Synthesis of Gold Nanoparticles Using Recovered Gold from Electronic Waste

Electronic waste contains considerable amounts of gold in its composition, especially some composting pieces like CPUs and memory cards. Recovered gold can have many uses, among those it can be an excellent alternative source for low-cost nanoparticles synthesis. Commercial chloroauric acid is the main precursor for nanoparticle synthesis, however its cost makes the process very expensive. Finding a lower cost alternative precursor is very important because it allows to economically enabling several gold nanoparticles applications. Through the hydrometallurgical method, it was possible to recover and to purify the appreciable amount of gold from old CPUs. This gold has been used to synthesize nanoparticles with a size of 198.5 nm and moderate stability. DOI:  http://dx.doi.org/10.17807/orbital.v13i2.145

Chemical and electrochemical oxidations of tris(3,5-di-tert-butylphenyl)phosphine. High Z’ crystal structures and conformational effects associated with bulky meta substituents

Sherpa Romeo yellow journal. This is a peer reviewed version of this article. It may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Version.Synthesis and single crystal X-ray diffraction structures of (3,5-tBu2-C6H3)3P, (3,5-tBu2-C6H3)3PO∙H2O, (3,5-tBu2C6H3)3PS and (3,5-tBu2-C6H3)3PSe are reported. The structure of (3,5-tBu2-C6H3)3P has Z' = 4, with both M and P enantiomers of a helical conformation and a conformation with one flat ring in the same lattice. The pyramidality index, ∑{CPC}, is smaller for the helical compared to the flat conformers. All four have structures that are more pyramidal than the corresponding Ph3P(E) derivatives, which is attributed to stronger intramolecular dispersion forces. The oxide crystallizes with Z' = 2 as a water-bridged dimer that is the most separated such dimer amongst 26 known structures, providing evidence for a distal (or perimeter) steric effect. Cyclic voltammetry in CH3CN/[nBu4N][ClO4] indicated anodic peak potentials of +0.785 V for (3,5tBu2-C6H3)3P, +0.745 for (3,5-Me2-C6H3)3P, +0.735 V for (4-MeO-3,5-Me2-C6H3)3P and +0.535 V for (4-MeOC6H3)3P, all relative to Fc+/0. On this scale, Ph3P oxidizes at +1.04 V. The unexpectedly high oxidation potentials for the first three phosphines is attributed to a more pyramidal structure resulting in lowering of the HOMO energy compared to expectations from Hammett constants and 1J(P,Se) NMR coupling constants.Ye

Synthesis of Gold Nanoparticles Using Recovered Gold from Electronic Waste

Electronic waste contains considerable amounts of gold in its composition, especially some composting pieces like CPUs and memory cards. Recovered gold can have many uses, among those it can be an excellent alternative source for low-cost nanoparticles synthesis. Commercial chloroauric acid is the main precursor for nanoparticle synthesis, however its cost makes the process very expensive. Finding a lower cost alternative precursor is very important because it allows to economically enabling several gold nanoparticles applications. Through the hydrometallurgical method, it was possible to recover and to purify the appreciable amount of gold from old CPUs. This gold has been used to synthesize nanoparticles with a size of 198.5 nm and moderate stability. DOI:  http://dx.doi.org/10.17807/orbital.v13i2.145

Ruthenium(II)-arene complexes with monodentate aminopyridine ligands: insights into redox stability, electronic structures and biological activity

Sherpa Romeo green journal. Permission to archive accepted author manuscript.The synthesis and spectroscopic characterization of four ruthenium(II) arene complexes with monodentate pyridine derivatives ([( 6–p-cymene)RuCl2L]: L = 2-aminopyridine, 2-methylaminopyridine, 2-benzylaminopyridine, and pyridine) are reported. Full characterization was undertaken using 1H and 13C NMR spectroscopy, vibrational and electronic spectroscopies and crystallography (2-methylaminopyridine derivative). UB3LYP//(6-31+G(d),SPK-DZCD) density functional theory calculations determined the molecular and electronic structures. Cyclic voltammetry determined a large electrochemical stability window (>2.2 V) extending well beyond the physiological E°. Interactions with CT-DNA and BSA, and activity against four cell lines (HeLa, B16F10, HEp-2 and Vero) were evaluated. The 2-methylaminopyridine shows weak cytotoxicity (IC50 = 346 molL-1) towards HeLa cells. All the complexes interact with DNA at relatively high concentrations as determined by UV-vis spectroscopic titration. Results of circular dichroism spectroscopy, ethidium bromide competition, fluorescence spectroscopy and DNA viscosity measurements identify electrostatic interactions between partly hydrolyzed cationic complexes and the phosphate backbone of DNA as the most likely interaction mode. Slower rates of hydrolysis may be the origin of lower cytotoxicity for 1 these complexesYe

