Analytical calculation of alchemical derivatives based on auxiliary density perturbation theory is described, coded, and validated. For the case where the nucleus is a hydrogen atom and the nuclear ...charge is changed from 1 to 0, it turns out that a good estimate of the proton binding energies can be obtained very efficiently. First-order results correspond exactly to the molecular electrostatic potential evaluated at the hydrogen nucleus location (removing self-repulsion), in agreement with previously reported extensive studies. Therefore, the second-order results reported here are refinements in accuracy that finally allow a quantitative exploration of differential acidity. Furthermore, the recently reported h function is produced in its analytical form as a byproduct and local descriptor associated with the proton binding energy values found with this approach. In an example application, proton binding energies are computed for a family of imidazolium derivatives to demonstrate the capabilities and the stability of the method with respect to changes in basis set or exchange–correlation functional.
Organometallic iridium complexes have been reported as water oxidation catalysts (WOCs) in the presence of ceric ammonium nitrate (CAN). One challenge for all WOCs regardless of the metal used is ...stability. Here we provide evidence for extensive modification of many Ir-based WOCs even after exposure to only 5 or 15 equiv of Ce(IV) (whereas typically 100–10000 equiv are employed during WOC testing). We also show formation of Ir-rich nanoparticles (likely IrO x ) even in the first 20 min of reaction, associated with a Ce matrix. A combination of UV–vis and NMR spectroscopy, scanning transmission electron microscopy, and powder X-ray diffraction is used. Even simple IrCl3 is an excellent catalyst. Our results point to the pitfalls of studying Ir WOCs using CAN.
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.
Functionalized carbene ligands: Increasing the steric bulk of R1 on 1 from H to tBu results in lengthening of the MN bond (by up to 9 %), lowered activation energy for chelate opening (cf. 2) by 17 ...kcal mol−1, and improved binding of an amine and intramolecular hydrogen bonding (3). Iridium species with R1=tBu are effective catalysts of base‐free intramolecular hydroamination, unlike less‐hindered analogues.
Carbon nanotubes (CNTs) have been used to prepare drug nanocarriers. Zinc (Zn) ions play a crucial role in biological processes. Polyethylene glycol (PEG) is a biopolymer used in the medical field. ...In this work, the synthesis of ion Zn-ion-functionalized CNTs/PEG nanocomposites is described. The prepared nanocomposites were characterized using the FE-SEM, FT-IR, XPS, and DSC techniques. The ability of the prepared nanocomposites to release the anticancer drug cisplatin (CP) was assessed. The cytotoxicity of the studied nanocomposites loaded or unloaded with CP toward HeLa cells was evaluated, and their capacity to inhibit the growth of the bacteria Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa was determined. The cytotoxicity tests show that HeLa cells showed considerably larger decrease in cell viability owing to exposure to CP compared to that owing to exposure to Zn-ion-functionalized CNTs/PEG nanocomposites.
Lithium bis(pyrazolyl)dialkylaluminates) complexes were prepared from equimolar amounts of Li(tBu2pz), AlR3 (R = Me, iBu) and tBu2pzH. These compounds have monomeric structure, with the presence of ...one Al-alkyl ··· Li intramolecular interaction, although they were isolated in the presence of the donor solvent THF.
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Two lithium bis(pyrazolyl)dialkylaluminates were prepared from equimolar amounts of Li(tBu2pz), AlR3 (R = Me, iBu) and tBu2pzH. Characterization was accomplished by microanalysis and spectroscopic methods as well as SCXRD. An important feature of these aluminates in solid state, is the presence of one Al-alkyl ··· Li agostic intramolecular interaction despite having used a coordinating solvent (THF) in the synthetic route.
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.
In the therapy of cancer, several treatments have been designed using nanomaterials, among which gold nanoparticles (AuNPs) have been featured as a promising antitumoral agent. Our research group has ...developed the synthesis of gold nanoparticles L-AuNPs and D-AuNPs stabilized with zwitterions of imidazolium (L-1 and D-1) derived from L-methionine and D-methionine. Because the stabilizer agent is chiral, we observed through circular dichroism that AuNPs also present chirality; such chirality as well as the fact that the stabilizing agent contains fragments of methionine and imidazolium that are commonly involved in biological processes, opens up the possibility that this system may have biological compatibility. Additionally, the presence of methionine in the stabilizing agent opens the application of this system as a possible antitumor agent because methionine is involved in methylation processes of molecules such as DNA.
The aim of this research is the evaluation of the antitumor activity of gold nanoparticles stabilized with zwitterions of imidazolium (L-AuNPs) derived from L-methionine in the model of BALB/c mice with lymphoma L5178Y.
Taking as a parameter cell density, the evaluation of the inhibitory effect of L-AuNPs was carried out with a series of in vivo tests in BALB/c type mice; three groups of five mice each were formed (Groups 1, 2 and 3); all mice were i.p. inoculated with the lymphoblast murine L5178Y. Group 1 consisted of mice without treatment. In the Groups 2 and 3 the mice were treated with L-AuNPs at 0.3 mg/Kg on days 1, 7 and 14 by orally and intraperitonally respectively.
These results show low antitumor activity of these gold nanoparticles (L-NPsAu) but interestingly, the imidazolium stabilizing agent of gold nanoparticle (L-1) displayed promising antitumor activity. On the other hand, the enantiomer of L-1, (D-1) as well as asymmetric imidazole derivate from L-methionine (L-2), do not exhibit the same activity as L-1.
The imidazolium stabilizing agent (L-1) displayed promising antitumor activity. Modifications in the structure of L-1 showed that, the stereochemistry (like D-1) and the presence of methionine fragments (like L-2) are determinants in the antitumor activity of this compound.
The synthesis of organometallic gold complexes with symmetric N-heterocyclic carbene ligand (NHC) derivatives derived from 2-(methylthio)aniline is reported. These complexes were obtained as either ...molecular monocarbene or cationic biscarbene complex. These compounds were tested as gold nanoparticle precursors that were stabilized by the corresponding NHC ligand.
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The synthesis of organometallic gold complexes with symmetric N-heterocyclic carbene ligand (NHC) derivatives derived from 2-(methylthio)aniline is reported. These complexes were obtained as either molecular monocarbene complexes Au(NHC)Cl, Au(NHC)Cl3, and Au(NHC)Br3) or cationic biscarbene complex Au(NHC)2PF6. These compounds were tested as gold nanoparticle precursors that were stabilized by the corresponding NHC ligand.
An L-glutathione-functionalized silica adsorbent was applied in this study to remove malathion from aqueous media. This adsorbent has demonstrated an improved adsorption efficiency of malathion. The ...maximum uptake achieved was 130 mg g−1 at pH 8. Equilibrium was reached after about 90 min. A pseudo-second-order model best described the adsorption kinetics. The adsorption isotherms were best simulated by the Freundlich model. The functional groups are thermally stable up to about 150 °C. The elemental analysis results indicated high glutathione ligand densities. The results of this study show that the environmentally friendly L-glutathione functionalized silica is a promising candidate for the removal of malathion from water at the industrial level.
