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gold-compounds
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Gold extraction from an oxide ore in iodine-iodide solutions
, Article Industrial Electrochemistry and Electrochemical Engineering General Session - 220th ECS Meeting, Boston, MA, 9 October 2011 through 14 October 2011 ; Volume 41, Issue 17 , 2012 , Pages 53-60 ; 19385862 (ISSN) ; 9781607683070 (ISBN) ; Sharif University of Technology
Abstract
Two types of gold ores were subjected to iodide/iodine leaching at room temperature. The effects of three factors, including ore type (a carbonaceous and an oxide gold ores), iodide/iodine concentration, and the presence of oxygen in solution on gold leaching performance were investigated. The carbonaceous ore showed only 20% gold extraction into the solution; since gold-iodide complexes would readily adsorb on organic matter. In contrast, gold extraction from the oxide ore in a solution containing 20 g/L iodide and 4 g/L iodine reached 77% in 6 h and 89% in 24 h. With iodate as the oxidant, no gold could be leached in 48 hours. When the iodate was partially converted to iodine by adding HCl...
The leaching kinetics of an oxide gold ore with iodide/iodine solutions
, Article Hydrometallurgy ; Volume 113-114 , 2012 , Pages 42-50 ; 0304386X (ISSN) ; Sharif University of Technology
2012
Abstract
Two types of gold ores were subjected to iodide/iodine leaching at room temperature. The effects of three factors, including ore type (a carbonaceous and an oxide gold ores), iodide/iodine concentration, and the presence of oxygen in solution on gold leaching performance were investigated. The carbonaceous ore showed only 20% gold extraction, since gold-iodide complexes readily adsorb on organic matter. In contrast, gold extraction from the oxide ore in a solution containing 20 g/L iodide and 4 g/L iodine reached 77% in 6 h and 89% in 24 h. With iodate as the oxidant, no gold could be leached in 48 h. When the iodate was partially converted to iodine by adding HCl to the solution, gold...
Synthesis of a new T-shaped heterobinuclear Pt0-AuI complex [(t-Bu3P)2PtAu(PPh3)]BF4 from trinuclear gold cluster complex [(PPh3)Au]3(μ-O)BF4
, Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 1089-1094 ; 10263098 (ISSN) ; Ashtiania, M. M ; Milic, D ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
The heterobinuclear platinum(0)-gold(I) complex [(t-Bu3P)2PtAu(PPh3)] BF4, 5, was synthesized by the reaction of trinuclear cluster complex f[(PPh3)Au]3(μ-O)gBF4, 4, with one equiv of [(t-Bu3P)2Pt] at room temperature. The heterobinuclear complex 5 was characterized using multinuclear NMR spectroscopy and elemental microanalysis and was further identified by single crystal X-ray structure determination. Crystal structure of 5 shows a T-shaped geometry with an unsupported short distance Pt-Au dative bond
Local density variation of gold nanoparticles in aquatic environments
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 84 , 2016 , Pages 489-497 ; 13869477 (ISSN) ; Shirazian, F ; Shahsavari, R ; Khoei, A. R ; Sharif University of Technology
Elsevier
2016
Abstract
Gold (Au) nanoparticles are widely used in diagnosing cancer, imaging, and identification of therapeutic methods due to their particular quantum characteristics. This research presents different types of aqueous models and potentials used in TIP3P, to study the effect of the particle size and density of Au clusters in aquatic environments; so it can be useful to facilitate future investigation of the interaction of proteins with Au nanoparticles. The EAM potential is used to model the structure of gold clusters. It is observed that in the systems with identical gold/water density and different cluster radii, gold particles are distributed in aqueous environment almost identically. Thus, Au...
Electrodeposition of well-defined gold nanowires with uniform ends for developing 3D nanoelectrode ensembles with enhanced sensitivity
, Article Materials Chemistry and Physics ; Volume 213 , 2018 , Pages 67-75 ; 02540584 (ISSN) ; Ghorbani, M ; Dolati, A ; Hosseini, D ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Fabrication of well-defined gold nanowires (GNWs) is of significant importance in many fields such as sensing applications. In this study, the electrodeposition of well-defined GNWs inside polycarbonate (PC) template has been discussed in detail. GNWs were potentiostatically electrodeposited at different filling rates. The growth of GNWs at different stages of pore filling was monitored by electrochemical measurements and field-emission scanning electron microscopy (FE-SEM). It was confirmed that under growth rates between 2.5 and 4 nm/s, GNWs with smooth ends grew uniformly inside the template without any imperfections or corrugations. The length of GNWs was electrochemically controlled to...