Aplicação do '[RuCl IND. 3(DPPB)H IND.2 O] na obtenção do complexos mono e binucleares

O complexo inédito mer-[RuCl3(dppb)H2O], foi caracterizado como precursor de uma série de compostos fosfínicos. Foram testadas sínteses do complexo título com ligantes providos de diferentes modos de coordenação, tais como os monodentados (L= DMSO, MeOH, NO e CO, py, 4-Mepy), exodentado (L= 4-CNpy), bidentados (L-L= 2,2'-bipy, fen) e ambidentado (L-L= 4,4'-bipy). Os produtos destas reações foram isolados como espécies bifosfínicas de rutênio (III) de fórmula geral mer-[RuCl3(dppb)(L)], cis-[RuCl2(dppb)(L-L)]+ e [Ru2Cl6(dppb)2(μ-4,4'-bipy)]. Reações do mer-[RuCl3(dppb)H2O] e fosfinas mono, bi e tridentadas, foram investigadas e a partir destas, obteve-se a série de complexos mono, bi e trifosfínicos de rutênio (II), conhecidos na literatura como reagentes para sínteses de compostos de rutênio, tais como [RuCl2(dppb)(PPh3)], [RuCl2(P-P)2] (P-P= dppm, dppe e dppp) e [Ru2Cl4(P-P)3] (PP= dppb), e [Ru2Cl3(P-P-P)2]Cl (P-P-P= tdpme e etp). A partir dos complexos do tipo [Ru2Cl3(P-P-P)2]Cl, obteve-se compostos do tipo [RuCl(P-P-P)(N-heterocíclico)]Cl, dando continuidade à nova série de complexos mononucleares solvato, [RuCl(P-P-P)(solvente)]Cl. Os compostos de Ru(II) e Ru(III) obtidos, foram caracterizados através de espectroscopia de absorção na região do infravermelho, ultravioleta-visível, RPE, RMN 31P, medidas de condutância molar, medidas de susceptibilidade magnética, análise elementar, voltametria cíclica e em alguns casos, difração de raios-X. O comportamento eletroquímico dos complexos bifosfínicos de Ru(III) mer- [RuCl3(dppb)H2O] e mer-[RuCl3(dppb)(L)], apresentou perfil bastante peculiar. A partir da metodologia empregada na obtenção por via eletroquímica, atribuiu-se as espécies Ru2II/III, [Ru2Cl5(dppb)2], de Ru(II), [Ru2Cl4(dppb)2], [RuCl2(dppb)(L)2] e [Ru2Cl4(dppb)2(L)], como produtos formados na superfície do eletrodo,...The new complex mer-[RuCl3(dppb)H2O] was characterized as precursor of a series of ruthenium (III) mono and biphosphines complexes. Syntheses of the complex title were tested with ligands provided from different coordination manners, such as the monodentates ligands (L = DMSO, MeOH, NO, CO, py, 4-Mepy), exobidentate ligand (L = 4-CNpy), chelate ligands (L-L = 2,2'-bipy, fen) and umbidentate ligand (L-L = 4,4'-bipy). The reaction products were isolated as ruthenium (III) phosphines complexes of general formula mer-[RuCl3(dppb)(L)], cis-[RuCl2(dppb)(L-L)]+, and [Ru2Cl6(dppb)2(μ-4,4'-bipy)], respectively. Reactions of the mer-[RuCl3(dppb)H2O] with monophosphines, diphosphines and triphosphines were investigated and starting from these, it was obtained the series of complex mono, di and triphosphines ruthenium (II), wich are known in the literature as starting material for syntheses of compounds of ruthenium, such as [RuCl2(dppb)(PPh3)], [RuCl2(P-P)2] (P-P = dppm, dppe and dppp) and [Ru2Cl4(P-P)3] (P-P = dppb), and [Ru2Cl3(PP- P)2]Cl (P-P-P = tdpme and etp). Mononuclear ruthenium complexes of the type [RuCl(P-PP)( N-heterocylic)]Cl, were isolated from the reaction of the binuclear [Ru2Cl3(P-P-P)2]Cl (PP- P = tdpme and etp) with excess of ligand. Standard spectroscopic methods, particularly IR, UV-Vis, EPR, 31P{1H} MNR, were extensively used to characterize (sometimes in conjunction with X-ray crystallography) all of the species discussed in this thesis. The complexes were also characterized by molar conductance, magnetic moment measurement, elementary analysis and cyclic voltammetry. The electrochemical behaviour of the biphosphine complexes Ru(III) presented quite peculiar profiles. Starting from the methodology using electrochemistry route, it was attributed the species of Ru2II/III, [Ru2Cl5(dppb)2], and of Ru(II), [Ru2Cl4(dppb)2], [RuCl2(dppb)(L)2] and [Ru2Cl4(dppb)2(L)], ...(Complete abstract, click electronic access below

