Metal Complexes Of Type Research Articles

The thermal behavior of silicone-based composite materials and the assessment of the gases that result from the thermal degradation process

A series of composite materials were prepared on the basis of polydimethylsiloxane (PDMS) having different siloxane functionality, filled with two types of metal complexes containing siloxane segment, derived from condensation of 1,3-bis(3-aminopropyl)tetramethyldisiloxane with 3,5-di-tert-butyl-2-hydroxibenzaldehyde and 5-chloro-2-hydroxibenzaldehyde. The main objective of the proposed study is to introduce transition metal complexes with Schiff-base ligands that contain siloxane spacers into the PDMS matrix and examine the effect these complexes have on thermal stability. We investigated the produced gases using thermogravimetry coupled with FTIR and MS in order to analyze the thermal stability and degradation pathways of a variety of silicone composite materials.

Square Planar Pt(II) Ion as Electron Donor in Pnictogen Bonding Interactions

It has been proposed that late transition metals with low coordination numbers (square planar or linear) can act as nucleophiles and participate in σ-hole interactions as electron donors. This is due to the existence, in this type of metal complexes, of a pair of electrons located at high energy d-orbitals (dz2 or dx2-y2), which are adequate for interacting with antibonding σ-orbitals [σ*(X–Y)] where Y is usually an electron withdrawing element and X an element of the p-block. This type of d[M]→σ*(X–Y) interaction has been reported for metals of groups 9–11 in oxidation states +1 and +2 (d8 and d10) as electron donors and σ-holes located in halogen and chalcogen atoms as electron acceptors. To our knowledge, it has not been described for σ-holes located in pnictogen atoms. In this manuscript, evidence for the existence of pnictogen bonding involving the square planar Pt(II) metal as the electron donor and Sb as the electron acceptor is provided by using an X-ray structure retrieved from the Cambridge Structural Database (CSD) and theoretical calculations. In particular, the quantum theory of atoms in molecules (QTAIM), the noncovalent interaction plot (NCIPlot) and molecular electrostatic potential (MEP) methods were used. Moreover, to further confirm the nature of the Sb···Pt(II) contact, a recently developed method was used where the electron density (ED) and electrostatic potential (ESP) distribution were compared along the Sb···Pt(II) bond path.

Binding ability of l-carnosine towards Cu2+, Mn2+ and Zn2+ in aqueous solution

A thermodynamic study on the interactions of a naturally occurring dipeptide, l-carnosine, and three transition metal cations, Cu2+, Mn2+ and Zn2+, is reported. Their characterization in solution evidences the chelating properties of carnosine that give rise to different types of metal complexes. Potentiometric data allowed to obtain a speciation model for each system, which includes species with 1:1 metal to ligand ratio for both Mn2+- and Zn2+- carnosine systems and 1:1 and 1:2 metal to ligand ratios for Cu2+. The dependence of formation constants of the complex species on ionic strength (in the range 0.15 ≤ I/mol/L ≤ 0.98) and temperature (288.15 ≤ T/K ≤ 310.15) was defined, as well as changes in enthalpy and entropy. 1H NMR titrations were also performed in the study of the Zn2+- carnosine system, and the results of the analysis of experimental data confirmed potentiometric ones. The integration with further investigation by High Resolution (HR) Matrix Assisted Laser Desorption Ionization (MALDI) Mass Spectrometry (MS) allowed to obtain the formation of species with 1:2 metal to ligand ratios for also Mn2+- and Zn2+- carnosine systems and to clarify the chelating mode. Finally, sequestering ability of carnosine towards Cu2+, Mn2+ and Zn2+ was quantified in physiological conditions (pH = 7.4, T = 310.15 K and I = 0.15 mol/L), and a sequestration profile of the dipeptide clearly describes its highest sequestering ability with respect to the Cu2+ ion, compared to that towards Mn2+ and Zn2+ cations.

