Diethyldithiocarbamate Complexes Research Articles

Dispersive liquid-liquid microextraction based on solidification of floating organic drop for simultaneous separation/preconcentration of nickel, cobalt and copper prior to determination by electrothermal atomic absorption spectrometry

A dispersive liquid–liquid microextraction based on solidification of floating organic drop for simultaneous extraction of trace amounts of nickel, cobalt and copper followed by their determination with electrothermal atomic absorption spectrometry was developed. 300 µL of acetone and 1-undecanol was injected into an aqueous sample containing diethyldithiocarbamate complexes of metal ions. For a sample volume of 10 mL, enrichment factors of 277, 270 and 300 and detection limits of 1.2, 1.1 and 1 ng L−1 for nickel, cobalt and copper were obtained, respectively. The method was applied to the extraction and determination of these metals in different water samples.

A Comparative Study of a Series of Dimethylgold(III) Complexes with S,S Chelating Ligands Used as MOCVD Precursors

Abstract Dimethylgold(III) complexes with S,S donor ligands having AuC 2 S 2 coordination core are compared as precursors for gold MOCVD. Three of them are liquids, the fourth one is low-melting compound. They are non-sensitive to air and light, stable under storage, do not require special handling conditions, and show a good volatility and sufficient vaporization stability. Based on monitoring of the gas phase during the programmed heating of the compound vapor in vacuum, in hydrogen and in oxygen presence, the information concerning stability of the precursor in the gas phase and gaseous products of thermolysis was obtained. It was established that decomposition mechanism in the presence of the studied gas- reactants changed in comparison with vacuum only for diethyldithiocarbamate complex. MOCVD experiments have been performed within the temperature range 210-300 o C with and without hydrogen or oxygen. The films obtained in hydrogen presence were more thick indicating higher growth rate. Effect of gas-reactant on the morphology of the films deposited is discussed.

Temperature and time dependence on ZnS microstructure and phases obtained through hydrothermal decomposition of diethyldithiocarbamate complexes

Zinc sulphide was obtained through hydrothermal decomposition of [Zn(S2CNEt2)] under different experimental conditions such as temperatures and reaction times. Hydrothermal reactions were carried out in a stainless steel autoclave at 160, 180 and 200 °C for 3, 6 and 24 hours. The obtained products were characterized using X-ray diffraction, scanning and high resolution transmission electron microscopies. Particle size and microstrain were determined by Rietveld refinement of experimental X-ray diffraction patterns. The obtained crystal size values were in the range of 6.1 to 30 nm and as the temperature and reaction times increase the particle size also increases. Band gap values are in the range of 3.34 to 3.60 eV and are highly dependent on the crystal microstrain. The catalyst activities were studied through the degradation of methylene blue dye solutions under ultraviolet radiation.

Speciation of Inorganic Antimony in Food and Water Samples by Flow Injection On-line Nano γ-Alumina Micro-column Solid-Phase Extraction Coupled with Slotted Tube Atom Trapping Flame Atomic Absorption Spectrometry

Nano γ-alumina, with ultra-high specific surface area (387.2 m2 g−1), has been synthesized and used as a promising adsorbent material in solid-phase extraction. A simple, sensitive, and economic method was developed for speciation of inorganic antimony by slotted tube atom trapping flame atomic absorption spectrometry (STAT-FAAS) after flow injection on-line nano γ-alumina micro-column solid-phase extraction. In this method, Sb(III)–diethyldithiocarbamate (DDTC) complexes produced on-line from DDTC and Sb(III) were adsorbed by the synthesized γ-alumina nanoparticles in a micro-column, then eluted by 1.0 mol L−1 HNO3 in methanol, whereas Sb(V) remained in aqueous solution. The total inorganic Sb was determined by the same procedure after Sb(V) was reduced with thiourea. Under optimal conditions, the enrichment factor was 56.5 and the detection sensitivity was improved 40-fold for antimony by STAT-FAAS compared to conventional FAAS. The limit of detection was 6.0 ng L−1 for Sb(III) and 8.2 ng L−1 for Sb(V), respectively. The intra-day precision (RSDs, n = 11) were 2.8 % for Sb(III) and 3.5 % for Sb(V), respectively, and the inter-day precision (n = 3) were 7.1 % for Sb(III) and 8.4 % for Sb(V), respectively. The recoveries for the spiked samples were 93–107 %. The proposed method was applied to speciation of inorganic antimony in water and food samples successfully.

