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Platinum compounds cytotoxicity is strictly related to their ability to be converted into active mono- and di-aquated species and consequently to the replacement of labile ligands by water molecules. This activation process makes the platinum center prone to nucleophilic substitution by DNA purines. In the present work, quantum mechanical density functional theory (DFT) computations and experimental investigations were carried out in order to shed light on the relationship between the internalization, aquation, and DNA binding of two isostructural anionic theranostic complexes previously reported by our group, NBu 4 [(PhPy)Pt(Aliz)], 1 ( IC 50 1.9 ± 1.6 μM), and NBu 4 [(PhPy)Pt(BrCat)], 2 ( IC 50 52.8 ± 3.9 μM). Cisplatin and a neutral compound [(NH 3 ) 2 Pt(Aliz)], 3 , were also taken as reference compounds. The computed energy barriers and the endergonicity of the hydrolysis reactions showed that the aquation rates are comparable for 1 and 2 , with a slightly higher reactivity of 1 . The second hydrolysis process was proved to be the rate-determining step for both 1 and 2 , unlike for compound 3 . The nucleophilic attack by the N7 site of guanine to both mono- and di-aquated forms of the complexes was computationally investigated as well, allowing to rationalize the observed different cytotoxicity. Computational results were supported by photostability data and biological assays, demonstrating DNA as the main target for compound 1 .

The synthesis and the electrochemical, photophysical, structural, and photoconductive properties of three new heteroleptic Pd(II) complexes with various 3',5'- disubstituted-2-(2'-pyridil) pyrroles H(N^N) as coordinated ligands are reported. The coordination of the metal center was completed by a functionalized Schiff base H(O^N) used as an ancillary ligand. The [(N^N)Pd(O^N)] complexes showed highly interesting photoconductive properties which have been correlated to their electronic and molecular structures. Theoretical density functional theory (DFT) and time-dependent DFT calculations were performed, and the results were confronted with the organization in crystalline phase, allowing to point out that the photoconductive properties are mainly a consequence of an efficient intramolecular ligand-to-metal charge transfer, combined to the proximity between the central metal and the donor moieties in the solid-state molecular stacks. The reported results confirm that these new Pd(II) complexes form a novel class of organometallic photoconductors with intrinsic characteristics suitable for molecular semiconductors applications.

The focus of this work is pointing out the different behavior of two structurally related Pt (II) complexes, the anionic cyclometalated NBu 4 [(Bzq)Pt(Thio)], 1 and the neutral [(Phen)Pt(Thio)], 2, (Bzq = benzo[h]quinoline, Phen = 1,10-phenantroline, Thio = 1,2-benzenedithiolate), on the interaction with human serum albumin (HSA), a key drug-delivery protein in the bloodstream. Being very limited the number of anionic Pt (II) complexes reported to date, this is a pioneering example of report on a protein-ligand interaction involving a negatively charged platinum compound. The study was carried out by using fluorescence spectroscopy, differential scanning calorimetry and molecular docking simulations. The results revealed a strong binding affinity between the anionic compound and the protein, whereas a weak/moderate binding interaction was highlighted for the neutral one. Comparative studies with site specific ligands (warfarin and ibuprofen), allowed us to identify the protein binding sites of the two compounds. The work aims to shed light on the relevance of the charge in designing new drugs with a favorable binding affinity for HSA, which strongly contributes to influence their pharmacological and toxicological profile., Competing Interests: Declaration of competing interest The authors declare that they have NO affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Neutral cyclometalated Ir(iii) complexes of general formula [Ir(ppy)2(O^O)squi], where ppy = 2-phenylpyridine and (O^O)squi = TBC (tetrabromocatechol) or TCC (tetrachlorocatechol) in their semiquinone (squi) monoanionic redox state, were synthesized by chemically oxidizing the anionic parent complexes NBu4[Ir(ppy)2(O^O)cat], in which (O^O)cat represents the corresponding ancillary dioxolene ligand in its dianionic catecholate (cat) redox state. This chemical oxidation leads to the modification of both the photophysical and the magnetic properties of the complexes. While the NBu4[Ir(ppy)2(O^O)cat] complexes are diamagnetic (D) and yellow-orange solids, the corresponding oxidized complexes [Ir(ppy)2(O^O)squi] display paramagnetic (P) properties and are characterized by a dark-green color. The conversion between the two forms (squi vs. cat) is electrochemically and chemically fully reversible. Indeed, the anionic NBu4[Ir(ppy)2(O^O)cat] complexes are quantitatively restored by chemical reduction of the neutral [Ir(ppy)2(O^O)squi] parents. These complexes therefore represent interesting redox based switches between multi-parameter states since they allow switching from a neutral paramagnetic to an anionic diamagnetic form together with a significant change in chromicity. Taking advantage of the significant color difference between the oxidized and the reduced form, an electrochromic cell was prepared with [Ir(ppy)2(TBC)squi] and its spectroelectrochemical properties are reported.

The ability of Nile Red to self-assemble into supramolecular packings on Au(111) was studied using scanning tunneling microscopy and modeled through theoretical semiempirical calculations. At both submonolayer (sub-ML) and ML coverages, two distinct molecular packings, that is, four-leaf clover and dense chain, were observed, both weakly interacting with the underlying metal surface. Theoretical calculations suggested that the dipole moment plays a subtle role in both molecular assemblies, held together by hydrogen bonds between the Nile Red molecules. Furthermore, although both molecular assemblies were observed in as-deposited samples, a mild thermal annealing caused the transition from the four-leaf clover to the dense-chain packing, pointing out the greater stability of the dense-chain configuration. The study further emphasized how the established interactions between the Nile Red molecules are strongly influenced by the surrounding environment.

