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Coordination Chemistry Reviews (v.250, #11-12)

Editorial Board (pp. co2).
Preface by Luigi Fabbrizzi (pp. 1209-1209).

Coordination and organometallic compounds and inorganic–organic hybrid crystalline materials for second-order non-linear optics by Elena Cariati; Maddalena Pizzotti; Dominique Roberto; Francesca Tessore; Renato Ugo (pp. 1210-1233).
This review concerns the main results obtained in the last few years by our research group at the Dipartimento di Chimica Inorganica Metallorganica e Analitica of the Università degli Studi di Milano, in the field of non-linear optics. After a brief introduction on the basic concepts of non-linear optics (NLO), we report our investigations on the second-order NLO properties of one-dimensional (1D) and 2D coordination and organometallic compounds and hybrid inorganic–organic crystalline materials. Our research has allowed to define some general rules for the design of new appealing NLO compounds and to isolate and identify some new interesting photonic materials.

Keywords: Non-linear optics; Hybrid materials; Organometallic and coordination compounds


Coordination chemistry of organic azides and amination reactions catalyzed by transition metal complexes by Sergio Cenini; Emma Gallo; Alessandro Caselli; Fabio Ragaini; Simone Fantauzzi; Cristiana Piangiolino (pp. 1234-1253).
The interaction of organic azides with transition metal complexes will be discussed with particular attention to the coordination modes of these molecules. The stoichiometric reactions of organic azides with coordinated ligands will be considered and their use in amination reactions catalyzed by transition metal complexes will be discussed in detail. The utility of these catalytic reactions for the synthesis of organic compounds will be stressed.

Keywords: Organic azides; Transition metal complexes; Homogeneous catalysis; Organic synthesis; Amination reactions


Ru(II)-bipyridine complexes in supramolecular systems, devices and machines by Vincenzo Balzani; Giacomo Bergamini; Filippo Marchioni; Paola Ceroni (pp. 1254-1266).
Because of a unique combination of chemical stability, redox properties, excited-state reactivity, and excited-state lifetime, [Ru(bpy)3]2+ (bpy=2,2′-bipyridine) and related complexes have long been used to obtain photoinduced intermolecular energy and electron-transfer processes. More recently these compounds have been employed as components to build up supramolecular species that exhibit peculiar photochemical and/or electrochemical properties. When suitably designed, such supramolecular species can behave as light-powered nanoscale electronic devices (e.g. wires, switches, antennas) or mechanical machines (e.g. shuttles). This paper reviews the results obtained in our research group on supramolecular species, devices and machines that exploit the properties of Ru(II) bipyridine complexes.

Keywords: Abbreviations; bpy; 2,2′-bipyridine; ph; 1,4-phenylene; 2,3-dpp; 2,3-bis(2-pyridyl)pyrazine; 2,5-dpp; 2,5-bis(2-pyridyl)pyrazine; biq; 2,2′-biquinolinePhotochemistry; Photophysics; Electrochemistry; Supramolecular chemistry; Molecular devices; Molecular machines


Design, synthesis, characterization and utilization of hydrogen bonded networks based on functionalized organometallic sandwich compounds and the occurrence of crystal polymorphism by Dario Braga; Stefano L. Giaffreda; Fabrizia Grepioni; Lucia Maini; Marco Polito (pp. 1267-1285).
The design and construction of hybrid organic–organometallic and inorganic–organometallic crystalline materials formed by hydrogen bonded functionalized organometallic sandwich compounds are described. It is shown that the ionic or neutral nature of the building blocks can be exploited to control the strength of intermolecular bonding and the structure–function relationship. The occurrence of crystal polymorphism associated with hydrogen bonded dimers and hydrogen bonded networks is discussed. It is also argued that solid–solid and solid–gas reactions involving preformed hydrogen bonded organometallic molecular crystals provide a viable “green� route to the preparation of novel hybrid molecular crystalline materials.

