Complexes 2a Research Articles

Nickel complex based electrodes for Li‐ion batteries

This work focuses on the development of nickel‐based quinone complexes as electrode materials for next‐generation rechargeable batteries. These complexes were synthesized with different substituents and their potential as anode materials in lithium‐based systems was investigated. Scanning electron microscopy (SEM) and energy‐dispersive X‐ray spectroscopy (EDX) confirmed the uniform distribution and composition of the electrode materials deposited by spin coating. Comprehensive electrochemical testing, including galvanostatic charge‐discharge cycling and impedance spectroscopy, showed that the dinickel complex 2a present low capacity (10 mA.h.g‐1) while the 2b presents a maximum specific capacity up to 28 mA.h.g‐1 at 0.4 C and very good stability over more than 200 cycles. Analogue 2c exhibited a maximum specific capacity up to 25 mA.h.g‐1 at 0.2 C, maintaining high cycling stability across different C‐rates but significantly lower capacity at higher C‐rates, indicating mass transport limitations.

Tetraarylantimony 2,2′-bipyridinecarboxylates: synthesis, photophysical and molecular docking studies

Tetraarylantimony(V) carboxylates based on 5-carboxyl and 6-carboxyl 2,2’-bipyridines (4 compounds) were synthesized for the first time. The structure of one of the compounds was confirmed by X-ray diffraction analysis. It was shown that the carboxyl group participates in the coordination of the antimony(V) cation, but the bipyridine fragment does not. The antitumor activity of the new complexes was assessed by molecular docking, and the most probable targets were determined. It was shown that the affinity of ligands to them is higher than that of the corresponding complexes. The best results were obtained for complex 3a; its inhibition of VEGFR2 is 74% more effective compared to the native ligand. In addition, the primary photophysical properties of the new carboxylates in acetonitrile solutions were studied. It was shown that the luminescence quantum yield values strongly depend on the position of the carboxyl group: for 5-substituted compounds they reach 65.0%, while for 6-substituted ones they have an extremely low ( 0.1%) value. At the same time, the absorption and emission maxima are within 300–314 nm and 364–403 nm, respectively.

Synthesis of Aluminum Complexes Based on 2,6‐Bis(2‐hydroxyphenyl)Pyridines: Efficient Initiators for Ring‐Opening Polymerization of Cyclic Esters

AbstractThe search for new initiators based on nontoxic metal complexes, allowing for the controlled production of polycaprolactone (PCL) and polylactide (PLA) is an actual task. In the present work, we report the synthesis of aluminum complexes 6a and 6b based on substituted 2,6‐bis(2‐hydroxyphenyl)pyridine pro‐ligands. The compositions and structures of the novel compounds were established by elemental analysis and 1H, 13C, NMR spectroscopy in the solid state by X‐ray diffraction analysis (6a and 6b). All the synthesized aluminum complexes are monomeric. Complexes 6a and 6b (in presence of benzyl alcohol (BnOH)) turned out to be active in the ring opening polymerization (ROP) of ε‐caprolactone (ε‐CL), L‐, rac‐lactide (L‐, rac‐LA) gave PCL and PLA with high molecular weights. The mechanism of the polymerization reaction for compounds С, 6a, and 6b was also investigated using the density functional theory (DFT) method. The substituent effect analyzed in terms of percent buried volume and non‐covalent interactions. The values of calculated Gibbs free activation energies correspond to the trend found experimentally.

De novo missense variants in the PP2A regulatory subunit PPP2R2B in a neurodevelopmental syndrome: potential links to mitochondrial dynamics and spinocerebellar ataxias.

The heterotrimeric protein phosphatase 2A (PP2A) complex catalyzes about half of Ser/Thr dephosphorylations in eukaryotic cells. A CAG repeat expansion in the neuron-specific protein PP2A regulatory subunit PPP2R2B gene causes spinocerebellar ataxia type 12 (SCA12). We established five monoallelic missense variants in PPP2R2B (four confirmed as de novo) as a cause of intellectual disability with developmental delay (R149P, T246K, N310K, E37K, I427T). In addition to moderate to severe intellectual disability and developmental delay, affected individuals presented with seizures, microcephaly, aggression, hypotonia, as well as broad-based or stiff gait. We used biochemical and cellular assays, including a novel luciferase complementation assay to interrogate PP2A holoenzyme assembly and activity, as well as deregulated mitochondrial dynamics as possible pathogenic mechanisms. Cell-based assays documented impaired ability of PPP2R2B missense variants to incorporate into the PP2A holoenzyme, localize to mitochondria, induce fission of neuronal mitochondria, and dephosphorylate the mitochondrial fission enzyme dynamin-related protein 1. AlphaMissense-based pathogenicity prediction suggested that an additional seven unreported missense variants may be pathogenic. In conclusion, our studies identify loss-of-function at the PPP2R2B locus as the basis for syndromic intellectual disability with developmental delay. They also extend PPP2R2B-related pathologies from neurodegenerative (SCA12) to neurodevelopmental disorders and suggests that altered mitochondrial dynamics may contribute to mechanisms.