A series of electropolymerizable cyclometallated Ir III complexes were synthesized and their electrochemical and photophysical properties studied. The triphenylamine electropolymerizable fragment was introduced by using triphenylamine-2-phenylpyridine and, respectively, triphenylamine-benzothiazole as cyclometalated ligands. The coordination sphere was completed by two differently substituted β-ketoiminate ligands deriving from the condensation of acetylacetone or hexafluoroacetylacetone with para-bromoaniline. The influence of the -CH 3 /-CF 3 substitution to the electrochemical and photophysical properties was investigated. Both complexes with CH 3 substituted β-ketoiminate were emissive in solution and in solid state. Highly stable films were electrodeposited onto ITO coated glass substrates. Their emission was quenched by electron trapping within the polymeric network as proven by electrochemical studies. The -CF 3 substitution of the β-ketoiminate leads instead to the quenching of the emission and inhibits electropolymerization., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Novel anionic cyclometalated Pt(ii) square-planar complexes NBu4[(C^N)PtII(S^S)], containing 2-phenylpyridine H(PhPy), 2-(2,4-difluorophenyl)-pyridine H(F2PhPy) and benzo[h]quinoline H(Bzq), respectively, as a cyclometalated ligand and the dianionic 1,2-benzenedithiolate (Thio)2- fragment as an (S^S) ligand, were synthesised. By the simple addition of an equivalent of (Thio)2- to the NBu4[(C^N)PtII(Thio)] complexes, octahedral anionic NBu4[(C^N)PtIV(Thio)2] analogues were obtained, representing, to the best of our knowledge, the first examples of Pt(iv) anionic cyclometalated complexes. The molecular structures of the obtained complexes in the case of the NBu4[(Bzq)PtII(Thio)] and the NBu4[(Bzq)PtIV(Thio)2] complexes were confirmed by single crystal X-ray diffraction analysis. Furthermore, the electrochemical and photophysical properties of the two series of Pt(ii) and Pt(iv) newly synthesised complexes were studied and DFT and TD-DFT calculations were performed in order to comprehensively investigate the displayed behaviour. All Pt(ii) and Pt(iv) complexes show intense luminescence in the solid state, with remarkable enhancement of the emission quantum yields, proving to be excellent examples of aggregation-induced emission systems.

A nanoplatform for simultaneous cellular imaging, and photodynamic and photothermal therapies has been designed and realized by embedding a purposely synthesized highly luminescent water soluble iridium(iii) compound into gold core-silica shell nanoparticles. These multifunctionalities arise mainly from the photophysical properties of the cyclometalated complex: (i) the heavy atom promotes, through excited triplet state formation, energy transfer processes towards molecular oxygen, with the generation of 1 O 2 (photodynamic effect); (ii) the overlap of the iridium(iii) complex emission band with the plasmonic resonance of gold nanostructures allows excitation energy transfer towards the metallic core (photothermal effect); (iii) the remarkable iridium(iii) complex luminescence feature, which is preserved despite energy transfer processes, makes the whole system an efficient luminescent bio-probe (imaging). Photophysical and photothermal investigations have been carried out, whereas in vitro photo-cytotoxicity tests have been performed on human glioblastoma cells (U87MG), highlighting significant cancer cell death at a very low photosensitizer concentration (<0.5 μM), by means of a synergistic photodynamic and photothermal effect.

The preparation and characterization of a new metallogelator based on the Ir III discrete cyclometalated complex [(ppy) 2 Ir(bpy)](CH 3 CH 2 OCH 2 CO 2 ) are reported, where H(ppy) is 2-phenylpiridine and bpy is 2,2'-bipyridine, which is used as an ancillary ligand. The compound is able to self-assemble in water in a range of concentrations between 3 % and 6 % w/w, creating a luminescent ordered supramolecular gel. The gel and xerogel architectures were investigated through polarized optical microscopy (POM), SEM and TEM microscopies coupled with powder X-ray diffraction. The gel supramolecular organization is characterized by columnar tetragonal strands, already present at high dilution conditions, of cations surrounded by counteranions. These strands, in turn, are self-assembled in an oblique columnar cell upon gelification. The xerogel thin films obtained upon complete dehydration maintained the gel supramolecular order and can be used as a precursor for the preparation of nanostructured IrO 2 thin films., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Two series of novel NBu 4 + salts of anionic cyclometallated Pt(ii) complexes were synthesized and fully characterized. These highly luminescent compounds (NBu 4 [(C^N)Pt(O^N)] and NBu 4 [(C^N)Pt(O^O)]) are incorporated as testing examples of cyclometallating ligands 2-phenylpyridine (PhPy), 2-(2,4-difluorophenyl)-pyridine (F 2 PhPy) and 2-thienylpyridine (ThPy), and a benzo[h]quinoline (Bzq) fragment. All complexes display a square-planar coordination sphere, wherein the "(C^N)Pt" fragment is completed either by an O^N orotate (Ort) or an O^O tetrabromocatecholate (Cat) ligand. The HOMO and LUMO levels of all complexes were estimated by cyclic voltammetry and a comprehensive electrochemical and photophysical study was performed. The new complexes are emissive in solution at 298 K and the NBu 4 [(ThPy)Pt(Ort)] complex displays good photosensitizing properties (Φ = 28% in deaerated solution vs. Φ = 1.4% in the presence of O 2 ). Both series of NBu 4 [(C^N)Pt(Ort)] and NBu 4 [(C^N)Pt(Cat)] complexes are highly luminescent in the solid state (emission quantum yields from 10 to 85%). Remarkably, the square-planar Pt(ii) anionic complexes showed an important increase in luminescence quantum yields on changing from the dilute solution to the solid state (the most significant from 0.13% to 85% for the NBu 4 [(PhPy)Pt(Ort)] complex, an ideal candidate as an active species for LEECs).

