AuCl3 Solution Research Articles

Biosynthesis of Gold Nanoparticles Using Sambiloto Leaf Extracts and its Characteristics

Gold nanoparticles (AuNPs) have been successfully synthesized using aqueous sambiloto (Andrographis Paniculata Ness) leaf extract as a reducing agent. This method of synthesizing nanoparticles is called biosynthesis. Characterization was carried out using various techniques including UV-Vis, FTIR, and TEM. The results showed that the optimal synthesis ratio, i.e., AuCl3 solution : sambiloto leaf extract, was 30 µl : 10 ml with a synthesis rate of 0.159 a.u./h. The characteristic of the gold nanoparticles synthesized is that the surface Plasmon resonance (SPR) wavelength is 529.00 nm; it was stable after 4 hours of synthesis and stayed until 24 hours at an SPR wavelength of 527.00-531.50 nm. The functional groups formed include O-H, aliphatic C-H, C=O stretch, aromatic C=C stretch, and C-O stretch. The size of the nanoparticles is in the range of 1-20 nm.

Controlled Bipolar Doping of One-Dimensional van der Waals Nb2Pd3Se8.

Tailoring the electrical properties of one-dimensional (1D) van der Waals (vdW) materials is desirable for their applications toward electronic devices by exploiting their unique characteristics. However, 1D vdW materials have not been extensively investigated for modulation of their electrical properties. Here we control doping levels and types of 1D vdW Nb2Pd3Se8 over a wide energy range by immersion in AuCl3 or β-nicotinamide adenine dinucleotide (NADH) solutions, respectively. Through spectroscopic analyses and electrical characterizations, we confirm that the charges were effectively transferred to Nb2Pd3Se8, and the dopant concentration was adjusted to the immersion time. Furthermore, we make the axial p-n junction of 1D Nb2Pd3Se8 by a selective area p-doping using the AuCl3 solution, which exhibits rectifying behavior with an Iforward/Ireverse of 81 and an ideality factor of 1.2. Our findings could pave the way to more practical and functional electronic devices based on 1D vdW materials.

Identification of Nano-Metal Oxides That Can Be Synthesized by Precipitation-Calcination Method Reacting Their Chloride Solutions with NaOH Solution and Their Application for Carbon Dioxide Capture from Air-A Thermodynamic Analysis.

Several metal oxide nanoparticles (NPs) were already obtained by mixing NaOH solution with chloride solution of the corresponding metal to form metal hydroxide or oxide precipitates and wash-dry-calcine the latter. However, the complete list of metal oxide NPs is missing with which this technology works well. The aim of this study was to fill this knowledge gap and to provide a full list of possible metals for which this technology probably works well. Our methodology was chemical thermodynamics, analyzing solubilities of metal chlorides, metal oxides and metal hydroxides in water and also standard molar Gibbs energy changes accompanying the following: (i) the reaction between metal chlorides and NaOH; (ii) the dissociation reaction of metal hydroxides into metal oxide and water vapor and (iii) the reaction between metal oxides and gaseous carbon dioxide to form metal carbonates. The major result of this paper is that the following metal-oxide NPs can be produced by the above technology from the corresponding metal chlorides: Al2O3, BeO, CaO, CdO, CoO, CuO, FeO, Fe2O3, In2O3, La2O3, MgO, MnO, Nd2O3, NiO, Pr2O3, Sb2O3, Sm2O3, SnO, Y2O3 and ZnO. From the analysis of the literature, the following nine nano-oxides have been already obtained experimentally with this technology: CaO, CdO, Co3O4, CuO, Fe2O3, NiO, MgO, SnO2 and ZnO (note: Co3O4 and SnO2 were obtained under oxidizing conditions during calcination in air). Thus, it is predicted here that the following nano-oxides can be potentially synthesized with this technology in the future: Al2O3, BeO, In2O3, La2O3, MnO, Nd2O3, Pr2O3, Sb2O3, Sm2O3 and Y2O3. The secondary result is that among the above 20 nano-oxides, the following five nano-oxides are able to capture carbon dioxide from air at least down to 42 ppm residual CO2-content, i.e., decreasing the current level of 420 ppm of CO2 in the Earth's atmosphere at least tenfold: CaO, MnO, MgO, CdO, CoO. The tertiary result is that by mixing the AuCl3 solution with NaOH solution, Au nano-particles will precipitate without forming Au-oxide NPs. The results are significant for the synthesis of metal nano-oxide particles and for capturing carbon dioxide from air.