Arylhydrazone‐Thioeter Palladium Pincer Complexes Catalyzed Carbonylative Suzuki–Miyaura Cross‐Coupling Using Fe(CO)5 as CO Surrogate

ABSTRACTA series of Pd(II)‐pincer complexes 3a–d have been synthesized and characterized in good yields, via C–H bond activation on arylhydrazone‐thioether ligands. The investigation of these new Pd(II)‐pincer complexes has proved that the possesses excellent catalytic activity for carbonylative Suzuki–Miyaura cross‐coupling reactions of aryl iodides with arylboronic acids using Fe(CO)5 as carbonyl source. Notably, this strategy offers several advantages such as shorter reaction time, nonrequirement of toxic CO gas, and good to excellent yield of the desired products for wide range of applicable substrate; mainly, carbonylative Suzuki–Miyaura coupling just requires only 0.5 mol% of Pd(II)‐pincer complexes. We have also demonstrated a new efficient route for the synthesis of an antineoplastic agent 4‐(methoxyphenyl)‐(3,4,5‐trimethoxyphenyl)methanone. Additionally, the possible mechanism of this Pd(II)‐pincer complexes process is further supported by the density functional theory (DFT) study.

T-shaped 14 Electron Rhodium Complexes: Potential Active Species in C-H Activation.

Two T-shaped 14-electron rhodium complexes 2a and 2b, "framed" and thus stabilized by PNP pincer ligands have been synthesized. The bis(t-butyl)phosphine derived PNPtBu-rhodium 2a was isolated from pentane as the more stable cyclometalated Rh(III) hydrido complex and found to be in equilibrium with the T-shaped 14e-Rh(I) complex 2aT which itself could be directly crystallized upon change of the solvent. The cyclometallation is suppressed using an adamantyl substituted PNPAd ligand to give the analogous T-shaped Rh(I) species 2b, stabilized through an agostic interaction with one of the adamantyl C-Hs. Depending on the solvent, complex 2a reacted with ethylene either by π-coordination (4a) or C-H activation giving a hydrido-vinyl Rh(III) species 4b, both isomers being in equilibrium in solution. Complex 2b C-H was found to reversibly activate arenes to form the hydrido-aryl Rh(III) complexes.

Revumenib for patients with acute leukemia: a new tool for differentiation therapy.

Treatment of acute leukemia is gradually moving away from a "one-size-fits-all" approach, as scientific and clinical advances expand the arsenal of available targeted therapies. One of the recent additions is the group of menin inhibitors; oral, selective, small molecules that disrupt the interaction between the chromatin adapter menin, and an epigenetic regulator, the lysine methyltransferase 2A (KMT2A) complex. Two susceptible leukemia subtypes have been identified: (i) acute myeloid leukemia with a mutation in nucleophosmin 1 (NPM1), and (ii) any acute leukemia, myeloid or lymphoid, with a translocation resulting in the rearrangement of KMT2A. These leukemias share a distinct genetic expression, maintained by the KMT2A-menin interaction. Together they account for approximately 40% of patients with acute myeloid leukemia and 10% of patients with acute lymphoblastic leukemia. This spotlight review follows the journey of revumenib, as a representative of menin inhibitors, from bench to bedside. It focuses on the pathophysiology of leukemias sensitive to menin inhibition, delineation of how this understanding led to targeted drug development, and data from clinical trials. The important discovery of resistance mechanisms is also explored, as well as future directions in the use of menin inhibitors for treating leukemia.

Stereoelectronic Tuning of Bioinspired Nonheme Iron(IV)-Oxo Species by Amide Groups in Primary and Secondary Coordination Spheres for Selective Oxygenation Reactions.