Synthesis and Characterization of Metal Complexes Based on Aniline Derivative Schiff Base for Antimicrobial Applications and UV Protection of a Modified Cotton Fabric

Antimicrobial textiles have played an increasingly important protection role in the medical field. With this aim, Schiff bases and nanometal complexes on the cotton fabric were in situ synthesized for achieving the conventional cotton fabric’s highly efficient and durable UV protection and antibacterial properties. Herein, a new Schiff base derived from the condensation reaction of 2,4-dihyroxybenzaldehyde with p-amino aniline was synthesized. Co, Ni, Cu, and Zn complexes of the Schiff base were also prepared and characterized by UV-Vis, Fourier-transform infrared spectroscopy, 1HNMR, 13CNMR, elemental analysis, and thermal analysis. The modified cotton fabric was also characterized via X-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transition electron microscope (TEM), and Energy Dispersive X-Ray Analysis (EDX). Moreover, the microbial, UV protection, and tensile strength of the samples were investigated. The antimicrobial was studied against Gram-positive bacteria, Gram-negative bacteria, and fungal strains. Modified cotton fabric exhibited highly antibacterial activity in contrast with fungal activity. These results depended on the Schiff base and the type of metal complex. The results also show that the cotton fabric modified by in situ nanometal complexes provides excellent UV protection.

Achieving High-Performance Molecular Rectification through Fast Screening Alkanethiol Carboxylate-Metal Complexes Electroactive Units

Achieving High-Performance Molecular Rectification through Fast Screening Alkanethiol Carboxylate-Metal Complexes Electroactive Units

Nonlinear absorption in phthalocyanine thin films and solutions using a continuous wave laser

The nonlinear absorption of nanoscale thin films of iron phthalocyanine, zinc phthalocyanine, and metal-free phthalocyanine fabricated via thermal evaporation at various deposition temperatures was studied using the open-aperture z-scan method with a continuous wave laser. A solution of tetra-tert-butyl-phthalocyanine in chloroform was also studied via z-scan. The thin films exhibit pronounced saturable absorption, with the degree of nonlinearity highly dependent on the type of metal complex. No significant correlation was found between deposition temperature and nonlinear absorption. The liquid sample exhibits a transition from saturable absorption to reverse saturable absorption at high irradiance.

Synthesis, Characterization and Bioactivity Studies of S-Allyl-β-N-(1-(4-methoxyphenyl)- ethylidene)dithiocarbazate and its Bis-chelated Cu(II), Ni(II) and Zn(II) Complexes

The general formula M(mAp-sadtc)2 type of metal complexes (where M = Cu2+, Ni2+, Zn2+) were synthesized by reaction of S-allyl-β-N-(1-(4-methoxyphenyl)ethylidene)dithiocarbazate ligand [H-(mAp-sadtc)] with metal(II) acetate salts (M = Ni2+, Cu2+ or Zn2+). The bis-chelated metal complexes were synthesized by subsequent reaction of metal(II) acetate salts and dithiocarbazate ligand in 1:2 proportion, respectively. The metal complexes and dithiocarbazate Schiff base were characterized by available methods like elemental analysis, 1H NMR, UV-Vis spectroscopy, 13C NMR, FT-IR spectroscopy, molar conductance and magnetic moments. Both nitrogen atoms of azomethine moiety (C=N) and deprotonated thiolate sulfur of dithiocarbazate ligand coordinated to the central metal ion formed five-membered rings on chelation. The synthesized dithiocarbazate ligand [H-(mAp-sadtc)] (1) and its bis-chelated M(mAp-sadtc)2 complexes (2-4) were screened for bioactivity against bacterial strains. The antibacterial results show that the metal(II) complexes exhibited significantly prominent antibacterial activity than dithiocarbazate ligand. Among the synthesized bis-chelated metal complexes, Ni-complex exhibited prominent antibacterial and antifungal activity as compared to other metal(II) complexes and ligand.

Determination of Stability Constants and Thermodynamic Parameters for Ciprofloxacin-HCl With Some Transition Metal Ions by Potentiometric Titration Technique

This study included calculating the stability constants and stoichiometries of some binary complexes formed from the interaction of seven of metal ions (Cr+3,Mn+2,Co+2,Ni+2,Cu+2,Zn+2 and Cd+2) with Ciprofloxacin-HCl. This study was carried out using Potentiometric Titration Technique at different concentrations of the drug and the metal ion and at temperatures (288,298,310,318 and 328 K±0.1) in aqueous solution. Although, there are many methods available to study the stability of metal-ligand complexes, pH-metric is most frequently used to determine the stability constants. Hence, (Calvin - Bjerrum pH-metric titration technique) as adopted by Irving–Rossotti was used to calculate of stability constants. The results of the concentration effect study showed that the formation of complexes were more stable in dilute solutions, and through study of the temperature effect it was concluded that the stability of the complexes can be increased with raising temperature, and the stability constants value obtained were used in the calculation of thermodynamic parameters 〖(S〗^o,H,〖G〗^o). The results of this study also showed that the ciprofloxacin tends to form two types of metal complexes in the solution (ML1),(ML2) and this indicates that the reaction ratio between the drug and the metal ion was (1:1) and (1:2)(M:L) respectively for all metal ions. These ratios depended on the nature of the ligand or the metal ion, and the stability of the complexes formed increases according to the following arrangement (Mn+ 2< Co+ 2< Ni+ 2< Cu+ 2> Zn+ 2) and this arrangement is compatible with Irving Williams’s arrangement for the stability of the elements.

