Ru(ii)-(PTA) and -mPTA complexes with N2-donor ligands bipyridyl and phenanthroline and their antiproliferative activities on human multiple myeloma cell lines

Evaluation of the Antiproliferative Properties of CpRu Complexes Containing N-Methylated Triazaphosphaadamantane Derivatives

Piano-stool-{CpRu} complexes containing 1,3,5-triaza-7-phosphaadamantane (PTA), N-methyl-1,3,5-triaza-7-phosphaadamantane (mPTA), and 3,7-dimethyl-1,3,7-triaza-5-phosphabyciclo[3.3.1]nonane (dmoPTA) were evaluated as drugs against breast cancer. The evaluated compounds include two new examples of this family, the complexes [RuCp(DMSO-κS)(HdmoPTA)(PPh3)](CF3SO3)2 (8) and [RuCp(PPh3)2-µ-dmoPTA-1κP-2κ2N,N'-PdCl2](CF3SO3) (11), which have been synthesized and characterized by NMR, IR, and single-crystal X-ray diffraction. The cytotoxic activity of compounds was evaluated against MDA-MB-231 breast cancer cells, and the three most active complexes were further tested against the hormone-dependent MCF-7 breast cancer cell line. Their cell death mechanism and ruthenium uptake were also evaluated, as well as their binding ability to human serum albumin.

Study of the biological activity of photoactive bipyridyl-Ru(II) complexes containing 1,3,5-triaza-7-phosphaadamantane (PTA)

The water-soluble ruthenium complex cis-[Ru(dcbpyH)₂(PTAH)₂]Cl₂·3H₂O (1) (dcbpy = 4,4'-dicarboxy-2,2'-bipyridine; PTA = 1,3,5-triaza-7-phosphaadamantane) has been synthesized and characterised by NMR, IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The optical properties of 1 were studied, including photoactivation under visible light, as well as its biological properties, together with those of the previously published Ru complexes cis-[Ru(bpy)₂(PTA)₂]Cl₂ (2), trans-[Ru(bpy)₂(PTA)₂](CF₃SO₃)₂ (3) and cis-[Ru(bpy)₂(H₂O)(PTA)](CF₃SO₃)₂ (4) (bpy = 2,2'-bipyridine). Anticancer activities of the complexes against human lung (A549), cervical (HeLa) and prostate (PC3) carcinoma cells were evaluated under dark conditions and upon photoactivation with visible light. None of the complexes exhibited cytotoxic activity in the absence of light irradiation (IC₅₀ > 100 μM). However, after photoactivation, the cytotoxicity of complexes 1, 2 and 3 against the three cell lines markedly increased, resulting in IC₅₀ values between 25.3 μM and 9.3 μM. Notably, these complexes did not show toxicity against red blood cells. These findings show the potential of complexes 1, 2 and, particularly, 3 for selective and controlled cancer photochemotherapy. The reactivity of the Ru complexes against DNA under UV-Vis irradiation was studied by analysing plasmid mobility. Experimental data shows that 4 unfolds supercoiled DNA (SC DNA) both in the dark and under visible irradiation, while 1 and 3 are only active under light, being 2 inactive in either case. The unfolding activities of complexes 3 and 4 were dependent on the air present in the reaction. The measured intracellular levels of reactive oxygen species (ROS) upon irradiation with complexes 1, 2 and 3 suggest that their mechanism of action is related to oxidative stress.

Therapeutic Potential of a Water-Soluble Silver-Diclofenac Coordination Polymer on 3D Pancreatic Cancer Spheroids

This work describes the traditional wet and green synthetic approaches, structural features, and extensive bioactivity study for a new coordination polymer [Ag(μ-PTA)(Df)(H₂O)]_n·3nH₂O (1) that bears a silver(I) center, a 1,3,5-triaza-phosphaadamantane (PTA) linker, and a nonsteroidal anti-inflammatory drug, diclofenac (Df^-). Compared to cisplatin, compound 1 exhibits both anti-inflammatory properties and very remarkable cytotoxicity toward various cancer cell lines with a high value of selectivity index. Additionally, the 3D model representing human pancreas/duct carcinoma (PANC-1) and human lung adenocarcinoma (A549) was designed and applied as a clear proof of the remarkable therapeutic potential of 1. The obtained experimental data indicate that 1 induces an apoptotic pathway via reactive oxygen species generation, targeting mitochondria due to their membrane depolarization. This study broadens a group of bioactive metal-organic networks and highlights the significant potential of such compounds in developing advanced therapeutic solutions.