Applying metal coatings to dielectric materials by photochemical processes

Abstract Photochemical processes in thin surface layers of solutions of compounds of the copper subgroup elements leading to the formation of dispersed metal particles on the surface of dielectrics are investigated. It is shown that dispersed particles of elemental gold are formed on dielectrics moistened with AuCl3 solution and exposed to sunlight. At the same time, there is no need to use any chemical reducing agents. On cotton fabrics moistened with solutions of AgNO3, CuBr2, when exposed to sunlight, silver and copper monohalides are formed, respectively. These processes take place with the participation of terminal cellulose molecules and also do not require the use of chemical reducing agents. In addition, it was found that copper monohalides can be converted into elemental copper particles by a photochemical reaction involving ascorbic acid. Examples of metallization of a number of dielectrics using photochemical activation using sunlight are given.

Effects of gold on the structure and electrochemical behavior of lead-gold composite in different temperatures sulfuric acid

Lead is still dominantly used as the main material for lead-acid batteries electrodes and active materials. Lead-gold composites were made in efforts to improve the performance of the active materials component for lead-acid batteries. The electrochemical behavior of Pb-Au composite in sulfuric acid solution (H2SO4) were investigated. Au was chosen as the reinforcement material for lead composite because of its high electrical conductivity and its resistance to chemical reaction which is important to resist the formation of lead sulfate (PbSO4) crystal on the surface of electrodes. Lead-gold composite were made by mixing lead powder and auric chloride (AuCl3) solution. The fabrication of Pb-Au composites was done by mixing Pb powders and auric chloride (AuCl3) solution and using hot-press method. Material characterizations were performed using X-ray fluorescence technique to investigate material composition and X-ray diffraction technique to investigate material structure. The electrochemical properties of Pb-Au composites were investigated by electrochemical polarization testing, specifically linear sweep voltammetry technique (LSV) in H2SO4 solution with various solution temperature at 10° C, 25° C, and 40° C to simulate common active vehicle condition. The results show that the crystal structure of lead-gold composites is face-centered cubic (FCC) structure. Also, the addition of Au lower the Icorr and shift the Ecorr to a more cathodic potential.

Biogenic Synthesis of Gold Nanoparticles from Aspartic Acid - A Preliminary Study

A nanoparticle is an ultra-fine particle with at least one dimension between 1-100 nanometers (nm). Metallic nanoparticles are considered as most promising as they contain remarkable antibacterial properties. Gold nanoparticles are of high importance in research. Aspartic acid is an alpha amino acid and contains one amino group and one carboxylic group. The aim of the current study was to bio synthesize gold nanoparticles using aspartic acid. Gold Chloride (AuCl3) and Aspartic acid (C₄H₇NO₄) were used for the study. AuCL3 solution (0.266 M) was slowly added to 250 aspartic acid with stirring at 45°C. The mixture of the solutions was kept in a long-necked borosilicate flask and continuously stirred on a magnetic stirrer. The formation of gold nanoparticles was confirmed by the change of the colorless solution to a reddish hue. Characterization of the newly formed nanoparticles was then done. After approximately 9 hour incubation and intermittent stirring with a magnetic stirrer the solution color changed from colorless to a reddish hue, which indicated the formation of AuNPs. The spectrometric reading was recorded at a scanning range of 400–700 nm. AuNPs nanoparticles at 24 hours showed an increased intensity and a Surface Plasmon Resonance (SPR) band at 575 nm. The gold nanoparticles by Transmission electron microscopy were confirmed to be spherical in shape and of 20 nm. A simple and efficient method for the synthesis of AuNPs from the aspartic acid was demonstrated. Nano particles were formed in approx. 9 hours with peak absorbance at 24 hours at 575nm. The synthesized nanoparticles were spherical in shape, with an average size of 20 nm. The synthesized nanoparticles showed excellent plasmon resonance and optical properties.