The synthesis and photophysical characterization of a new family of luminescent water-soluble ionic iridium(iii) complexes of the general formula [(ppy) 2 Ir(bpy)]X are reported. The Ir(iii) complexes incorporate a cyclometalated 2-phenylpyridine (ppy), the ancillary ligand 2,2'-bipyridyl (bpy) and different counterions (X - = EtO - , OH - , EtOCH 2 CO 2 - , MeOCH 2 CO 2 - ). These complexes were obtained starting from the cyclometalated Ir(iii) chloro-bridged dimer [(ppy) 2 Ir(μ-Cl)] 2 , for the first time synthesized through a new microwave assisted synthetic procedure, and subsequently converted into the corresponding hydroxy-bridged dimer [(ppy) 2 Ir(μ-OH)] 2 . The latter was eventually used as a sole reagent for the synthesis of all the reported complexes by simply varying the nature of the reaction solvent from water to alcohols and glycol ethers. This study demonstrates the versatility of the [(ppy) 2 Ir(μ-OH)] 2 complex as a precursor to water soluble ionic Ir(iii) complexes. Indeed, [(ppy) 2 Ir(μ-OH)] 2 has shown its peculiar chemical reactivity due to both a strong base character and an unexpected oxidative ability towards the alcoholic function of glycol ethers. All the synthesized complexes exhibit, in water solution, an orange emission centred at 606 nm. Moreover, all complexes display the ability to give rise to gel phases in water upon increasing their concentration, and the photophysical study evidenced the various interactions governing the gelification process. The water-solubility of these new luminescent Ir(iii) complexes makes them potentially useful in bio-related systems.

Homogeneous thin films of controlled thickness obtained from cyclometalated complexes of general formula [(C(∧)N)M(O(∧)N)], where M = Pd(II) or Pt(II), H(C(∧)N) = 2-phenylpyridine and, respectively, 2-thienylpyridine and H(O(∧)N) = a triphenylamine functionalized Schiff base, have been deposited by oxidative electropolymerization. The films have been electrochemically and morphologically characterized. The metallopolymeric thin films present stable reversible redox behavior and typical cauliflower-like textures in agreement with a nucleation-growth electropolymerization mechanism. However, the film growth is greatly influenced by the nature of the metal center, with a higher tendency of the Pt complexes to promote the 3D growth. Furthermore, a complete spectroelectrochemical study has been performed on electrodeposited films showing near-IR absorption in the oxidized state, high contrast ratios (up to 65%) and low response times.

The complete characterization of novel electropolymerizable organometallic complexes is presented. These are newly synthesized cyclometalated complexes of general formula (PPy)M(O ∧ N)(n) (H(PPy) = 2-phenylpyridine, M = Pd(II) or Pt(II), H(O ∧ N)(n) = Schiff base). Polymeric thin films have been obtained from these complexes by electropolymerization of the triphenylamino group grafted onto the H(O ∧ N)(n) ancillary ligand. The redox behavior and the photoconductivity of both of the monomers (PPy)M(O ∧ N)(n) and the electropolymerized species have been investigated. The polymeric films of (PPy)M(O ∧ N)(n) have shown a very significant enhancement of photoconductivity when compared to their monomeric amorphous counterparts. The high stability of the obtained films strongly suggests that electropolymerization of cyclometalated complexes represents a viable deposition technique of quality thin films with improved photoconduction properties, hence opening the door to a new class of materials with suitable properties for optoelectronic applications.

A new combination of luminescent ionic transition-metal complexes (M = Ru(II) or Ir(III)) with gold silica-based nanoparticles (GSNPs) gives a promising nanomaterial for application in biomedical fields. Herein we report the synthesis and the photophysical properties of Ru(II) and Ir(III) complexes doped gold core-polysiloxane shell particles prepared by microemulsion method and characterized by Transmission Electron Microscopy, Dynamic Light Scattering and UV-Vis spectroscopy. The cytotoxicity and photodynamic activity of the obtained 50 nm-diameter nanoparticles were evaluated in vitro, providing noteworthy results. Furthermore, their intrinsic phosphorescence allows the localization of the photosensitizing nanoparticles into the cytosol of tumor cells by fluorescence confocal microscope. These valuable features designate them as multifunctional nanoplatforms for theranostic purposes.

In order to obtain new functional soft systems for use as templating agents for the construction of functional mesostructured materials, the dynamic ordered soft systems formed by a hydrophilic ionic iridium(III) complex (IrPa) embedded into two different concentration F127-water mixtures have been investigated. To this aim, combined spectral and time-resolved photophysical techniques and rheological methods have been employed. The position of the chromophore inside the micellar, cubic and hexagonal phases of the F127 polymeric neutral surfactant in water was effectively determined. The hydrophilic character of the iridium(III) complex chosen allowed preferential functionalization of the F127 corona in the micellar and cubic phases.

Two anionic iridium complexes [(R-ppy)2Ir(O^N)]TBA with R-ppy = 2-phenylpyridine or 4,5'-dimethyl-2-phenylpyridine, O^N = dianionic form of orotic acid and TBA = tetrabutylammonium have been synthesised and fully characterised by UV-Vis, emission, IR, NMR and cyclic voltammetric studies. These cyclometallated luminescent complexes containing a dianionic bidentate ancillary ligand show bright emission (60-70% PLQY) with maxima in the green region of the visible spectrum. Coupled with the ionic iridium complexes [(ppy)2Ir(N^N)]X, where N^N = 2-picolylamine or 2,2'-bipyridyl, and X = Cl(-) or CH3CO2(-), a series of new soft salts of general formula [(ppy)2Ir(N^N)][(R-ppy)2Ir (O^N)] have been obtained and fully characterized, with enhanced luminescent properties up to ca. 80% of phosphorescence quantum yields.