Neutron Scattering Techniques for Studying Metal Complexes in Aqueous Solution

Neutron scattering combined with ab initio calculations provides a powerful tool for studying metal complexes in different solvents and, particularly, in water. The majority of traditional characterization techniques in catalysis provide only limited information on homogeneous catalytic processes. Neutron scattering, on the other hand, thanks to its sensitivity to hydrogen atoms, and therefore water molecules, can be used to build detailed models of reaction paths and to observe, at a molecular level, the influence of solvent molecules on a catalytic process. In this Mini-Review we describe several examples on how neutron scattering combined with ab initio calculations can be used to examine the nature of the interaction of water molecules with catalytically active metal complexes in solution.

N–C bond formation between two anilines coordinated to a ruthenium center in cis-form affording a 3,5-cyclohexadiene-1,2-diimine moiety

Four-electron oxidation of two anilines coordinated to a ruthenium(ii) center in a cis-form affords N1-phenylcyclohexa-3,5-diene-1,2-diimine through an N–C bond formation with N–H and C–H bond activation.

Investigating the reactivity of neutral water-soluble Ru(ii)-PTA carbonyls towards the model imine ligands pyridine and 2,2'-bipyridine

As a continuation of our strategy for preparing new Ru(ii) precursors to be exploited as building blocks in the construction of metal-mediated supramolecular assemblies with improved solubility in water, here we describe the reactivity of selected neutral Ru(ii)-PTA carbonyls (PTA = 1,3,5-triaza-7-phosphaadamantane) towards the model imine ligands pyridine (py) and 2,2'-bipyridine (bpy) and the preparation and characterization of several neutral and cationic water-soluble derivatives: trans,trans,trans-[RuCl2(CO)(py)(PTA)2] (7), cis,cis,trans-[RuCl2(CO)2(py)(PTA)] (9), cis,trans-[Ru(bpy)Cl(CO)(PTA)2]Cl (10), mer-[Ru(bpy)(CO)(PTA)3](Cl)2 (12), cis,trans-[Ru(bpy)(CO)2Cl(PTA)]Cl (13), cis,trans-[Ru(bpy)(CO)2(PTA)2](NO3)2 (14NO3). In addition, we found that light-induced isomerization in some bpy compounds could be induced. The following species, either side-products isolated in low yield or compounds obtained exclusively in solution, were also unambiguously identified: cis,cis,trans-[RuCl2(CO)(py)(PTA)2] (8), trans-[RuCl2(bpy)(CO)(PTA)] (11), cis,cis-[Ru(bpy)Cl(CO)(PTA)2]Cl (15) and cis,cis-[Ru(bpy)(CO)2Cl(PTA)]Cl (16). The X-ray structures of 7, 11·H2O, and 12·7H2O are also reported. All compounds are new and - with few exceptions - show a good solubility in water.

Synthesis, Structural, and Cytotoxic Properties of New Water-Soluble Copper(II) Complexes based on 2,9-Dimethyl-1,10-Phenanthroline and Their One Derivative Containing 1,3,5-Triaza-7-Phosphaadamantane-7-Oxide

A series of water-soluble copper(II) complexes based on 2,9-dimethyl-1,10-phenanthroline (dmphen) and mixed-ligands, containing PTA=O (1,3,5-triaza-7-phosphaadamantane-7-oxide) have been synthesized and fully characterized. Two types of complexes have been obtained, monocationic [Cu(NO₃)(O-PTA=O)(dmphen)][PF₆] (1), [Cu(Cl)(dmphen)₂][PF₆] (2), and neutral [Cu(NO₃)₂(dmphen)] (3). The solid-state structures of all complexes have been determined by single-crystal X-ray diffraction. Magnetic studies for the complex 1–3 indicated a very weak antiferromagnetic interaction between copper(II) ions in crystal lattice. Complexes were successfully evaluated for their cytotoxic activities on the normal human dermal fibroblast (NHDF) cell line and the antitumor activity using the human lung carcinoma (A549), epithelioid cervix carcinoma (HeLa), colon (LoVo), and breast adenocarcinoma (MCF-7) cell lines. Complexes 1 and 3 revealed lower toxicity to NHDF than A549 and HeLa cells, meanwhile compound 2 appeared to be more toxic to NHDF cell line in comparison to all cancer lines. Additionally, interactions between the complexes and human apo-transferrin (apo-Tf) using fluorescence and circular dichroism (CD) spectroscopy were also investigated. All compounds interacted with apo-transferrin, causing same changes of the protein conformation. Electrostatic interactions dominate in the 1/2 – apo- Tf systems and hydrophobic and ionic interactions in the case of 3.

