Isolation of the Au(SR)X compound (R = -butyl, -pentyl; X = Br, Cl): novel gold nanoclusters that exhibit properties subtly distinct from the ubiquitous icosahedral Au(SR) compound.

We report the identification and quantitative isolation of Au(SR)X (R = -butyl, -pentyl; X = halide) along with elucidation of key properties as compared to the corresponding ubiquitous chiral-icosahedral Au(SR) cluster known to have a central vacancy. The stoichiometries were assessed by electrospray mass spectrometry (ESI-MS) at isotopic resolution, and induced dissociation patterns indicate the 'extra' (Au,Br) atoms are strongly bound components of these structures. Voltammetric and spectroscopic characterization reveals Au(SR)X behaviors that are qualitatively similar to yet fascinatingly distinct from those of Au(SR).

Synthesis, Characterization and Biological Activity of Novel Cu(II) Complexes of 6-Methyl-2-Oxo-1,2-Dihydroquinoline-3-Carbaldehyde-4n-Substituted Thiosemicarbazones.

Three new 6-methyl-2-oxo-1,2-dihydroquinoline-3-carbaldehyde-thiosemicarbazones-N-4-substituted pro-ligands and their Cu(II) complexes (, -NH; , -NHMe; , -NHEt) have been prepared and characterized. In both the X-ray structures of and , two crystallographically independent complex molecules were found that differ either in the nature of weakly metal-binding species (water in and nitrate in ) or in the co-ligand (water in and methanol in ). Electron Paramagnetic Resonance (EPR) measurements carried out on complexes and confirmed the presence of such different species in the solution.

Metal Doping of Au(SR) Clusters: Insights and Hindsights.

The study of the structures and properties of atomically precise gold nanoclusters is the object of active research worldwide. Recently, research has been also focusing on the doping of metal nanoclusters through introduction of noble metals, such as platinum, and less noble metals, such as cadmium and mercury. Previous studies, which relied extensively on the use of mass spectrometry and single-crystal X-ray crystallography, led to the assignment of the location of each of these foreign-metal atoms.

Atomically precise Au(SR) nanoclusters (R = Et, Pr) are capped by 12 distinct ligand types of 5-fold equivalence and display gigantic diastereotopic effects.

For two decades, Au(SR) has been one of the most studied and used thiolate (SR) protected gold nanoclusters. In many ways, however, it proved to be a challenging and elusive case, also because of the difficulties in solving its structure by single-crystal X-ray crystallography. We used very short thiols and could prepare Au(SCH) and Au(SCH) in a very pure form, which was confirmed by UV-vis absorption spectroscopy and very regular electrochemistry patterns.

Nuclear and Electron Magnetic Resonance Spectroscopies of Atomically Precise Gold Nanoclusters.

Atomically precise gold nanoclusters display properties that are unseen in larger nanoparticles. When the number of gold atoms is sufficiently small, the clusters exhibit molecular properties. Their study requires extensive use of classic molecular physical chemistry and, thus, methods such as vibrational spectroscopies, electrochemistry, density functional theory and molecular dynamics calculations, and of course nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopies.

Gold Fusion: From Au(SR) to Au(SR), the Most Unexpected Transformation of a Very Stable Nanocluster.

The study of the molecular cluster Au(SR) has provided a wealth of fundamental insights into the properties of clusters protected by thiolated ligands (SR). This is also because this cluster has been particularly stable under a number of experimental conditions. Very unexpectedly, we found that paramagnetic Au(SR) undergoes a spontaneous bimolecular fusion to form another benchmark gold nanocluster, Au(SR).

Synthesis, characterization and cytotoxic activity of novel copper(II) complexes with aroylhydrazone derivatives of 2-Oxo-1,2-dihydrobenzo[h]quinoline-3-carbaldehyde.

