Evaluation of Au(III) complexes as Plasmodium falciparum aquaglyceroporin (PfAQP) inhibitors by in silico and in vitro methods.

The onset of resistance to artemisinin for malaria treatment has stimulated the quest for novel antimalarial drugs. Herein, the gold(III) coordination complexes Aubipy [Au(bipy)Cl] (bipy = 2,2'-bipyridine), Auphen [Au(phen)Cl] (phen = phenanthroline), Auterpy [Au(terpy)Cl] (terpy = 2,2';6',2″-terpyridine), and corresponding hydrolyzed species, have been investigated as inhibitors of the Plasmodium falciparum aquaglyceroporin (PfAQP) protein by computational methods. Through an in-silico approach using an Umbrella Sampling protocol to sample how Aubipy, Auphen, and Auterpy permeate through the PfAQP, their permeability coefficients were estimated using the Inhomogeneous Solubility Diffusion (ISD) model with promising results.

The influence of thioether-substituted ligands in dicopper(II) complexes: Enhancing oxidation and biological activities.

This paper describes the synthesis, structural analysis, as well as the magnetic and spectroscopic characterizations of three new dicopper(II) complexes with dinucleating phenol-based ligands containing different thioether donor substituents: aromatic (1), aliphatic (2) or thiophene (3). Temperature-dependent magnetometry reveals the presence of antiferromagnetic coupling for 1 and 3 (J = -2.27 cm and -5.

C-H Bond Oxidation by Mn-Oxo Complexes: Hydrogen-Atom Tunneling and Multistate Reactivity.

The reactivity of six Mn-oxo complexes in C-H bond oxidation has been examined using a combination of kinetic experiments and computational methods. Variable-temperature studies of the oxidation of 9,10-dihydroanthracene (DHA) and ethylbenzene by these Mn-oxo complexes yielded activation parameters suitable for evaluating electronic structure computations. Complementary kinetic experiments of the oxidation of deuterated DHA provided evidence for hydrogen-atom tunneling in C-H bond oxidation for all Mn-oxo complexes.

Aminoquinoline-based Re(I) tricarbonyl complexes: Insights into their antiproliferative activity and mechanisms of action.

In an effort to develop new potent anticancer agents, two Schiff base rhenium(I) tricarbonyl complexes, containing the ubiquitous aminoquinoline scaffold, were synthesized. Both aminoquinoline ligands and Re(I) complexes showed adequate stability over a 48-h incubation period. Furthermore, the cytotoxic activity of the precursor ligands and rhenium(I) complexes were evaluated against the hormone-dependent MCF-7 and hormone-independent triple negative MDA-MB-231 breast cancer cell lines.

Nonheme Fe═O Complexes Supported by Four Pentadentate Ligands: Reactivity toward H- and O- Atom Transfer Processes.

Four new pentadentate N5-donor ligands, [-(1-methyl-2-imidazolyl)methyl--(2-pyridyl)-methyl--(bis-2-pyridylmethyl)-amine] (), [-bis(1-methyl-2-imidazolyl)methyl--(bis-2-pyridylmethyl)amine] (), (-(isoquinolin-3-ylmethyl)-1,1-di(pyridin-2-yl)--(pyridin-2-ylmethyl)methanamine (), and ,-bis(isoquinolin-3-ylmethyl)-1,1-di(pyridin-2-yl)methanamine (), have been synthesized based on the N4Py ligand framework, where one or two pyridyl arms of the N4Py parent are replaced by (-methyl)imidazolyl or -(isoquinolin-3-ylmethyl) moieties. Using these four pentadentate ligands, the mononuclear complexes [Fe(CHCN)()] (), [Fe(CHCN)()] (), [Fe(CHCN)()] (), and [Fe(CHCN)()] () have been synthesized and characterized. The half-wave potentials () of the complexes become more positive in the order: < < ≤ ≤ [Fe(N4Py)(CHCN)].

Synthesis of phosphine derivatives of [Fe(CO)(μ-sdt)] (sdt = SCHSCHS) and investigation of their proton reduction capabilities.