Ambipolar MoS2 Field‐Effect Transistor by Spatially Controlled Chemical Doping

Molybdenum disulfide (MoS2) is a widely studied 2D semiconductor, which intrinsically exhibits n‐type transport even using the high work function elemental metals as contacts. It is technically challenging to achieve ambipolar field‐effect transistors with MoS2. Herein, an effective method to prepare p‐doped MoS2 using gold chloride (AuCl3) solution is demonstrated. The doping strength can be controlled well by the process parameters. The AuCl3 doping can also be spatially selected using hexagonal‐boron nitride (h‐BN) capping masks. Subsequently, ambipolar transport can be realized in MoS2 with the coexisting parallel n‐type and p‐type channels. The resulting ambipolar MoS2 transistor presents a high room‐temperature performance, showing a high on/off ratio of 107 and a mobility of 10 s cm2 V−1 s−1 for both electron and hole.

Chemisorption Activity of Mercury(II) Cyclopentamethylenedithiocarbamate: Synthesis, Structure, and Thermal Behavior of the [Hg2{S2CN(CH2)5}4] and [Au3{S2CN(CH2)5}6][Au{S2CN(CH2)5}2][Hg2Cl6]2 Complexes

The dinuclear complex mercury(II) cyclopentamethylenedithiocarbamate (piperidine-1-carbodithioate) [Hg2{S2CN(CH2)5}4] was synthesized and its chemisorption activity toward a solution of AuCl3 in 2 M HCl was studied. The chemisorption of gold from the solution forms an ionic gold(III)‒mercury(II) dithiocarbamato-chlorido complex comprising three isomeric gold cations and an unsymmetrical hexachlorodimercurate anion. The structural organization and thermal behavior of the resulting compounds was studied.

Flexible transparent electrodes for organic light-emitting diodes simply fabricated with AuCl3-modied graphene

Abstract We used chemical doping method (using AuCl3 solution in nitromethane) to incorporate gold into graphene sheets. Gold cations reduced on the surface of the graphene film forming pure gold particles. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed that the sizes of gold particles were proportional to the doping time. Gold particles mainly accumulated at the graphene defects and wrinkles, effectively reducing the surface resistance and increasing the carrier concentration without significantly affecting the optical properties of graphene. Resistance of the doped single-layer graphene (SLG) sheet can be reduced from 365Ω/sq to 190Ω/sq. Optical transmittance slightly decreased with the soaking time: the light transmittance at 550 nm gradually decreased from 87.6% (for undoped graphene) to 85.6% (for graphene soaked in 1 mg/ml AuCl3 solution for 10 min). Organic light-emitting device (OLED) prepared based on the doped SLG transparent conductive electrode showed much higher performance than a device made of pure graphene as an anode. The maximum luminance of the OLED with doped graphene anode was increased by 135% and the maximum current efficiency was improved by 25.2%.

Emergence of photoluminescence on bulk MoS2 by laser thinning and gold particle decoration

We demonstrate a facile and effective approach to significantly improve the photoluminescence of bulk MoS2 via laser thinning followed by gold particle decoration. Upon laser thinning of exfoliated bulk MoS2, photoluminescence emerges from the laser-thinned region. After further treatment with an AuCl3 solution, gold particles self-assemble on the laser-thinned region and thick edges, further increasing the fluorescence of bulk MoS2 28 times and the Raman response 3 times. Such fluorescence enhancement can be attributed to both surface plasmon resonance and p-type doping induced by gold particles. The combination of laser thinning and AuCl3 treatment enables the functionalization of bulk MoS2 for optoelectronic applications. It can also provide a viable strategy for mask-free and area-selective p-type doping on single MoS2 flakes.