Diethyldithiocarbamate complex with copper: the mechanism of action in cancer cells

The idea of "repurposing" of existing drugs provides an effective way to develop and identify new therapies. Disulfiram (Antabuse), a drug commonly used for the treatment of alcoholism, shows promising anticancer activity in both preclinical and clinical studies. In the human body, disulfiram is rapidly converted to its reduced metabolite, diethyldithiocarbamate. If copper ions are available, a bis(diethyldithiocarbamate)-copper(II) complex is formed. Disulfiram's selective anticancer activity is attributed to the copper(II) complex's ability to inhibit the cellular proteasome. It is assumed that the complex inhibits the proteasome by a mechanism that is distinct to the clinically used drug bortezomib, targeting the 19S rather than the 20S proteasome. This difference could be explained by inhibition of the JAMM domain of the POH1 subunit within the lid of the 19S proteasome.

Ionic liquid-assisted synthesis, structural characterization, and photocatalytic performance of CdS nanocrystals

With the assistance of the ionic liquid trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentylphosphinate), we have successfully synthesized short nanorods, quasi-nanospheres and faceted CdS nanoparticles via thermal decomposition of cadmium diethyldithiocarbamate complexes. It was shown that the shape, size and crystallinity of the products could be controlled through delicate regulation of the reaction temperature, monomer concentration, reaction time, and ionic liquid ratio. We found that higher temperature was beneficial to the good crystallinity, while the lower temperature and higher monomer concentration were in favor of anisotropic structures. The used ionic liquid contributed to the formation of hexagonal phase CdS nanocrystals, and its ratio played an important role in determining the ultimate morphology of products. The possible mechanism for the formation CdS nanocrystals was proposed. Furthermore, the as-prepared CdS samples demonstrated a highly photocatalytic activity in the degradation of methyl orange under visible light irradiation.

Oxygen-free precursor for chemical vapor deposition of gold films: thermal properties and decomposition mechanism

Thermal properties of oxygen-, phosphorus-, and halogen-free dimethylgold(III) diethyldithiocarbamate complex (CH3)2AuS2CN(C2H5)2 (gold, dimethyl(diethylcarbamodithioato -S,S′)-) having excellent storage stability and the mechanism of its decomposition to elemental gold were studied. Saturated vapor pressure was found to be ~10−3–10−1 Torr at 50–90°C. Decomposition of the vapor on the surface starts at T = 210°C. The temperature dependence of gas phase composition was studied using the original mass spectrometric technique, it was established that the decomposition of the compound on the surface in vacuum follows three main pathways. Two of them result in the formation of elemental gold, saturated C2–C4 alkanes and (1) protonated ligand or (2) methylated ligand. The third one results in elemental gold and gaseous products: C2–C3 alkylmercaptanes and CH3SCN(C2H5)2. The formation of gold as a sole solid product within the temperature range 210–240°C was confirmed by X-ray photoelectron spectroscopy analysis. It was shown that the compound exhibits the best combination of volatility, thermal, and storage stability among volatile organogold complexes and thus it may be a promising precursor for obtaining gold films by chemical vapor deposition.

Nitric oxide release using natural rubber latex as matrix

Nitric oxide (NO) is a diffusible messenger that has been involved in numerous physiological processes ranging from vasodilatation and antimicrobial properties to wound healing. The beneficial effects can be attributed to the role NO plays in angiogenesis, inflammation and tissue remodeling. In the present work, a polymeric device for the sustained site specific delivery of nitric oxide using a latex rubber matrix from Hevea brasiliensis which encapsulates the spin trap iron(II)- diethyldithiocarbamate complex (FeDETC) was developed. The release profiles of NO from latex rubber matrix were studied and stability studies were carried out. Electron Paramagnetic Resonance (EPR) signal of NO was detected in the membrane exposed to ambient atmosphere at room temperature (25 °C) even after 350 hours. FTIR spectroscopy data indicated that NO-FeDETC retained its structural and spectroscopic properties upon encapsulation in the latex matrix. The NO delivery system developed in this work as a membrane, presented high stability.