The reactions of [Fe(CO)(μ-sdt)] (1) (sdt = SCHSCHS) with phosphine ligands have been investigated. Treatment of 1 with dppm (bis(diphenylphosphino)methane) or dcpm (bis(dicyclohexylphosphino)methane) affords the diphosphine-bridged products [Fe(CO)(μ-sdt)(μ-dppm)] (2) and [Fe(CO)(μ-sdt)(μ-dcpm)] (3), respectively. The complex [Fe(CO)(μ-sdt)(κ-dppv)] (4) with a chelating diphosphine was obtained by reacting 1 with dppv (cis-1,2-bis(diphenylphosphino)ethene).

Enhanced Understanding of Structure-Function Relationships for Oxomanganese(IV) Complexes.

A series of manganese(II) and oxomanganese(IV) complexes supported by neutral, pentadentate ligands with varied equatorial ligand-field strength (N3pyQ, N2py2I, and N4py) were synthesized and then characterized using structural and spectroscopic methods. On the basis of electronic absorption spectroscopy, the [Mn(O)(N4py)] complex has the weakest equatorial ligand field among a set of similar Mn-oxo species. In contrast, [Mn(O)(N2py2I)] shows the strongest equatorial ligand-field strength for this same series.

An investigation of steric influence on the reactivity of Fe(O)(OH) tautomers in stereospecific C-H hydroxylation.

Two new tetradentate N4 ligands (LN4), LN4 = Me2,Me2PyzTACN (1-(2-(3,5-dimethyl-1-pyrazol-1-yl)ethyl)-4,7-dimethyl-1,4,7-triazacyclononane) and Me2,MeImTACN (1-((1-methyl-1-imidazol-1-yl)methyl)-4,7-dimethyl-1,4,7-triazacyclononane) have been synthesized and their corresponding Fe(II) complexes [Fe(Me2,Me2PyzTACN)(CFSO)], 1Pz, and [Fe(Me2,MeImTACN)(CFSO)], 1Im, have been prepared and characterized. Complexes 1Pz and 1Im catalyse the hydroxylation of C-H bonds of alkanes with excellent efficiencies, using hydrogen peroxide as oxidant. The high H/D kinetic isotope effect values for C-H hydroxylation, large normalized tertiary/secondary C-H (C3/C2) bond selectivities in adamantane oxidation, and high degrees of stereoretention in the oxidation of -1,2-dimethylcyclohexane are indicative of metal-based oxidation processes.

A di‑iron(III) μ-oxido complex as catalyst precursor in the oxidation of alkanes and alkenes.

The oxido-bridged diiron(III) complex [Fe(μ-O)(μ-OAc)(DPEAMP)](OCH) (1), based on a new unsymmetrical ligand with an NO donor set, viz. [2-((bis(pyridin-2-ylmethyl)amino)methyl)-6-((ethylamino)methyl)-4-methylphenol (HDPEAMP)], has been prepared and characterized by spectroscopic methods and X-ray crystallography. The crystal structure of the complex reveals that each Fe(III) ion is coordinated by three nitrogen and three oxygen donors, two of which are the bridging oxido and acetate ligands.

Hydrogen-atom and oxygen-atom transfer reactivities of iron(IV)-oxo complexes of quinoline-substituted pentadentate ligands.

A series of iron(II) complexes with the general formula [Fe()(L)] ( = 1, L = F, Cl; = 2, L = NCMe, HO) have been isolated and characterized. The X-ray crystallographic data reveals that metal-ligand bond distances vary with varying ligand field strengths of the sixth ligand. While the complexes with fluoride, chloride and water as axial ligand are high spin, the acetonitrile-coordinated complex is in a mixed spin state.

A heterotrinuclear bioinspired coordination complex capable of binding to DNA and emulation of nuclease activity.

The investigation of compounds capable of strongly and selectively interacting with DNA comprises a field of research in constant development. In this work, we demonstrate that a trinuclear coordination complex based on a dinuclear Fe(III)Zn(II) core designed for biomimicry of the hydrolytic enzyme kidney bean purple acid phosphatase, containing an additional pendant arm coordinating a Pd(II) ion, has the ability to interact with DNA and to promote its hydrolytic cleavage. These results were found through analysis of plasmid DNA interaction and cleavage by the trinuclear complex 1 and its derivatives 2 and 3, in addition to the analysis of alteration in the DNA structure in the presence of the complexes through circular dichroism and DNA footprinting techniques.