Electrothermal silver nanowire thin films for In-Situ observation of thermally-driven chemical processes

We develop a novel device comprised of high optical transmittance thin films containing silver nanowires (AgNWs) in poly(methyl methacrylate) (PMMA) acting as heating elements. The electrothermal control of the AgNWs network allows us to externally trigger and tune the temperature conditions required to run chemical reactions and physicochemical processes. The device was successfully applied for the spectroscopic in-situ observation of three different model reactions: i) the thermal equilibrium of a CoCl2/HCl/H2O complex, ii) the reversible macromolecular phase transition of a pNIPAM solution, and iii) the nucleation and growth of gold nanoparticles (AuNPs). In the first case, the color of the Co2+ complex was reversibly switched from pink to blue when changing the thermal equilibrium condition. In the second one, the optical transmittance of an aqueous solution of carboxylic-terminated pNIPAM polymer was cycled from high to low as the temperature of the solution was below or above the lower critical solubility temperature (LCST) respectively. Finally, the electrothermal control on the device was applied to the study of the nucleation and growth of AuNPs in an organic solution of AuCl3 containing oleylamine acting as both the reducer and the stabilizing agent. The versatility of the electrothermal device provides an easy way to undertake thermally controlled processes and develop optical elements such as smart windows and lab-on-a-chip devices. The AgNWs-PMMA nanocomposite was also applied successfully as an electrothermal ink on the external side walls of a test tube.

Selective AuCl3 doping of graphene for reducing contact resistance of graphene devices

Low contact resistance between metal-graphene contacts remains a well-known challenge for building high-performance two dimensional materials devices. In this study, CVD-grown graphene film was doped via AuCl3 solution selectively only to metal (Ti/Au) contact area to reduce the contact resistances without compromising the channel properties of graphene. With 10mM-AuCl3 doping, doped graphene exhibited low contact resistivity of ∼897Ωμm, which is lower than that (∼1774Ωμm) of the raw graphene devices. The stability of the contact resistivity in atmospheric environment was evaluated. The contact resistivity increased by 13% after 60days in an air environment, while the sheet resistance of doped graphene increased by 50% after 30 days. The improved stability of the contact resistivity of AuCl3-doped graphene could be attributed to the fact that the surface of doped-graphene is covered by Ti/Au electrode and the metal prevents the diffusion of AuCl3.

Improvement of Contact Resistance of Graphene Devices Via AuCl3 Doping

Graphene, an atomically thin semi-metal with sp2–bonded carbon atoms arranged in a honeycomb lattice is at center stage of intense research in the field of fundamental physics as well as in low-cost flexible transparent electronics, photovoltaics or microelectronics devices. For electronic devices application, the metal - graphene contact resistance is forefront obstacles hindering further progress of any graphene-based devices. The contact resistance degrades the on-state current of charge-based field-effect-transistor. Gold chloride (AuCl3) doping has been reported for reducing the sheet resistance of graphene films for transparent electrodes. In this work, we used the gold chloride (AuCl3) solution doping only to the metal-graphene contact area to reduce the contact resistance without changing graphene film properties. First, graphene film was grown using chemical vapor deposition (CVD) method. Active pattern was formed by lithography and reactive ion etching (RIE). The metal-graphene pad area was defined by lithography. The exposed graphene surface area for metal pads was dipped in AuCl3 solution. Here we changed the AuCl3 concentration to see the concentration effect. After that, Ti/Au pad metal was evaporated using thermal evaporator. AuCl3 doping was done only to metal-graphene contact interface. KPFM was employed to measure the surface potential of graphene. The Raman spectroscopy and XPS spectra were analyzed before/after the doping of AuCl3 solution on contact area. The contact resistance of un-treated graphene devices, 1773 Ohm.um decreased to 987 Ohm.um after 5mM-treatment, and decreased to 897 Ohm.um after 10mM-AuCl3 doping. At doping above 10mM doping, the contact resistance did not decreased further. We also characterized the contact resistance change with time. The contact resistance of AuCl3-treated graphene increased by ~13% after 2 months. On the contrary, the sheet resistance of AuCl3-treated graphene film(without any photomask) increased by ~50% after 1 month. The contact resistance increase is much less than the sheet resistance change. This could be explained by the fact that the metal pad covers the AuCl3. This research was supported by the MOTIE (10052928) and KSRC (Korea Semiconductor Research Consortium) support program for the development of future semiconductor devices.

