Search Results (37)

Lung cancer is a leading cause of cancer-related death worldwide that needs updated therapies to contrast both the serious side effects and the occurrence of drug resistance. A panel of non-small cell lung cancer (NSCLC) cells were herein employed as cancer models. Eight structurally related gold(I) and gold(III) complexes with NHC and halides or triphenylphosphane ligands were investigated as lung cancer cell growth inhibitors. As expected, gold compounds with PPh₃ were found to be more cytotoxic than homoleptic [(NHC)₂-Au(I)]X or heteroleptic NHC-Au(I)X or NHC-Au(III)X₃ complexes. Mixed ligand gold(I) compounds exhibiting the linear NHC-AuPPh₃ (compound 7) or the trigonal NHC-Au(Cl)PPh₃ (compound 8) arrangements at the central metal were found to be the best lung cancer cytotoxic compounds. Analysis of the TrxR residual activity of the treated cells revealed that these compounds efficiently inhibit the most accredited molecular target for gold compounds, the TrxR, with compound 8 reaching more than 80% activity reduction in lung cells. Some of the current cancer lung therapy protocols consist of specific lung cancer cell cytotoxic agents combined with antifolate drugs; interestingly, the herein gold compounds are both TrxR and antifolate inhibitors. The human DHFR was inhibited with IC₅₀ ranging between 10–21 µM, depending on substrate concentrations, proceeding by a likely allosteric mechanism only for compound 8. Full article

The new 3-monosubstituted acetylacetone ligands, 3-(phenyl(1H-pyrazol-1-yl)methyl)pentane-2,4-dione (HL^acPz) and 3-((3,5-dimethyl-1H-pyrazol-1-yl)(phenyl)methyl)pentane-2,4-dione (HL^acPzMe), were synthesized and used as supporting ligands for new copper(II) and copper(I) phosphane complexes of the general formulae [Cu(HL^acX)₂(L^acX)₂] and [Cu(PPh₃)₂(HL^acX)]PF₆ (X = Pz (pyrazole) or PzMe (3,5-dimethylpyrazole)), respectively. In the syntheses of the Cu(I) complexes, the triphenylphosphine coligand (PPh₃) was used to stabilize copper in the +1 oxidation state, avoiding oxidation to Cu(II). All compounds were characterized by CHN analysis, ¹H-NMR, ¹³C-NMR, FT-IR spectroscopy, and electrospray ionization mass spectrometry (ESI-MS). The ligands HL^acPz (1) and HL^acPzMe (2) and the copper complex [Cu(PPh₃)₂(HL^acPz)]PF₆ (3) were also characterized by X-ray crystallography. The reactivity of these new compounds was investigated and the new compounds 4-phenyl-4-(1H-pyrazol-1-yl)butan-2-one (7) and 4-(3,5-dimethyl-1H-pyrazol-1-yl)-4-phenylbutan-2-one (8) were obtained in basic conditions via the retro-Claisen reaction of related 3-monosubstituted acetylacetone, providing efficient access to synthetically useful ketone compounds. Compound 8 was also characterized by X-ray crystallography. Full article

The di-iron carbonyl dithiolene bridged complex [Fe₂(CO)₆(µ-S₂C₂(CO₂Me)₂)] (1) reacts with 1 equivalent of phosphane PR₃ (R = Ph, OMe) to give, as major products, monosubstituted derivatives [Fe₂(CO)₅L(µ-S₂C₂(CO₂Me)₂)] (L = PPh₃ (2), P(OMe)₃ (3)). In the presence of an excess (3–4 equiv.) of P(OMe)_3, the cleavage of 1 arises partly and a mixture of the mononuclear species [Fe(CO)(P(OMe)₃)₂(κ²-S₂C₂(CO₂Me)₂)] (4) and 3 is obtained. The compounds 2–4 were analyzed by IR and ¹H, ³¹P-{¹H} NMR spectroscopies. Their structures in solid state were determined by X-ray diffraction analyses, which accord with their spectroscopic characteristics. Full article