Two mononuclear iron(II) complexes, [(6-amide2-BPMEN)FeII](OTf)2 (1) and [(6-amide-Me-BPMEN)FeII(OTf)](OTf) (2), supported by two BPMEN-derived (BPMEN = N1,N2-dimethyl-N1,N2-bis(pyridine-2-yl-methyl)ethane-1,2-diamine) ligands bearing one or two amide functionalities have been isolated to study their reactivity in the oxygenation of C-H and C═C bonds using isopropyl 2-iodoxybenzoate (iPr-IBX ester) as the oxidant. Both 1 and 2 contain six-coordinate high-spin iron(II) centers in the solid state and in solution. The 6-amide2-BPMEN ligand stabilizes an S = 1 iron(IV)-oxo intermediate, [(6-amide2-BPMEN)FeIV(O)]2+ (1A). The oxidant (1A) oxygenates the C-H and C═C bonds with a high selectivity. Oxidant 1A, upon treatment with 2,6-lutidine, is transformed into another oxidant [{(6-amide2-BPMEN)-(H)}FeIV(O)]+ (1B) through deprotonation of an amide group, resulting in a stronger equatorial ligand field and subsequent stabilization of the triplet ground state. In contrast, no iron-oxo species could be observed from complex 2 and [(6-Me2-BPMEN)FeII(OTf)2] (3) under similar experimental conditions. The iron(IV)-oxo oxidant 1A shows the highest A/K selectivity in cyclohexane oxidation and 3°/2° selectivity in adamantane oxidation reported for any synthetic nonheme iron(IV)-oxo complexes. Theoretical investigation reveals that the hydrogen bonding interaction between the -NH group of the noncoordinating amide group and Fe═O core smears out the equatorial charge density, reducing the triplet-quintet splitting, and thus helping complex 1A to achieve better reactivity.

Covalent Inhibitors of S100A4 Block the Formation of a Pro-Metastasis Non-Muscle Myosin 2A Complex.

The S100 protein family functions as protein-protein interaction adaptors regulated by Ca2+ binding. Formation of various S100 complexes plays a central role in cell functions, from calcium homeostasis to cell signaling, and is implicated in cell growth, migration, and tumorigenesis. We established a suite of biochemical and cellular assays for small molecule screening based on known S100 protein-protein interactions. From 25 human S100 proteins, we focused our attention on S100A4 because of its well-established role in cancer progression and metastasizes by interacting with nonmuscle myosin II (NMII). We identified several potent and selective inhibitors of this interaction and established the covalent nature of binding, confirmed by mass spectrometry and crystal structures. 5b showed on-target activity in cells and inhibition of cancer cell migration. The identified S100A4 inhibitors can serve as a basis for the discovery of new cancer drugs operating via a novel mode of action.

Selective Oxidative Scission of Olefins to Aldehydes Enabled by Ruthenium Complexes Containing Salicylaldimine Ligands

ABSTRACTTreatment of Ru3(CO)12 with salicylaldimine ligands [ArNCH(3‐tBuC6H3OH) [ArC6H5 (L1H); 4‐OMeC6H4 (L2H); 4‐MeC6H4 (L3H); 2,4,6‐Me3C6H2 (L4H); 4‐ClC6H4 (L5H); 4‐BrC6H4 (L6H)] in refluxing toluene afforded six bis‐ligand mononuclear ruthenium carbonyl complexes [ArNCH(3‐tBuC6H3O)]2Ru(CO)2 1a–1f in good yields. All of the Ru(II) complexes were characterized using IR, NMR, and elemental analysis. The molecular structures of complexes 1a, 1b, 1e, and 1f were further confirmed through X‐ray diffraction analysis. Additionally, the catalytic performance of these complexes was investigated in the oxidation of olefins to aldehydes, using TBHP as the oxidant in refluxing trichloromethane. With 1.0 mol% catalyst loading, these ruthenium complexes displayed high reactivity and good functional‐group compatibility, selectivity providing the corresponding oxidation product aldehydes in 73%–94% yields.