Dynamic electrochromic play via “mix-and-match” reversible metal-ligand interactions

In this issue of Chem, Zhang and co-workers report on the development of a novel methodology for creating electrochromic materials based on dynamic metal-ligand interactions. The proposed approach for the search of new systems is interesting and could allow fast developments in the area of electrochromic materials for non-emissive displays.

Determination of Stability Constants and Thermodynamic Parameters for Ciprofloxacin-HCl With Some Transition Metal Ions by Potentiometric Titration Technique

This study included calculating the stability constants and stoichiometries of some binary complexes formed from the interaction of seven of metal ions (Cr+3,Mn+2,Co+2,Ni+2,Cu+2,Zn+2 and Cd+2) with Ciprofloxacin-HCl. This study was carried out using Potentiometric Titration Technique at different concentrations of the drug and the metal ion and at temperatures (288,298,310,318 and 328 K±0.1) in aqueous solution. Although, there are many methods available to study the stability of metal-ligand complexes, pH-metric is most frequently used to determine the stability constants. Hence, (Calvin - Bjerrum pH-metric titration technique) as adopted by Irving–Rossotti was used to calculate of stability constants. The results of the concentration effect study showed that the formation of complexes were more stable in dilute solutions, and through study of the temperature effect it was concluded that the stability of the complexes can be increased with raising temperature, and the stability constants value obtained were used in the calculation of thermodynamic parameters . The results of this study also showed that the ciprofloxacin tends to form two types of metal complexes in the solution (ML1),(ML2) and this indicates that the reaction ratio between the drug and the metal ion was (1:1) and (1:2)(M:L) respectively for all metal ions. These ratios depended on the nature of the ligand or the metal ion, and the stability of the complexes formed increases according to the following arrangement (Mn+ 2< Co+ 2< Ni+ 2< Cu+ 2> Zn+ 2) and this arrangement is compatible with Irving Williams’s arrangement for the stability of the elements.

Interactions Between Ionic Liquid (ALiCY) and TBP and their Use in Hydrometallurgy for Extracting Co(II) and Ni(II)

Ionic liquids have emerged in hydrometallurgy as potential extractants for metals. In this work, the interactions of ALiCY (R4N&lt;sup&gt;+&lt;/sup&gt;A&lt;sup&gt;-&lt;/sup&gt;) synthesized by Aliquat336 and Cyanex272, and a mixture of ALiCY and TBP, were analyzed using extraction data and FT-IR spectroscopy. Co(II) and Ni(II) were extracted from two HCl concentrations (1.0×10&lt;sup&gt;-4&lt;/sup&gt; and 6.8 mol·L&lt;sup&gt;-1&lt;/sup&gt;) using ALiCY and its mixture with TBP. The extraction results indicated that ALiCY has a dual function, as a cationic extractant at low HCl concentration and an anionic extractant at high HCl concentration depending on the types of metal complexes. The addition of TBP to ALiCY had a negative effect on the extraction of Co(II) from the 6.8 mol·L&lt;sup&gt;-1&lt;/sup&gt; HCl, while the effect was negligible from the 1.010&lt;sup&gt;-4&lt;/sup&gt; mol·L&lt;sup&gt;-1&lt;/sup&gt; HCl. The solvation of R4N&lt;sup&gt;+&lt;/sup&gt; by TBP significantly affected the extraction behavior of ALiCY for metal ions. The formation of hydrogen bonding between TBP and Cyanex272 was verified. These findings shed light on the behavior and interaction occurring between bif-ILs and solvating extractants for the extraction of metals in acidic media.

Customizing the Structure, Composition, and Properties of Alloy Nanoclusters by Metal Exchange.