New Zn(II)-curcumin based heteroleptic complexes (1-5) have been synthesized and fully characterized, with the aim to improve the bioactivity of the precursor derivative [(bpy-9)Zn(curc)Cl] (A), a potentially intercalating antitumor agent recently reported. Some structural changes have been made starting from the reference complex A, in order to introduce new functionalities, such as electrostatic and/or covalent interactions. In particular, keeping the same N,N chelating ligand, namely bpy-9, two completely different Zn(II) species have been obtained: a tetracoordinated Zn(II) cation with tetrafluoroborate as counterion (1) and a dimeric neutral complex in which the sulfate anion acts as a bridging group through two Zn(II) centres (2). Moreover, by changing the N,N chelating unit, [(L(n))Zn(curc)Cl] complexes (3-5), in which the Zn(II) ion shows the same pentacoordination seen in the precursor complex A, have been obtained. The antitumour activity of all new Zn(II) complexes was tested in vitro against the human neuroblastoma cell line SH-SY5Y in a biohybrid membrane system and the results indicate that all species exhibit strong cytotoxic activity. In particular the ionic tetrafluoroborate Zn(II) complex, 1, and the neutral phenanthroline based Zn(II) derivative, 4, show the strongest growth inhibition, being even more effective than the model complex A. Both complexes have a dose-dependent anti-proliferative effect on cells as demonstrated by the decrease of viability and the increase of Annexin V and PI-positive cells with the increase of their concentration. Cells treated with complexes 1 and 4 undergo apoptosis that involves the activation of JNK, caspase 3 and MMP changes. Finally, complex 1 is more effective in the induction of caspase-3 activation demonstrating its ability to trigger the execution-phase of cell apoptosis.

Two new heteroleptic Zn(II) complexes of the 4,4'-bis(hydroxymethyl)-2,2'-bipyridine have been synthesized by using different stoichiometric ratios of tropolone. In an attempt to induce the formation of metal complex co-crystals, liquid assisted solid state reaction followed by solvent crystallization has been conducted by using the new Zn(II) tropolonate derivatives 1 and 2 with saccharin. The novel Zn(II) species obtained exhibits different structures and properties with respect to their precursors, due to a hydrogen exchange between saccharin and the tropolonate coordinated ligand.

The synthesis, crystal structure and luminescence properties of three cyclometalated Ir(III) complexes of general formula [(ppy)(2)Ir(pam)]X, where X = Cl(-) (1), PF(6)(-) (2), ClO(4)(-)(3), and pam = 2-picolylamine, are described. While 2 and 3 crystallize in a unique form, two pseudo-polymorphs, a solvated (1a) and a non-solvated (1b) species, have been observed for compound 1. 1a crystallizes in the monoclinic centrosymmetric space group P2(1)/c. On the contrary, 1b, 2 and 3 crystallize in the non-centrosymmetric space group P2(1)2(1)2(1) (1b) and Pca2(1) (2 and 3), respectively. All the crystalline supramolecular materials have been fully photophysically characterized. While 1 shows a bright blue-green emission in both solution and solvated crystalline state 1a, crystals of 1b, 2 and 3 show a significantly red shifted emission with respect to solution. Unexpectedly, and differently from 1a, mechanical stimuli-responsive colour and luminescence changes have been observed for 1b, 2 and 3. Upon mechanical grinding the colour of the crystalline solids changes from orange to yellow while the emission energy is partially (2 and 3) or completely (1b) converted from orange to green. The grinding-triggered colour and luminescence changes have been attributed to a crystal-to-amorphous phase conversion for all crystalline solids.

Synthesis, crystal structural determination and photophysical properties of a series of heteroleptic cationic cyclometalated iridium(III) derivatives of general formula [(ppy)(2)Ir(en)]X (X = ClO(4)(-) (1), PF(6)(-) (2), Cl(-) (3), BPh(4)(-) (4)), are described. The assembly of the common molecular building block allows to get highly luminescent crystalline materials or to assemble poorly luminescent supramolecular channelled architectures, for which the additional contribution of oxygen quenching effects has been observed. Moreover, the high reproducibility of the preparations of the crystalline materials in their specific crystalline phases, makes the control of the supramolecular organization of photo-active iridium(III) complexes within the crystalline structures a useful synthetic procedure for the construction of highly luminescent materials., (This journal is © The Royal Society of Chemistry 2012)

Four cyclometalated Pt(IV) compounds, 1a,b and 2a,b, were successfully obtained by oxidative addition of I(2) to 2-phenylpyridinate (PhPy) and Nile Red (NR) derived Pt(II) complexes with acetylacetonate (acac) or hexafluoroacetylacetonate (hacac) ancillary ligands. Single crystal X-ray diffraction, electrochemical, photophysical and computational studies have been performed in comparison with the analogues Pt(II) compounds, shedding new light on the role of the oxidation state of the metal centre towards both the luminescence properties and the dioxygen quenching.