Synthesis and characterization of 3,5-bis((2-hydroxybenzylidene)amino)-N-(2-hydroxyphenyl)benzamide and Zn(II) complex: Investigation of chromic, fluorescence and DPPH radical scavenging behaviours

Novel amido-Schiff base 3,5-bis((2-hydroxybenzylidene)amino)-N-(2-hydroxyphenyl)benzamide (2a) has been obtained by the reaction of Schiff base 1a with 2-hydroxyaniline in the presence of coupling agent N,N′-dicyclohexylcarbodiimide. Schiff base (1a) which serves as the starting compound in amide synthesis was produced from the condensation of 3,5-diaminobenzoic acid with salicylaldehyde in a 1:2 mol ratio. Tetrahedral geometry with 1:1 [M:L] stoichiometry Zn(II) complex (3a) was newly synthesized by the complexation reaction of ligand 2a with zinc(II) nitrate. 1a and 2a displayed a broad emission band at λem = 456 and 472 nm with a blue fluorescent in pure DMSO, while 3a emitted a strong greenish-blue fluorescent with the λem = 485 nm (λexc = 365 nm). The fluorescence efficiency of 1a was poor compared to the others. The λem in aqueous DMSO solution (v/v, 1:1) had ∼8–33 nm red-shift with respect to that of pure solution. The λem gave ∼1–15 nm red-shift with very low emission efficiency in acidic DMSO media. The results suggested that the aggregation caused quenching properties of 1a–3a in pure, aqueous, and acidic DMSO system with a 50 % water fraction. The fluorescence of the compounds appeared to be visibly very bright in basic DMSO media. All the compounds were also screened for antioxidant activity using UV–Vis spectroscopy. They were found to be not effective DPPH radical scavengers in DMSO.

Picornavirus Evolution: Genomes Encoding Multiple 2ANPGP Sequences-Biomedical and Biotechnological Utility.

Alignment of picornavirus proteinase/polymerase sequences reveals this family evolved into five 'supergroups'. Interestingly, the nature of the 2A region of the picornavirus polyprotein is highly correlated with this phylogeny. Viruses within supergroup 4, the Paavivirinae, have complex 2A regions with many viruses encoding multiple 2ANPGP sequences. In vitro transcription/translation analyses of a synthetic polyprotein comprising green fluorescent protein (GFP) linked to β-glucuronidase (GUS) via individual 2ANPGPs showed two main phenotypes: highly active 2ANPGP sequences-similar to foot-and-mouth disease virus 2ANPGP-and, surprisingly, a novel phenotype of some 2ANPGP sequences which apparently terminate translation at the C-terminus of 2ANPGP without detectable re-initiation of downstream sequences (GUS). Probing databases with the short sequences between 2ANPGPs did not reveal any potential 'accessory' functions. The novel, highly active, 2A-like sequences we identified substantially expand the toolbox for biomedical/biotechnological co-expression applications.

Unsymmetric Ir2 and RhIr Dinuclear Complexes Supported by a Linear Tetraphosphine meso-dpmppp, Showing High Reactivity for O2, H2, and HCl.

Unsymmetric dinuclear Ir(I) complexes, [Ir2Cl2(L)(meso-dpmppp)] (L = XylNC (1aIr2), tBuNC (1bIr2), CO (1cIr2)), were synthesized using meso-Ph2PCH2P(Ph)(CH2)3P(Ph)CH2PPh2 (meso-dpmppp), which supports cis-P,P (M1) and trans-P,P (M2) metal sites, and exhibited high reactivity for O2, H2, and HCl. The IrRh heterodinuclear complexes, [M1M2Cl2(L)(meso-dpmppp)] (1xM1M2) (M1M2 = IrRh, RhIr; L = XylNC, CO (x = a, c)), were also synthesized and used together with the Rh2 complexes (1a,cRh2) to elucidate the role of each metal site. For the reactions of O2, 1aIr2 and 1aRhIr showed higher reactivity than those of 1aIrRh and 1aRh2, giving η2-peroxide complexes [{M1Cl2}{M2(η2-O2)(XylNC)}(meso-dpmppp)] (2aIr2, 2aRhIr), from which O2 would not dissociate. All the CO complexes 1cM1M2 (M1, M2 = Ir or Rh) showed no reactivity for O2. In the reactions with H2, 1aIr2 reacted with H2 to give the dihydride complex, [{IrCl2}{Ir(H)2L}(meso-dpmppp)] (11aIr2) and the tetrahydride complex, [{Ir(H)Cl2}(μ-H){Ir(H)2L}(meso-dpmppp)] (12aIr2), while 1aRhIr gave the dihydride complex, and 1aIrRh and 1aRh2 gave no hydride complexes. Reactions of 1a,cM1M2 with HCl afforded the dihydride complexes, [{IrCl3}(μ-H){Ir(H)Cl(XylNC)}(meso-dpmppp)] (14aIr2), [{Ir(H)Cl2}(μ-H){M2Cl2(L)}(meso-dpmppp)] (M2 = Ir, L = CO (15cIr2); M2 = Rh, L = XylNC (15aIrRh), CO (15cIrRh)), and [{Rh(H)Cl2}(μ-Cl){Ir(H)Cl(XylNC)}(meso-dpmppp)] (18aRhIr), the structures varying depending on M1 and M2 as well as L.

