Salvatrice Millesi

Olefin epoxidation by a (salen)Mn(III) catalyst covalently grafted on glass beads

The asymmetric epoxidation of unfunctionalized prochiral olefins catalyzed by chiral (salen)Mn(III) complexes is an important viable route to obtain chiral epoxides. Recently we proposed a monolayer of (salen)Mn(III) molecules on functionalized flat silica substrates as an active heterogeneous catalyst for enantioselective epoxidation of 6-cyano-2,2-dimethylchromene with huge turnover values. In the present study we synthesized a monolayer of modified (salen)Mn(III) molecules on previously functionalized glass bead substrates in order to increase the active surface area. The catalyst activity of this system was tested with different olefins and in some cases we observed enantioselectivity higher than in solution. The system was reused up to seven times with no variation in performance.

Long range order in Si(100) surfaces engineered with porphyrin nanostructures

Engineering of Si(100) with ordered organic nanostructures represents an advanced method to manufacture hybrid organic/inorganic systems useful for different applications. Well-ordered and densely packed molecules can be obtained by a self-assembly process that depends on directional inter-molecular interactions such as π–π stacking, electrostatic, dipole–dipole or van der Waals interactions, and other more complex forces. Macrocycles are well known to aggregate both in solution and in thin films as a result of some of the above-mentioned interactions. In our study, Si(100) substrates were functionalized with a covalent 4-ClCH2C6H4SiCl3 monolayer that binds to the surface using the –SiCl3 group and leaves a –CH2Cl group unreacted. The remaining alkyl chloride functionality at the top of the Si(100) substrate allowed additional covalent functionalization with a porphyrin monolayer that resulted in ordered, surface-confined porphyrin assemblies. X-ray photoelectron spectroscopy gave indication of the porphyrin grafting mode. Atomic force microscopy showed a long range order of these nanostructures. Emission measurements confirmed the porphyrin luminescence.

Optical properties of porphyrin–Eu-β-diketonate supramolecular nanostructures

Hybrid nanostructures obtained by the assembly of organic/inorganic chemical systems can show novel molecular properties. The combination of different optical properties belonging to different molecular components represents an advanced method to manufacture hybrid assemblies useful for improved optical applications. In our study, silanized quartz substrates were functionalized with a covalent tetrakis hydroxyphenyl porphine monolayer. The remaining hydroxyphenyl substituents, not involved in the covalent bond with the silane coupling layer, allowed additional functionalization with the tris(dibenzoylmethane) mono(5-amino-1,10-phenanthroline)europium(III) complex by means of ionic interactions. X-ray photoelectron spectroscopy and UV-visible spectrophotometry gave indication of the porphyrin–Eu-complex grafting mode. In these supramolecular architectures both through bond (covalent) and through space (mainly ionic) electronic interactions between the two molecular units resulted in unprecedented macroscopic properties. In fact, emission measurements confirmed that the porphyrin and Eu-complexes influence each other and the photoluminescence relative intensities are strongly affected.

Nerve Gas Simulant Sensing by a Uranyl–Salen Monolayer Covalently Anchored on Quartz Substrates

A uranyl complex monolayer that easily allows the optical detection of a nerve gas simulant, namely, dimethyl methylphosphonate, is reported. Both UV/Vis spectroscopy and photoelectron data confirm that the functional hybrid material coordinates a Lewis base by means of the P=O group, which interacts with the uranium equatorial site available for complexation.

Communication between Discrete Nanostructures Triggered by Fine Tuning of an External Stimulus

The design of molecular architectures able to transfer mass to each other is a field of extreme importance. In the present study it is shown that two especially designed covalently assembled nanostructures can interchange Cu(2+) ions upon an external OH(-) trigger. The obtained solid interfaces are of interest for signaling, communication, memory storage and optical devices.

Spectroscopic and morphological characterization of inflow cannulas of left ventricular assist devices.

Despite the consistent clinical data on the positive effects of left ventricular assist devices (LVADs) in the treatment of refractory heart failure, unfortunately these devices yet show some limitations such as the risk of stroke, infection, and device malfunction. The complex interplay between blood and the foreign material has a major role in the occurrence of these complications and biocompatibility of the inflow cannula would be pivotal in these terms. In this study, we carried out an in-depth physicochemical characterization of two commercially available LVADs by means of field emission gun scanning electron microscopy, energy dispersive X-ray, and X-ray photoelectron spectra. Our results show that, despite both pumps share the same physicochemical concepts, major differences can be identified in the surface nature, morphology, and chemical composition of their inflow cannulas

Recognition and optical sensing of amines by a quartz-bound 7-chloro-4-quinolylazopillar[5]arene monolayer

Covalent bonding of 7-chloro-4-quinolylazo-octamethoxypillar[5]arene molecules to silylated quartz substrates readily produced a new chromogenic reusable pillararene-coated quartz slide, for the direct UV detection of “transparent” analytes in solution. This device provides an analyte-selective optical response towards linear (di)amines with a highly reproducible optical read-out.