Keywords: Hydrogen bonded network; Crystal polymorphism; Solid-state chemistry; Organometallic compound


Reactive nitrogen species generated by heme proteins: Mechanism of formation and targets by Raffaella Roncone; Marica Barbieri; Enrico Monzani; Luigi Casella (pp. 1286-1293).
Nitration of tyrosine residues in proteins represents a pathological event that is associated with several human and animal diseases. Besides the classical pathways of formation of reactive nitrogen species (RNS) by NO oxidation, several studies show that heme peroxidases also play an important role in RNS generation. The mechanism of generation of these species has been studied in detail focusing on the nitration of several tyrosine and tryptophan derivatives. Also the O2-storage and O2-carrier heme proteins, myoglobin and hemoglobin, can induce RNS formation and promote self-nitration and oxidation. These reactions bear biological relevance and, therefore, the identification of the sites of endogenous modification of these proteins has been carried out by proteomic analysis.

Keywords: Abbreviations; Hb; human hemoglobin; hhMb; horse heart myoglobin; HMb; human myoglobin; HRP; horseradish peroxidase; LPO; lactoperoxidase; RNS; reactive nitrogen species; ROS; reactive oxygen speciesPeroxidase; Myoglobin; Hemoglobin; Reactive nitrogen species; Peroxynitrite; Nitrogen dioxide


Recent trends on nanocomposites based on Cu, Ag and Au clusters: A closer look by Lidia Armelao; Davide Barreca; Gregorio Bottaro; Alberto Gasparotto; Silvia Gross; Cinzia Maragno; Eugenio Tondello (pp. 1294-1314).
Nanocomposite materials based on metal nanoparticles (NPs, guest) in/on oxide matrices ( host) have attracted increasing attention thanks to their intriguing chemico-physical properties that can be tailored as a function of NP size, shape and mutual interactions. The possibility to obtain a controlled dispersion of metal particles in/on suitable oxides ( inside- and outside- cluster systems, respectively) paves the way to a broad spectrum of technological applications, ranging from heterogeneous catalysis, to gas sensing and non-linear optics. The control of functional performances relies on tailoring the system properties by design through a suitable choice of the synthesis and processing routes.In this context, the present review provides a synoptic overview on our recent research activity concerning nanocomposites containing 11th group metal clusters (Cu, Ag and Au), dispersed in/on oxide matrices (SiO2, TiO2, Al2O3). We begin by briefly outlining the interest and size-dependent properties of such systems. Subsequently, the attention is switched to a survey on the preparation strategies previously adopted in the literature, focusing in particular on the use of soft methods, such as sol–gel (SG), RF-sputtering and their innovative combination. The most relevant results on M′/M xO y nanocomposites (where M′=Cu, Ag, Au and M=Si, Ti, Al) obtained by these routes are then comparatively discussed, highlighting analogies and differences between them. Finally, the most attractive research perspectives in the field are briefly presented.

Keywords: Abbreviations; 0D; zero-dimensional; 1D; mono-dimensional; 2D; bi-dimensional; 3D; three-dimensional; α; Auger parameter; AAO; anodic aluminum oxide; AFM; atomic force microscopy; BE; binding energy; BF; bright field; CVD; chemical vapor deposition; DC; direct current; GIXRD; glancing incidence X-ray diffraction; EDS; energy dispersive X-ray spectroscopy; fcc; face-centered cubic; HR-TEM; high resolution-transmission electron microscopy; KE; kinetic energy; LRI; laser reflection interferometry; MDR; morphological dependent resonance; NPs; nanoparticles; NTs; nanotubes; p; total pressure applied to a plasma discharge; PE-CVD; plasma enhanced-chemical vapor deposition; R; reflectance; RF; radio-frequency; SAED; selected area electron diffraction; SEM; scanning electron microscopy; SERS; surface-enhanced Raman scattering; SG; sol–gel; SIMS; secondary ion mass spectrometry; SMMs; single-molecule magnets; SPR; surface plasmon resonance; t; deposition time; T; temperature; TEOS; tetraethoxysilane; V; bias; self-bias potential; W; RF-power applied to a plasma discharge; χ; (3); third-order non-linear susceptibility; XE-AES; X-ray excited auger electron spectroscopy; XPS; X-ray photoelectron spectroscopyMetal nanoparticles; Nanocomposites; Preparation techniques; Sol–gel; RF-sputtering


