Antonino Mamo

Luminescent Mononuclear and Dinuclear Iridium(III) Cyclometalated Complexes Immobilized in a Polymeric Matrix as Solid-State Oxygen Sensors.

Oxygen quenching of the luminescence of mononuclear and dinuclear Ir(III) cyclometalated complexes immobilized in the pPEGMA matrixes has been studied. Linear Stern-Volmer plots, even when experiments at different emission wavelengths have been performed, were evidenced. Despite the different luminescence lifetimes of the chromophores in the absence of quencher, similar Stern-Volmer slopes have been calculated. This behavior was tentatively interpreted by taking into account the size and charge of the chromophores. Increased sizes and lower charges seem to enhance the sensitivity of the systems. Such findings could be of interest for the design of new solid-state luminescent oxygen sensors with improved performance.

High resolution XPS investigation of photocured films containing perfluoropolyether acrylates

Abstract The paper reports an XPS investigation on films obtained by photopolymerising new perfluoropolyether methacrylates as pure products or added in low amounts to a typical UV-curable resin (Bisphenol A bis-ethylether diacrylate). The structure of the fluorinated monomers is Rf–Rh type, where Rh=–CH 2 O–CO–NH–CH 2 –CH 2 –OCOC(CH 3 ) CH 2 while Rf=CF 3 –CF 2 O–(CF 2 O) n (CF 2 –CF 2 O) m –CF 2 – for monomer 1 (PM 890, m / n =1.68), and Rf=Cl–CF 2 –CF(CF 3 )–O–(CF 2 CF(CF 3 )–O) 2 –CF 2 – for monomer 2 . Quantitative evaluation of the different atomic ratios was performed using take-off angles of 45 and 10° (very surface region) on both film sides, the one in contact with the glass substrate and the one exposed to air. The results obtained indicate strong fluorine enrichment on the air side of the films and a concentration gradient at the surface, while the glass side has a composition similar to the bulk.

Thermal and thermo-oxidative degradations of poly(2,6-dimethyl- 1,4-phenylene oxide) (PPO)/copoly(aryl ether sulfone) P(ESES-co-EES) block copolymers: a kinetic study

The thermal degradation of a series of three novel ABA block copolymers of different molar mass (Mn), were the block A is a poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), while the block B is a random copoly(aryl ether sulfone) P(ESES-co-EES), was studied in both inert (flowing nitrogen) and oxidative (static air) atmospheres, to investigate the effects of Mn of the central block on the thermal stability. Copolymers were synthesized with a two step method: in the first stage, a linking molecule is selectively attached as end group to the P(ESES-co-EES) which reacts in the second step with the phenolic hydroxyl group of PPO. Degradations were carried out into a thermobalance, in the scanning mode, at various heating rates, and the characteristic parameters of thermal stability, namely initial decomposition temperature (Ti) and the activation energy (Ea) of degradation, of the various copolymers were determined. Both Ti and degradation Ea values increased exponentially as a function of Mn of copolymers. The results were discussed and interpreted.

Synthesis and characterization of pendantly amine functionalized poly(arylene ether sulfone)

Abstract The synthesis of new pendantly functionalized polyaromatic thermoplastics using pre-functionalized monomers is reported. These will have potential applications as either toughening agents in thermosetting resins or, with the incorporation of crosslinking moieties, as matrices in their own right.

Synthesis of Substituted 2-Pyridyl-4-phenylquinolines

The acid-catalyzed condensation of o-aminobenzophenones with aromatic acetyl derivatives, in a basic methanol/tetrahydrofuran medium, has been used to prepare a series of substituted 2-pyridyl-4-phenylquinolines. Derivatives having two aza binding sites can act as asymmetric bidendate ligands to complex transition metals such as ruthenium, osmium or iridium. All the compounds were characterized by elemental analysis, Ei or FAB (+) MS, 1H- and 13C-NMR spectroscopies. Complete assignments of the 1H spectra were accomplished by using a combination of one- and two-dimensional NMR techniques.