Three new 2-oxo-1,2-dihydrobenzo[h]quinoline-3-carbaldehyde terminal substituted aroylhydrazone ligands (2-Oxo-1,2-dihydrobenzo[h]quinoline-3-carbaldehyde(2'-hydroxybenzoyl)hydrazine, HL1, 1, 2-Oxo-1,2-dihydrobenzo[h]quinoline-3-carbaldehyde(2'-hydroxybenzoyl)hydrazine, HL2, 2, 2-Oxo-1,2-dihydrobenzo[h]quinoline-3-carbaldehyde(2'-hydroxybenzoyl)hydrazine, HL3, 3) and the corresponding novel copper(II) complexes [Cu(L)(CHOH)(NO)](L = HL1 (4), HL2 (5), HL3 (6-6), have been synthesized to compare their coordination behaviour and biological activity with respect to the presence of an OH group in different positions of the phenyl ring in the hydrazone moieties. The new ligands and their copper complexes were characterized by elemental analysis and spectroscopic techniques. The molecular structures of the new complexes 4 and 6-6 were determined by single crystal X-ray diffraction.

A SERRS/MRI multimodal contrast agent based on naked Au nanoparticles functionalized with a Gd(iii) loaded PEG polymer for tumor imaging and localized hyperthermia.

Multimodal contrast agents offer new interesting diagnostic possibilities, summing the benefits of multiple imaging techniques. Magnetic resonance and optical imaging are complementary techniques. The first allows total body screening, even though it suffers from low spatial resolution and needs high loadings, whereas the second shows lower penetration, but bright signals, and a higher spatial resolution and needs lower loadings.

Ion Pair Formation between Tertiary Aliphatic Amines and Perchlorate in the Biphasic Water/Dichloromethane System.

The ability of aliphatic amines (AAs), namely, tripropylamine (TPrA), trisobutylamine (TisoBuA), and tributylamine (TBuA), to form ion pairs with perchlorate anion (ClO) in biphasic aqueous/dichloromethane (CHCl) mixtures containing ClO 0.1 M has been demonstrated by GC with flame ionization (FID) and mass detectors (MS) and by NMR measurements. The extraction efficiency of the AAs to the organic phase was modeled by equations that were used to fit the experimental GC data, allowing us to determine values for K (partition constant of the free AA), K (formation constant of the ion pair), and K (partition constant of the ion pair) for TPrA, TisoBuA, and TBuA at 25 °C.

A magnetic look into the protecting layer of Au clusters.

The field of molecular metal clusters protected by organothiolates is experiencing a very rapid growth. So far, however, a clear understanding of the fine interactions between the cluster core and the capping monolayer has remained elusive, despite the importance of the latter in interfacing the former to the surrounding medium. Here, we describe a very sensitive methodology that enables comprehensive assessment of these interactions.

Atom Transfer Radical Polymerization of Methacrylic Acid: A Won Challenge.

Polymerization of acidic monomers is one of the biggest challenges for atom transfer radical polymerization (ATRP). An intramolecular cyclization reaction leading to the loss of the C-X chain-end functionality was found to be the main reason for the partial termination of the growing polymer chains. Three approaches were used to overcome this problem: using Cl as the chain-end halogen, lowering the pH (to 0.

Smart and Covalently Cross-Linked: Hybrid Shape Memory Materials Reinforced through Covalent Bonds by Zirconium Oxoclusters.

The first examples of organic-inorganic hybrid materials reinforced by transition-metal oxoclusters that exhibit shape memory properties, based on the covalent incorporation of zirconium-based inorganic building blocks, are reported. Methacrylate-functionalized zirconium oxoclusters Zr O (OMc) and [Zr O (OH) (OOCCH CH ) {OOCC(CH )=CH } ] , with the covalent incorporation in a butyl acrylate (BA)/polycaprolactone dimethacrylate (PCLDMA) copolymer and the noncovalent incorporation of [Zr O (OH) (OOCCH CH ) ] are focused upon herein. Shape recovery and fixity rates are studied to observe if the shape memory properties are preserved upon going from a simple copolymer to noncovalent or covalent-based hybrids.

Gold nanowired: a linear (Au25)(n) polymer from Au25 molecular clusters.

Au25(SR)18 has provided fundamental insights into the properties of clusters protected by monolayers of thiolated ligands (SR). Because of its ultrasmall core, 1 nm, Au25(SR)18 displays molecular behavior. We prepared a Au25 cluster capped by n-butanethiolates (SBu), obtained its structure by single-crystal X-ray crystallography, and studied its properties both experimentally and theoretically.

Au₂₅(SEt)₁₈, a nearly naked thiolate-protected Au₂₅ cluster: structural analysis by single crystal X-ray crystallography and electron nuclear double resonance.