Non-covalent interactions in adducts of platinum drugs with nucleobases in nucleotides and DNA as revealed by using chiral substrates by Giovanni Natile; Luigi G. Marzilli (pp. 1315-1331).
Selective binding of coordinating agents (cisplatin) to target molecules (DNA) and the contribution of H-bonding, electrostatic interactions, and steric effects in such binding are fundamentally important subjects. To address some of these questions, simple models of the platinum–DNA cross-links, such as cis-(NH3)2PtG2 (G=detached or tethered guanine bases) complexes, have been investigated extensively. The fast interconversion between possible conformers on the NMR time scale led us to construct analogs of cisplatin with bulky ligands designed to reduce the dynamic motion by destabilizing the transition state for Pt-G rotation. The term “retro modeling� was introduced to emphasize that the models are more complicated than the relevant molecule, cisplatin. Retro models have been proved to be particularly useful in unraveling the existence of different conformations, and in the most favorable cases have also allowed the full characterization of the stereochemistry of single conformers. Moreover, several interligand interactions that escaped detection for a long time have been identified and grouped into three categories: First-to-First, First-to-Second, and Second-to-Second sphere Communication. A hierarchy ranking these interactions has been established. The new analysis has allowed us to rationalize computational, solution-state, and solid-state results on cross-linked oligonucleotides directly relevant to the cis-(NH3)2Pt adducts themselves.

Keywords: Abbreviations; 1-Me-5′-GMP; N1-methylguanosine-5′-monophosphate; A; 2; two amines or a diamine ligand; bip; 2,2′-bipiperidine; C; 2; two-fold rotation axis; CL; cross-link; CCC; chirality-controlling chelate ligands; dab; 2,3-diaminobutane; dach; 1,2-diaminocyclohexane; d(GpG); guanine bases N9-bridged by a deoxyribo-phosphodiester backbone; DS; double-stranded; en; 1,2-diaminoethane; FFC; first-to-first sphere communication; FSC; first-to-second sphere communication; G; guanine base, nucleoside, or nucleotide; GpG; guanine bases N9-bridged by a ribo-phosphodiester backbone; HH; head-to-head; HMG; high-mobility group; HMG1 or HMGB1; Protein containing HMG domain; HT; head-to-tail; Me; 2; dab; N; ,; N; ′-dimethyl-2,3-diaminobutane; Me; 2; dap; N; ,; N; ′-dimethyl-2,4-diaminopentane; Me; 2; en; N; ,; N; ′-dimethyl-1,2-diaminoethane (Me; 2; dae); Me; 2; pip; N; ,; N; ′-dimethyl-1,4-piperazine; NER; nucleotide excision repair; tn, trimethylenediamine (1; ,3-diaminopropane); SS; single-stranded; SSC; second-to-second sphere communicationNon-covalent interactions; Platinum–DNA; Antitumor drugs; Circular dichroism; Chiral diamines


X-ray structural chemistry of cobalamins by Lucio Randaccio; Silvano Geremia; Giorgio Nardin; Jochen Wuerges (pp. 1332-1350).
In recent years, X-ray structural determinations of cobalamins (Cbl) have become very accurate thanks to the use of new detectors and synchrotron radiation. This has allowed in depth study of the geometrical features of cobalamins, regarding the large equatorial ligand and, more importantly, their axial fragment, which is involved in the binding of Cbl to proteins and in the catalytic mechanisms of Vitamin B12 based enzymes. These structural aspects, together with their particular crystal packing, are the focus of this review. Several chemical properties, derived from their structural chemistry and not reported in other reviews, are underlined. A comparison to the well-known simple Cbl model, the cobaloximes is also presented and discussed, as this furnishes useful insights into cobalamin chemistry.