Synthesis and luminescent properties of a EuIII complex with a macrocyclic ligand incorporating 2,2′-bipyridyl-1,1′-dioxide units

A novel ligand incorporating two 2,2′-bipyridyl-1,1′-dioxide units forms a very stable EuIII complex, which exhibits very excellent luminescent characteristics in water solution.

Kinetics and mechanism of selenium-catalyzed isomerization of some cis-diarylacrylonitriles

Abstract The kinetics of the cis-trans isomerization of some α,β-diarylacrylonitriles has been investigated in decahydronaphthalene at 150–190° with selenium as a catalyst. The reaction is first order with respect to olefin and 1 2 apparent order with respect to catalyst. Isomerization rate is increased by electron donating groups in the α-phenyl and by electron withdrawing ones in the β-phenyl. Satisfactory correlations between log k and substituent σ + values are observed. Evidence is obtained for a free radical mechanism. The results are consistent with a reaction path involving the formation of a σ-complex between the α-C atom and selenium diradical, followed by a free rotation around the single bond and removal of the catalyst. The effects of heteroaromatic nuclei linked to α-C atom on the isomerization rate (phenyl>2-furyl>2-thienyl) indicate the lack of conjugation from heteroatom to the side chain in the rate determining step.

Asymmetric Ruthenium(II) and Osmium(II) Complexes with New Bidentate Polyquinoline Ligands. Synthesis and NMR Characterization

A series of Ru(II) and Os(II) tris-chelate complexes with new bidentate 2-pyridylquinoline ligands have been synthesized and fully characterized by EA,1H-NMR and FAB-MS techniques. The new ligands are: L1 = 4-p-methoxyphenyl-6-bromo-2-(2′-pyridyl)quinoline (mphbr-pq) and L2 = 4-p-hydroxyphenyl-6-bromo-2-(2′-pyridyl)- quinoline (hphbr-pq). The complexes studied are: [Ru(bpy)2L1](PF6)2 (C1), [Ru(bpy)2L2](PF6)2 (C2), [Os(bpy)2L1](PF6)2 (C3), [Os(bpy)2L2](PF6)2 (C4) (bpy = 2,2′-bipyridine), [Ru(dmbpy)2L1](PF6)2 (C5), [Ru(dmbpy)2L2](PF6)2 (C6), [Os(dmbpy)2L1](PF6)2 (C7), and [Os(dmbpy)2L2](PF6)2 (C8) (dmbpy = 4,4′-dimethyl-2,2′-bipyridine). Moreover, new functionalized complexes C9-C12 were obtained by the base-catalyzed direct alkylation of C2, C4, C6, and C8 with 6-bromo-1-hexene. The complete assignment of the 1H-NMR spectra for the two new ligands (L1 and L2), and their Ru(II) or Os(II) complexes has been accomplished using a combination of one- and two-dimensional NMR techniques. The JH,H values have been determined for the majority of the resonances.

Poly(ether sulphone) copolymers with novel reactive chain-ends

Abstract This paper describes the synthesis of new model compounds and copolyether sulphones with different reactive chain-ends from the OH and NH 2 ends which are well documented for this type of polymer. These materials were characterised by 1 H NMR, Fourier transformed infrared (FTIR) spectroscopy and elemental analysis. They are seen to have potential applications both in the chain-extension of low molecular weight thermoplastics and in the preparation of well-defined block copolymers.

Synthesis and Characterization of an Epoxy Ended Poly(Ether Sulphone)/Poly(Ether Ether Sulfphone) Copolymer

This paper describes the synthesis of new model compounds and copolyether sulphones with epoxy functionalities as reactive groups at the end of the chain. The materials were characterised by 1 H-NMR, FTIR and elemental analysis. They are very promising as new toughening agents of thermosets such as epoxy resins.