Pentafluorophenyl Platinum(II) Complexes of PTA and its N-Allyl and N-Benzyl Derivatives: Synthesis, Characterization and Biological Activity

From the well-known 1,3,5-triaza-phosphaadamantane (PTA, 1a), the novel N-allyl and N-benzyl tetrafuoroborate salts 1-allyl-1-azonia-3,5-diaza-7-phosphaadamantane (APTA(BF₄), 1b) and 1-benzyl-1-azonia-3,5-diaza-7-phosphaadamantane (BzPTA(BF₄), 1c) were obtained. These phosphines were then allowed to react with (Pt(μ-Cl)(C₆F₅)(tht))₂ (tht = tetrahydrothiophene) affording the water soluble Pt(II) complexes trans-(PtCl(C₆F₅)(PTA)₂) (2a) and its bis-cationic congeners trans-(PtCl(C₆F₅)(APTA)₂)(BF₄)₂ (2b) and trans-(PtCl(C₆F₅)(BzPTA)₂)(BF₄)₂ (2c). The compounds were fully characterized by multinuclear NMR, ESI-MS, elemental analysis and (for 2a) also by single crystal X-ray diffraction, which proved the trans configuration of the phosphine ligands. Furthermore, in order to evaluate the cytotoxic activities of all complexes the normal human dermal fibroblast (NHDF) cell culture were used. The antineoplastic activity of the investigated compounds was checked against the human lung carcinoma (A549), epithelioid cervix carcinoma (HeLa) and breast adenocarcinoma (MCF-7) cell cultures. Interactions between the complexes and human serum albumin (HSA) using fluorescence spectroscopy and circular dichroism spectroscopy (CD) were also investigated.

Light-stable polypyridine silver(i) complexes of 1,3,5-triaza-7-phosphaadamantane (PTA) and 1,3,5-triaza-7-phosphaadamantane-7-sulfide (PTA[double bond, length as m-dash]S): significant antiproliferative activity of representative examples in aqueous media

A series of novel silver(i) 2,2':6',2''-terpyridine (tpy), 4'-(4-methylphenyl)-2,2':6':2''-terpyridine (tpy-Ph-Me) and 1,10-phenanthroline-5,6-dione (dione) derivatives containing PTA (1,3,5-triaza-7-phosphaadamantane) or 1,3,5-triaza-7-phosphaadamantane-7-sulfide (PTA[double bond, length as m-dash]S) have been synthesized and fully characterized. Two types of complexes have been obtained, monocationic [Ag(tpy)(PTA)](NO₃) (1), [Ag(tpy-Ph-Me)(PTA)](NO₃) (2), [Ag(dione)(PTA[double bond, length as m-dash]S)](BF₄) (4) and [Ag(dione)₂](PF₆) (5) and neutral [Ag(dione)(PTA[double bond, length as m-dash]S)(NO₃)] (3). The solid-state structures of four complexes have been determined by single-crystal X-ray diffraction. Complexes 1 and 2 are luminescent at room temperature and 77 K while 5 shows emission only at 77 K. Compounds 3 and 4 are not emissive. Furthermore, representative light-stable and water-soluble 1 and 3 were evaluated for their cytotoxic activities on the normal human dermal fibroblast (NHDF) cell line and their antitumor activity using the human lung carcinoma (A549), epithelioid cervix carcinoma (HeLa) and human breast adenocarcinoma (MCF-7) cell lines. Interactions between the complexes and human serum albumin (HSA) using UV-Vis, fluorescence and circular dichroism spectroscopy (CD) were also investigated.