The properties of metal materials can be greatly enriched by including various elements to generate alloys. The galvanic replacement represents a classical method for the preparation of both bulk- and nanoalloy materials. The difference of the electrochemical potential between the two metals acts as the driving force for the galvanic replacement reaction. However, this classical rule partially fails at the ultrasmall size scale, for that novel chemistry emerges by the decrease of the size of materials down to less than 3 nm due to the strong quantum effect. In this Account, we discuss an emerging topic of nanochemistry, the metal exchange in atomically precise ultrasmall (<3 nm) metal nanoparticles (or nanoclusters). The metal exchange method uses different types of metal sources (e.g., AuBrPPh3 or AgSR complexes) to react with templating metal nanoclusters (e.g., Au25(SR)18-), and finally alloy nanoclusters are produced. We demonstrate that the metal exchange reaction between metal nanoclusters and metal complexes does not follow the classical metal activity sequence (i.e., Fe > Cd > Co > Ni > Pb > Cu > Hg > Ag > Pd > Pt > Au) and such metal exchange reactions in the nanocluster range is, to a large extent, related with the electron shell closing and the structural stability of nanoclusters. In the subsequent sections, we present effective control over the number, position, and distribution of the dopants. The shape and structure of the final alloy products can be tailored by recently developed metal exchange methods. More importantly, modulation and enhancement of the properties of NCs through metal exchange are realized. For example, the largely increased quantum yield and the significantly improved catalytic activity. In addition, we shall also discuss the real-time characterization of the metal exchange reaction by the combination of UV-vis absorption spectroscopy, high resolution electrospray ionization mass spectrometry (ESI-MS), matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and single crystal X-ray diffraction (SC-XRD). By controlling the charge of the templating metal nanoclusters and the different types of metal complexes, the driving force of metal exchange has been studied, which is considered to be the thermodynamics rather than the electrochemical potential. In summary, the metal exchange reactions in the ultrasmall nanocluster range are totally different compared with the case of larger-sized metal nanoparticles. Depending on this novel method, atomically precise alloy nanoclusters can be prepared by reacting the nanocluster composed of inert metal (such as Au) with complexes of high-activity metals (e.g., Cd/Hg/Cu/Ag). We anticipate that future research on the metal exchange will contribute to the fundamental understanding of reaction behavior of metal atoms in ultrasmall nanoclusters and to the design of alloy nanoclusters with enhanced properties.

Complexation equilibria of ambroxol hydrochloride in solution by potentiometric and conductometric methods

The formation constants of Li(I), Mg(II), Sr(II), Ca(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Ba(II), Pb(II), Al(III), Cr(III), Fe(III) and Th(IV) ions with ambroxol hydrochloride (AMB) were calculated using the half-n value. In presence of 0.1 M NaNO3, metal ions such as Zn(II), Cd(II), Ni(II), Cr(III), Li(I), Mg(II) and Al(III) forms three types of metal-ligand complexes (1:1, 1:2 and/or 1:3), while Sr(II) and Co(II) tend to form two types of metal complexes 1:1 and 1:2 (M:L). For ligand protonation constants, two logarithmic association constant values were calculated by the half-n method and are 10.7 and 7.6, respectively. The effect of ionic strength on stability constant of AMP, with different metal ions viz. Fe(III), Th(IV), Al(III), Cr(III) and Cu(II) was studied. Based on relationship between the ionic strength studied values and the 1st stability constants (Log K1H), we can conclude that the stability constants of the formed metal-ligand complex (1:1) were decreased as the ionic strength increased. The stoichiometry of the formed complexes in solution were determined by conductometric method and it is found to be of 1:1, 1:2 and/or 1:3 (M:L) complex species is formed in alkaline media. Also, study the species distribution diagrams of AMP for the calculated mole fraction αML and αML2 were discussed.

Palladium‐Assisted Cleavage of Peptides and Proteins Containing a Backbone with Thiazolidine Linkage

The design and synthesis of biomolecules that are responsive to external stimuli is of great interest in various research areas, such as in the preparation of smart biomaterial and chemical biology. Polypeptide backbone disassembly as a response to a particular stimulus is of interest, as it leads to a complete loss of the protein tertiary structure and, as a result, to a loss of function. In this study, a strategy based on palladium-assisted efficient cleavage of backbone thiazolidine linkage in peptides and proteins was developed. Using a fluorescence-based assay, encompassing ubiquitinated peptide with a quenching florescence pair, it was possible to optimize the cleavage step after rapid screening of various conditions, such as the type of metal complexes and reaction additives. The optimized conditions prompted fast cleavage of the thiazolidine linkage. The straightforward introduction of a backbone thiazolidine linkage in peptide and proteins coupled with the chemical methods used offers new opportunities in controlling macromolecule function and might, with the aid of cellular protein delivery methods, be applied in cellular settings.