Chemisorption binding of gold(III) from solutions with bismuth dipropyldithiocarbamate: Supramolecular self-assembly (role of the secondary Au…S and aurophilic interactions) and thermal behavior of the solvated heteropolynuclear ionic type complex ([Au{S2CN(C3H7)2}2]3[Bi2Cl9] • 0.5CO(CH3)2 • 0.5HCl) n

The reaction of binuclear bismuth(III) N,N-dipropyldithiocarbamate [Bi2{S2CN(C3H7)2}6] with a solution of AuCl3 in 2 M HCl was studied. Crystallization of the heterogeneous reaction products from an acetone solution afforded the polymeric solvated heteropolynuclear gold(III)–bismuth complex, ([Au{S2CN(C3H7)2}2]3[Bi2Cl9] · 1/2CO(CH3)2 · 1/2HCl)n (I). According to X-ray diffraction data (CIF file CCDC no. 1050766), the structure of I comprises four isomeric [Au{S2CN(C3H7)2}2]+ cations in 1: 1: 2: 2 ratio, namely: cation “A” with the Au(1) atom, cation “B” with the Au(2) atom, cation “C” with the Au(3) atom, and cation “D” with the Au(4) atom, and the discrete binuclear [Bi2Cl9]3– anions. The isomeric gold(III) complex cations are involved in the construction of two types of cationic triads, [“C”···“A”···“C”] and [“D”···“B”···“D”], through secondary bonds and short Au···S contacts. The cation types differ by both the nature of binding and the Au–Au distances. The weak aurophilic binding between the cationic triads (Au···Au 3.5416(2) A) gives rise to zigzag-like polymeric chains (···[“C”···“A”···“C”]···[“D”···“B”···“D”]···)n extended along the y axis. In turn, the [Bi2Cl9]3– anions located on one side of polymer chains are held by the secondary Cl···S bonds. The outer-sphere CO(CH3)2 and HCl solvate molecules joined by hydrogen bonds are located in the space between bismuth anions. The thermal behavior of I was studied by simultaneous thermal analysis. The thermal destruction of the complex includes desolvation and thermolysis of the dithiocarbamate moiety and [Bi2Cl9]3– with liberation of gold metal and bismuth chloride (which is subsequently evaporated) and partial formation of Bi2S3. In the temperature range of 712–828°C, bismuth sulfide is oxidized to (BiO)2SO4, which decomposes above 828°C to give Bi2O3. Bismuth(III) oxide and reduced gold are the final products of thermal transformations.

Metal nanoparticle-enhanced photocurrent in GaAs photovoltaic structures with microtextured interfaces.

The photocurrent enhancement effect caused by Au and Ag nanoparticles for GaAs-based photovoltaic structures of surface barrier or p-n junction type with microtextured interfaces has been investigated in dependence on the conditions of nanoparticles deposition and, respectively, on the shape and local dielectric environment of obtained nanoparticle arrays. Three nanoparticle deposition methods have been checked: 1) photoinduced chemical deposition of Au from aqueous AuCl3 solution forming nanowires on the ridges of quasigrating-type surface microrelief, 2) deposition of Ag nanoparticles from colloidal suspension on the GaAs substrate covered with poly(vinylpyridine), and 3) drop and dry deposition of Au/SiO2 core-shell nanoparticles from aqueous colloid solution. The comprehensive investigation of optical reflectance, photoelectric, and electrical characteristics of the fabricated barrier structures has shown the highest photovoltaic parameters for surface microrelief of quasigrating-type and electroless Au nanoparticle deposition. The analysis of characteristics obtained allowed us also to define the mechanisms of the total photocurrent enhancement.