The effect of liquid environment on size and aggregation of gold nanoparticles prepared by pulsed laser ablation
, Article Journal of Nanoparticle Research ; Volume 9, Issue 5 , 2007 , Pages 853-860 ; 13880764 (ISSN) ; Iraji zad, A ; Mahdavi, S. M ; Sharif University of Technology
2007
Abstract
The effects of liquid environment on nucleation, growth and aggregation of gold nanoparticles were studied. Gold nanoparticles were prepared by pulsed laser ablation in deionised water with various concentrations of ethanol and also in pure ethanol. UV/visible extinction and TEM observations were employed for characterization of optical properties and particle sizes respectively. Preparation in water results in smaller size, shorter wavelength of maximum extinction and stable solution with an average size of 6 nm. Nanoparticles in solution with low concentration ethanol up to 20 vol% are very similar to those prepared in water. In the mixture of deionised water and 40 up to 80 vol% ethanol,...
Effects of ligands on (de-)enhancement of plasmonic excitations of silver, gold and bimetallic nanoclusters: TD-DFT+TB calculations
, Article Physical Chemistry Chemical Physics ; Volume 23, Issue 33 , 2021 , Pages 17929-17938 ; 14639076 (ISSN) ; Pototschnig, J ; Jamshidi, Z ; Visscher, L ; Sharif University of Technology
Royal Society of Chemistry
2021
Abstract
Metal nanoclusters can be synthesized in various sizes and shapes and are typically protected with ligands to stabilize them. These ligands can also be used to tune the plasmonic properties of the clusters as the absorption spectrum of a protected cluster can be significantly altered compared to the bare cluster. In this paper, we computationally investigate the influence of thiolate ligands on the plasmonic intensity for silver, gold and alloy clusters. Using time-dependent density functional theory with tight-binding approximations, TD-DFT+TB, we show that this level of theory can reproduce the broad experimental spectra of Au144(SR)60 and Ag53Au91(SR)60 (R = CH3) compounds with...
Equatorial magnetoplasma waves
, Article Physical Review B ; Volume 105, Issue 20 , 2022 ; 24699950 (ISSN) ; Kargarian, M ; Efimkin, D. K ; Sharif University of Technology
American Physical Society
2022
Abstract
Due to its rotation, Earth traps a few equatorial ocean and atmospheric waves, including Kelvin, Yanai, Rossby, and Poincaré modes. It has been recently demonstrated that the mathematical origin of equatorial waves is intricately related to the nontrivial topology of hydrodynamic equations describing oceans or the atmosphere. In the present work, we consider plasma oscillations supported by a two-dimensional electron gas confined at the surface of a sphere or a cylinder. We argue that in the presence of a uniform magnetic field, these systems host a set of equatorial magnetoplasma waves that are counterparts to the equatorial waves trapped by Earth. For a spherical geometry, the equatorial...
Glucose interaction with Au, Ag, and Cu clusters: Theoretical investigation
, Article International Journal of Quantum Chemistry ; Volume 113, Issue 8 , 2013 , Pages 1062-1070 ; 00207608 (ISSN) ; Farhangian, H ; Tehrani, Z. A ; Sharif University of Technology
2013
Abstract
Interactions of α-D-glucose with gold, silver, and copper metal clusters are studied theoretically at the density functional theory (CAM-B3LYP) and MP2 levels of theory, using trimer clusters as simple catalytic models for metal particles as well as investigating the effect of cluster charge by studying the interactions of cationic and anionic gold clusters with glucose. The bonding between α-D-glucose and metal clusters occurs by two major bonding factors; the anchoring of M atoms (M = Cu, Ag, and Au) to the O atoms, and the unconventional M.H-O hydrogen bond. Depending on the charge of metal clusters, each of these bonds contributes significantly to the complexation. Binding energy...
Interactions of glutathione tripeptide with gold cluster: Influence of intramolecular hydrogen bond on complexation behavior
, Article Journal of Physical Chemistry A ; Volume 116, Issue 17 , 2012 , Pages 4338-4347 ; 10895639 (ISSN) ; Jamshidi, Z ; Javan, M. J ; Fattahi, A ; Sharif University of Technology
2012
Abstract
Understanding the nature of the interaction between metal nanoparticles and biomolecules has been important in the development and design of sensors. In this paper, structural, electronic, and bonding properties of the neutral and anionic forms of glutathione tripeptide (GSH) complexes with a Au 3 cluster were studied using the DFT-B3LYP with 6-31+G**-LANL2DZ mixed basis set. Binding of glutathione with the gold cluster is governed by two different kinds of interactions: Auâ€"X (X = N, O, and S) anchoring bond and Au··•·•H-X nonconventional hydrogen bonding. The influence of the intramolecular hydrogen bonding of glutathione on the interaction of this peptide with the gold cluster has been...
