Synthesis and Characterization of Novel [2 + 1] Tricarbonyl Rhenium Complexes with the Hydrophilic Phosphine Ligands PTA and CAP

In the pursuit of hydrophilic model fac-[Re(CO)₃]⁺ complexes for (radio) pharmaceutical applications, six novel [2 + 1] mixed-ligand complexes of the general type fac-[Re(CO)₃(bid)P] were synthesized and characterized, where bid is a bidentate ligand bearing either (N, O) or (S, S′) donor atom sets and P is the hydrophilic phosphine 1,3,5-triaza-7-phosphoadamantane (PTA) or its macrocyclic homologue 1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane (CAP). The (N, O) ligands used in this study were picolinic and quinaldic acid, while the (S, S′) ligand was diethyldithiocarbamate. The complexes were synthesized in generally high yields and purity and the characterization was performed by spectroscopic methods, IR, NMR, and elemental analysis. Detailed X-ray crystallographic study of molecular packing by using Hirshfeld analysis tools revealed a plethora of intermolecular interactions such as hydrogen bond, π⋯π, C-H⋯π, and carbonyl-carbonyl interactions. To our knowledge, the CAP complexes reported herein are the first example of [2 + 1] mixed-ligand fac-[Re(CO)₃]⁺ complexes with CAP. The new complexes might have the potential to serve as platforms for the design of target-specific complexes with favorable pharmacokinetics.

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.

Cyclopalladated organosilane–tethered thiosemicarbazones: novel strategies for improving antiplasmodial activity

Ferrocenyl- and aryl-derived cyclopalladated organosilane thiosemicarbazone complexes were synthesised via C–H bond activation and evaluated for antiplasmodial activity.

Synthesis, antimicrobial and antiproliferative activity of novel silver(I) tris(pyrazolyl)methanesulfonate and 1,3,5-triaza-7-phosphadamantane complexes

Five new silver(I) complexes of formulas [Ag(Tpms)] (1), [Ag(Tpms)(PPh(3))] (2), [Ag(Tpms)(PCy(3))] (3), [Ag(PTA)][BF(4)] (4), and [Ag(Tpms)(PTA)] (5) {Tpms = tris(pyrazol-1-yl)methanesulfonate, PPh(3) = triphenylphosphane, PCy(3) = tricyclohexylphosphane, PTA = 1,3,5-triaza-7-phosphaadamantane} have been synthesized and fully characterized by elemental analyses, (1)H, (13)C, and (31)P NMR, electrospray ionization mass spectrometry (ESI-MS), and IR spectroscopic techniques. The single crystal X-ray diffraction study of 3 shows the Tpms ligand acting in the N(3)-facially coordinating mode, while in 2 and 5 a N(2)O-coordination is found, with the SO(3) group bonded to silver and a pendant free pyrazolyl ring. Features of the tilting in the coordinated pyrazolyl rings in these cases suggest that this inequivalence is related with the cone angles of the phosphanes. A detailed study of antimycobacterial and antiproliferative properties of all compounds has been carried out. They were screened for their in vitro antimicrobial activities against the standard strains Enterococcus faecalis (ATCC 29922), Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Streptococcus pyogenes (SF37), Streptococcus sanguinis (SK36), Streptococcus mutans (UA159), Escherichia coli (ATCC 25922), and the fungus Candida albicans (ATCC 24443). Complexes 1-5 have been found to display effective antimicrobial activity against the series of bacteria and fungi, and some of them are potential candidates for antiseptic or disinfectant drugs. Interaction of Ag complexes with deoxyribonucleic acid (DNA) has been studied by fluorescence spectroscopic techniques, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA-EB system on addition of Ag complexes shows that the fluorescence quenching of DNA-EB complex occurs and compound 3 is particularly active. Complexes 1-5 exhibit pronounced antiproliferative activity against human malignant melanoma (A375) with an activity often higher than that of AgNO(3), which has been used as a control, following the same order of activity inhibition on DNA, i.e., 3 > 2 > 1 > 5 > AgNO(3)≫ 4.

Thiolato gold(I) complexes containing water-soluble phosphane ligands: a characterization of their chemical and biological properties

A series of thiolate gold(I) derivatives bearing water soluble phosphanes--namely sodium triphenylphosphane monosulfonate (TPPMS), sodium triphenylphosphane trisulfonate (TPPTS), 1,3,5-triaza-7-phosphaadamantane (PTA) and 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA)--is reported and the compounds studied for their luminescence properties in the solid state. Two of these derivatives, [Au(SMe(2)pyrim)(PTA)] and [Au(SBenzoxazole)(DAPTA)], are also structurally characterized by X-ray diffraction analysis. Strong antiproliferative effects are observed for most of the compounds in the human ovarian carcinoma cell lines (A2780/S) and its cisplatin-resistant variant (A2780/R), which depend on both the type of thiolate and phosphane ligands. ICP-MS studies were also performed to evaluate the influence of the gold uptake on the cytotoxic potency of the compounds.