Frustrated and realized hydrogen bonding in 4-hydroxy-3,5- ditertbutylphenylphosphine derivatives

Accepted author manuscript. Embargo in effect until Feb. 28, 2023Synthesis and molecular and supramolecular structures of a series of triarylphosphines P(Ph)3–n{4-RO-3,5-(tBu)2-C6H2}n (n = 1, 3; R = SiMe3, H) are reported. Chemical oxidation products E=P(Ph)3–n{4-RO-3,5-(tBu)2-C6H2}n (E = O, S, and Se; n = 1, 3; R = SiMe3, H) are also reported. Crystal structures of the reported compounds were determined by single-crystal X-ray diffraction, using a Hirshfeld atom refinement with NoSpherA2 through OLEX2, which provides an average improvement in C–C bond distance precision of 35%. Phosphine basicity for the phosphines with n = 1, R = H and n = 3, R = SiMe3, H was determined using the 1JP,Se values of the respective selenides; 1JP,Se = 699 Hz for E = Se, n = 3, and X = H identifies the most basic triarylphosphine ever reported. Intermolecular interactions allow classification of the 17 structures into 4 categories: those with only dispersion-induced short contacts, those with frustration of H-bonding, those with only classic H-bonding, and those with combinations of classic and frustration of H-bonding. A “double phenol embrace” classified by an R22(4) graph set is a weak intermolecular synthon organizing lattices with 2,6-ditertbutylphenol functional groups. Classic H-bonding occurs only when E = O.Ye

Bulky 2,6-disubstituted aryl siloxanes and a disilanamine

Open access article. Creative Commons license (CC BY) appliesThe crystal structures of 5-bromo-1,3-di-tert-butyl-2-[(tri­methyl­sil­yl)­oxy]benzene, C17H29BrOSi, (I), 1,3-di-tert-butyl-2-[(tri­methyl­sil­yl)­oxy]benzene, C17H30OSi, (II), and N-(2,6-diiso­propyl­phen­yl)-1,1,1-trimethyl-N-(tri­methyl­sil­yl)silanamine, C18H35NSi2, (III), are reported. Compound (I) crystallizes in space group P21/c with Z′ = 1, (II) in Pnma with Z′ = 0.5 and (III) in Cmcm with Z′ = 0.25. Consequently, the mol­ecules of (II) are constrained by m and those of (III) by m2m site symmetries. Despite this, both (I) and (II) are distorted towards mild boat conformations, as is typical of 2,6-di-tert-butyl-substituted phenyl compounds, reflecting the high local steric pressure of the flanking alkyl groups. Compound (III) by contrast is planar and symmetric, and this lack of distortion is compatible with the lower steric pressure of the flanking 2,6-diisopropyl substituents.Ye