Keywords: X-ray crystallography; Cobalamin; Cobaloxime; Vitamin B; 12; B; 12; -enzyme model; cis; and; trans; effectAbbreviations; acacen; N; ,; N; ′-bis-(aceylacetone)ethylendiimine; AdoCbl; 5′-deoxyadenosylcobalamin (coenzyme B; 12; ); BDE; bond dissociation enthalpy; Bzm; 5,6-dimethylbenzimidazole; Cbl; cobalamin; DFT; density functional theory; DH; monoanion of dimethylglyoxime; E.S.D.; estimated standard deviation; ESR; electron spin resonance; MD; molecular dynamics; MeCbl; methylcobalamin; MM; molecular mechanics; NMR; nuclear magnetic resonance; rms; root mean square; salen; N; ,; N; ′-bis-(salicylaldehyde)-ethylendiimine


Mononuclear metallacarboranes of groups 6–10 metals: Analogues of metallocenes by Maddalena Corsini; Fabrizia Fabrizi de Biani; Piero Zanello (pp. 1351-1372).
Metallacarboranes containing carborane ligands possessing a pentagonal open face can coordinate metal atoms in a η5-manner quite similar to the cyclopentadienyl monoanion, thus affording metallocene analogues. By virtue of such an analogy, their electron transfer aptitude plays an important role in their physico-chemical characterisation. We review such an aspect, also providing evidence for the structural consequences of their electron transfer processes.At variance with metallocenes, electrochemical investigations on the metallacarboranes have not yet become a routine tool to search for their potential application in fields which require electronic mobility.

Keywords: Metallacarboranes; Metallocenes; Electrochemistry; X-ray


Azobenzenes and heteroaromatic nitrogen cyclopalladated complexes for advanced applications by Mauro Ghedini; Iolinda Aiello; Alessandra Crispini; Attilio Golemme; Massimo La Deda; Daniela Pucci (pp. 1373-1390).
The five-membered “(C,N)Pd� metallacycle is a structural feature common to a number of stable photoactive molecular materials. This review is centred on the connection among molecular geometries, types of ligand and photophysical, optical, thermal and electrooptical properties of several series of dinuclear and mononuclear cyclopalladated species, based on HC,N ligands (HC,N=azobenzenes or nitrogen containing heteroaromatic ligands). In the discussion, some representative examples of complexes featuring an useful set of physical properties, were selected and divided into different classes, depending on the nature of the ancillary ligands bonded to the “(C,N)Pd� fragment.

Keywords: Cyclopalladated complexes; Molecular materials; Liquid crystals; Luminescence; Photoconductivity; Photorefractivity


Ethylene oligomerization, homopolymerization and copolymerization by iron and cobalt catalysts with 2,6-(bis-organylimino)pyridyl ligands by Claudio Bianchini; Giuliano Giambastiani; Itzel Guerrero Rios; Giuseppe Mantovani; Andrea Meli; Anna M. Segarra (pp. 1391-1418).
In this review are highlighted the key advances that have occurred in the discovery and development of 2,6-bis(imino)pyridyl iron(II) and cobalt(II) catalysts for the transformation of ethylene into linear and branched homopolymers or into α-olefins with either Schulz–Flory or Poisson distribution. Particular attention has been paid to studies of the electronic and geometrical structure of both supporting ligands and metal complexes as well as to the mechanisms of precatalyst activation, chain-propagation and chain-transfer.