Experimental and Computational Insights Into Organotellurium (IV) Complexes as Potent PfNDH2 Inhibitors: Synthesis, Characterization, and Antimalarial Evaluation

ABSTRACTThe study examines the binding affinities and pharmacological potential of synthesized metal compounds with PfNDH2 in Plasmodium falciparum. So as to identify the combatting agent for malaria, six new organotellurium (IV) complexes (8a–8f) were prepared through a condensation reaction of 3‐methyl‐2‐thiophene carboxaldehyde and p‐nitroaniline. The synthesized compounds were inclusively characterized through physical and spectral techniques signifying a distorted octahedral geometry. The reported complexes were screened for antimalarial and antioxidant activities and analyzed using micro assays and DPPH assays, respectively. Using docking interactions, the research evaluates the binding energies, hydrogen bonds, and steric interactions of various compounds with PfNDH2, aiming to identify promising candidates for antimalarial drug development. Among the compounds, 8f showed the strongest binding affinity, with the lowest binding energy of −135.626 kcal/mol, and diverse hydrogen bonds with the target enzyme. Structure‐based pharmacophore modeling revealed critical interaction profiles and selectivity scores for the compounds, with 8f emerging as a promising candidate. Molecular electrostatic potential (MESP) analysis offered insights into the distribution of electron density within the compounds, influencing their reactivity and potential as antimalarial agents. ADMET analysis highlighted the pharmacokinetic and toxicological profiles of the compounds, revealing critical aspects for optimizing safety and efficacy. Overall, the findings provide valuable information for further development and optimization of potential antimalarial drugs.

Construction of Mo/S/Ag Cluster Complexes from Dinuclear Molybdenum Precursors [R4N]2[(edt)2Mo2S2(μ‐S)2] (R = Et, nPr; edt = −SCH2CH2S−)

AbstractWe have demonstrated that complexes [(edt)2Mo2O2(μ‐S)2Ag2(dppm)2]·4CH3OH·DMF (2, edt = 1,2‐ethanedithiolate dianion, dppm = bis(diphenylphosphino)methane, DMF = N,N‐dimethylformamide) and [(μ‐Cl)2Ag4(μ3‐Cl)2(dppm)2]·4DMF (3), were generated by combining a dinuclear molybdenum precursor [Et4N]2[(edt)2Mo2S2(μ‐S)2] (1a) with two equimolar AgCl and dppm in a CH3OH‐DMF mixed solution. Treatment of complex 1a with one equimolar AgCl and DPEPhos in CH3OH and DMF mixed solutions, producing complex [Et4N][(edt)2Mo2S2(μ‐S)2Ag(DPEPhos)]·CH3OH (4, DPEPhos = bis(2‐diphenylphosphinophenyl)ether). Treatment of complex [nPr4N]2[(edt)2Mo2S2(μ‐S)2] (1b) with AgBr in acetonitrile followed by addition of (NH4)2S produced a dodecanuclear Mo–Ag–S cage cluster [nPr4N]2[{Mo2Ag2S2O2(edt)2}3(μ6‐S)]·1.5CH3CN (5). Complexes 2−5 have been characterized by infrared(IR), 1H NMR, UV‐vis, and fluorescence spectroscopies. Moreover, molecular structures of complexes 2−5 have been established by single‐crystal X‐ray crystallography.

