Palladium complexes: new candidates for anti-cancer drugs

Platinum complexes which are most studied metal complexes due to their importance as adjuvant therapy of cancers aiming to induce tumor-cell-death. Some of the platinum-based antitumor drugs like cisplatin, carboplatin and oxaliplatin, have several disadvantages including side effects, cisplatin-resistant tumors, limited solubility in aqueous media, and so on. Thus, to achieve lower undesirable toxicity, enhanced solubility, and tumor selectivity, significant amount of work have been devoted to the preparation of modified platinum complexes. One of the ways to design the new anti-tumor agents related to cisplatin is to change the nature of central metal ion. Among the non-platinum metal complexes studied for cancer treatment, palladium(II) derivatives were readily chosen due to their structural analogy with those containing Pt(II) complexes. This review focuses on anti-tumor property of Pd(II) complexes and makes comparisons with similar property of cisplatin. Then, in the review, palladium(II) complexes have been classified according to their leaving ligands into palladium(II) complexes. In the last part, the most important factors affecting on the anti-tumor activity of the Pd(II) complexes were discussed. These factors are encouraging more researches in this field, for future applications.     

Organic–inorganic hybrid materials based on organophosphorus coupling molecules: from metal phosphonates to surface modification of oxides

Organophosphorus acids (phosphoric, phosphonic, and phosphinic) and their derivatives (salts, esters) are highly promising coupling molecules that allow the anchoring of organic groups to inorganic solids. In this article we briefly review our contribution in the preparation of materials based on organophosphorus coupling molecules: new sol–gel routes to microporous zirconium phosphonates and metal oxide/phosphonate or phosphinate hybrids, and surface modification of metal oxide nanoparticles. The potentialities of the sol–gel and surface modification approaches are illustrated by the immobilization of organometallic metal complexes using phosphine-phosphonate molecules. To cite this article: P.-H. Mutin et al., C. R. Chimie 6 (2003).     

Non-woven cotton fabric based intimately coupling of photocatalysis and biodegradation system for efficient removal of Cu(II) complex in water

The efficient remediation of heavy metal complexes in water has become a difficult and challenging task owing to their high stability and strong mobility. In this study, a novel strategy was employed for highly efficient removal of Cu-citrate by using intimately coupled photocatalysis and biodegradation (ICPB) system with non-woven cotton fabric as a carrier. Experimental results showed that the ICPB system caused 94% Cu removal, which was higher than those of single photocatalysis. After 5 cycles, Cu removal efficiency could still reach 78% within 5 h. The existence of 0–40 mg/L citrate had negligible influence, whereas the presence of 60–100 mg/L citrate exhibited a limited adverse effect on Cu removal (～70%). The decomplexation of Cu-citrate was realized via the function of free radicals and microorganisms. Two main processes, such as bio-adsorption of Cu²⁺ by microorganisms, deposition of Cu⁰ on the surface of material, played important role in Cu removal from aqueous solution. The dominant microorganisms in the system were Proteobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Chlorophyta, Planctomycetes, and Verrucomicrobia. Furthermore, the performance of ICPB system was also validated through treatment of other heavy metal complexes. This study provided a feasible strategy for the decontamination of heavy metal complexes in wastewater.     

Chemistry of λ-2H-azaphosphirene metal complexes

In this review, important aspects of λ³-2H-azaphosphirene metal complexes are discussed in relation to synthesis, physical properties and synthetic applications; ab-initio calculations on relative energies of CH₂NP isomers and of λ³-2H-azaphosphirene metal complexes (Cr, Mo, W) are also presented. Currently, there are three routes to this unsaturated three-membered ring system, which are discussed in detail: two of them use a rearrangement of metal carbene complexes, whereas the other relies on [2+1] cycloaddition reactions of electrophilic terminal phosphanediyl complexes and carbonitriles. The structural data show characteristics of a very strained heterocyclic ring system, which partially helps to understand the reactivity of this heterocycle complex in solution. The synthetic potential of λ³-2H-azaphosphirene metal complexes is illustrated by selected examples, which demonstrate their ability to serve, under very mild conditions as precursor for various new building blocks, i.e. nitrilium phosphanylide complexes, electrophilic terminal phosphanediyl complexes and phosphavinyl-nitrene complexes.     