Preparation, supramolecular self-organization and thermal behavior of polymeric complex of composition ([Au{S2CN(C3H7)2}2]3[Bi3Cl12]) n with unusual geometry of bismuth(III) complex anion

A reaction of freshly precipitated bismuth(III) N,N-dipropyldithiocarbamate (PDtc) with AuCl3 solution in 2 M HCl was studied. A heteropolynuclear gold(III)-bismuth complex of ionic type [Au{S2CN(C3H7)2}2]3[Bi3Cl12] (I) was isolated by crystallization of products of the heterogeneous reaction from acetone-chloroform (1: 1) solution. Crystal and supramolecular structure of compound I established by X-ray diffraction study includes structurally nonequivalent complex cations [Au{S2CN(C3H7)2}2]+ related to each other as conformers (hereinafter cations A, B, C, and D) in 1: 1: 2: 2 ratio. Due to secondary Au⋯S bonds (3.386–3.617 A), the isomeric cations form trinuclear species of two types: [C⋯A⋯C] and [D⋯B⋯D] that differ in the character of intercationic binding and Au-Au distances. Relatively weak aurophilic Au⋯Au bonds (3.4704(3) A) unite the neighboring cationic triads into zigzag polymeric chains of type (⋯[C⋯A⋯C]⋯[D⋯B⋯D]⋯)n oriented along the crystallographic axis b. The spatial isolation of neighboring chains is provided by discrete trinuclear anions [Bi3Cl12]3− where metal atoms bind four bridging (μ2 and μ3) chlorine atoms, while each bismuth atom forms distorted octahedral chromophore [BiCl6]. The complex tribismuth anion in the structure I is the first example of [Bi3Cl12]3− anion of angle rather than linear structure: Bi(1)Bi(2)Bi(3) angle is 72.358°. The thermal behavior of compound I was studied by simultaneous thermal analysis. The multistage process of thermal destruction includes the thermolysis of dithiocarbamate portion of the complex and [Bi3Cl12]3− accompanied by reduction of gold(III) to metal and release of BiCl3 (followed by its evaporation) and partial formation of Bi2S3. In the temperature range 680–760°C, bismuth sulfide undergoes oxidation to (BiO)2SO4, which decomposes above 760°C to give Bi2O3. Residue after thermolysis of compound I is gold metal and bismuth(III) oxide.

Microlandscaping of Au nanoparticles on few-layer MoS2 films for chemical sensing.

Surface modification or decoration of ultrathin MoS2 films with chemical moieties is appealing since nanointerfacing can functionalize MoS2 films with bonus potentials. In this work, a facile and effective method for microlandscaping of Au nanoparticles (NPs) on few-layer MoS2 films is developed. This approach first employs a focused laser beam to premodify the MoS2 films to achieve active surface domains with unbound sulfur. When the activated surface is subsequently immersed in AuCl3 solution, Au NPs are found to preferentially decorate onto the modified regions. As a result, Au NPs can be selectively and locally anchored onto designated regions on the MoS2 surface. With a scanning laser beam, microlandscapes comprising of Au NPs decorated on laser-defined micropatterns are constructed. By varying the laser power, reaction time and thickness of the MoS2 films, the size and density of the NPs can be controlled. The resulting hybrid materials are demonstrated as efficient Raman active surfaces for the detection of aromatic molecules with high sensitivity.