The reaction of bis(pentafluorophenyl)mercury with the ligands bis(diphenylphosphano) methane P,P’-dioxide ({Ph₂P(O)}₂CH₂) (1), bis{2-(N,N,N’N’-tetraethyldiaminophosphano) imidazol-1-yl} methane P,P’-dioxide ({2-PO(NEt₂)₂C₃N₂H₂}₂CH₂) (2) and bis (2-diphenylphosphanophenyl) ether P,P’-dioxide ({2-PPh₂(O)C₆H₄}₂O) (3) afforded crystalline ?-donor complexes [{Hg(C₆F₅)₂}₂{Ph₂P(O)}₂CH₂] (1Hg), [Hg(C₆F₅)₂{2-PO(NEt₂)₂C₃N₂H₂}₂CH₂]_n (2Hg) and [Hg(C₆F₅)₂{2-PPh₂(O)C₆H₄}₂O] (3Hg), respectively. The molecular structures of 1Hg, 2Hg and 3Hg show considerable differences. In complex 1Hg, a single bridging bidentate ligand connects two three-coordinate T-shape mercury atoms with a near linear C-Hg-C atom array. Complex 2Hg is a one-dimensional coordination polymer in which adjacent four-coordinate mercury atoms with a linear C-Hg-C atom array are linked by bridging bidentate O,O’- ligands, whilst in complex 3Hg a T-shape three-coordinate mercury atom is ligated by (3) in a monodentate fashion. The Hg-O bond lengths of complexes 1Hg, 2Hg and 3Hg differ substantially (range 2.5373(14)-2.966(3) Å) owing to structural and bonding differences. Full article

Bis(pyrazol-1-yl)acetic acid (HC(pz)₂COOH) and bis(3,5-dimethyl-pyrazol-1-yl)acetic acid (HC(pz^Me2)₂COOH) were converted into the methyl ester derivatives 1 (L^OMe) and 2 (L^2OMe), respectively, and were used for the preparation of silver(I) complexes 3–5. The Ag(I) complexes were prepared by the reaction of AgNO₃ and 1,3,5-triaza-7-phosphaadamantane (PTA) or triphenylphosphine (PPh₃) with L^OMe and L^2OMe in methanol solution. All Ag(I) complexes showed a significant in vitro antitumor activity, proving to be more effective than the reference drug cisplatin in the in-house human cancer cell line panel containing examples of different solid tumors. Compounds were particularly effective against the highly aggressive and intrinsically resistant human small-cell lung carcinoma (SCLC) cells, either in 2D and 3D cancer cell models. Mechanistic studies revealed their ability to accumulate into cancer cells and to selectively target Thioredoxin (TrxR), thus leading to redox homeostasis unbalance and ultimately inducing cancer cell death through apoptosis. Full article

The enantiomerically pure ligand BisNap-Phos was obtained in a straightforward sequence of reactions beginning with inexpensive starting materials under the readily affordable conditions in high overall yield. An asymmetric BisNap-Phos-palladium complex-catalyzed Suzuki–Miyaura coupling leading to axially chiral biaryl compounds was described. The reactions were carried out under mild conditions in aqueous and organic media. A series of atropisomeric biaryls were synthesized with excellent yields and high enantioselectivities (up to 86% ee). The methodology provides an efficient and practical strategy for the synthesis of novel multifunctionalized axially chiral biaryl compounds under mild environmentally friendly and easily affordable conditions. Full article

Deprotonation of a bis(amino)phosphane H₂L = PhP(HNBtd)₂ bearing a heterocyclic Btd = 2,1,3-benzothiadiazol-4-yl substituents at nitrogen atoms by silylamides LiNTms₂ and Y(NTms₂)₃ (Tms = trimethylsilylamide) results in lithium and yttrium complexes with the deprotonated HL^– and L^2– forms as κ²-N and κ⁴-N chelating ligands. A binuclear complex [LiHL]₂ was crystallized from Et₂O, and was shown to reversibly dissociate in thf (tetrahydrofuran) with the NH_(soln)–PH_(crystal) tautomeric shift; the compound [Li₂L] was spectroscopically characterized. Yttrium readily forms stable bis-ligand complexes [YL₂]^– and [YL(HL)]. In the latter, the H atom in HL resides on phosphorus; the coordination sphere remains accessible to another ligands, and it was crystallized as [{YL(HL)}₂(µ-dioxane)] species (YN₈O coordination). In the former complex, the coordination sphere was saturated (YN₈) by closer bound ligands; it was crystallized as a salt with [Li(thf)₄]⁺. The monoligand complex could not be cleanly obtained in a 1:1 reaction of H₂L and Y(NTms₂)₃, and was only crystallographically characterized as a dimer [YL(NTms)₂]₂. Partial oxidation of the central P atom with the formation of phosphine-oxide ligands PhP(O)(NBtd)^2– was observed. They co-crystallize in the same position as non-oxidized ligands in [YL₂]^– and [YL(NTms₂)]₂ species and participate in bonding between two units in the latter. TD-DFT calculations reveal that main transitions in the visible region of electronic spectra correspond to the charge transfer bands mostly associated with the orbitals located on Btd fragments. Full article