X-ray crystallography has been fundamental in discovering fine structural features of ultrasmall gold clusters capped by thiolated ligands. For still unknown structures, however, new tools capable of providing relevant structural information are sought. We prepared a 25-gold atom nanocluster protected by the smallest ligand ever used, ethanethiol.

Electron transfer through 3D monolayers on Au25 clusters.

The monolayer protecting small gold nanoparticles (monolayer-protected clusters, MPCs) is generally represented as the 3D equivalent of 2D self-assembled monolayers (SAMs) on extended gold surfaces. However, despite the growing relevance of MPCs in important applied areas, such as catalysis and nanomedicine, our knowledge of the structure of 3D SAMs in solution is still extremely limited. We prepared a large series of monodisperse Au25(SCnH2n+1)18 clusters (n=2, 4, 6, 8, 10, 12, 14, 16, 18) and studied how electrons tunnel through these monolayers.

Characterization and quantification of N-(3-aminopropyl)-N-dodecyl-1,3-propanediamine biocide by NMR, HPLC/MS and titration techniques.

The present paper reports the determination of the tri-amine N-(3-aminopropyl)-N-dodecyl-1,3-propanediamine (TA) present in a raw material called LONZABAC used to formulate various, widely used commercial biocides. The active principle, TA, is present in LONZABAC together with other molecules at lower concentration levels. Three independent analytical approaches, namely solution NMR spectroscopy, liquid chromatography coupled to high resolution mass spectrometry (LC/HRMS) and acid-base titration in mixed solvent, were used to overcome the problem of the non-availability of the active principle as high purity standard.

β-Fe2O3 nanomaterials from an iron(II) diketonate-diamine complex: a study from molecular precursor to growth process.

Iron oxide is a key multi-functional material in many different fields of modern technology. The β-Fe(2)O(3) cubic phase, one of the least studied Fe-O systems, was obtained by Chemical Vapor Deposition (CVD) using for the first time a Fe(II) β-diketonate diamine complex, Fe(hfa)(2)·TMEDA, as the molecular source (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N',N'-tetramethylethylenediamine). The strong visible light absorption of β-Fe(2)O(3) deposits highlights their possible functional application in photocatalytic hydrogen production under solar light.

Effect of the charge state (z = -1, 0, +1) on the nuclear magnetic resonance of monodisperse Au25[S(CH2)2Ph]18(z) clusters.

Monodisperse Au(25)L(18)(0) (L = S(CH(2))(2)Ph) and [n-Oct(4)N(+)][Au(25)L(18)(-)] clusters were synthesized in tetrahydrofuran. An original strategy was then devised to oxidize them: in the presence of bis(pentafluorobenzoyl) peroxide, the neutral or the negatively charged clusters react as efficient electron donors in a dissociative electron-transfer (ET) process, in the former case yielding [Au(25)L(18)(+)][C(6)F(5)CO(2)(-)]. As opposed to other reported redox methods, this dissociative ET approach is irreversible, easily controllable, and clean, particularly for NMR purposes, as no hydrogen atoms are introduced.

Platinum(II) chloride indenyl complexes: electrochemical and biological evaluation.

Four platinum(II) complexes of general formula [PtCl(η(1)-C(9)H(7))L(2)] [where L(2) is 1,2-bis(diphenylphosphino)ethane (dppe) 1 or cycloocta-1,5-diene (cod) 3] and [PtCl(2)L(2)] (where L(2) is dppe 2 or cod 4) were studied. Inhibition growth assays on human tumor cell lines evidenced for 1 and 3 an antiproliferative effect and, interestingly, the cytotoxic effect exerted by 1 is similar to that of cisplatin. Electrochemical and NMR measurements allowed us to determine the structural and redox properties.

From thioxo cluster to dithio cluster: exploring the chemistry of polynuclear zirconium complexes with S,O and S,S ligands.