The synthesis and characterization of a series of 2,2'-biquinolines differently substituted in the 4,4'-position and their corresponding silver(I) derivatives obtained through reaction with silver triflate in a 1 : 1 stoichiometric ratio are reported. In order to perform a systematic investigation on the role played by the substituents on the coordination to the silver(I) centre, structural studies through single crystal X-ray diffraction have been performed on two Ag(I) model complexes. Unlike their analogous 2,2'-bipyridine ligands, the biquinolines have been found to behave only as chelated ligands towards the silver(I) ion, irrespective of the substituents. The coordination sphere of the Ag(I) is filled by a solvent molecule and, depending on the presence and nature of the substituents on the organic ligand, by an oxygen atom coming from a coordinated triflate or from a carboxylic group of a symmetrically related molecule, giving rise to neutral or ionic species. For the highest Ag(I) triflate homologues the presence of long and flexible peripheral tails makes it possible to achieve liquid crystalline properties with columnar organization whose high order is due to the large and rigid core. Moreover, the metal coordination induces in all the Ag(I) species interesting emission properties both in solution and condensed states, giving rise to blue or green emitters, depending on the nature of the substituents on the biquinoline units.

New heteroleptic complexes (1-8) containing Zn(II) ion coordinated to an N,N-chelating ligand (the 4,4'-dinonyl-2,2'-bipyridine, bpy-9) and to diketonates L such as tropoloids (Tropolone and Hinokitiol) or 1-phenyl-3-methyl-4-R-5-pyrazolones have been synthesized by using different stoichiometric ratio with respect to the L ancillary ligand. The molecular structure of the bis-tropolonate derivative [(bpy-9)Zn(L)(2)] 5 has been determined by single-crystal X-ray diffraction. The antitumour activity of all Zn(II) complexes was tested in vitro against three different human prostate cancer cells: DU145, LNCaP and PC-3. Moreover, their effect on cell survival signalling and/or inhibitors of the PC-3 cell cycle have been analyzed. The results indicate that 1-8 exhibit strong cytotoxic activity against all cell lines affecting key molecules such as p-AKT and p21 waf, involved in the cell proliferation and/or arrest. Zinc(II) is thus a promising alternative to Pt(II) ion in the design of new, better performing antitumour agents.

The solvent induced polymorphism observed in a cyclometalated iridium(iii) ethylenediamine ionic complex is a new tool to modulate and enhance emission in the solid crystalline state.

New concepts for the synthesis of metallomesogens have been recently developed in order to use the metal centre as a scaffold for grafting different functionalities and inducing non-conventional shapes and properties in the resulting complexes. Our strategy was based on the synthesis of mesogenic coordination complexes whose molecular architectures are controlled by the modulation of different and tunable molecular motifs: the nature of the metal ion and the surrounding ligands as central unit, the number of flexible chains at the periphery, and the nature of counter-ions in ionic complexes. The appropriate choice of molecular construction motifs allows control at global architectures and induces pre-selected properties from the level of single molecule to supramolecular network, confirming that metal coordination provides a helpful tool for obtaining multifunctional soft materials.

The reaction of the promesogenic dihexadecyl-2,2'-bipyridine-4,4'-dicarboxylate (L16) with a number of AgX salts produces a series of silver(I) complexes [(L16)Ag(sac)], 1, [(L16)Ag(NO3)], 2, [(L16)Ag(OTf)], 3, and [(L16)3Ag2](ClO4)2, 4, whose stoichiometries, molecular architectures, supramolecular networks and mesomorphic behaviour are "anion dependent". In spite of the large differences in the single molecular structure, the one-dimensional coordination networks involving the triflate and perchlorate in complexes 3 and 4, are the key element for inducing significant argentophilic intermolecular interactions responsible for the induction of lamello-columnar mesomorphism in both Ag(I) derivatives. Moreover, a series of Ag(I) triflate model complexes have been synthesized and in order to get more insights about their solid state architectures, systematic structural studies have been performed.

The incorporation of a rigid core, formed by a cyclopalladated azobenzene fragment bonded to an ancillary Schiff base ligand, into molecules with 12 or 11 peripheral alkyl chains has been successfully achieved. These new complexes, 1 and 2, respectively, are columnar liquid crystals between room temperature and about 50 degrees C. Both cyclometallated and ancillary ligands have been polyalkylated through either aryl ester (electron-withdrawing group) or aryl ether (electron-releasing group) linkages, in order to tune the HOMO/LUMO energy levels. The photoconductive properties of 1 and 2 have been studied as a function of their absorption properties before and after annealing, from the UV/Vis to NIR region. Compared with the reference compounds, tris-alkynyl benzene discotics, these new materials gave similar performances (sigma/I approximately 8x10(-13) S cm W(-1) with E = 10 V microm(-1) at lambda = 370 nm). Moreover, complex 2 shows a normalized photoconductivity sigma/I = 8.5x10(-13) S cm W(-1) at lambda = 760 nm. Organic photoconductors in such a high wavelength spectral range are not common and are usually assembled by mixing dyes with organic semiconductors.

The first cyclopalladation of 3,5-disubstituted-2-(2'-pyridyl)pyrroles leads to columnar metallomesogens of non-conventional molecular shape.

A new ionic Pd(II) complex, [(bipy)Pd(Pcurc)][CF(3)SO(3)], 1, with the metal center coordinated to two different chelating ligands, the pure curcumin (Pcurc) and the 4,4'-dinonyl-2,2'-bipyridine (bipy), has been synthesized, fully characterized, and its antitumoral mechanism and oxidant property have been investigated. The Pd(II) complex induces both cell growth inhibition and apoptosis of human prostate cancer cells, (LnCaP, PC3, and DU145) through the production of ROS and JNK phosphorylation associated with GSTp1 down-regulation. ROS production induced by complex 1 treatment activated apoptosis through mitochondrial membrane depolarization in all prostate cancer cells, with up-regulation of Bax and down-regulation of Bcl-2 proteins. In addition, while curcumin determines DNA damage and PARP cleavage, complex 1 does not elicit any activation of PARP enzyme. Taken together, these data validate the significance of curcumin complexation to a metal center and its conjugation to another functionalized bioactive ligand in the apoptosis signal transduction and enhancement of cell death in prostate cancer cell lines and suggest the potential of this design strategy in the improvement of the metal-based drugs cytotoxicity.

