Staff directory Claudio Roscini

Publications

2018

  • Molecular-based upconversion in homo/heterogeneous liquids and in micro/nanostructured solid materials

    Latterini L., Massaro G., Penconi M., Gentili P.L., Roscini C., Ortica F. Dalton Transactions; 47 (26): 8557 - 8565. 2018. 10.1039/c8dt00020d.

    Radiation upconversion can be an elegant and efficient strategy to minimize waste in energy harvesting and storage processes. The upconversion based on triplet-triplet annihilation processes of molecular dyes is a very versatile approach, but it requires a systematic photophysical characterization of the systems to optimize the upconversion yields and develop materials for technological applications. This paper represents an overview of the work carried out in our laboratories for the study and characterization of a molecular dye pair, 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(ii) (PtOEP) and 1,3,6,8-tetraphenylpyrene (TPPy), suitable as the sensitizer and emitter, respectively, in a triplet-triplet annihilation based upconversion process. The investigation has been carried out in various media with increasing complexity. First, we used the dye pair to characterize the UC-efficiencies in homogeneous solvents of different viscosities and in oil-in-water microemulsions; then we explored the possibility to achieve upconversion in solid materials, like nanostructured silica matrices and liquid filled microcapsules. The possibility to achieve upconversion emission even in confined and rigid media has been confirmed and can inspire further applications of the process. © The Royal Society of Chemistry 2018.


  • Off/On Fluorescent Nanoparticles for Tunable High-Temperature Threshold Sensing

    Julià López A., Ruiz-Molina D., Landfester K., Bannwarth M.B., Roscini C. Advanced Functional Materials; 28 (28, 1801492) 2018. 10.1002/adfm.201801492.

    Herein, a versatile threshold temperature sensor based on the glass transition temperature-triggered fluorescence activation of a dye/developer duo, encapsulated in polymeric nanoparticles is reported. The emission enhancement, detectable even by unaided eye is completed within a narrow temperature range and activates at adjustable threshold temperatures up to 200 °C. Fluorescence is chosen as sensing probe due to its high detection sensitivity together with an advanced spatial and temporal resolution. The strategy is based on nanoparticles prepared from standard thermoplastic polymers, a fluorescence developer, and the commercially available Rhodamine B base dye, a well-known and widely used fluorescent molecule. By making nanoparticles of different thermoplastic polymers, fast, abrupt, and irreversible disaggregation induced fluorescence enhancement, with tunable threshold temperature depending on the nanoparticles polymer glass transition is achieved. As a proof-of-concept for the versatility of this novel family of NPs, their use for sensing the thermal history of environments and surfaces exposed to the threshold temperature is showed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


  • Solvent-Tuned Supramolecular Assembly of Fluorescent Catechol/Pyrene Amphiphilic Molecules

    Nador F., Wnuk K., Roscini C., Solorzano R., Faraudo J., Ruiz-Molina D., Novio F. Chemistry - A European Journal; 24 (55): 14724 - 14732. 2018. 10.1002/chem.201802249.

    The synthesis and structuration of a novel low-molecular-weight amphiphilic catechol compound is reported. The combination of a hydrophilic tail containing a catechol unit and a pyrene-based hydrophobic head favors solvent-tuned supramolecular assembly. Formation of hollow nanocapsules/vesicles occurs in concentrated solutions of polar protic and nonprotic organic solvents, whereas a fibril-like aggregation process is favored in water, even at low concentrations. The emission properties of the pyrene moiety allow monitoring of the self-assembly process, which could be confirmed by optical and electronic microscopy. In organic solvents and at low concentrations, this compound remains in its nonassembled monomeric form. As the concentration increases, the aggregation containing preassociated pyrene moieties becomes more evident up to a critical micellar concentration, at which vesicle-like structures are formed. In contrast, nanosized twist beltlike fibers are observed in water, even at low concentrations, whereas microplate structures appear at high concentrations. The interactions between molecules in different solvents were studied by using molecular dynamics simulations, which have confirmed different solvent-driven supramolecular interactions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim


  • Sonochemical Synthesis of Optically Tuneable Conjugated Polymer Nanoparticles

    Bellacanzone C., Roscini C., del Carmen Ruiz Delgado M., Ponce Ortiz R., Ruiz-Molina D. Particle and Particle Systems Characterization; 35 (2, 1700322) 2018. 10.1002/ppsc.201700322.