Keywords: Polyethylene; 2,6-Bis(iminopyridyl) ligands; Iron; Cobalt; Catalysis


An Italian contribution to structural genomics: Understanding metalloproteins by Fabio Arnesano; Lucia Banci; Ivano Bertini; Francesco Capozzi; Simone Ciofi-Baffoni; Stefano Ciurli; Claudio Luchinat; Stefano Mangani; Antonio Rosato; Paola Turano; Maria Silvia Viezzoli (pp. 1419-1450).
In this review, the contribution of the Magnetic Resonance Center of the University of Florence (CERM) to structural genomics is described. This contribution focuses on metalloproteins. Particular emphasis is given to those metalloproteins that belong to the same biochemical pathway, such as the proteins involved in copper trafficking, in metal detoxification, in the assembly of cytochrome c oxidase, and in the assembly of the urease nickel cofactor. Calcium-dependent signalling proteins studied at CERM are also reviewed, for their peculiar conformational features that are at the basis of the signalling process as well as for the importance of the methodological NMR approach based on the substitution of calcium with lanthanide ions. The structural determination in solution of iron–sulfur proteins and cytochromes was pioneered by us in a pre-genomic era and constitutes the methodological basis of the subsequent studies. Our methodological approach is indeed largely based on NMR, even if not exclusively, with important contributions deriving also from X-ray crystallography and X-ray absorption spectroscopy. The use of NMR is particularly useful for the characterization of proteins that occur in vivo as largely or completely unfolded, or that can become unfolded under extreme solution conditions or upon chemical manipulations. Examples in this sense are provided for the different classes of metal binding proteins and in particular for cytochromes and CuZn superoxide dismutase.Within the worldwide frame of structural genomics, we are pursuing also the characterization of known naturally occurring pathogenic mutations. As the three-dimensional structures provided by structural genomics projects constitute a starting database for post-genomic drug design, mention is also made to the perspectives in this field by reviewing our activity.

Keywords: Structural genomics; Metalloproteins; Protein structure


Some guidelines for the design of anion receptors by Valeria Amendola; Marco Bonizzoni; David Esteban-Gómez; Luigi Fabbrizzi; Maurizio Licchelli; Felix Sancenón; Angelo Taglietti (pp. 1451-1470).
Anions can be recognized by either positively charged or neutral artificial receptors. Positive charges within receptor's cavity can be provided by transition metal ions (e.g. CuII), which offer a binding site to one donor atom of the envisaged anion. Dicopper(II) bistren cryptates are ideal receptors for ambidentate anions, capable to bridge the two CuII centres: the size of the ellipsoidal cavity and consequent inclusion selectivity can be modulated by varying the length of the spacers linking the two tren subunits. Examples are discussed of the selective recognition of halides, polyatomic anions, aromatic and aliphatic dicarboxylates. Among neutral receptors, attention is centred to systems containing the urea subunit. Urea behaves as a bifurcate H-bond donor towards oxoanions. On the basis of equilibrium studies in aprotic solvents (mainly MeCN and DMSO), it is shown that the energy of the hydrogen bonding interaction and selectivity are solely related to the acidic tendencies of the receptor and to the basic properties of the anion. In particular, the H-bond interaction can be conveniently viewed as a more or less advanced (and ‘frozen’) proton transfer from theNH fragment of urea and the oxygen atom of the anion. Addition of excess fluoride may induce deprotonation of theNH fragment, essentially due to the unique stability of the [HF2]− self-complex which forms.

Keywords: Anion receptors; Oxoanions; H-bond


Photophysical properties of metal-mediated assemblies of porphyrins by Franco Scandola; Claudio Chiorboli; Anna Prodi; Elisabetta Iengo; Enzo Alessio (pp. 1471-1496).
The metal-driven construction of multi-porphyrin assemblies, which exploits the formation of coordination bonds between peripheral basic site(s) on the porphyrins and metal centers, has recently allowed the design and preparation of sophisticated supramolecular architectures whose complexity and function begin to approach the properties of naturally occurring systems. Within this framework, meso-pyridyl/phenyl porphyrins (PyPs), or strictly related chromophores, can provide geometrically well-defined connections to as many as four metal centers by coordination of the pyridyl peripheral groups. Several discrete assemblies of various nuclearities, in which the pyridylporphyrins are linkers binding metalloporphyrins and/or coordination compounds, have been constructed in recent years. In this review, we summarize recent work from our laboratories on metal-mediated multi-porphyrin assemblies and their photophysical properties. The review is organized as follows: after a brief summary of relevant concepts on energy and electron transfer processes and their implications in charge separation and the antenna effect (Section 2), the main assembling strategies leading to side-to-face and metal-mediated assemblies are synthetically reviewed (Section 3). The photophysical studies leading to the identification and kinetic characterization of the photoinduced energy and/or electron transfer processes within the supramolecular structures are surveyed in Section 4.