Antimicrobial Activity of Anionic Bis(N-Heterocyclic Carbene) Silver Complexes

The antimicrobial properties of a series of anionic bis(carbene) silver complexes Na3[Ag(NHCR)2] were investigated (2a–2g and 2c′, where NHCR is a 2,2′-(imidazol-2-ylidene)dicarboxylate-type N-heterocyclic carbene). The complexes were synthesized by the interaction of imidazolium dicarboxylate compounds with silver oxide in the presence of aqueous sodium hydroxide. Complexes 2f,g were characterized analytically and spectroscopically, and the ligand precursor 1f and complexes 2c and 2g were structurally identified by X-ray diffraction methods. The anions of 2c and 2g, [Ag(NHCR)2]3−, showed a typical linear disposition of Ccarbene-Ag-Ccarbene atoms and an uncommonly eclipsed conformation of carbene ligands. The antimicrobial properties of complexes 2a–g, which contains chiral (2b–2e and 2c′) and non-chiral derivatives (2a,f,g), were evaluated against Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, and a Gram-positive bacterium, Staphylococcus aureus. From the observed values of the minimal inhibitory concentration and minimal bactericidal concentration, complexes 2a and 2b showed the best antimicrobial activity against all strains. An interesting chirality–antimicrobial relationship was found, and eutomer 2c′ showed better activity than its enantiomer 2c against the three bacteria. Furthermore, these complexes were investigated experimentally and theoretically by 109Ag nuclear magnetic resonance, and the electronic and steric characteristics of the dianionic carbene ligands were also examined.

Facile C[sbnd]H aryl and O[sbnd]H bonds activation at dirhenium site of [Re2(CO)8(THF)2] complex

The activation of small molecules is a topic of great interest and previously we reported on the easy activation of different types of EH bonds at the dinuclear complex [Re2(CO)8(THF)2] (1) where labile THF molecules coordinate to adjacent rhenium(0) atoms. Here we extend the reactivity of 1 reporting on the oxidative addition of benzene and toluene at room temperature to give [Re2(μ-H)(μ-κC-Ar)(CO)8], Ar = −C6H5 (2) and −C6H4Me (3). Compound 3 is a new example of μ-κC-Ar dinuclear rhenium complex and has been obtained as para and meta isomers (3a,b). It is known from the literature that 2 can activate arenes and heteroarenes via reductive elimination of benzene and oxidative addition of CH bonds to the dinuclear fragment. Here we have studied the reaction of 2 with C6D6 and H2CC(H)Ph and determined the kinetic constants by 1H NMR (1.4 × 10−5 s−1 at 308 K and 1.1 × 10−5 s−1 at 298 K, respectively). The results indicate that the rate-determining step of the reaction is the reductive elimination of benzene, while the oxidative addition is fast. Water and methanol react with 1 in toluene at room temperature to give the hydroxo and methoxo hydrido complexes [Re2(μ-H)(μ-OR)(CO)8], RH (5) and CH3 (6). On reacting 1 with water in deuterated toluene, and monitoring by 1H/2H NMR, a preferential deuteration of the hydride site to give [Re2(μ-D)(μ-OH)(CO)8] is evidenced. This finding excludes the oxidative addition of water on the dinuclear “Re2(CO)8” fragment while supporting a heterolytic addition of water via protonation at the µ-κC-tolyl group, elimination of toluene and addition of OH−. Single crystal X-ray diffraction analyses have been performed for complexes 3a, 5 and 6 and their solid state structures have been determined. In particular, the crystal structure of 5 results in a new polymorphic form (5b) and it is discussed in comparison with the already known one (5a).

Pharmacologically significant penta, hexa, and heptacoordinate mono organosilicon (IV) Schiff base complexes derived from phenyl alanine: Synthesis, spectral characterization, antimicrobial, antioxidant, anti-inflammatory, and anti-diabetic studies

Mono organosiliocn (IV) Schiff base complexes 1a-2c derived from phenyl alanine were prepared and characterized. Six new complexes were evaluated in vitro against different bacteria; besides their antioxidant, anti-inflammatory and antidiabetic properties were also tested. Combination of infrared and multinuclear NMR (1H NMR, 13C NMR and 29Si NMR) techniques evidenced the formation of penta, hexa, and heptacoordinated species. The in-vitro antileishmanial study for complexes 1a and 2b against the amastigote stage of the parasite, a mouse macrophage cell line infected with promastigotes expressing luciferase, the IC50 for all tested complexes was lower than that of the miltefosine (standard drug). In antibacterial activity, with the increase in the concentration the zone of inhibition increased. 2c showed the maximum percent inhibition for most number of bacteria which are E. coli (87.50 ± 4.17 %), S. typhi (85.96 ± 3.04 %), S. aureus (70.71 ± 1.75 %), K. pneumonia (7.97 ± 1.26 %) and while 2a and 2b only showed maximum percent inhibition of 77.78 ± 1.92 % and 66.67 ± 2.31 for the bacterium B. subtilis and S. abony respectively at a concentration of 10 mg/ml. Also the methyl silicon (IV) Schiff base complexes showed less antibacterial activity than the ethyl silicon (IV) Schiff base complexes. Pharmacological activities of mono organosilicon (IV) complexes increase with an increase in the number of organo group as well as ligands. 2c possessed the best antioxidant, anti-inflammatory, and anti-diabetic activities.