Lability of nanoparticulate metal complexes in electrochemical speciation analysis

Lability concepts are elaborated for metal complexes with soft (3D) and hard (2D) aqueous nanoparticles. In the presence of a non-equilibrium sensor, e.g. a voltammetric electrode, the notion of lability for nanoparticulate metal complexes, M-NP, reflects the ability of the M-NP to maintain equilibrium with the reduced concentration of the electroactive free M²⁺ in its diffusion layer. Since the metal ion binding sites are confined to the NP body, the conventional reaction layer in the form of a layer adjacent to the electrode surface is immaterial. Instead an intraparticulate reaction zone may develop at the particle/medium interface. Thus the chemodynamic features of M-NP complexes should be fundamentally different from those of molecular systems in which the reaction layer is a property of the homogeneous solution (μ?=?(D _M/k _a ^′)^1/2). For molecular complexes, the characteristic timescale of the electrochemical technique is crucial in the lability towards the electrode surface. In contrast, for nanoparticulate complexes it is the dynamics of the exchange of the electroactive metal ion with the surrounding medium that governs the effective lability towards the electrode surface.     

The identity confirmation of 99gTc-DMSA complexes by using NMR and HPLC–MS/MS methods

The analyses of ^99gTc-DMSA complexes prepared under alkali and acidic reactions were reported. Modern analytical, separation and spectral methods such as NMR (¹H-NMR, ¹³C-NMR, APT, COSY and HSQC) and Q-TOF HPLC–MS/MS system with ESI were employed to determine the identity and characterization of the products. The structure of ^99gTc(V)DMSA was clearly confirmed and its fragmentation path in negative and positive ionisation mode was suggested. The effect of ascorbic acid and new alternative labelling with the use of NH ₄ ^99g TcOCl₄ was examined. Surprisingly, ^99gTc(III)DMSA complex was not formed under acidic reaction conditions. ^99gTc(V)DMSA complex was the main reaction product under both experimental conditions. This result suggests the key role of ^99g/99mTc concentration during the process of radiopharmaceuticals preparation.     

Stability Constants for Dimercaptosuccinic Acid with Bismuth(III), Zinc(II), and Lead(II)

Abstract

Stability constants for the complexation of zinc(II), lead(II), and bismuth(III) by the vicinal dithiolate chelating agent meso-dimercaptosuccinic acid (DMSA) have been determined by a combination of potentiometric titration and spectrophotometric competition at 25°C and 0.1 M ionic strength. The spectrophotometric studies use the shifts in the ultraviolet bands of the thiol groups to quantitate metal binding to DMSA in the presence of competitive aminocarboxylic acids. Bismuth(III) forms a bis(DMSA) chelate with an exceptionally high stability constant of 10^43,87. This complex undergoes a series of protonations over the pH range 10 to 2, but there appears to be no measurable dissociation of ligand over this pH range. The zinc-DMSA system is dominated by a Zn₂(DMSA)₂ dimer, which has a protonation constant of 10⁶ and dissociates completely at lower pH. No more than 20% of total zinc exists as a monomeric complex at any pH. Lead forms a 1:1 complex with a stability constant of 10^17,4. Insoluble protonated lead complexes precipitate at pH < 6.5. Speciation calculations have been used to evaluate the potential competition from serum zinc to the binding of Pb²⁺ and Bi³⁺ by DMSA. The results indicate that DMSA should be relatively effective for the in vivo chelation of both Bi³⁺ and Pb^{2 +}.     

A new approach to fabrication of a self-organizing film of heterostructured polymer/CdS nanoparticles

In this paper, we alternately deposit transition metal Cd²⁺ neutralized polyelectrolytes and ligands pyridine contained polymer via the formation of complexes, and by sequential reaction with H₂S gas, in situ fabricate CdS nanoparticles/polymer heterostructured film. The driving force for the construction of multilayered films is based on covalent coordination.     

Cu(II), Co(II), Ni(II), Mn(II), and Fe(II) metal complexes containing N,N′-(3,4-diaminobenzophenon)-3,5-But2-salicylaldimine ligand: Synthesis,structural characterization,thermal properties,electrochemistry, and spectroelectrochemistry

The synthesis, structure, spectroscopic and electro-spectrochemical properties of steric hindered Schiff-base ligand [N,N′-(3,4-benzophenon)-3,5-Bu^t₂-salicylaldimine (LH₂)] and its mononuclear Cu(II), Co(II), Ni(II), Mn(II) and Fe(II) complexes are described in this work. The new dissymmetric steric hindered Schiff-base ligand containing a donor set of NONO was prepared through reaction of 3,4-diaminobenzophenon with 3,5-Bu^t₂-salicylaldehyde. Certain metal complexes of this ligand were synthesized by treating an ethanolic solution of the ligand with an equimolar amount of metal salts. The ligand and its complexes were characterized by FT-IR, UV–vis, ¹H NMR, elemental analysis, molar conductivity and thermal analysis methods in addition to magnetic susceptibility, electrochemistry and spectroelectrochemistry techniques. The tetradentate and mononuclear metal complexes were obtained by reacting N,N′-(3,4-benzophenon)-3,5-Bu^t₂-salicylaldimine (LH₂) with some metal acetate in a 1:1 mole ratio. The molar conductance data suggest metal complexes to be non-electrolytes.     