Keywords: Abbreviations; TPP; tetraphenylporphyrin; OEP; octaethylporphyrin; 4′MPyP; 5-(4′pyridyl)-10,15,20-triphenylporphyrin; 3′MPyP; 5-(3′pyridyl)-10,15,20-triphenylporphyrin; 4′-; cis; DPyP; 5,10-bis(4pyridyl)-15,20-diphenylporphyrin; 3′-; cis; DPyP; 5,10-bis(3′pyridyl)-15,20-diphenylporphyrin; 4′-; trans; DPyP; 5,15-bis(4′pyridyl)-10,20-diphenylporphyrin; 4′-; trans; DPyP-npm; 5,15-bis(4′-pyridyl)-2,8,12,18-tetranormalpropyl-3,7,13,17-tetramethylporphyrin; 4′TPyP; 5,10,15,20-tetra(4′pyridyl)porphyrin; 3′TPyP; 5,10,15,20-tetra(3′pyridyl)porphyrin; DPyPBI; N; ,; N; ′-di(4-pyridyl)-1,6,7,12-tetra(4-; tert; -butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide; pyz; pyrazine; pym; pyrimidine; dppp; 1,3-bis(diphenylphosphino)propane; OTf; triflateMulti-porphyrin assemblies; Metal-mediated assemblies; Pyridylporphyrins; Photo-induced processes; Electronic energy transfer; Electron transfer; Antenna effect


Ab initio molecular dynamics simulations of organometallic reactivity by Filippo De Angelis; Simona Fantacci; Antonio Sgamellotti (pp. 1497-1513).
The energetics and reaction mechanism of prototypical organometallic reactions have been investigated by combining static and dynamic density functional calculations, based on the Car–Parrinello method. Such an approach allows us to dynamically sample the potential energy surface of the reactive system at finite temperature, providing useful insights into the reaction mechanism and evidencing the presence of reaction intermediates. Applications of this methodology are presented, ranging from the migratory insertions of carbon monoxide and alkyl-isocyanides into different metal–carbon bonds, to the SiH oxidative addition to Pt(PH3)2 and the acetylene to vinylidene isomerization in the coordination sphere of a transition metal center.

Keywords: Ab initio molecular dynamics; Car-Parrinello; Organometallic reactivity; DFT calculations


EPR of molecular nanomagnets by Dante Gatteschi; Anne Laure Barra; Andrea Caneschi; Andrea Cornia; Roberta Sessoli; Lorenzo Sorace (pp. 1514-1529).
Electron paramagnetic resonance has played a crucial role in the determination of the properties and in explaining the origin of the peculiar behaviour of molecular nanomagnets, i.e., the slow relaxation of the magnetization at low temperature and the observation of quantum tunnelling of the magnetization. This is due to its ability to probe directly the spin levels rather than providing thermodynamic averages as in standard magnetic measurements. In particular, thanks to recent technical improvements in both reliability and sensitivity, high-field high-frequency EPR has gained widespread use for the characterization of these systems. We will briefly review here the different aspects underlying the use of this technique, highlighting some results of general interest obtained in the last decade on different class of magnetic clusters.

Keywords: Molecular nanomagnets; High frequency EPR; Magnetic properties; Magnetic anisotropy


Novel families of phthalocyanine-like macrocycles—Porphyrazines with annulated strongly electron-withdrawing 1,2,5-thia/selenodiazole rings by Maria Pia Donzello; Claudio Ercolani; Pavel A. Stuzhin (pp. 1530-1561).
Tetrakis(thiadiazole)porphyrazines and tetrakis(selenodiazole)porphyrazines, first described in the years 1998–2001, have later attracted the attention of different scientific groups in the world. Since the beginning and in the most recent times, a number of aspects concerning their relevance as phthalocyanine-like macrocycles, their distinct structural, electronic and UV–visible spectroscopic features, and electrochemical behavior have brought to knowledge the important role played by the externally annulated electron-withdrawing thia- and selenodiazole rings. Much has been learned about the acid–base properties of the new macrocycles, their facile electron uptake and negative charge redistribution capability within the entire macrocyclic framework. Further work has been directed to the synthesis and characterization of several low-symmetry species carrying peripherally annulated benzene or substituted benzene rings and thia- or selenodiazole rings and the structural and electronic effects caused by the progressive annulation of the heterocyclic rings in a basic phthalocyanine structure has been examined. Deselenation processes at the annulated selenodiazole rings in symmetrical and low-symmetry macrocycles and the formation of vicinal diamino functionalities have allowed diversified derivatization procedures with formation of new porphyrazine macrocycles by ring reclosure or designed external sites for exocyclic metalation in dinuclear species.

