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Venezia, Italy

Fiorani G.,University of Venice | Selva M.,University of Venice | Perosa A.,University of Venice | Benedetti A.,University of Venice | And 4 more authors.
Green Chemistry

Five new luminescent ionic liquids (LILs) derived from tryptophan (Trp), phenylalanine (Phe) and the dipeptide Gly-Gly functionalized with a dansyl chromophore moiety, were synthesized by an original protocol involving both green reagents/solvents such as non-toxic dimethyl carbonate (DMC: MeOCO2Me) and 2-propanol, and reaction conditions. In particular, DMC was used for: (i) the synthesis of methyltrioctyl methylcarbonate onium salts [Q1mmn][MeOCO2] (Q = N, m = 1, n = 8; Q = P, n = m = 4, 8) by P- and N-methylation of trioctylphosphine and trioctylamine, respectively, and (ii) acid-catalyzed esterifications of Trp and Phe to produce the corresponding methyl esters (Trp-OMe and Phe-OMe). Both reactions proceeded with >90% isolated yields and a mass index (esterifications) as low as 4.5. 2-propanol was used as the solvent for N-dansylation reactions where Trp-OMe and Gly-Glyethyl ester hydrochloride (Gly-Gly-OEt) were coupled to dansyl chloride (DNS-Cl) as a luminescent precursor. A final anion metathesis step between methylcarbonate onium salts and N-dansyl amino acid derivatives gave desired LILs of general formula [Q1mmn][DNS-X] (X = Trp, Phe, and Gly-Gly) in quantitative yields and with by-products minimization. Upon excitation (λex = 340 nm) in MeCN, all LILs exhibited green luminescence with emission quantum yields in the range of 33-41% and monoexponential emission lifetimes of 12.6 ± 0.5 ns. Moreover, each compound showed a remarkable hypsochromic shift in the peak emission wavelength when dissolved in solvents of decreasing polarity (from water to MeCN, toluene and CH2Cl2, respectively). A photostability test by a 350 nm continuous excitation on thin films of LILs proved that, after 10 min, the GlyGly derivative fully retained its PL intensity, while this (intensity) decreased from 10 to 25% for other LILs. © 2015 The Royal Society of Chemistry. Source

Rinaldi C.,RSE SpA | Del Corno A.,RSE SpA | Enrichi F.,Veneto Nanotech
Proceedings of the ASME Turbo Expo

This paper describes some examples of the use of two optical spectroscopy techniques to study thermal barrier coating (TBC) degradation preceeding failure. The first part describes photoluminescence piezospectroscopy (PLPS) results obtained on a series of specimens with EB-PVD TBC and Pt-aluminised bond coats. The monotonic decrease of the alumina compressive stress level with ageing and thermal cycling confirms that TGO compressive stress levels can be used as residual life indicators in this type of coating. The automatic mapping system implemented by RSE (Ricerca sul Sistema Energetico) provides precise and reliable results about the level of damage at the BC/TBC interface, well before failure; mapping provides data regarding the precise positions where the first macroscopic detachment (a few millimeters wide) occurs. As PLPS is not applicable to thermal-sprayed APS TBCs, the second part of the paper describes some examples of the contribution that Raman spectroscopy can provide to detect phase changes due to degradation preceeding failure of the TBCs. Possible problems relating to the presence of undesired RE elements in the ceramic layer due to strong fluorescence are also described; solutions are proposed. Finally, examples of how innovative confocal microRaman produces maps evidencing areas where high temperature exposure and thermal cycling-produced phase transformation of the Yttria partially stabilised Zirconia from tetragonal to monoclinic (which typically occurs during cracking processes preceeding final TBC failure) are provided. Copyright © 2012 by ASME. Source

Ricco R.,CSIRO | Konstas K.,CSIRO | Styles M.J.,CSIRO | Richardson J.J.,CSIRO | And 4 more authors.
Journal of Materials Chemistry A

The recent combination of Metal-Organic Frameworks (MOFs) and magnetic nanoparticles has shown their potential as a composite material in practical applications including drug delivery, catalysis and pollutant sequestration. Here, we report for the first time the preparation of a robust magnetic nanocomposite material based on an aluminium MOF (MIL-53) and iron oxide nanoparticles for the uptake of lead(ii) ions. Different aminofunctionalized MIL-53 MOFs were prepared by increasing the 2-aminoterephthalic/terephthalic acid ratio. The composite materials were tested to determine the sequestration capability of heavy metals from various solvents (methanol, DMSO and water), pH (2, 7, 12) and a range of Pb(ii) concentrations (10-8000 ppm). The magnetic composite based on MIL-53 showed remarkable capacity to sequester Pb(ii) ions from water (up to 492.4 mg g-1 of composite), the highest recorded for a MOF sorbent system to date. While the MOF played a crucial role in the efficient heavy metal uptake, the magnetic nanoparticles allowed the prompt collection of the sorbent from solution. The triggered release of Pb(ii) was investigated using an alternating magnetic field. The exceptional adsorption capacity and the response to the magnetic field make this class of innovative functional material a promising candidate for environmental remediation technologies. © The Royal Society of Chemistry 2015. Source

Cattaruzza E.,University of Venice | Caselli V.M.,University of Venice | Mardegan M.,University of Venice | Gonella F.,University of Venice | And 4 more authors.
Ceramics International

The suitability of the Ag+→Na+ ion exchange process was tested for the production of luminescent cover glasses with down-shifting properties suitable for solar cells. The photoluminescence properties were investigated as a function of the preparation parameters (i.e., Ag salt bath concentration, post-synthesis annealing temperature and duration). The performance of the samples was tested by measuring the output power of a Si solar cell covered with the treated glass slides and exposed to a solar simulator radiation; the photoluminescence quantum yield of the best performing samples was also estimated. © 2015 Elsevier Ltd and Techna Group S.r.l. Source

Mardegan A.,University of Venice | Scopece P.,Veneto Nanotech | Ugo P.,University of Venice | Moretto L.M.,University of Venice
Journal of Nanoscience and Nanotechnology

3D-ensembles of gold nanowires electrodes (3D-NEEs) are produced by electroless gold deposition in track-etched polycarbonate (PC) membranes, followed by partial etching (plama or chemical) of the polymeric membrane. These electrodes are applied to the anodic stripping voltammetric determination of inorganic As. The controlled etching of the PC template increased the gold surface area, widening the linear range of the analytical response with respect to ensembles of gold nanodisk electrodes (2D-NEEs). 3D-NEEs prepared using a chemical etching time of 10 s allows the anodic stripping determination of As(III) with a detection limit of 0.08 -g/L and a linear range extended up to 20μ g/L. The speciation of inorganic As (As(III) and (As(V)) in river water is possible by difference between As(III) and total inorganic As, determined after reduction of As(V) with cysteine. The proposed method is successfully validated by comparison with ICP-MS determination. © 2015 American Scientific Publishers All rights reserved. Source

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