Synthesis and structure of the cyclometalated hetero-binuclear Pt-Au complexes with bridging 2-diphenylphosphinopyridine ligand
, Article Journal of Organometallic Chemistry ; Volume 786 , 2015 , Pages 14-20 ; 0022328X (ISSN) ; Jamali, S ; Sharif University of Technology
Elsevier
2015
Abstract
The heterobinuclear cyclometalated PtII-AuI complexes of the type [MePt(bhq)(μ-dppy)AuL]PF6, in which, bhq = benzo{h}quinoline, dppy = 2-diphenylphosphinopyridine, L = PPh3, 5; PPh2Me, 6; PPhMe2, 7; have been prepared by reaction of the mononuclear platinum(II) complex [MePt(bhq)(dppy)], 1, with 1 equiv. [AuL]+. Also, the reaction of complex 1 with 1 equiv AuCl(SMe2) at -60 °C gave the neutral heterobinuclear complex [MePt(bhq)(μ-dppy)AuCl], 8. All of the complexes were characterized using NMR spectroscopy and elemental microanalysis and complexes 5 and 8 were further identified by single crystal X-ray structure determination. Time-dependent density functional theory (TD-DFT) is used to...
Does gold cluster promote or scavenge radicals? A controversy at DFT
, Article Journal of Physical Organic Chemistry ; 2017 ; 08943230 (ISSN) ; Kassaee, M. Z ; Fattahi, A ; Sharif University of Technology
John Wiley and Sons Ltd
2017
Abstract
Anticancer character of gold cluster has been indicated through its free radical scavenging properties. This is in contrast to its free radical promoting ability suggested by other workers. Here, we address this controversy by probing the stabilizing effects of Au3 cluster on RO• vs its impacts on RO-H bond dissociation enthalpy, at B3LYP/ LACVP+* level (RH, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, and phenyl). In the presence of Au3 cluster, bond dissociation enthalpy of O-H bond and the spin density at the RO• oxygen are reduced dramatically. These are clear evidences for both the Au3 facilitation of the RO-H bond breakage and its scavenging of RO• radical. Since O-Au anchoring...
Does gold cluster promote or scavenge radicals? A controversy at DFT
, Article Journal of Physical Organic Chemistry ; Volume 31, Issue 3 , 2018 ; 08943230 (ISSN) ; Kassaee, M. Z ; Fattahi, A ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
Anticancer character of gold cluster has been indicated through its free radical scavenging properties. This is in contrast to its free radical promoting ability suggested by other workers. Here, we address this controversy by probing the stabilizing effects of Au3 cluster on RO• vs its impacts on RO–H bond dissociation enthalpy, at B3LYP/ LACVP+* level (R═H, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, and phenyl). In the presence of Au3 cluster, bond dissociation enthalpy of O–H bond and the spin density at the RO• oxygen are reduced dramatically. These are clear evidences for both the Au3 facilitation of the RO–H bond breakage and its scavenging of RO• radical. Since O–Au...
Self-assembly of tryptophan-capped gold nanoparticles onto DNA network template
, Article Journal of Dispersion Science and Technology ; Volume 30, Issue 2 , 2009 , Pages 254-258 ; 01932691 (ISSN) ; Vosoughi, M ; Alemsadeh, I ; Sharif University of Technology
2009
Abstract
In this study, a simple route to the formation of DNA-gold complex has been reported, using immobilized DNA as a template. The nanoporous gold films have been prepared by the electrostatic self assembly of gold nanoparticles capped with tryptophan. Tryptophan would improve surface properties of gold nanoparticles for strongly attaching to DNA. Fourier transform infrared spectroscopy confirmed that gold nanoparticles have been capped by tryptophan. Also measured zeta potential shows that there are positive charges on the surface of gold nanoparticles. Investigations by atomic force microscopy substantially confirm that tryptophan-capped gold nanoparticles can be bonded to DNA template...
Improvement of planar perovskite solar cells by using solution processed SnO2/CdS as electron transport layer
, Article Solar Energy ; Volume 191 , 2019 , Pages 647-653 ; 0038092X (ISSN) ; Javadpour, S ; Taghavinia, N ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
The efficiency of planar perovskite solar cells (PSCs) with SnO2 as electron transport layer is already more than 19% achieved under controlled atmosphere. PSCs with solution processed SnO2 show high hysteresis and low fill factor. One way to improve the planar PSCs is using buffer layer between electron transport layer and perovskite to enhance the photo-electron extraction process. In this study, SnO2 and SnO2/CdS layers were fabricated by solution process using a suspension including CdS nanoparticles synthesized via a simple solution route. Then planar PSCs with the structure of Glass/FTO/ETL/Perovskite/Sprio-OMeTAD/Au were fabricated in ambient air condition using SnO2 and SnO2/CdS as...
