Eliano Diana

A Carborane‐Derivative “Click” Reaction under Heterogeneous Conditions for the Synthesis of a Promising Lipophilic MRI/GdBNCT Agent

In this study, the Huisgen reaction has been used to functionalise a carborane cage with a lipophilic moiety and a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) ligand to obtain a new Gd boron neutron-capture therapy (BNCT)/magnetic resonance imaging (MRI) agent. The introduction of the triazole units has been accomplished under both heterogeneous conditions, by the use of a Cu-supported ionic-liquid catalyst, and homogeneous conditions. The ability of the Gd complex of the synthesised ligand to form stable adducts with low-density lipoproteins (LDLs) has been evaluated and then MRI has been performed on tumour melanoma cells incubated in the presence of a Gd-complex/LDL imaging probe. It has been concluded that the high amount of intracellular boron necessary to perform BNCT can be reached even in the presence of a relatively low-boron-containing LDL concentration.

Highly Water Soluble C60 Derivatives: A New Synthesis

Abstract Unprecedented protocol, consisting in reduction of Buckminsterfullerene with Na/K alloy and successive stirring in presence of O2, affords polyhydroxylated fullerenols which are highly water soluble, from strongly basic to medium acidic conditions. The products have been characterized by means of cross polarization magic angle spinning (CPMAS) NMR, 1H‐NMR, electron, FT‐IR, Raman and mass spectroscopies. Possible paths of reaction and the role of molecular oxygen in fullerene cage‐oxidation are discussed.

Efficient Direct Water‐Solubilisation of Single‐Walled Carbon Nanotube Derivatives

Abstract Application under mild conditions of a one‐pot reductive–oxidative synthetic protocol to single‐walled carbon nanotubes (SWNT) affords water‐soluble oxygenated products that have been characterised by mean of XPS, solution 1H‐NMR, UV‐VIS‐NIR, vibrational FTIR and Raman, SEM–energy dispersive x‐ray (EDX), XRD, and ESI‐MS techniques. Different oxygenated functionalities are evicted to be covalently bonded to carbon nanotubes frameworks, due to electrophilic insertion of O2 upon reduced carbon structures. The pH‐dependent behaviour in water solution and the observed partial fragmentation of oxidised nanotubes, that can contribute in enhancing water solubility by shortening structures, are discussed. Prolonged heating of the material affords a higher graphitisation index of the functionalised carbonaceous water‐soluble frameworks, and possible chemical paths for the partial recovering of pristine carbon nanostructures are reported. The achieved hydrophily due to polar oxygen moieties insertions on nanostructures provides a remarkable unprecedented water solubility for these carbon substrates without the attachment of large polar appendages. #Dedicated to Professor Pier Luigi Stanghellini on the occasion of his 65th birthday.

Synthesis, structural and spectroscopic study of the donor–acceptor complexes between fluorene and D2h cyano molecular building blocks

Three solid molecular complexes of fluorene with electron-withdrawing tetracyanoethylene, 1,2,4,5-tetracyanobenzene and 7,7,8,8-tetracyanoquinodimethane were synthesized. Single-crystal X-ray diffraction data elucidated the order–disorder aspects of the crystal structures ascribed to the different molecular symmetries of the employed building blocks. This hypothesis was confirmed by the structural and energetic results of ab initio periodic calculations. Donor–acceptor solid state interactions between molecular counterparts have been highlighted by electron and vibrational IR and Raman solid state spectroscopy, indicating a significant extent of electron density transfer from the fluorene unit towards the cyano-molecules. The experimental evidences of donor–acceptor interactions between molecular counterparts were compared to the lattice energies and solid state band-gaps, obtained by periodic calculations, and to the cluster HOMO–LUMO differences, obtained by isolated cluster calculations. A good agreement between spectral and theoretical data was found.

Facile synthesis of novel blue light and large Stoke shift emitting tetradentate polyazines based on imidazo[1,5-a]pyridine – Part 2

A series of new imidazo[1,5-a]pyridines was obtained through a facile multiple condensation procedure, involving the reaction of two methanamine and several largely available and inexpensive diand tricarboxylic acids. Such poliazine products show different and tuneable coordination motifs suitable for mono-, di-, and tritopic coordination sites. Furthermore they display interesting optical properties: tuneable luminescence, significant quantum yields, large Stokes’ shifts and strong halochromic effects, enabling their technological application.

The influence of the chelating/combustion agents on the structure and magnetic properties of zinc ferrite

AbstractThe present study is reporting the influence of the chelating/combustion agents on the magnetic properties of Zn ferrite. Six chelating/combustion agents, citric acid, egg white, tartaric acid, glycine, glucose and urea, were used to obtain monophase zinc nanoferrite via a sol-gel auto-combustion method. The samples were subjected to a comparative study of structural features and magnetic properties by means of infrared spectroscopy, X-ray diffractometry, scanning electron microscopy and vibrating sample magnetometry. Significant influence of fuel and combustion mode was observed in the magnetic behavior of as-obtained samples. Values of the structural parameters were discovered to vary as a function of fuel choice, and to obtain crystallite size between 38 and 62 nm, inversion degree between 0.239 and 0.807, lattice parameter between 8.4125 and 8.4432 Å. The optimization of sol-gel method synthesis of zinc ferrite nanoparticles by chosing the appropriate fuel is providing structural and magnetic properties of zinc nanoferrite as potential materials to be used in biomedical applications.