Treatment of bis(iminophosphorane)phosphane ligands 2a–2e with Li₂PdCl₄ gave a set of novel diphosphane-derived complexes bearing two metallacycle rings, each one enclosing a P=N double bond: the unprecedented bis(iminophosphorane)phosphane-[C,N,S] palladacycles. In the case of the ligand derived from bis(diphenylphosphino)methane, 2a, both the single and the double palladacycle complexes were obtained. Reaction of 3a with bis(diphenylphosphino)ethane did not yield the expected product with the diphosphane bonded to both palladium atoms, but rather the novel coordination compound 5. The crystal structures of 3c and 5 are described. Full article

For decades, ligands such as phosphanes or cyclopentadienyl ring derivatives have dominated Coordination and Organometallic Chemistry. At the same time, alternative compounds have emerged that could compete either for a more practical and accessible synthesis or for greater control of steric and electronic properties. Guanidines, nitrogen-rich compounds, appear as one such potential alternatives as ligands or proligands. In addition to occurring in a plethora of natural compounds, and thus in compounds of pharmacological use, guanidines allow a wide variety of coordination modes to different metal centers along the periodic table, with their monoanionic chelate derivatives being the most common. In this review, we focused on the organometallic chemistry of guanidinato compounds, discussing selected examples of coordination modes, reactivity and uses in catalysis or materials science. We believe that these amazing ligands offer a new promise in Organometallic Chemistry. Full article

Starting from [Ru(pyO)₂(nbd)] 1 and a N,P,N-tridentate ligand (2a: PhP(pic)₂, 2b: PhP(pyO)₂) (nbd = 2,5-norbornadiene, pic = 2-picolyl = 2-pyridylmethyl, pyO = 2-pyridyloxy = pyridine-2-olate), the compounds [PhP(μ-pic)₂(μ-pyO)Ru(κ²-pyO)] (3a) and [PhP(μ-pyO)₃Ru(κ²-pyO)] (3b), respectively, were prepared. Reaction of compounds 3 with CO and CNtBu afforded the opening of the Ru(κ²-pyO) chelate motif with the formation of compounds [PhP(μ-pic)₂(μ-pyO)Ru(κ-O-pyO)(CO)] (4a), [PhP(μ-pic)₂(μ-pyO)₂Ru(CNtBu)] (5a), [PhP(μ-pyO)₄Ru(CO)] (4b) and [PhP(μ-pyO)₄Ru(CNtBu)] (5b). In dichloromethane solution, 4a underwent a reaction with the solvent, i.e., substitution of the dangling pyO ligand by chloride with the formation of [PhP(μ-pic)₂(μ-pyO)Ru(Cl)(CO)] (6a). The new complexes 3a, 4a, 5a, 5b and 6a were characterized by single-crystal X-ray diffraction analyses and multi-nuclear (¹H, ¹³C, ³¹P) NMR spectroscopy. The different coordination behaviors of related pairs of molecules (i.e., pairs of 3, 4 and 5), which depend on the nature of the P–Ru-bridging ligand moieties (μ-pic vs. μ-pyO), were also studied via computational analyses using QTAIM (quantum theory of atoms in molecules) and NBO (natural bond orbital) approaches, as well as the NCI (non-covalent interactions descriptor) for weak intramolecular interactions. Full article