Reversible PCET and Ambient Catalytic Oxidative Alcohol Dehydrogenation by {V=O} Perfluoropinacolate Complexes.

A new air-stable catalyst for the oxidative dehydrogenation of benzylic alcohols under ambient conditions has been developed. The synthesis and characterization of this compound and the related monomeric and dimeric V(IV)- and V(V)-pin (pin = perfluoropinacolate) complexes are reported herein. Monomeric V(IV) complex (MeN)[V(O)(pin)] () and dimeric (μ-O)-bridged V(V) complex (MeN)[V(O)(μ-O)(pin)] () are prepared in water under ambient conditions.

Luminescent PhotoCORMs: Enabling/Disabling CO Delivery upon Blue Light Irradiation.

The new luminescent carbonyl compounds [Mn(Oxa-H)(CO)Br] () and [Mn(Oxa-NMe)(CO)Br] () were synthesized and fully characterized. Complexes and showed CO release under blue light (λ). Spectroscopic techniques and TD-DFT and SOC-TD-DFT calculations indicated that and release the Oxa-H and Oxa-NMe coligands in addition to the carbonyl ligands, increasing the luminescence during photoinduction.

Quinoline-triazole half-sandwich iridium(III) complexes: synthesis, antiplasmodial activity and preliminary transfer hydrogenation studies.

Iridium(iii) half-sandwich complexes containing 7-chloroquinoline-1,2,3-triazole hybrid ligands were synthesised and their inhibitory activities evaluated against the Plasmodium falciparum malaria parasite. Supporting computational analysis revealed that metal coordination to the quinoline nitrogen occurs first, forming a kinetic product that, upon heating over time, forms a more stable cyclometallated thermodynamic product. Single crystal X-ray diffraction confirmed the proposed molecular structures of both isolated kinetic and thermodynamic products.

Electrocatalytic proton-reduction behaviour of telluride-capped triiron clusters: tuning of overpotentials and stabilization of redox states relative to lighter chalcogenide analogues.

Reaction of [Fe3(CO)9(μ3-Te)2] (1) with the corresponding phosphine has been used to prepare the phosphine-substituted tellurium-capped triiron clusters [Fe3(CO)9(μ3-Te)2(PPh3)] (2), [Fe3(CO)8(μ3-Te)2(PPh3)] (3) and [Fe3(CO)7(μ3-Te)2(μ-R2PXPR2)] (X = CH2, R = Ph (4), Cy (5); X = NPri, R = Ph (6)). The directly related cluster [Fe3(CO)7(μ3-CO)(μ3-Te)(μ-dppm)] (7) was isolated from the reaction of [Fe3(CO)10(μ-Ph2PCH2PPh2)] with elemental tellurium. The electrochemistry of these new clusters has been probed by cyclic voltammetry, and selected complexes have been tested as proton reduction catalysts.

Electron Transfer Mediated by Iron Carbonyl Clusters Enhance Light-Driven Hydrogen Evolution in Water by Quantum Dots.

Photocatalytic water splitting has become a promising strategy for converting solar energy into clean and carbon-neutral solar fuels in a low-cost and environmentally benign way. Hydrogen gas is such a potential solar fuel/energy carrier. In a classical artificial photosynthetic system, a photosensitizer is generally associated with a co-catalyst to convert photogenerated charge into (a) chemical bond(s).

Asymmetric hydrogenation of an α-unsaturated carboxylic acid catalyzed by intact chiral transition metal carbonyl clusters - diastereomeric control of enantioselectivity.

Twenty clusters of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P-P*)] (P-P* = chiral diphosphine of the ferrocene-based Walphos or Josiphos families) have been synthesised and characterised. The clusters have been tested as catalysts for asymmetric hydrogenation of tiglic acid [trans-2-methyl-2-butenoic acid]. The observed enantioselectivities and conversion rates strongly support catalysis by intact Ru3 clusters.

Structural Characterization of a Series of N5-Ligated Mn -Oxo Species.

Analysis of extended X-ray absorption fine structure (EXAFS) data for the Mn -oxo complexes [Mn (O)( N4py)] , [Mn (O)(2pyN2B)] , and [Mn (O)(2pyN2Q)] ( N4py=N,N-bis(4-methoxy-3,5-dimethyl-2-pyridylmethyl)-N-bis(2-pyridyl)methylamine; 2pyN2B=(N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine, and 2pyN2Q=N,N-bis(2-pyridyl)-N,N-bis(2-quinolylmethyl)methanamine) afforded Mn=O and Mn-N bond lengths. The Mn=O distances for [Mn (O)( N4py)] and [Mn (O)(2pyN2B)] are 1.72 and 1.