Three different zirconium thio and oxothio clusters, characterized by different coordination modes of dithioacetate and/or monothioacetate ligands, were obtained by the reaction of monothioacetic acid with zirconium n-butoxide, Zr(O(n)Bu)4, in different experimental conditions. In particular, we isolated the three polynuclear Zr3(μ3-SSSCCH3)2(SSCCH3)6·2(n)BuOH (Zr3), Zr4(μ3-O)2(μ-η(1)-SOCCH3)2(SOCCH3)8(O(n)Bu)2 (Zr4), and Zr6(μ3-O)5(μ-SOCCH3)2(μ-OOCCH3)(SOCCH3)11((n)BuOH) (Zr6) derivatives, presenting some peculiar characteristics. Zr6 has an unusual star-shaped structure.

A new class of antitumor trans-amine-amidine-Pt(II) cationic complexes: influence of chemical structure and solvent on in vitro and in vivo tumor cell proliferation.

The reactions of cyclopropylamine, cyclopentylamine, and cyclohexylamine with trans-[PtCl2(NCMe)2] afforded the bis-cationic complexes trans-[Pt(amine)2(Z-amidine)2]2+[Cl-]2, 1-3. The solution behavior and biological activity have been studied in different solvents (DMSO, water, polyethylene glycol (PEG 400), and polyethylene glycol dimethyl ether (PEG-DME 500)). The biological activity was strongly influenced by the cycloaliphatic amine ring size, with trans-[Pt(NH2CH(CH2)4CH2)2{N(H) horizontal lineC(CH3)N(H)CH(CH2)4CH2}2]2+[Cl-]2 (3) being the most active compound.

Irreversible insertion of benzonitrile into platinum(II)-nitrogen bonds of nucleobase complexes. Synthesis and structural characterization of stable azametallacycle compounds.

Deprotonation of 1-methylcytosine (1-MeCy) and 9-methyladenine (9-MeAd) promoted by cis-[L(2)Pt(mu-OH)](2)(NO(3))(2) (L = PPh(3), PMePh(2), (1)/(2)dppe) in PhCN causes the irreversible insertion of a nitrile molecule into the Pt-N4 and Pt-N6 bonds of the cytosinate and adeninate ligands, respectively, to form the stable azametallacycle complexes cis-[L(2)PtNH=C(Ph){1-MeCy(-2H)}]NO(3) (L = PPh(3), 1; PMePh(2), 2; (1)/(2)dppe, 3) and cis-[L(2)PtNH=C(Ph){9-MeAd(-2H)}]NO(3) (L = PPh(3), 4; PMePh(2), 5) containing the deprotonated form of the molecules (Z)-9-N-(1-methyl-2-oxo-2,3-dihydropyrimidin-4(1H)-ylidene)benzimidamide and (Z)-N-(9-methyl-1H-purin-6(9H)-ylidene)benzimidamide. Single-crystal X-ray analyses of 2 and 4 show the metal coordinated to the N3 cytosine site [Pt-N3 = 2.112(7) A] and to the N1 site of adenine [Pt-N1 = 2.

Cytotoxicity of cis-platinum(II) cycloaliphatic amidine complexes: Ring size and solvent effects on the biological activity.

A series of new platinum(II) amidine derivatives of the type cis-[PtCl(2){Z-NHC(NHR)Me}(2)] (R=cyclopropyl, 1; cyclopentyl, 2; cyclohexyl, 3) were prepared in high yield by addition of the corresponding cyclic aliphatic amine RNH(2) to the coordinated acetonitrile ligands in cis-[PtCl(2)(NCMe)(2)]. The solution behaviour of 1-3 has been studied in DMSO, PEG 400 (polyethylene glycol) and PEG-DME 500 (polyethylene glycol dimethylether). The amidine complexes 1-3 were evaluated for their cytotoxic properties against a panel of human tumor cell lines containing examples of cervix (HeLa), breast (MCF7), lung (A549) and colon (HCT-15) cancer.

Evaluation of 2-methyl-3-hydroxy-4-pyridinecarboxylic acid as a possible chelating agent for iron and aluminium.

In view of a possible application to Fe and Al chelation therapy, 2-methyl-3-hydroxy-4-pyridinecarboxylic acid (DT2) was synthesised, and its complex formation, electrochemical and cytotoxic properties were studied. The complexing properties of DT2 towards Fe(III) and Al(III) were investigated in aqueous 0.6 m (Na)Cl at 25 degrees C by means of potentiometric titrations, UV-vis spectrophotometry, and 1H NMR spectroscopy.