A simple and direct method is described to prepare cationic bis(NHC)-Au(i) complexes containing N-alkyl or N-aryl NHC ligands to generate relevant gold complexes using metallic gold as the starting ...material.
Sixty percent of global agricultural production depends on the use of pesticides, despite their adverse effects on human health and the ecosystem. In Mexico, the application of these products has ...been exacerbated, including pesticides already banned in other countries. The objective of this study was to determine pesticide concentrations in samples of water purification plants and surface water from the Cienega area of Jalisco, Mexico. A survey of 119 farmers with occupational exposure to pesticides was carried out in order to obtain information on the most frequently used pesticides. Subsequently, 51 samples taken at 7 different sites were analyzed using liquid chromatography and mass-mass spectrometry. The most frequently used pesticides were organophosphates (28.87%), pyrethroids (12.89%), and the herbicide paraquat (31.95%). In surface water, the prevalent pesticides were glyphosate (56.96–510.46 ppb) and malathion (311.76–863.49 ppb). Glyphosate levels were higher than the limits acceptable in daily water intake in Cumuato. Malathion levels exceeded the limits permissible by EPA in water purification plants in urban public establishments (100 ppb for children, and 200 ppb for adults). In addition, a multidimensional scaling analysis showed that the sampled sites could be grouped into 2 different bodies of water, based on similarities in their glyphosate concentrations (stress = 0.005), while the concentrations of malathion were heterogeneous (stress = 0.001).
The synthesis of cis and trans geometrical isomers of platinum( ii ) complexes with a symmetric N-heterocyclic carbene ligand ( Me NHC) is reported. These complexes were obtained from ...1,3-dimethylimidazolium-2-carboxylate, a masked NHC precursor. Their cytotoxicity, oxidative nature, and antibacterial behavior were investigated. The highest cytotoxic effect (IC 50 = 1.21 μM) was observed with the cis -Pt( Me NHC) 2 Cl 2 complex in the cervix cancerous cell line HeLa.
A family of water soluble gold(I) complexes with NHC carbene ligands derived from amino acids were prepared via the direct transmetalation reaction of the respective silver NHC complexes. The ...oxidative addition of Br2 to Au(I)-NHC complexes was studied and the crystal structure of AuBr3(NHC) compound derived from alanine is presented.
A series of Au(NHC)2 (1a–4a) complexes supported by NHC ligands derived from glycine, alanine, methionine and phenylalanine (1–4 respectively) were prepared via a direct transmetalation reaction of their respective silver complexes. The Au complexes were characterized by ESI-MS and NMR spectroscopy in solution. These compounds exhibit instability when the solvent is removed; they displayed a strong tendency to form colored solutions in the order 4a>3a>2a>1a, which is associated with gold nanoparticles. 1a and 2a undergo oxidative addition of elemental bromine, yielding Au(NHC)2Br2 (1b) for 1a and a mixture of Au(NHC)2Br2 (2b) and Au(NHC)Br3 (2c) for 2a. 2b and 2c were characterized by single crystal X-ray diffraction.
The synthesis of Rh(III)Cp*–NHC and Ir(III)Cp*–NHC complexes from amino acid ligand precursors is reported. These complexes were tested as catalysts in TH with good conversions in 2 h and TON values ...greater than 100.
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Heteroleptic RhIIICp*(NHC) and IrIIICp*(NHC) complexes bearing a N-amino acid functionality derived from imidazolium salts were synthesized and characterized by NMR, IR, HR-MS, and single-crystal X-ray diffraction. A discussion of the structure of the RhCp*{κ2(C,O)–NHC}Cl complex 3f as a pair of diastereomers is presented. Catalysts were assessed for the transfer hydrogenation (TH) of ketones in basic propan-2-ol, obtaining good yields for the reduction products. A chromatographic method applied for measurements of compounds in TH as analytes was validated. The Rh and Ir complexes described here offer an original approach in the development of catalysts based in classic NHC precursors.