Redox Behavior of the Hexacyanoferrate Complex Immobilized into an Ionic Liquid-Modified Electrode By Using Seiras Measurement

Self-assembled monolayer (SAM) is a useful technique to modify a functional compound on a surface. However, the compounds modified on a surface often change their chemical properties. We have recently studied an ionic liquid (IL)-modified surface as a new technique to immobilize a functional compound on a substrate surface and as a material providing a novel reaction field on the surface, instead of the typical SAM method. IL is an ionic compound being in the liquid state at room temperature and a designable compound. Previously, we modified a bulky phosphonium-type IL onto a Au electrode, and succeeded in entrapping three types of metal complexes into the vacant space formed with the IL molecules without any chemical bindings, regardless of the net charges of the complexes.1) The immobilization of the complexes into the surfaces were confirmed with the electrochemical measurements, which indicated that the electrochemical properties of the complexes were similar to those in homogeneous condition. However, we did not have any structural information about the surfaces. In order to investigate the structure of the compounds modified on the surface, the surface enhanced infra-red absorption spectroscopy (SEIRAS) measurement was applied on the IL modified electrode. The SEIRAS provides an enhanced IR absorption intensity by 10-100 times stronger than that of IR-RAS measurement and simultaneous electrochemical information.2) Therefore it is expected that the redox behavior of the compound entrapped on the surface can be observed spectroscopically. In this report, we will discuss the immobilization of a hexacyanoferrate (Fe(CN)6]3−/4−) complex into the IL-modified electrode and the redox behavior by using a SEIRAS measurement. We prepared a chemical deposited Au thin film on a Si prism as a working electrode. According to our previous report,1) the phosphonium type IL with a disulfide group has been modified on the Au electrode (IL/Au). The [Fe(CN)6]3−/4− complex was immobilized into the IL/Au by using CV measurement in the complex solution (Fe@IL/Au). The SEIRAS measurement of the IL/Au has performed during the electrochemical measurement. The IR band intensity assignable to C≡N group in the complex was increased gradually during the immobilization. After the immobilization, the redox potential of the complex immobilized on the surface has been observed at 0.1 V vs. Ag/AgCl. This redox potential is almost equal to that in an aqueous solution. The SEIRAS measurement of Fe@IL/Au was also performed during the electrochemical measurement. These results indicate that the environment of C≡N groups in Fe@IL/Au are different from the homogeneous conditions, suggesting that the coordinated C≡N groups statically interact to the cation parts of IL modified on the surface. 1) T. Kitagawa et al., Chem. Commun., 2013, 49, 10184-10186. 2) M. Osawa, et al., Appl. Spectroscopy., 1993, 47, 1497-1502. This study was supported by the Cooperative Research Program of Catalysis Research Center, Hokkaido University. Figure 1

Labile Low-Molecular-Mass Metal Complexes in Mitochondria: Trials and Tribulations of a Burgeoning Field.

Iron, copper, zinc, manganese, cobalt, and molybdenum play important roles in mitochondrial biochemistry, serving to help catalyze reactions in numerous metalloenzymes. These metals are also found in labile "pools" within mitochondria. Although the composition and cellular function of these pools are largely unknown, they are thought to be comprised of nonproteinaceous low-molecular-mass (LMM) metal complexes. Many problems must be solved before these pools can be fully defined, especially problems stemming from the lability of such complexes. This lability arises from inherently weak coordinate bonds between ligands and metals. This is an advantage for catalysis and trafficking, but it makes characterization difficult. The most popular strategy for investigating such pools is to detect them using chelator probes with fluorescent properties that change upon metal coordination. Characterization is limited because of the inevitable destruction of the complexes during their detection. Moreover, probes likely react with more than one type of metal complex, confusing analyses. An alternative approach is to use liquid chromatography (LC) coupled with inductively coupled plasma mass spectrometry (ICP-MS). With help from a previous lab member, the authors recently developed an LC-ICP-MS approach to analyze LMM extracts from yeast and mammalian mitochondria. They detected several metal complexes, including Fe580, Fe1100, Fe1500, Cu5000, Zn1200, Zn1500, Mn1100, Mn2000, Co1200, Co1500, and Mo780 (numbers refer to approximate masses in daltons). Many of these may be used to metalate apo-metalloproteins as they fold inside the organelle. The LC-based approach also has challenges, e.g., in distinguishing artifactual metal complexes from endogenous ones, due to the fact that cells must be disrupted to form extracts before they are passed through chromatography columns prior to analysis. Ultimately, both approaches will be needed to characterize these intriguing complexes and to elucidate their roles in mitochondrial biochemistry.