Gold(III) ionic complexes [Au{S2CN(C2H5)2}2]Cl and ([Au{S2CN(C2H5)2}2][AuCl4]) n : Synthesis, supramolecular self-assembly, polymorphism, and thermal behavior

A heterogeneous reaction between freshly precipitated oxovanadium(IV) diethyldithiocarbamate [VO{S2CN(C2H5)2}2] and a solution of AuCl3 in 2 M HCl has been shown to yield two ionic gold(III) compounds: the water-soluble ionic complex [Au{S2CN(C2H5)2}2]Cl (I) and the coordination polymer ([Au{S2CN(C2H5)2}2][AuCl4])n (II), which was preparatively separated from the precipitate phase. The molecular and crystal structures of the synthesized complexes have been established by X-ray diffraction. The crucial role in the supramolecular self-assembly of the compounds obtained belongs to C-H⋯Cl hydrogen bonds (in I) and Au⋯S and Au⋯Cl secondary interactions (in II). Polymeric complex II has been found to be able to form two polymorphs, which differ from each other by the building mode of cation-anion polymeric chains. The study of the thermal behavior of the synthesized complexes by simultaneous thermal analysis in an argon atmosphere has allowed us to recognize conditions for the recovery of bound gold. In both cases, reduced metallic gold is the only final thermolysis product.

Interaction of binuclear zinc diethyldithiocarbamate with H[AuCl4]/2 M HCl: The preparation, supramolecular self-organization, and thermal behavior of the heteropolynuclear complex ([Au{S2CN(C2H5)2}2]2[ZnCl4] · 1/2CO(CH3)2 · 1/2CHCl3) n

The interaction of the freshly precipitated binuclear zinc diethyldithiocarbamate (EDtc) [Zn2{S2CN(C2H5)2}4] with a solution of AuCl3 in 2 M HCl was studied. A water-soluble gold(III)-zinc complex was formed as a result of this interaction; it was preparatively isolated as the solvated polymeric species ([Au{S2CN(C2H5)2}2]2[ZnCl4] · 1/2CO(CH3)2 · 1/2CHCl3) n (I). According to single-crystal X-ray diffraction (XRD) analysis data, the resulting compound includes four structurally nonequivalent complex cations [Au{S2CN(C2H5)2}2]+ (with Au(1), Au(2), Au(3), and Au(4) atoms, A-D, respectively) and two [ZnCl4]2− anions (E = Zn(1), F = Zn(2)), which are related to each other as conformers. At the supramolecular level, isomeric cations are characterized by a complex structural ordering mode: complex cations B, C, and D form polymeric chains like (⋯B[⋯A]⋯ D⋯C⋯) n oriented along the crystallographic a axis, in which cation A serves as a side substituent, due to secondary Au⋯S bonds and short contacts between the nearest neighbors. Outer-sphere solvating molecules and isomeric distorted tetrahedral [ZnCl4]2− anions linked to [Au{S2CN(C2H5)2}2]+ cations by secondary Cl⋯S bonds are localized between the chains. The thermal behavior of compound I was studied by simultaneous thermal analysis. The multistage process of thermal decomposition includes the desolvation of the complex and the thermolysis of its dithiocarbamate moiety and [ZnCl4]2− with the release of gold metal and zinc chloride and the partial formation of ZnS. The final products of these thermal transformations are reduced gold and ZnS.

Functionalization of Amorphous Carbon Nanotubes for Au Nanoparticles Hybridization

Our study focuses on selection of nitric acid, sulfuric acid, citric acid, and hydrochloric acid as the most suitable oxidation agent for a-CNT. Nitric acid functionalized a-CNT has the highest value of zeta potential −142.9 mV, followed by H2SO4, citric acids, and HCl functionalized samples of −60.3 mV, −15.9 mV, and −3.2 mV, respectively. High values of zeta potential represents surface charges, which refers to carboxyl groups present on tubes’ bodies. At the same time, auric chloride (AuCl3) solution treatment was applied on citric acid, nitric acid, hydrochloric acid, and sulfuric acid treated a-CNT at the same condition. Nitric acid treated a-CNT was found to have the highest weight percentage of gold (Au) content. Therefore, indirectly, we have proven that nitric acid adds the most carboxyl groups upon functionalization.