Phthalates are esters of phthalic acid used in a broad array of consumer products and food contact surfaces. Phthalates are known endocrine disruptors and oxidant stressors, and exposure has been ...associated with premature birth, asthma, obesity, insulin resistance and endometriosis. Though many industrializing countries are known to manufacture phthalates, few studies have examined exposure to phthalates in this context, let alone in rural communities where phthalate-containing products are widely used. We evaluated the presence of 16 phthalate metabolites in third trimester pregnant women in three rural communities near the largest lake in Mexico, Lake Chapala, by liquid chromatography coupled to tandem mass spectrometry in 90 urine samples. Phthalate metabolites were found in all samples, where the highest concentration was 1830 ng/mL in mono-ethyl phthalate (mEP), and it was present in 98.9% of all samples. These findings suggest the need for further research on the effect of endocrine disrupting chemicals in developing countries, and public health guidance on opportunities for prevention.
The synthesis of
cis
and
trans
geometrical isomers of platinum(
ii
) complexes with a symmetric N-heterocyclic carbene ligand (
Me
NHC) is reported. These complexes were obtained from ...1,3-dimethylimidazolium-2-carboxylate, a masked NHC precursor. Their cytotoxicity, oxidative nature, and antibacterial behavior were investigated. The highest cytotoxic effect (IC
50
= 1.21 μM) was observed with the
cis
-Pt(
Me
NHC)
2
Cl
2
complex in the cervix cancerous cell line HeLa.
Cis
- and
trans
-NHC-Pt(
ii
) isomers from the masked carbene 1,3-dimethylimidazolium-2-carboxylate: the relevance of isomerism in the biological activity.
The synthesis and characterization of Cp∗Ir complexes containing ortho-functionalized 1,3-bis(aryl)triazenide ligands has been carried out. The molecular structures of all of the complexes confirm ...the bonding of the triazenide ligands as chelates. Display omitted
•Bis(aryl)triazene including hydroxymethyl groups was synthesized and characterized.•Iridium (III) bis(aryl)triazenide complexes were synthesized and characterized.•Molecular structures of the four iridium triazenide complexes were obtained.•Triazenide coordination as monoanionic bidentate ligands was confirmed.
Iridium (III) 1,3-bis(aryl)triazenide complexes Cp∗IrCl(ArNNNAr′) (Cp∗=C5Me5, Ar=Ar′=C6H5, 1; Ar=Ar′=o-CF3-C6H4, 2; Ar=Ar′=o-HOCH2-C6H4, 3; Ar=o-HOCH2-C6H4, Ar′=p-CH3-C6H4, 4) have been obtained by reaction of iridium dimer Cp∗IrCl22 with the corresponding triazenes in the presence of NEt3 in CH3CN. The iridium complexes 1–4 were characterized by IR, ESI-MS and NMR spectroscopy. In all of the complexes, the triazenes are coordinated to iridium (III) as monoanionic bidentate N,N′-donor ligands. Compounds 1–4 are the first examples studied by single crystal X-ray diffraction of mononuclear bis(aryl)triazenide iridium complexes, where the N-N-N fragment effectively chelates the Ir (III) central atom.
A simple and direct method is described to prepare cationic bis(NHC)-Au(
i
) complexes containing
N
-alkyl or
N
-aryl NHC ligands to generate relevant gold complexes using metallic gold as the ...starting material.
A simple and direct method is described to prepare cationic bis(NHC)-Au(
i
) complexes using metallic gold as the starting material.
A hybrid silica mesoporous material with l-glutathione (LG) (SG-LGPS) was synthesized by a modified sol–gel process. The chemical and structural characterization of the SG-LGPS material was achieved ...by Fourier transform infrared, solid-state 13C and 19Si NMR, and X-ray diffraction. Surface analysis showed a specific surface area of 466.8 m2 g–1. X-ray photoelectron spectroscopy and energy dispersive X-ray spectrometry measurements demonstrated the chemical composition of the hybrid material and the presence of As(V) after the uptake process. The adsorption performance for SG-LGPS reached a maximum arsenic uptake of 45.22 mg g–1 at pH = 4; kinetics and equilibrium results were better described by the pseudo-second-order and Temkin models, respectively. Competitive ion adsorption studies were also performed. The uptake mechanism proposed for this material is a bidentate arsenic–glutathione complex. The present material proposed is as follows: (1) a new scope for environmentally friendly materials with amino acids and (2) a versatile adsorption application extended to other heavy metal ions due to the LG functional group composition.
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