A comparative photophysical, electrochemical and computational study of a series of Nile Red cyclopalladated and newly synthesised cycloplatinated complexes is reported. All complexes are luminescent at room temperature and the emission properties are governed by the nature of the cyclometallated dye. However, the presence of platinum(II) as metal centre decreases severely the emission quantum yield, while the electronegativity of the ancillary hexafluoroacetylacetonato ligand enhanced the emission properties of the Nile Red complexes.

A photophysical, electrochemical and computational study has been performed on a homologous series of cyclometallated Pd(II) (1a-f) and Pt(II) (2a-f) complexes of general formula [(C,N)M(O,O)]; (H(C,N) = azobenzene, 2-phenylpyridine, benzo[h]quinoline; M = Pd, Pt; H(O,O) = acetylacetone, hexafluoroacetylacetone). Experimental and computational data have shown the strong influence exerted by electronegativity of the ancillary ligand on the frontier orbitals of the complexes, such an effect being enhanced for the Pt(II) species.

The synthesis of the first gallium(III)-based liquid crystal has been achieved grafting around the metal centre two chelating 2-methylquinolin-8-olate anions and one monodentate 3,4,5-tris(hexadecyloxy)benzoyloxy ligand, allowing the resulting complex to be a soft luminescent material with the typical high quantum yield of pentacordinated gallium species.

Nanocrystals (50-250 nm) of a Palladium complex within a polyisobutylmethacrylate matrix were prepared by a phase separation method. In these dispersions, a light-induced birefringence with Deltan approximately 10(-3) was induced, without the application of an electric field. This effect was related to the photoconducting properties of the dispersion. Evidence for charge photogeneration without any applied field was obtained. The photorefractive behaviour of the material confirmed that the nanocrystals reorientation is a consequence of photoconducting properties. A light-generated electric field approximaely E 3 V/microm was estimated. These results illustrate the potential of materials with a nano-crystalline dispersion morphology as light-responsive media.

The coordination of the N,N ligands 2,2-bipyridine (bipy) and 1,10-phenanthroline (phen) to Ga(III) has been investigated via the formation of new ionic hexacoordinated complexes of general formula [Q'(2)Ga(N,N)][X], where HQ' stands for 2-methyl-8-hydroxyquinoline and the counter anion X(-) is nitrate (NO(3)(-)) or hexafluorophosphate (PF(6)(-)). All synthesized complexes were characterized by single-crystal X-ray diffraction analysis. The geometry of the Ga(III) cations is octahedral and a single geometric isomer (all N, N trans conformation) has been obtained in all cases. The role of both the N,N ligand and the counter anion has been investigated in the formation of the crystal supramolecular motifs occurring in the 3D-crystal networks of these new class of ionic Ga(III) derivatives. A full investigation of the photophysical properties of the new synthesized ionic species is reported and discussed in relation to their crystalline packing and the degree of crystallinity of thin solid films as well as the nature of the N,N ligand and the counter anion.

The low fluorescence quantum yield of 8-hydroxyquinoline cannot be correctly interpreted without knowing the form that such a compound assumes in different environments. The commonly accepted emission-quenching excited-state proton transfer can follow different reaction paths if 8-hydroxyquinoline is dimeric or monomeric or if it exists in the form of cis and trans conformers; in this light, the knowledge of the compound form in a particular environment is basic. We have performed a spectroscopic and computational investigation aimed at the determination of the form of 8-hydroxyquinoline in different solvents. UV-vis, fluorescence, and IR spectral features have been assigned by ab initio computations based on the density functional theory and time-dependent density functional theory; the density functional theory and MP2 computations have been applied to the determination of the relative stability of the dimeric and monomeric cis and trans forms of 8-hydroxyquinoline in different solvents. Molecular dynamics computations have been used to determine the compound behavior in water solutions. According to our results, 8-hydroxyquinoline shows a clear preference for the cis conformation (as dimer or monomer), but, in water solutions, a small fraction of the trans conformation is also present.

The first examples of binuclear and mononuclear ortho-palladated complexes based on a functionalized 2-phenylquinoline ligand have been synthesized and fully characterized. Conjugating cyclopalladated fragments to curcumin family biologically active beta-diketones gives in one single molecule two different functionalities. The structural variations based on the curcuminoid structure have been tested for their in vitro cytotoxic activity. The activity of complexes comprised of a cyclopalladated fragment conjugated to functionalized bioactive ligands, represents the potential of organometallic systems in generating new bifunctional biomaterials.

This paper reports the synthesis, characterization, photophysical and structural properties of the homologous series of good emitting pentacoordinated GaQ'2L complexes 1-3, where Q' is 2-methyl-quinolin-8-olate and L is a phenolate substituted in para position with respect to the oxygen donor atom. A combined approach between the experimental structural analysis (i.e. the molecular fragments involved in intermolecular pi-pi interactions) and the computational study (i.e. the nature of the molecular orbitals residing therein) is discussed in order to compare the charge transport aptitude of complexes 1-3, in relation to the facing of their LUMO/LUMO, HOMO/HOMO and HOMO/LUMO arising from the molecular packing. The different phenolate ligands significantly change the packing characteristics of 1-3, with indirect effects on the electron hopping kinetics responsible for conduction in amorphous thin films. The observed preference for pyridyl-pyridyl stacking proves a faster electron conduction in comparison to hole conduction in the three complexes studied.