Synthesis of CuS and Cu1.1Fe1.1S2 crystals and their electrochemical properties

CuS and Cu1.1Fe1.1S2 crystals have been synthesized by the hydrothermal decomposition of Cu or Cu/Fe diethyldithiocarbamate complex obtained by mixing sodium diethyldithiocarbamate, CuCl2 and FeCl3 in absolute ethanol. CuS crystals with a hexagonal structure exhibit irregular particles with an average size of less than 500nm and rod-shaped morphology with a diameter of less than 100nm. Cu1.1Fe1.1S2 crystals with a cubic structure contain irregular particles and some rod-shaped structures with length and diameter of about 1μm and less than 100nm, respectively. The electrochemical responses of the Cu1.1Fe1.1S2 crystal modified glassy carbon electrode in NaCl and PBS solution show the irreversible and semi-reversible electrochemical process, respectively, which may originate from the NaCl, PBS solution and ascorbic acid. The Cu1.1Fe1.1S2 crystal modified electrodes exhibit definite potential to be used as the electrochemical sensors for detecting cysteine and ascorbic acid.

Corrosion Inhibition of Carbon Steel by a Multi-component Blend Containing Zinc Diethyldithiocarbamate Complex in Combination with Trisodium Orthophosphate

Corrosion Inhibition of Carbon Steel by a Multi-component Blend Containing Zinc Diethyldithiocarbamate Complex in Combination with Trisodium Orthophosphate

Sequential injection dispersive liquid–liquid microextraction based on fatty alcohols and poly(etheretherketone)-turnings for metal determination by flame atomic absorption spectrometry

A novel, simple and efficient sequential injection (SI) on-line dispersive liquid–liquid microextraction (DLLME) procedure was described and was demonstrated for the assay of trace silver determination by flame atomic absorption spectrometry (FAAS). Fatty alcohols, such as 1-undecanol and 1-dodecanol, were examined as extraction solvents at microlitre volume, overcoming a major problem of the DLLME methods, the high toxicity of the extraction solvents used. Furthermore, the extractant fine droplets can be easily separated from the aqueous phase using a micro-column packed with a novel hydrophobic sorbent material, poly(etheretherketone)-turnings. In this method fine droplets of 1-dodecanol were on-line generated and dispersed into the stream of aqueous sample. By this continuous process, silver diethyldithiocarbamate (Ag-DDTC) complex was formed and extracted into the dispersed extraction solvent. No specific conditions such as ice bath for low temperature or special tools are required for extractant isolation. All significant parameters that influence the efficiency of the system such as sample acidity, concentration of complexing reagent and extraction solvent, flow-rate of disperser and sample solution as well as the preconcentration time were investigated and optimized by full factorial design. Under the optimized conditions a detection limit of 0.15μgL−1, a relative standard deviation (RSD) of 2.9% at 5.00μgL−1 Ag(I) concentration level and an enhancement factor of 186 were obtained. The developed method was evaluated by analyzing certified reference material and was applied successfully to the analysis of environmental water samples.

A General Synthesis of Cu−In−S Based Multicomponent Solid-Solution Nanocrystals with Tunable Band Gap, Size, and Structure

A general approach has been developed to synthesize high-quality Cu−In−S based multicomponent solid-solution nanocrystals (NCs) of Zn2x(CuIn)1−xS2, (CuIn)1−xCd2xS2, and (ZnS)x(CuInS2)y(CdS)z at relatively low temperature. This was achieved in a noncoordinating solvent system (toluene) by a simple solvothermal process using metal diethyldithiocarbamate complexes as the precursors. The composition, crystalline structure, size, and bang gap of the NCs could be readily tuned by the precursors used and synthesis conditions. This work provides useful understanding for the synthesis of solid-solution NCs that are of interest for photocatalyst, solar cell, and other applications.

Solid‐Phase Extraction with Diethyldithiocarbamate as Chelating Agent for Preconcentration and Trace Determination of Copper, Iron and Lead in Fruit Wine and Distilled Spirit by Flame Atomic Absorption Spectrometry