The charge distribution on metal-bonded cyclopentadienyl rings from infrared intensities

Abstract The IR intensities of the CH vibrational modes of a hydrocarbon fragment bonded to a metal atom are a useful probe to evaluate the charge distribution on the fragment. The values of R , the ratio of the overall CH bending and CH stretching IR intensities of the cyclopentadienyl ligand, are reported for several organometallic complexes containing the η 5 -C 5 H 5 M unit. The parameter R is related to several properties of the complexes, such as the ionic charge, the nature of the metal and of the ancillary ligands, the CH bending force constant and to the solid-state structure.

Characterization, redox properties and structures of the iron nitridocarbonyl clusters [Fe4N(CO)11{PPh(C5H4FeC5H5)2}]–, [Fe6N(CO)15]3– and [Fe6H(N)(CO)15]2–

The redox condensation of [Fe2(CO)8]2– with [Fe4N(CO)12]– yielded the cluster [Fe6N(CO)15]3–. Single-crystal X-ray analysis showed it to possess an octahedral metal cage, with an interstitial nitride ligand. Under the D3 idealized symmetry, all iron vertices are equivalent, being bound to one edge-bridging and two terminal carbonyls. The ion [Fe6N(CO)15]3– can be oxidized to [Fe5N(CO)14]– or protonated to the hydridic dianion [Fe6H(N)(CO)15]2–. The molecular structure of the latter was determined, and is strikingly similar to that of the parent trianion. Small deformations of the ligand shell or elongations of the Fe–Fe distances are not sufficient to determine the location of the hydride. Electrochemical experiments were consistent with the chemical findings, showing that [Fe6N(CO)15]3– undergoes three irreversible one-electron oxidation steps, ultimately generating [Fe5N(CO)14]–. A lifetime of about 15 s was evaluated for the transient radical [Fe6N(CO)15]2–. Thermal activation induces substitution of one carbonyl ligand of [Fe4N(CO)12]– by PPh(C5H4FeC5H5)2, yielding [Fe4N(CO)11{PPh(C5H4FeC5H5)2}]–, the molecular structure of which was also determined. The cluster adopts a butterfly arrangement of iron atoms, having an exposed µ4-N atom and the phosphine ligand at a wingtip position. Cyclic voltammetry showed that communication between the two ferrocenyl units of the ligand PPh(C5H4FeC5H5)2 is rather low in the free state, and is notably improved by co-ordination to the tetrairon cluster. The 15N-labelled [Fe6N(CO)15]3– and [Fe6H(N)(CO)15]2– complexes were synthesized, and the NMR chemical shifts and IR bands of the interstitial µ6-N ligands measured.

Ironnickel mixed metal clusters: synthesis, reactivity and vibrational spectroscopy of [FeNi5(CO)13]2−. Solid state structure of the anions [FeNi5(CO)13]2− and [Fe3Ni(CO)12]2−

Abstract The cluster [FeNi5(CO)13]2− (1) was obtained by reaction of Fe(CO)5 and [Ni6(CO)12]2− (2), in acetonitrile at room temperature. Its solid state structure was determined on the [NEt4]+ salt, and consists of a trigonally distorted octahedron, with six edge-bridging ligands. This assembly strictly recalls the architecture of the prototypical [Ni6(CO)12]2− anion, by formal replacement of one Ni(CO) unit with the Fe(CO)2 fragment. However, the requirements of the additional ligand have sterical consequences on the other carbonyl groups, which can not be coplanar as in the all-nickel cluster. [FeNi5(CO)13]2− reacts readily with acids, to yield the already known [HFe3Ni(CO)12]− (3), and with CO, being stepwise fragmented to species of lower nuclearity, ending with [Fe3Ni(CO)12]2− (4) or [Fe2(CO)8]2−. The solid state structure of the tetranuclear [Fe3Ni(CO)12]2− was also determined, and is reported here.

Non-linear optical properties of β-D-fructopyranose calcium chloride MOFs: an experimental and theoretical approach

The second harmonic generation (SHG) properties of two MOFs, obtained from fructose and calcium chloride, were studied using a Non-Linear Optics Multimodal microscope. The first-order hyperpolarizability and the second-order susceptibility were calculated at the DFT level of theory. Moreover, a semi-classical approach to non-linearities in the optical behaviour was used in order to determine the features responsible for the SHG. The MOFs were synthesized both in ethanol and by solid–solid interaction, with a simple, rapid and low-cost methodology with no environmental impact, and were characterized with IR and RAMAN spectroscopy and both the single-crystal and powder X-ray diffraction. Both the metal–carbohydrate-based MOFs show an interesting SHG intensity: in particular, compound 1 shows an average SH intensity more than twice that of sucrose, in agreement with the theoretical results. A favourable combination of optical properties, transparency, thermal and chemical stability makes compound 1 a potential candidate for applications in electro-optics devices.