Gold nanoparticles functionalized with fullerene derivative as an effective interface layer for improving the efficiency and stability of planar perovskite solar cells
, Article Advanced Materials Interfaces ; Volume 7, Issue 21 , 2020 ; Prochowicz, D ; Bończak, B ; Tavakoli, M. M ; Yadav, P ; Fiałkowski, M ; Hong, C. K ; Sharif University of Technology
Wiley-VCH Verlag
2020
Abstract
Titanium dioxide (TiO2) is an extensively used electron transporting layer (ETL) in n–i–p perovskite solar cells (PSCs). Although, TiO2 ETL experiences the high surface defect together with low electron extraction ability, which causes severe energy loss and poor stability in the PSC. In this study, a new intermediate layer consisting of gold nanoparticles functionalized with fully conjugated fullerene C60 derivative (C60-BCT@Au NPs) that enhances the interfacial contact at ETL/perovskite interface leading to a perovskite film with improved crystallinity and morphology is reported. Moreover, the studies demonstrate that the interface modification of the TiO2 ETL with C60-BCT@Au NPs...
Selective colorimetric detection of pentaerythritol tetranitrate (PETN) using arginine-mediated aggregation of gold nanoparticles
, Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 228 , 2020 ; Ghasemi, F ; Hormozi Nezhad, M. R ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Detection of pentaerythritol tetranitrate (PETN) as an explosive has been of great interest because of public safety and military concerns. Here, we have presented a simple, selective and sensitive colorimetric method for direct detection of PETN. The gold nanoparticles (AuNPs) were first exposed to arginine which has primary amines in its structure. Electron deficient –NH2 groups from arginine could strongly interact with –NO2 groups of PETN as electron donors. Hydrogen bonding happens between the –NO2 group of PETN and –NH2 group of arginine molecules. Therefore, selective aggregation of AuNPs happened because of the donor-acceptor and hydrogen bonding interactions. Due to the aggregation,...
Gold at crossroads of radical generation and scavenging at density functional theory level: Nitrogen and oxygen free radicals versus their precursors in the face of nanogold
, Article Journal of Physical Organic Chemistry ; Volume 34, Issue 1 , 2021 ; 08943230 (ISSN) ; Kassaee, M. Z ; Ayoubi Chianeh, M ; Fattahi, A ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
In our previous report (J. Phys. Org. Chem., 2017), we discussed the dual behavior of gold nanocluster (Au3 NC), where it scavenged reactive oxygen species (ROS) while promoted their generation to a lesser extent. Continuing this quest, we investigate the effects of Au3 NC on common reactive nitrogen species (RNS: O=N˙ and O=N-O) and their precursors (O=N-H and O=N-O-H, respectively), at B3LYP/LACVP+* level of theory. We compare the results with those of prevalent ROS (H-O˙ and H-O-O˙) and their precursors (H-O-H and H-O-O-H, respectively). To this end, various parameters are probed such as binding energy (Eb), bond dissociation energy (BDE), bond lengths, Mullikan spin density (MSD),...
Gold at crossroads of radical generation and scavenging at density functional theory level: Nitrogen and oxygen free radicals versus their precursors in the face of nanogold
, Article Journal of Physical Organic Chemistry ; Volume 34, Issue 1 , 2021 ; 08943230 (ISSN) ; Kassaee, M.Z ; Ayoubi-Chianeh, M ; Fattahi, A ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
In our previous report (J. Phys. Org. Chem., 2017), we discussed the dual behavior of gold nanocluster (Au3 NC), where it scavenged reactive oxygen species (ROS) while promoted their generation to a lesser extent. Continuing this quest, we investigate the effects of Au3 NC on common reactive nitrogen species (RNS: O=N˙ and O=N-O) and their precursors (O=N-H and O=N-O-H, respectively), at B3LYP/LACVP+* level of theory. We compare the results with those of prevalent ROS (H-O˙ and H-O-O˙) and their precursors (H-O-H and H-O-O-H, respectively). To this end, various parameters are probed such as binding energy (Eb), bond dissociation energy (BDE), bond lengths, Mullikan spin density (MSD),...
Role of BCP layer on nonlinear properties of perovskite solar cell
, Article Solar Energy ; Volume 213 , 2021 , Pages 383-391 ; 0038092X (ISSN) ; Milani Moghaddam, H ; Bahari, A ; Mohammadpour, R ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Organic-inorganic hybrid halide perovskite materials have been most attractive for wide range of optoelectronic applications. Investigating the photo-response in these devices will be very useful to understanding cell performance in different conditions and applications. For understanding non-linearity photo-response we use the Bathocuproine (BCP) as blocking layer in two interfaces of inverted perovskite solar cell (FTO/NiO/BCP/Perovskite/PCBM/Au and FTO/NiO/Perovskite/PCBM/BCP/Au). Employing thick BCP layer (≈15 nm) caused s-shaped JV curve due to charge accumulation at interfaces. The nonlinearity effect was also explored for devices with s-shaped JV and established that device parameters...