New water-soluble azido- and derived tetrazolato-platinum(II) complexes with PTA. Easy metal-mediated synthesis and isolation of 5-substituted tetrazoles

The water-soluble four- and five-coordinate diazido-platinum(II) complexes cis-[Pt(N3)2(PTA)2] (1) (PTA = 1,3,5-triaza-7-phosphaadamantane), cis-[Pt(N3)2(Me-PTA)2]I2 (2) (Me-PTA = N-methyl-1,3,5-triaza-7-phosphaadamantane cation) and [Pt(N3)2(PTA)3] (3) were obtained by reactions of cis-[Pt(N3)2(PPh3)2] with PTA or [Me-PTA]I in dichloromethane. [2 + 3] cycloadditions of with organonitriles NCR gave the bis(tetrazolato) complexes trans-[Pt(N4CR)2(PTA)2] (R = Ph (4), 4-ClC6H4 (5) or 3-NC5H4 (6)), the reactions being greatly accelerated by microwave irradiation. 5-R-1H-Tetrazoles N4CR (R = Ph, 4-ClC6H4 and 3-NC5H4) were easily liberated from the tetrazolato complexes and isolated in high yields, in a single-pot process, upon reaction with aqueous diluted HCl, with concomitant formation of the water soluble cis-[Pt(Cl)2(PTA-H)2] complex 7. Alternatively, in a less convenient method, the tetrazoles could be liberated on reaction of 4-6 with propionitrile which also leads to the dicyano trans-[Pt(CN)2(PTA)2] complex 8. The compounds were characterized by IR, 1H, 13C and 31P[1H] NMR spectroscopies, FAB+-MS or ESI-MS, elemental analyses and (for and 4) also by X-ray diffraction.

Cu(I) complexes bearing the new sterically demanding and coordination flexible tris(3-phenyl-1-pyrazolyl)methanesulfonate ligand and the water-soluble phosphine 1,3,5-triaza-7-phosphaadamantane or related ligands

The new sterically hindered scorpionate tris(3-phenylpyrazolyl)methanesulfonate (Tpms(Ph))(-) has been synthesized and its coordination behavior toward a Cu(I) center, in the presence of 1,3,5-triaza-7-phosphaadamantane (PTA), N-methyl-1,3,5-triaza-7-phosphaadamantane tetraphenylborate ((mPTA)[BPh4]) or hexamethylenetetramine (HMT) has been studied. The reaction between Li(Tpms(Ph)) (1) and [Cu(MeCN)4][PF6] yields [Cu(Tpms(Ph))(MeCN)] (2) which, upon further acetonitrile displacement on reaction with PTA, HMT, or (mPTA)[BPh4], gives the corresponding complexes [Cu(Tpms(Ph))(PTA)] (3), [Cu(Tpms(Ph))(HMT)] (4), and [Cu(Tpms(Ph))(mPTA)][PF6] (5). All the compounds have been characterized by (1)H, (31)P, (13)C, COSY or HMQC-NMR, IR, elemental analysis, and single crystal X-ray diffraction. In the complexes (3) and (5), which bear a phosphine ligand (i.e., PTA and mPTA, respectively), the new scorpionate ligand shows the typical N, N, N-coordination mode, whereas in (2) and (4), bearing a N-donor ligand (i.e., MeCN and HMT, respectively), it binds the metal via the N,N,O chelating mode, involving the sulfonate moiety.

Extending the coordination chemistry of 1,3,5-triaza-7-phosphaadamantane (PTA) to cobalt centers: first examples of co-PTA complexes and of a metal complex with the PTA oxide ligand

Water-soluble Co (III) and Co (II) complexes with P- or N-coordinated PTA or PTA oxide ligands, respectively, have been prepared and fully characterized, constituting the first examples of cobalt compounds bearing PTA or any ligand with a cage-like PTA core, the latter complex providing also the first PTA oxide coordination to a metal center.

1-Methyl-1-azonia-3,5-diaza-7-phosphatricyclo-[3.3.1.1]decane tetra-fluoro-borate

The title compound, C₇H₁₅N₃P⁺·BF₄⁻ or [PTA-Me][BF₄], is the N-methyl­ated derivative of the well known water-soluble amino­phosphine 1,3,5-triaza-7-phosphaadamantane (PTA). The asymmetric unit consists of a cage-like cation [PTA-Me]⁺ and a disordered tetra­fluoro­borate anion; two F atoms are disordered equally over two sites. A network of weak inter­molecular C—H⋯F hydrogen bonds results in a three-dimensional supra­molecular assembly.

1-Methyl-1-azonia-3,5-diaza-7-phospha-tricyclo-[3.3.1.1]decane 7-oxide triiodide

The title compound, C(7)H(15)N(3)OP(+)·I(3) (-), is a derivative of the well known water-soluble amino-phosphine 1,3,5-triaza-7-phosphaadamantane (PTA). The crystal structure is composed of a cage-like 1-methyl-1-azonia-3,5-diaza-7-phospha-tricyclo-[3.3.1.1]decane 7-oxide cation and a triiodide anion. The N-methyl-ation of the PTA cage results in a slight elongation of the corresponding C-N bonds, while the oxidation of the P atom leads to a slight shortening of the C-P bonds in comparison with those of PTA. In general, most of the bonding parameters are comparable with those reported for related compounds bearing the PTA core. Two inter-molecular C-H⋯O hydrogen bonds between methyl-ene groups and the P=O group are responsible for the linkage of neighbouring cations into linear one-dimensional hydrogen-bonded chains.