Metal Coordination Properties of a Chromophoric Desferrioxamine (DFO) Derivative: Insight on the Coordination Stoichiometry and Thermodynamic Stability of Zr4+ Complexes

Desferrioxamine (DFO) is the current “gold standard” chelator for ⁸⁹Zr⁴⁺, which is used to label monoclonal antibodies for applications in immunopositron emission tomography. Recently, controversial data have been reported regarding the speciation and the stability of the complexes formed by DFO with Zr⁴⁺ in solution. To shed some light on this point, we studied the coordination properties in solution ofa chromophoric DFO derivative bearing a substituted pyrimidine residue (DFO–Pm) toward several metal ions (Zr⁴⁺, Cu²⁺, Zn²⁺, Mg²⁺, Ca²⁺, Na⁺, K⁺). Potentiometric titrations showed that DFO–Pm and pristine DFO form complexes with very similar stoichiometry and stability. DFO–Pm, which can consequently be taken as a model system for DFO, provides a photochemical response to metal coordination that can be used to further define the complexes formed. In the critical case of Zr⁴⁺, spectrophotometric measurements allowed the verification of the formation of 1:1 and 2:3 complexes that, together with 2:2 complexes form the coordination model that was obtained through the use of our potentiometric measurements. Additionally, mass spectrometry measurements verified the formation of 1:1 and 2:3 complexes and showed that 1:2 species can be easily generated through the fragmentation of the 2:3 species. In conclusion, the results obtained with DFO–Pm validate the complexation model of Zr⁴⁺/DFO composed of 1:1, 2:2, and 2:3 metal-to-ligand complexes. Convergences and conflicts with other works are addressed.     

Sono-photocatalytic degradation of 2-chlorophenol in water: kinetic and energetic comparison with other techniques.

The degradation of 2-chlorophenol in water was kinetically investigated using the following different techniques, employed either separately or simultaneously, always with the same experimental set-up: light irradiation (315-400 nm), sonication, photocatalysis with different types of TiO2, photocatalysis with sonication. The influence of the reaction volume and of different gas mixtures, containing Ar and O2, as well as O2/O3, was also investigated. Finally, an energetic comparison among these different techniques was performed, focused on an industrial application of some of them.     

Chromium doped γ-Al2O3 powders. Features of the electrical double layer and state of the surface species

γ-Al₂O₃ samples, both pure and Cr doped, were prepared by heating at 470°C sol–gel precursors obtained by using aluminum tri-sec-butoxide [Al(OC₄H₉)₃] as the starting compound. The samples were characterised for phase composition (X-ray diffraction) and surface area (BET). Electrochemical determinations of the double layer reactivity of the pure and doped oxides were performed both by surface charge and by electrokinetic sonic amplitude (ESA) determinations. The interfacial electrostatic response is discussed and analysed also with reference to the sample surface state obtained by X-ray photoelectron spectroscopy (XPS).     

Interpolation of Herz Spaces and Applications

C. Herz introduced in [Hr] some new spaces to study properties of functions. An Interesting account, with many applications, of some particular cases of the generalized Herz spaces is given in [BS]. In this paper we first identify the duals of the generalized Herz spaces. Then, we characterize their intermediate spaces when the complex method of interpolation for families of spaces Is used. Applications are given that show the bounded ness of many operators on the generalized Herz spaces.     

A slightly shorter route to carbocyclic nucleosides. Synthesis of (±)-trans-1-[2-(hydroxymethyl)cyclopentylmethyl]uracil

(±)-trans-1-[2-(Hydroxymethyl)cyclopentylmethyl]uracil ( 1 ) was prepared in two steps and 56% yield from 2-hydroxymethylcyclopentylmethylamine (7) and 3-methoxy-2-propenoylisocyanate ( 6 ). Isocyanate 6 was prepared from methyl 3-methoxy-2-propenoate in four steps and 38% overall yield.     

A Note on Equilibrium Problems with Properly Quasimonotone Bifunctions

In this paper, we consider some well-known equilibrium problems and their duals in a topological Hausdorff vector space X for a bifunction F defined on K x K,where K is a convex subset of X. Some necessary conditions are investigated, proving different results depending on the behaviour of F on the diagonal set. The concept of proper quasimonotonicity for bifunctions is defined, and the relationship with generalized monotonicity is investigated. The main result proves that the condition of proper quasimonotonicity is sharp in order to solve the dual equilibrium problem on every convex set.     

Synthesis and characterization of some coumarins with two hydroxy or methoxy substituents

The first synthesis of the 6‐hydroxy‐4‐methoxycoumarin ( 5 ) was carried out in 25 % overall yield from 6‐methoxy‐4‐hydroxycoumarin ( 1 ) by hydrolysis of the methoxy group and subsequent selective methylation of the hydroxyl group at position 4. The ¹H and ¹³C NMR data of compounds 1–6 are reported.     

O‐Doped Nanographenes: A Pyrano/Pyrylium Route Towards Semiconducting Cationic Mixed‐Valence Complexes

Herein we report an efficient synthesis to prepare O‐doped nanographenes derived from the π‐extension of pyrene. The derivatives are highly fluorescent and feature low oxidation potentials. Using electrooxidation, crystals of cationic mixed‐valence (MV) complexes were grown in which the organic salts organize into face‐to‐face π‐stacks, a favorable solid‐state arrangement for organic electronics. Variable‐temperature electron paramagnetic resonance (EPR) measurements and relaxation studies suggest a strong electron delocalization along the longitudinal axis of the columnar π‐stacking architectures. Electric measurements of single crystals of the MV salts show a semiconducting behavior with a remarkably high conductivity at room temperature. These findings support the notion that π‐extension of heteroatom‐doped polycyclic aromatic hydrocarbons is an attractive approach to fabricate nanographenes with a broad spectrum of semiconducting properties and high charge mobilities.