Some heavy metals that present in wine and distilled spirit as background contamination are generally found at trace level particularly less than detection limit of common analytical techniques including flame atomic absorption spectrometry (FAAS). Thus, preconcentration method of the trace metals was developed. The optimum conditions for diethyldithiocarbamate (DDTC) complexes of Cu, Fe and Pb were then investigated for the preconcentration step using C18 solid‐phase extraction prior to measurement by FAAS. The preconcentration factor of 15‐fold was obtained with the appropriate ratio of sample volume used (150 mL) to 10 mL final volume giving their method recoveries of Cu, Fe and Pb found in the ranges of 96.5‐107, 102‐116 and 91.7‐107%, respectively. Precision determinations (n = 10) for 0.1 mg L-1 of Cu, Fe and Pb each in a model solution were 3.7, 4.2 and 7.1 %RSD respectively. The detection limits (3SD) of Cu, Fe and Pb were found to be 1.4, 3.3 and 5.7 μg L-1, respectively. The developed method was applied to ten samples of local fruit wines and five samples of distilled spirits, resulting in the ranges of 0.012‐0.80 and 0.12‐8.8 mg L-1 for Cu; 0.18‐3.4 and 0.036‐0.29 mg L-1 for Fe and 0.0070‐0.053 and 0.014‐0.026 mg L-1 for Pb, respectively. Therefore, the method is simple and inexpensive for routine analysis of the trace metals in these samples to overcome limit of detection of the instrument used.

Determination of Trace Inorganic Mercury in Mineral Water by Flow Injection On-line Sorption Preconcentration-Cold Vapor Atomic Fluorescence Spectrometry

Abstract Flow injection on-line sorption preconcentration and separation in a knotted reactor (KR) was coupled to cold vapor atomic fluorescence spectrometry for the determination of trace mercury in mineral water. Mercury was preconcentrated by on-line formation of mercury diethyldithiocarbamate complex (Hg-DDTC) and absorption of the resulting neutral complex on the inner walls of a knotted reactor. A 20% (v/v) HNO 3 solution heated by Electromagnetic induction heating technique was used as eluent to remove the absorbed Hg-DDTC from the KR, and then the vapor mercury generated by mixing the resulting solution and KBH 4 was determined on-line by cold vapor atomic fluorescence spectrometry. The 20% HNO 3 was used as both the efficient eluent and the required acidic medium for subsequent mercury vapor generation. Using 20% HNO 3 instead of conventional organic solvent as eluent, the proposed method is simple, easy operational and environmental friendly. Under the optimal experimental conditions, the sample throughput was approximately 30 per hour with the enhancement factor of 35. The detection limit of mercury was 2.0 ng l −1 . The precision (RSD, n = 11) was 2.2% at the 0.1 μg l −1 Hg 2+ level.

Preconcentration and Determination of Chromium Species Using Octadecyl Silica Membrane Disks and Flame Atomic Absorption Spectrometry

AbstractA novel and selective method for the fast determination of trace amounts of chromium species in water samples has been developed. The procedure is based on the selective formation of chromium diethyldithiocarbamate complexes at different pH in the presence of Mn(II) as an enhancement agent of chromium signals followed by elution with organic eluents and determination by atomic flame absorption spectrometry. The maximum capacity of the employed disks was found to be (396±3) µg and (376±2) µg for Cr(III) and Cr(VI), respectively. The detection limit of the proposed method is 49 and 43 ng·L−1 for Cr(III) and Cr(VI), respectively. The proposed method was successfully applied for determination of chromium species Cr(III) and Cr(VI) in different water samples.

Bonding Analyses, Formation Energies, and Vibrational Properties of M−R2dtc Complexes (M = Ag(I), Ni(II), Cu(II), or Zn(II))

Detailed theoretical studies based on density functional theory (DFT)/B3LYP calculations of dimethyl- and diethyldithiocarbamate complexes of Ni(II), Cu(II), Zn(II), and Ag(I) are performed to characterize the metal-ligand bonding type as well as the metal-ligand bonding strength depending on the metal and the dialkyl substituent. The metal-ligand interactions in the studied complexes are investigated by means of charge decomposition analysis, energy partitioning analysis (EPA), and natural bond orbital analysis. According to the EPA calculations, the electrostatic attraction is the dominant contribution to the M-S2(R2dtc) (dtc=dithiocarbamate) bonding. The electrostatic and the orbital energies follow the order of the total binding energy, and hence both contributions are responsible for the binding energy order of M(R2dtc)2 complexes. The stability of the M(R2dtc)2 complexes is estimated by means of calculated formation reaction energies in the gas phase and solution, and it decreases in the order Ni(R2dtc)2>Cu(R2dtc)2>Zn(R2dtc)2. Larger formation reaction energies are found for M(Et2dtc)2 than for M(Me2dtc)2 complexes. The calculations predict stabilization of M(II)(R2dtc)2 complexes going from the gas phase to a polar solvent and destabilization of the bidentate AgR2dtc complex in a polar solvent. Gas-phase frequency calculations of all possible bonding types, symmetrical, asymmetrical, and uni- and bidentate, predict one band due to the nu(CS) IR absorption, and therefore the number of the bands in the 1060-920 cm(-1) region could not be used to discern the metal-ligand bonding type. Periodic DFT frequency calculations for Cu(Et2dtc)2 reveal that the splitting observed in the solid-state spectra of the complexes arises from the nonplanar MS4 fragment and intermolecular contacts but not from asymmetrical bonding. The calculations suggest that the important vibrational characteristic that can be used to discern uni- and bidentate bonding is the Raman activity of the nu(CS) band: It is very high for the unidentate dtc bonding (nu(C=S)) and low for the bidentate bonding (nuas(CS)).