Highly enantioselective epoxidation of olefins by HO catalyzed by a non-heme Fe(ii) catalyst of a chiral tetradentate ligand.

The chiral tetradentate N4-donor ligand, 1-methyl-2-({(S)-2-[(S)-1-(1-methylbenzimidazol-2-yl methyl)pyrrolidin-2-yl]pyrrolidin-1-yl}methyl) benzimidazole (S,S-PDBzL), based on a chiral dipyrrolidine backbone, has been synthesized and its corresponding Fe(ii) complex has been prepared and characterized. The X-ray structure of the complex reveals that the Fe(ii) ion is in a distorted octahedral coordination environment with two cis-oriented coordination sites occupied by (labile) triflate anions. The ability of the iron complex to catalyze asymmetric epoxidation reactions of olefins with H2O2 was investigated, using 2-cyclohexen-1-one, 2-cyclopenten-1-one, cis-β-methylstyrene, isophorone, chalcones and tetralones as substrates.

Mn-Oxo complex of a bis(benzimidazolyl)-containing N5 ligand reveals different reactivity trends for Mn-oxo than Fe-oxo species.

Using the pentadentate ligand (N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine, 2pyN2B), presenting two pyridyl and two (N-methyl)benzimidazolyl donor moieties in addition to a central tertiary amine, new MnII and MnIV-oxo complexes were generated and characterized. The [MnIV(O)(2pyN2B)]2+ complex showed spectroscopic signatures (i.e.

Di- and Tetrairon(III) μ-Oxido Complexes of an N3S-Donor Ligand: Catalyst Precursors for Alkene Oxidations.

The new di- and tetranuclear Fe(III) μ-oxido complexes [Fe(μ-O)(PTEBIA)](CFSO)(CHCN)] (), [Fe(μ-O)Cl(PTEBIA)](CFSO) (), and [Fe(μ-O)(HCOO)(PTEBIA)](ClO) (MeOH) () were prepared from the sulfur-containing ligand (2-((2,4-dimethylphenyl)thio)-N,N-bis ((1-methyl-benzimidazol-2-yl)methyl)ethanamine (PTEBIA). The tetrairon complex features four μ-oxido bridges, while in dinuclear , the sulfur moiety of the ligand occupies one of the six coordination sites of each Fe(III) ion with a long Fe-S distance of 2.814(6) Å.

A Mononuclear Nonheme Iron(IV)-Oxo Complex of a Substituted N4Py Ligand: Effect of Ligand Field on Oxygen Atom Transfer and C-H Bond Cleavage Reactivity.

A mononuclear iron(II) complex [Fe(N4Py)(OTf)](OTf)(1), supported by a new pentadentate ligand, bis(6-methylpyridin-2-yl)- N, N-bis((pyridin-2-yl)methyl)methanamine (N4Py), has been isolated and characterized. Introduction of methyl groups in the 6-position of two pyridine rings makes the N4Py a weaker field ligand compared to the parent N4Py ligand. Complex 1 is high-spin in the solid state and converts to [Fe(N4Py)(CHCN)](OTf) (1a) in acetonitrile solution.

Evaluation of PTA-derived ruthenium(II) and iridium(III) quinoline complexes against chloroquine-sensitive and resistant strains of the Plasmodium falciparum malaria parasite.

Cationic 1,3,5‑triaza‑phosphaadamantane (PTA) quinoline ruthenium(II) and iridium(III) complexes were successfully synthesized and characterized using standard spectroscopic and analytical techniques. The complexes were evaluated for their in vitro antiplasmodial activities against the chloroquine-sensitive (CQS) NF54 and chloroquine-resistant (CQR) K1 strains of the Plasmodium falciparum species of the malaria parasite and were found to exhibit good activities in the sensitive strain but moderate activities in the resistant strain, suggesting a resistance mechanism similar to chloroquine (CQ). Selected samples were screened for their ability to inhibit synthetic haemozoin formation and were found to be inhibitors with similar activity to CQ.