic (NMR, UV-vis, Mo?ssbauer, EPR), and magnetochemical methods. Reactions with a range of hydrazines reveal complex chemical behavior that includes not only N-N bond reduction for 1,2-di- and trisubstituted arylhydrazines, but also catalytic disproportionation for 1,2-diarylhydrazines, N-C bond cleavage for 1,2-diisopropylhydrazine, and no reaction for hindered and tetrasubstituted hydrazines.     

New colorimetric and fluorometric chemosensor based on a cationic polythiophene derivative for iodide-specific detection

Electrostatic interactions between anions and a new water-soluble, cationic, affinitychromic poly(3-alkoxy-4-methylthiophene) derivative provide a new tool for a selective optical detection method (colorimetric or fluorometric) for iodide ions.     

Colorimetric and fluorescent dual probe based on a polythiophene derivative for the detection of cysteine and homocysteine

Colorimetric and fluorescent dual detection of cysteine (Cys) and homocysteine (Hcy) has been realized based on the ionic self-assembly of a cationic polythiophene derivative with aromatic derivatives of Cys and Hcy formed in situ.