Inventory of metal complexes circulating in plant fluids: a reliable method based on HPLC coupled with dual elemental and high-resolution molecular mass spectrometric detection.

Description of metal species in plant fluids such as xylem, phloem or related saps remains a complex challenge usually addressed either by liquid chromatography-mass spectrometry, X-ray analysis or computational prediction. To date, none of these techniques has achieved a complete and true picture of metal-containing species in plant fluids, especially for the least concentrated complexes. Here, we present a generic analytical methodology for a large-scale (>10 metals, >50 metal complexes) detection, identification and semiquantitative determination of metal complexes in the xylem and embryo sac liquid of the green pea, Pisum sativum. The procedure is based on direct injection using hydrophilic interaction chromatography with dual detection by elemental (inductively coupled plasma mass spectrometry) and molecular (high-resolution electrospray mass spectrometry) mass spectrometric detection. Numerous and novel complexes of iron(II), iron(III), copper(II), zinc, manganese, cobalt(II), cobalt(III), magnesium, calcium, nickel and molybdenum(IV) with several ligands including nicotianamine, citrate, malate, histidine, glutamine, aspartic acid, asparagine, phenylalanine and others are observed in pea fluids and discussed. This methodology provides a large inventory of various types of metal complexes, which is a significant asset for future biochemical and genetic studies into metal transport/homeostasis.

Redox flexibility of iron complexes supported by sulfur-based tris(o-methylenethiophenolato)amine relative to its tripodal oxygen-based congener.

Tripodal ligands designed to generate a local C3 symmetry have resulted in novel types of metal complexes that feature unusual bonding and electronic properties. However, most complexes reported to date are characterised by strong field ligands that enforce low or intermediate-spin states for the metal centres. Moreover, anionic sulfur-based tripodal ligands are particularly scarce due to their challenging synthesis. In this context, we herein report the synthesis, spectral characterization, structural, and electronic properties of an iron complex supported by the tripodal, trianionic ligand [N(CH2ArS)3](3-) as the trigonal-bipyramidal complexes [Fe{N(CH2ArS)3}(X)] ((X), X = DMSO, THF). The solid-state structures reveal local C3v symmetry around the Fe(3+) ions, while electron spin resonance measurements established a high-spin state (S = 5/2). Electrochemical studies demonstrate the redox flexibility of the FeS3 fragment by direct comparison with the oxygen-based analogue N(CH2ArOH)3, which displays an irreversible reduction; in contrast, (THF) has a reversible Fe(3+)/Fe(2+) redox process at -0.83 V (relative to the ferrocenium/ferrocene redox couple). The high spin and redox properties of (THF) are attributable to the weak ligand field provided by the NS3 fragment, as confirmed by the electronic structure calculated by density functional theory, which reveals substantial electronic delocalisation and covalency of the Fe-S bonds in (X).

A versatile salicyl hydrazonic ligand and its metal complexes as antiviral agents

Acylhydrazones are very versatile ligands and their coordination properties can be easily tuned, giving rise to metal complexes with different nuclearities. In the last few years, we have been looking for new pharmacophores able to coordinate simultaneously two metal ions, because many enzymes have two metal ions in the active site and their coordination can be a successful strategy to inhibit the activity of the metalloenzyme. As a part of this ongoing research, we synthesized the acylhydrazone H2L and its complexes with Mg(II), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Their characterization, both in solution – also by means of potentiometric studies – and in the solid state, evidenced the ability of the o-vanillin hydrazone scaffold to give rise to different types of metal complexes, depending on the metal and the reaction conditions. Furthermore, we evaluated both the free ligand and its metal complexes in in vitro studies against a panel of diverse DNA- and RNA-viruses. In particular, the Mg(II), Mn(II), Ni(II) and Zn(II) complexes had EC50 values in the low micromolar range, with a pronounced activity against vaccinia virus.

ChemInform Abstract: Reactions of Pd and Pt Complexes with Molecular Oxygen

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