99mTc-DMSA complex preparation: the effect of pH and tin(II) chloride amount on reaction

Labelling of meso-2,3-dimercaptosuccinic acid (DMSA) with technetium-99m was reinvestigated. Dependence of the ^99mTc-DMSA complex formation on the molar ratio of DMSA:reducing agent (SnCl₂·2H₂O) and pH was studied. Five different types of ^99mTc-DMSA complexes were determined. Especially three different complexes were established in the clinically used and prepared DMSA kit labelled with ^99mTc under alkaline condition. This radiopharmaceutical is used as imaging agent of the primary medullary carcinoma in the thyroid gland and different metastasis types. The existence of all complexes was observed by paper chromatography, paper electrophoresis and high performance liquid chromatography.     

Metal centered ligand field excited states: Their roles in the design and performance of transition metal based photochemical molecular devices

Transition metal complexes are vital components in a wide range of photooptical applications; these range from targeted drug delivery to devices for the conversion of solar energy to electrical and/or stored chemical energy. Metal centered (MC) ligand field excited states play important roles in the photophysics of those complexes having partially filled d-orbitals. This review offers a broad perspective on key investigations that have characterized the chemistry and physics of MC excited states in d³ and d⁶ transition metal complexes. It will also illustrate the impact of these excited states on various photooptical applications and highlight efforts to understand, control, and tune these MC excited states in the context of such applications.     

Green Synthesized Gold Nanoparticles as a Probe for the Detection of Fe3+ Ions in Water

Pure water which is free of toxic chemicals is necessary for human health. So, detection and control of heavy metal ions in water is very important. Keeping this in mind, selective and sensitive optical sensor based on surface plasmon resonance for detection of various heavy metals in water using gold nanoparticles was explained in this present study. These AuNPs were prepared using Hibiscus cannabinus leaf extract as reducing agent with the average particle size of 22 nm. These gold nanoparticles are considerably selective and sensitive towards Fe³⁺ and it was used to detect the concentration of Fe³⁺ ions in water in the range 29.82–173.74 μM by tracking the absorbance changes of SPR band and the sensitivity of the system towards the Fe³⁺ concentration and it was found to be 0.0037 μM^?1. We hope that these gold nanoparticles can be used for detecting Fe³⁺ ions concentration, in the water purification processes.     

Interaction of copper nanoparticles with liposomes

The reduction of copper(II) ions in an aqueous dispersion of positively charged liposomes results in the formation of stable sols of a complex of copper nanoparticles with the surface of liposomes. The mean size (7 nm) and the narrow size distribution of metal nanoparticles are similar to those observed in the case of metal sol formation in polymer solutions. The labile character of bonds between nanoparticles and liposomes makes the latter able to compete with a linear polymer (poly-N-vinylpyrrolidone) in binding to nanoparticles. This ability is manifested in the independence of an almost even distribution of nanoparticles between these competitors from the sol preparation mode in a system including both poly(N-vinylpyrrolidone) macromolecules and liposomes. The evenness of the distribution indicates an approximately identical stability of complexes of copper nanoparticles with both competitors. The replacement of liposomes with poly(N-vinylpyrrolidone) macromolecules in the protective shields of nanoparticles is accompanied by the detachment of the nanoparticles from the surface, thereby allowing the measurement of their size and size distribution in the case where such measurements are impossible because of a high density of nanoparticles on the liposome surface.     

Synthesis and characterization of an unsymmetric salicylaldimine ligand derived from 1-(2-Aminoethyl) piperazine and investigation of its analytical properties for the extraction and preconcentratoion of some divalent cations