A series of bischelate ionic silver complexes [Ag(L*)(2)][X] was prepared by complexation of a newly synthesized 2,2'-bipyridine containing chiral alkoxy chains in the 4,4' positions. The appropriate choice of the construction motifs allows the preparation of new materials in which several functionalities can be introduced. Indeed, when the anion X(-) is a triflate or a dodecylsulfate group, the right combination of intermolecular interactions promotes the production of liquid crystalline mesophases. Therefore, the presence of coordinating anions, which drives the supramolecular assembly, is essential to generate, at the same time, room-temperature columnar hexagonal mesomorphism, the columnar helical supramolecular structure, and excimeric emission.

The synthesis and the characterization (elemental analysis, (1)H NMR and X-ray) of the first cyclopalladated complexes containing 4-hydroxyacridinate as complementary ligand are described. 4-Hydroxyacridine acts as a bidentate [N,O] chelating ligand, giving rise to square planar Pd(II) complexes in the coordination of a cyclopalladated fragment of phenylpyridine or phenylpyrimidine, characterized by the presence of two almost coplanar metalated rings. The biological activity studies conducted on these new Pd(II) complexes proved that the phenylpyridine Pd(II) derivative is more efficient than cis-platinum. The intrinsically substitutional inertness of the cyclopalladated ring and the presence of the [N,O] chelated acridine ligand make these systems of particular interest in their promising biological activity.

This paper reports the synthesis, characterisation and photophysical investigation of the homologous series of blue-emitting pentacoordinated AlQ'(2)L complexes 1-6, where Q' is 2-methylquinolin-8-olate and L is a phenolate substituted in para to the oxygen donor atom. Both electron attracting and electron releasing substituents have been considered. Also binuclear complexes of formula Q'(2)Al-L'-AlQ'(2), where L' = OC(6)H(4)C(6)H(4)O, OC(6)H(4)(CH(2))(3)C(6)H(4)O and OC(6)H(4)C(CH(3))(2)C(6)H(4)C(CH(3))(2)C(6)H(4)O have been synthesised and characterised. These are interesting blue-emitting materials for OLED (organic light emitting diode) fabrication. A comparison between computational and experimental results allowed the description of the absorption and fluorescence processes. A study of the frontier orbitals involved in the electric conduction and fluorescence emission has been performed. Influences of the phenolate-based ligands on the compounds spectroscopy have been particularly taken into account.

Tris-beta-diketonate lanthanide(III) complexes (Ln = Eu, Er, Yb, Tb), of general formula [Ln(acac)3 L(m)], with chelating ligands such as 4,7-disubstituted-1,10-phenanthrolines and 4,4'-disubstituted-2,2'-bipyridines, have been synthesized and fully characterized. The inductive effects of the para-substituents on the aromatic N-donor ligands have been investigated both in the solid and in the solution states. Single-crystal X-ray structures have been determined for the diethyl 1,10-phenanthroline-4,7-dicarboxylate europium and 4,4'-dimethoxy-2,2'-bipyridine erbium derivatives, revealing a distorted square antiprismatic geometry around the lanthanide atom in both cases. The influence exerted by the p,p'-substituents with respect to the nitrogen coordinating atoms on the Ln-N bond distances is discussed comparing the geometrical parameters with those found for the crystal structures containing the fragments [Ln(III)(phen)] and [Ln(III)(bipy)] obtained from the Cambridge Structural Database. The influence exerted by the electron-attracting groups on the coordination ability of the ligands, that in some cases becomes lack of coordination of the lanthanide ions, has been also detected in solution where the loss of the ligand has been followed by UV-vis spectroscopy. Moreover, the use of relatively long alkoxy chains as substituents on the 1,10-phenanthroline ligand led to the formation of a promesogenic lanthanide complex, whose thermal behavior is encouraging for the synthesis of new lanthanide liquid-crystalline species.

2,7-Dimethoxynaphthalene (DMN) is proposed as matrix to investigate the structure of polymetallic porphyrins through matrix-assisted laser desorption/ionization tandem time-of-flight experiments. The peculiarity of DMN is represented by the formation of molecular radical cations and of some diagnostic fragments only. The traditional matrixes do not afford the expected molecular species. The experiments have been performed on extremely labile species such as zinc porphyirinate complexes with aluminum and gallium quinolinate to prove the softness of the methodology.

A new series of 5-(4'-substituted)phenylazo-8-hydroxyquinolines (H[L-R]; R = N(CH(3))(2), C(2)H(5), n-C(4)H(9), C(CH(3))(3), H, and F, ) has been prepared and the corresponding Zn[L-R](2) (1a-6a) and Al[L-R](3) (1b-6b) complexes successfully synthesized. These compounds have been studied in order to design new molecular materials with enhanced electron transport properties. The obtained species have been extensively characterized by absorption and emission spectra and by cyclic voltammetric measurements. Experimental and computational results show that the Zn[L-N(CH(3))(2)].2H(2)O (1a) and Al[L-N(CH(3))(2)](1b) complexes only feature luminescence (at 620 and 600 nm), respectively. The unique effects, which are induced by the N=N-C(6)H(4)-N(CH(3))(2) group, are further proved by a reversible electron transfer process detected by cyclic voltammetry. These outcomes, discussed on the basis of theoretical calculations performed on the (H[L-N(CH3)2])-, H[L-N(CH3)2] and (H[L-N(CH3)(2)])+ species, suggest that metal complexes formed by 5-(4'-N,N-dimethylamino)phenylazo-8-hydroxyquinoline should be considered as electron transport materials suitable for applications in photonic devices.