Ruthenium-p-Cymene Complexes Incorporating Substituted Pyridine–Quinoline Ligands with –Br (Br-Qpy) and –Phenoxy (OH-Ph-Qpy) Groups for Cytotoxicity and Catalytic Transfer Hydrogenation Studies: Synthesis and Characterization

Organometallic ruthenium complexes with p-cymene = 1-methyl-4-(1-methylethyl)-benzene and N^N = bidentate polypyridyl ligands constitute interesting candidates with biological and catalytic properties. Towards this aim, we have synthesized four ruthenium(II)–arene complexes of the type [Ru(η6-p-cymene)(N^N)Cl][X] (N^N = Br-Qpy = 6-bromo-4-phenyl-2-pyridin-2-yl-quinoline, X = Cl− (1a); PF6− (1b); N^N = OH-Ph-Qpy = 4-(4-phenyl-2-(pyridin-2-yl)quinolin-6-yl)phenol, X = Cl− (2a); PF6− (2b)). This is the first report of ruthenium(II) p-cymene complexes incorporating substituted pyridine–quinoline ligands, with –Br and –C6H4OH groups in the 6-position of quinoline. We also refer to the cytotoxicity of the ligands and their possible effect of modulating the activity of the ruthenium(II) complexes. These were characterized by a combination of spectroscopic methods (ATR-IR, UV–Vis, multinuclear NMR), elemental analysis, and conductivity measurements. The solid-state structure of 2b, determined by single-crystal X-ray diffraction, reveals a three-legged piano-stool geometry. The in vitro cytotoxic activities of the new complexes were evaluated in HEK293T (human embryonic kidney cells) and in HeLa cells (cervical cancer cells), via the MTT assay. Poor in vitro anticancer activities were observed for the HeLa cancer cell line, with 2a being the most potent (IC50 = 75 μΜ). The cytotoxicity of Br-Qpy in HEK293T is comparable to that of cisplatin. Both complexes 1a and 1b successfully catalyze the transfer hydrogenation of benzophenone to benzhydrol by 2-propanol at 82 °C. The catalytic performance of 1a in the ratio of S:Cat:B = 400:1:40 (S = substrate, Cat = catalyst, B = base = KOiPr) leads to a conversion of 94%, within 3 h of reaction. Presumably, catalytic transformation takes place via ruthenium(II) hydride species being the active catalyst.

A Caged Neutral 17-Valence-Electron Iron(I) Radical [Fe(CO)2(Cl)(P((CH2)10)3P)]•: Synthetic, Structural, Spectroscopic, Redox, and Computational Studies.

UV irradiation of yellow CH2Cl2 solutions of trans-Fe(CO)3(P((CH2)10)3P) (2a) and PMe3 (10 equiv) gives, in addition to the previously reported dibridgehead diphosphine P((CH2)10)3P (46%), a green paramagnetic complex that crystallography shows to be the trigonal-bipyramidal iron(I) radical trans-[Fe(CO)2(Cl)(P((CH2)10)3P)]• (1a•; 31% after workup). This is a rare example of an isolable species of the formula [Fe(CO)4-n(L)n(X)]• (n = 0-3, L = two-electron-donor ligand; X = one-electron-donor ligand). Analogous precursors with longer P(CH2)nP segments (n = 12, 14, 16, 18) give only the demetalated diphosphines, and a rationale is proposed. The magnetic susceptibility of 1a•, assayed by Evans' method and SQUID measurements, indicates a spin (S) of 1/2. Cyclic voltammetry shows that 1a• undergoes a partially reversible one-electron oxidation, but no facile reduction. The UV-visible, EPR, and 57Fe Mössbauer spectra are analyzed in detail. Complex 2a is similarly studied, and, despite the extra valence electron, exhibits a comparable oxidation potential (ΔE1/2 ≤ 0.04 V). The crystal structure shows a cage conformation, solvation level, disorder motif, and unit cell parameters essentially identical to those of 1a•. DFT calculations provide much insight regarding the structural, redox, and spectroscopic properties.