The synthetic, structural, spectroscopic and analytical properties of steric hindered Schiff-base ligand [N-(3,5-di-tert-butylsalicylaldimine)-1-(2-Aminoethyl) piperazine (HL)] and its mononuclear Cu(II), Co(II) and Ni(II) complexes are described. The new unsymmetric steric hindered Schiff base ligand containing a donor set of NONO was prepared by the reaction of 1-(2-Aminoethyl) piperazine with 3,5-di-tert-butylsalicylaldehyde. Certain metal complexes of this ligand were synthesized by treating an ethanolic solution of the ligand with an equimolar amount of metal salts. The ligand and its metal complexes were characterized by FT-IR, UV-Vis, ¹H NMR, elemental analysis, molar conductivity and magnetic susceptibility techniques. The reaction of this ligand in a 1:2 mole ratio with metal acetate afforded mononuclear metal complexes. The molar conductivity (??_M) values of the metal complexes of Ni(II), Co(II) and Cu(II) were in the range of 6.4 to 9.8 ??^?1 cm² mol^?1 at room temperature. Preconcentration and separation of Cu²⁺ from aqueous solution using N-(3,5-di-tert-butylsalicylaldimine)-1-(2-Aminoethyl) piperazine (HL) as a new extractant were studied. The extraction experiments were carried out at various pHs. While Cu²⁺ showed the highest extractability and selectivity at pH 7.0, extractions of Co²⁺ and Ni²⁺ were unsuccessful due to precipitate formation.     

N‐Heterocyclic Carbene–Phosphinidyne Transition Metal Complexes

The N‐heterocyclic carbene–phosphinidene adduct IPr?PSiMe₃ is introduced as a synthon for the preparation of terminal carbene–phosphinidyne transition metal complexes of the type [(IPr?P)ML_n] (ML_n=(η⁶‐p‐cymene)RuCl) and (η⁵‐C₅Me₅)RhCl). Their spectroscopic and structural characteristics, namely low‐field ³¹P NMR chemical shifts and short metal–phosphorus bonds, show their similarity with arylphosphinidene complexes. The formally mononegative IPr?P ligand is also capable of bridging two or three metal atoms as demonstrated by the preparation of bi‐ and trimetallic RuAu, RhAu, Rh₂, and Rh₂Au complexes.     

Metal chelates of heterocyclic nitrogen-containing ketones: XVII. effect of temperature and gamma irradiation on the electrical conductivity of 2-quinaldyl phenyl ketone and its metal complexes

The measurements of the electrical conductivity of 2-quinaldyl phenyl ketone, QPK, and its metal complexes were carried out in the temperature range 298–373 K. These compounds are found to possess semiconducting behaviour. The effect of gamma-irradiation on the electrical conductivity of these compounds in the 10³–10⁷ rad range was studied. The conductivity of the complexes decreased on increasing the radiation dose and approaches that of the ligand. The increase in the activation energy, ΔE (eV), by radiation was found to be dependent on the crystal field stabilization energy in the case of a high spin tetrahedral field and the ionic potential of the metal ion.     

The unusual coordination chemistry of phosphorus-rich linear and cyclic oligophosphanide anions

In this review, the synthesis, reactivity and properties of linear and cyclic oligophosphanides are described. Specifically the structures and versatile reactivity of the anionic ligands (P₄R₄)^2? (R = Bu^t, Ph, Mes), (P₄HR₄)^? (R = Ph and Mes) and cyclo-(P₅Bu^t₄)^? towards main group and transition metal complexes is elucidated. In addition, potential application of metal oligophosphanides as precursors for the preparation of metal phosphides is also briefly discussed.     

New Mononuclear and Binuclear Cu(II), Co(II), Ni(II), and Zn(II) Thiosemicarbazone Complexes with Potential Biological Activity: Antimicrobial and Molecular Docking Study

Herein, we report the synthesis of eight new mononuclear and binuclear Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ methoxy thiosemicarbazone (MTSC) complexes aiming at obtaining thiosemicarbazone complex with potent biological activity. The structure of the MTSC ligand and its metal complexes was fully characterized by elemental analysis, spectroscopic techniques (NMR, FTIR, UV-Vis), molar conductivity, thermogravimetric analysis (TG), and thermal differential analysis (DrTGA). The spectral and analytical data revealed that the obtained thiosemicarbazone-metal complexes have octahedral geometry around the metal center, except for the Zn²⁺-thiosemicarbazone complexes, which showed a tetrahedral geometry. The antibacterial and antifungal activities of the MTSC ligand and its (Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) metal complexes were also investigated. Interestingly, the antibacterial activity of MTSC- metal complexes against examined bacteria was higher than that of the MTSC alone, which indicates that metal complexation improved the antibacterial activity of the parent ligand. Among different metal complexes, the MTSC- mono- and binuclear Cu²⁺ complexes showed significant antibacterial activity against Bacillus subtilis and Proteus vulgaris, better than that of the standard gentamycin drug. The in silico molecular docking study has revealed that the MTSC ligand could be a potential inhibitor for the oxidoreductase protein.