2-Benzoylpyridine N-methyl-N-phenylhydrazone, HL, is a versatile ligand which reacts with [Pd(PhCN)2Cl2] forming the coordination compound [HLPdCl2], 1, characterized by the presence of the N(py)/N(im) chelate ring. When HL reacts with [Pd3(OAc)6] this gives rise to the orthometallated complex [LPd(OAc)],. In this case the Pd(II) environment consists of a N(py)/N(im) ring fused to the N(im)/C palladacycle and a monodentate acetate anion. Complex undergoes methatetical reactions with alkaline halides and complexes of general formula [LPdX](3: X = Cl; 4: X = Br; 5: X = I) are obtained. The molecular structures 3-5 of determined by single-crystal X-ray analysis proved the formation in all cases of mononuclear Pd(II) complexes containing a N(py)/N(im)/C terdentate ligand. As solid samples only compounds 3-5 exhibited luminescence at room temperature (lambdamax approximately 610 nm). This property, quite unusual in Pd(II) complexes, is discussed in terms of pi-pi] interactions, which are mainly responsible for the existence in the crystalline solid state of dimeric units.

The newly synthesized complexes formed by cyclopalladated 2-phenylpyridine co-ordinated to 5-substituted-8-hydroxyquinolines, are at room temperature and in fluid solution, luminescent with an absolute photoluminescent quantum yield which depends on the nature of the substituent in position 5.

The skeletal status was investigated with noninvasive diagnostic procedures in 44 renal transplant patients (mean time since intervention: 5 to 195 months) treated with steroid and azathioprine (21 cases) or with steroid, azathioprine and cyclosporine (23 cases). 38.6% of the patients had reduced renal function (creatininemia: 1.6-3.0 mg/dl). Our patients underwent biochemical and hormonal tests of bone metabolism, digital radiographs of the skeleton and bone mineral density measurement with dual-energy X-ray absorptiometry (DXA, Hologic QDR 1000). All the patients exhibited moderate to severe osteopenia at both radiographic and densitometric investigations; the risk of fracture was high in 47% of cases. Radiographic signs of vertebral fractures were observed in 4.5% of cases. Other major radiographic patterns were the aseptic necrosis of femoral head (9%), of carpal bone (4.5%) and of humeral head (2.2%). Fibrous osteitis was demonstrated in three patients. Geodes in the wrist were also observed. The correlation of bone densitometry values and time since renal transplantation was statistically significant (r = 0.381; p < 0.01). Moreover, the grade of osteopenia correlated with serum levels of calcitonin and calcitriol--the latter especially in the patients with severe osteopenia.

Platyspondylia was observed in 14 patients affected with thalassemia major (7 males and 7 females, age range: 10-18 years) who received an intensive transfusion regimen combined with continuous chelation therapy (desferrioxamine: 50-80 mg/kg daily). Height/width ratio was decreased at all the investigated tracts--i.e., cervical and/or dorsal and/or lumbar spine. The range of height/width ratio values was 0.41-0.55 at the 5th cervical body, 0.33-0.53 at the 8th dorsal body, 0.43-0.56 at the 12th dorsal body and 0.47-0.62 at the 2nd lumbar body. The flattening of the vertebral bodies seems to be due to the depletion of hematopoetic tissue determined by the high transfusion regimen. The reduced intramedullary pressure is thought to counteract neither weight-bearing nor other biological stresses, which might ultimately provoke the thinning of vertebral bodies.

The term "osteogenesis imperfecta" refers to a heterogeneous group of hereditary diseases characterized by osteopenia, increased bone fragility, blue sclerae and dentinogenesis imperfecta. The abnormal synthesis of type-I collagen is responsible for the pathologic changes occurring not only in bone, but also in skin, tendons and ligaments, sclerae and teeth. The clinical and radiographic features of 5 cases (2 males and 3 females; age range: 1 month to 29 years) were analyzed. The patients were unrelated with each other. The diagnosis of the different types of osteogenesis imperfecta is as difficult as the identification of the various genotypes which are responsible for the different clinical pictures. The most characteristic radiographic pattern--which is observed in any type of the disease--consists in osteopenia associated, in most cases, with multiple fractures and deformities--e.g., micromelia, large metaphysis, archon long bones. Typically, "pop corn" calcifications are observed in both epiphysis and metaphysis of long bones. Dentinogenesis imperfecta is one of the most significant clinical patterns, and it can be the only bone abnormality. The prognosis of osteogenesis imperfecta is as varied as its genetics--i.e., the fractures discovered at birth are not necessarily a negative prognostic sign.

Osteoarticular complications, which are characterized by osseous pain, pathologic fractures, and decreased articular mobility, represent one of the major problems affecting long-term (over 15 years) hemodialysis patients. These changes seem to have a multifactorial etiology; they include osteomalacia, secondary hyperparathyroidism, and dialysis-related amyloidosis. Ten patients (5 males and 5 females, mean age 55 +/- 7 years) on long-term (over 15 years) hemodialysis were submitted to X-ray examinations of the skull, spine, shoulders, wrists, pelvis, and knees. Serum calcium, phosphorous, parathyroid hormone, alkaline phosphatase, and basal aluminium levels were also calculated. Osteopenia was demonstrated in all patients. Seven of them had alterations due to hyperparathyroidism. Six patients exhibited signs related to dialysis spondyloarthropathy; in 9 cases amyloid lesions, geodes, and erosions were present in wrists, humeral heads, or hips. One patient exhibited osteomalacic changes. Most long-term dialysis patients presented multifactorial osteoarticular changes due to hyperparathyroidism, osteomalacia, and dialysis-related amyloidosis. Clinical symptoms and decreased articular mobility appeared to be due mainly to amyloid osteoarthropathy.