Breast cancers (BCs) may present dramatic diagnoses, both for ineffective therapies and for the limited outcomes in terms of lifespan. For these types of tumors, the search for new drugs is a primary necessity. It is widely recognized that gold compounds are highly active and extremely potent as anticancer agents against many cancer cell lines. The presence of the metal plays an essential role in the activation of the cytotoxicity of these coordination compounds, whose activity, if restricted to the ligands alone, would be non-existent. On the other hand, gold exhibits a complex biochemistry, substantially variable depending on the chemical environments around the central metal. In this review, the scientific findings of the last 6–7 years on two classes of gold(I) compounds, containing phosphane or carbene ligands, are reviewed. In addition to this class of Au(I) compounds, the recent developments in the application of Auranofin in regards to BCs are reported. Auranofin is a triethylphosphine-thiosugar compound that, being a drug approved by the FDA—therefore extensively studied—is an interesting lead gold compound and a good comparison to understand the activities of structurally related Au(I) compounds. Full article

Overheating can affect solubility or lipophilicity, among other properties, of some anticancer drugs. These temperature-dependent changes can improve efficiency and selectivity of the drugs, since they may affect their bioavailability, diffusion through cell membrane or activity. One recent approach to create thermosensitive molecules is the incorporation of fluorine atoms in the chemical structure, since fluor can tune some chemical properties such as binding affinity. Herein we report the anticancer effect of gold derivatives with phosphanes derived from 1,3,5-triaza-7-phosphaadamantane (PTA) with long hydrocarbon chains and the homologous fluorinated chains. Besides, we analysed the influence of temperature in the cytotoxic effect. The studied gold(I) complexes with phosphanes derived from PTA showed antiproliferative effect on human colon carcinoma cells (Caco-2/TC7 cell line), probably by inhibiting cellular TrxR causing a dysfunction in the intracellular redox state. In addition, the cell cycle was altered by the activation of p53, and the complexes produce apoptosis through mitochondrial depolarization and the consequent activation of caspase-3. Furthermore, the results suggest that this cytotoxic effect is enhanced by hyperthermia and the presence of polyfluorinated chains. Full article

This review is a comprehensive account of reactions with the participation of nickel complexes that result in the formation of carbon–phosphorus (C?P) bonds. The catalytic and non-catalytic reactions with the participation of nickel complexes as the catalysts and the reagents are described. The various classes of starting compounds and the products formed are discussed individually. The several putative mechanisms of the nickel catalysed reactions are also included, thereby providing insights into both the synthetic and the mechanistic aspects of this phosphorus chemistry. Full article

The Lucite Alpha process is the predominant technology for the preparation of acrylics. This two-stage process involves the palladium-catalysed formation of methyl propanoate from ethene, CO, and methanol, followed by the oxidative formylation of methyl propanoate into methyl methacrylate. A range of bis-1,2-disubstituted aminomethylferrocenes has been prepared and characterised. These complexes serve as precursors to a variety of bulky ferrocenylmethyldiphosphanes that, in turn, function as ligands in the palladium-catalysed process. We describe the crystal structures of five ligand precursors and provide a rationale for their design. In situ catalyst testing on palladium complexes derived from ferrocenylphosphanes demonstrates that these are highly selective (>99.5%) catalysts for the formation of methyl propanoate from ethene, CO, and methanol and have turnover numbers exceeding 50,000. This article credits those researchers who worked on this project in the early days, who received little or no credit for their achievements and endeavours. Full article

The synthesis of two new phosphane-gold(I)–napthalimide complexes has been performed and characterized. The compounds present luminescent properties with denoted room temperature phosphorescence (RTP) induced by the proximity of the gold(I) heavy atom that favors intersystem crossing and triplet state population. The emissive properties of the compounds together with the planarity of their chromophore were used to investigate their potential as hosts in the molecular recognition of different polycyclic aromatic hydrocarbons (PAHs). Naphthalene, anthracene, phenanthrene, and pyrene were chosen to evaluate how the size and electronic properties can affect the host:guest interactions. Stronger affinity has been detected through emission titrations for the PAHs with extended aromaticity (anthracene and pyrene) and the results have been supported by DFT calculation studies. Full article