Separation and enrichment of gold(III) from environmental samples prior to its flame atomic absorption spectrometric determination

A simple and accurate method was developed for separation and enrichment of trace levels of gold in environmental samples. The method is based on the adsorption of Au(III)–diethyldithiocarbamate complex on Amberlite XAD-2000 resin prior to the analysis of gold by flame atomic absorption spectrometry after elution with 1 mol L −1 HNO 3 in acetone. Some parameters including nitric acid concentration, eluent type, matrix ions, sample volume, sample flow rate and adsorption capacity were investigated on the recovery of gold(III). The recovery values for gold(III) and detection limit of gold were greater than 95% and 16.6 μg L −1, respectively. The preconcentration factor was 200. The relative standard deviation of the method was <6%. The adsorption capacity of the resin was 12.3 mg g −1. The validation of the presented procedure was checked by the analysis of CRM–SA–C Sandy Soil certified reference material. The presented procedure was applied to the determination of gold in some environmental samples.

Synthesis and biodistribution of the 99mTc(CO)3-DEDT complex as a potential new radiopharmaceutical for brain imaging

The 99mTc(CO)3(H2O)-DEDT complex was prepared by a two-step procedure involving the preparation of the precursor fac-[99mTc(CO)3(H2O)3]+, followed by the addition of sodium salt of diethyl dithiocarbamate (DEDT). The radiochemical purity (RCP) of the product was over 90% as measured by thin layer chromatography (TLC). No decomposition of the complex at room temperature was observed over a period of 6 hours. Its partition coefficient indicated that it was a lipophilic complex. The electrophoresis results showed the complex was neutral. Biodistribution in mice demonstrated that the complex can penetrate the intact blood-brain barrier (BBB) and the brain uptake (ID%/g) was 4.22 at 5-minute post-injection, suggesting the complex may lead to a further development of the radiopharma ceutical as a brain perfusion tracer.

Solid State Nitric Oxide Sensor Using a Latex Rubber Matrix

AbstractIn this work we propose a sensor made of a spin trap (iron(II)‐diethyldithiocarbamate complex, FeDETC) encapsulated in a latex rubber matrix. Latex was used as solid matrix due to its excellent mechanical properties, biocompatibility and natural angiogenic properties. The fabrication and optimization processes were done by varying: FeCl36H2O and DETC concentrations in the system, polymerization temperature, FeDETC/latex ratio. The sensor presents high stability, the observed Electron Paramagnetic Resonance signal can be detected even after the sensor is exposed to ambient atmosphere for 40 days. It can be reused and is able to measure NO concentration as low as 0,1 mM. These results make NO‐FeDETC in the rubber matrix a promising NO sensor.

Reactivity of the [CpM(PPh 3) 2] + (M = Ru, Os) fragment with diethyldithiocarbamate

This paper reports on the reaction of [CpM(PPh 3) 2(L)] +/0(Cp = η 5–C 5H 5; M = Os, L = CH 3CN, DMSO Br; M = Ru, X = Cl, CH 3CN) with diethyldithiocarbamate ( S 2 CNEt 2 - ). The exceptional kinetic stability of [Os–PPh 3] compared to [Ru–PPh 3] is reflected from the isolation of the monodentate diethyldithiocarbamate complex [CpOs(PPh 3) 2(κ 1-S 2CNEt 2)] ( 3) and the bidentate diethyldithiocarbamate complex [CpRu(PPh 3)(κ 2-S 2CNEt 2)] ( 5) as the only products. The structure of [CpOs(PPh 3) 2(CH 3CN)]BF 4 ( 2 · BF 4 ) and 5 were determined by X-ray diffraction.