Keywords: Annulated porphyrazines; 1,2,5-Thia/selenodiazole; Synthesis; Structure; Spectroscopy; Electrochemistry; Acid–base properties


High sensitivity lanthanide(III) based probes for MR-medical imaging by S. Aime; S. Geninatti Crich; E. Gianolio; G.B. Giovenzana; L. Tei; E. Terreno (pp. 1562-1579).
To date, Gd(III) based contrast agents are commonly used in MR-medical imaging. In the last 15 years, our overall goal has been to develop targeting and responsive Gd(III) containing probes for innovative magnetic resonance imaging (MRI) applications. Understanding the relationships between structure and dynamics of lanthanide(III) chelates has been fundamental for the development of high sensitive Gd(III) based agents. Moreover, the observed relaxivity may act as a reporter of a specific parameter of the microenvironment in which the contrast agent distributes by using properly designed systems in which one structural or motional parameter is affected by the parameter of interest.From targeting human serum albumin for the development of angiographic agents, our research efforts are now addressing the visualization of molecules (characterizing diseased states) that are present at much lower concentration. By different routes, it has become possible to visualize, in an MR image, cells that have been labeled with Gd(III) chelates.Finally, the shift properties of paramagnetic lanthanide(III) complexes (Ln≠Gd) have been exploited for designing a novel class of contrast agents based on the transfer of saturated magnetization to the bulk water signal from exchangeable protons on the contrast agent molecules (chemical exchange saturation transfer (CEST) agents) or from water molecules interacting with a lanthanide shift reagent.

Keywords: Paramagnetic lanthanide(III) complexes; MRI contrast agents; Gd-complexes; CEST agents; Targeting agents; Responsive agents


The possible role of metal carbonyl clusters in nanoscience and nanotechnologies by Cristina Femoni; M. Carmela Iapalucci; Francesco Kaswalder; Giuliano Longoni; Stefano Zacchini (pp. 1580-1604).
Although a few nanosized metal carbonyl clusters were already obtained in the seventies, these structurally and compositionally well-defined molecules attracted the interest of nanoscientists only as possible precursors of finely dispersed metal particles for heterogeneous catalysis. This review article has the aim to give a brief account of most recent results in the field of high-nuclearity metal carbonyl clusters and their emerging properties. In doing that, a look to related behaviour of ligand-stabilised and ligand-free clusters, including almost mono-dispersed ligand-stabilised metal nanoparticles, is given. At the end, we will deliberately venture in some speculations on the possible contribution of metal carbonyl clusters to some aspects of nanoscience and nanotechnologies.

Keywords: Metal carbonyls; Clusters; Electrochemical behaviour; Magnetic properties; Functional materials; Nanomaterials


Lanthanide “second-generation� precursors for MOCVD applications: Effects of the metal ionic radius and polyether length on coordination spheres and mass-transport properties by Graziella Malandrino; Ignazio L. Fragalà (pp. 1605-1620).
The panorama of trishexafluoroacetylacetonato polyether complexes of rare-earth metals is considered. The methods of preparation have been classified according to the nature of the starting rare-earth metal. The relationship between the coordination sphere and mass-transport properties is discussed as well as applications of these adducts to metal organic chemical vapor deposition (MOCVD) processes of rare-earth containing films. This review represents the first comprehensive study of the “second-generation� MOCVD rare-earth metal precursors from syntheses to applications.

Keywords: MOCVD; Rare-earth; Adducts; Volatility; Thermal stability; Thin films
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