    The development of novel and simple methodologies for the obtaining of semiconductive polymer nanoparticles with fine-tuned optical properties represents nowadays a challenging research area as it involves a simultaneous chemical modification and nanostructuration of the polymer. Here, starting from poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], this objective is achieved with the one-pot synthesis of oligomers with tunable conjugation length and their nanostructuration, employing a miniemulsion method. Ultrasound irradiation of heterogeneous mixtures leads to the formation of hypochlorous acid that disrupts the electronic conjugation through polymer chain cleavage. Moreover, control over the degree of the electronic conjugation of the oligomers, and therefore of the optical properties, is achieved simply by varying the polymer concentration of the initial solution. Finally, the presence of surfactants during the sonication allows for the formation of nanoparticles with progressive spectral shift of the main absorption (from λmax = 476 to 306 nm) and emission bands (from λmax = 597 to 481 nm). The integration of conducting polymer nanoparticles into polymeric matrices yields self-standing and flexible fluorescent films. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


2017

  • Photochromism of dihydroazulene-based polymeric thin films

    Torres-Pierna H., Roscini C., Vlasceanu A., Broman S.L., Jevric M., Cacciarini M., Nielsen M.B. Dyes and Pigments; 145: 359 - 364. 2017. 10.1016/j.dyepig.2017.06.015. IF: 3.473

    We report on the preparation of polymeric thin films doped with six dihydroazulene derivatives whose photochromic properties were previously screened in organic solution studies. Spectroscopic investigations into the photochromic behavior of the polymeric matrices have given important insights on the stability and the photophysical properties of the photoswitches impregnated into polymers. © 2017 Elsevier Ltd


2016

  • Switchable colloids, thin-films and interphases based on metal complexes with non-innocent ligands: The case of valence tautomerism and their applications

    Vázquez-Mera N.A., Novio F., Roscini C., Bellacanzone C., Guardingo M., Hernando J., Ruiz-Molina D. Journal of Materials Chemistry C; 4 (25): 5879 - 5889. 2016. 10.1039/c6tc00038j. IF: 5.066

    Successful nanostructuration approaches developed in the last few years have allowed the preparation of robust valence tautomeric (VT) switchable (micro-/nano-) structures of a variety of dimensions and morphologies. These results are expected to definitely foster the implementation of these materials on hybrid molecular electronic devices but also endorse new applications in other different fields such as sensing, drug delivery or water remediation, among others. © The Royal Society of Chemistry 2016.


  • Temperature-Controlled Switchable Photochromism in Solid Materials

    Julià-López A., Hernando J., Ruiz-Molina D., González-Monje P., Sedó J., Roscini C. Angewandte Chemie - International Edition; 55 (48): 15044 - 15048. 2016. 10.1002/anie.201608408. IF: 11.709

    A novel strategy to achieve thermally switchable photochromism in solid materials is reported, which relies on the preparation of polymeric core–shell capsules containing solutions of photochromic dyes in acidic phase-change materials. Upon changing the phase (solid or liquid) of the encapsulated medium, one of the two photochromic states of the system is selectively stabilized on demand, allowing for reversible interconversion between direct and reverse photochromism when thermally scanning through the melting temperature of the phase-change material. This strategy, which does not require the addition of external agents or chemical modification of the dyes, proved to be general for different spiropyran photochromes and to be applicable to the fabrication of a variety of functional materials by simply embedding the capsules obtained into a solid matrix of choice. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim


  • Thermally Switchable Molecular Upconversion Emission

    Massaro G., Hernando J., Ruiz-Molina D., Roscini C., Latterini L. Chemistry of Materials; 28 (3): 738 - 745. 2016. 10.1021/acs.chemmater.5b03532. IF: 9.407

    In this work a novel strategy is introduced to achieve thermally switchable emission from photon upconversion (UC) systems based on organic dyes. When these molecules were dissolved at low concentrations in phase-change media, a reversible, sharp, and nearly complete interconversion from blue upconverted emission to red luminescence was observed around the solid-to-liquid transition of the system. This result was rationalized in terms of dye aggregation, which selectively occurs in the solid state and dramatically enhances the inter-chromophoric energy transfer processes leading to UC. Notably, this behavior is extendable to different media and dyes, which allows an easy tuning of the switching temperature and emission colors. In addition, with proper selection of the phase-change medium, our strategy permits facile preparation of solid molecular materials showing photon UC at room temperature and even at sub-micromolar dye concentrations. © 2016 American Chemical Society.


2015

  • Liquid-Filled Valence Tautomeric Microcapsules: A Solid Material with Solution-Like Behavior

    Vázquez-Mera N.A., Roscini C., Hernando J., Ruiz-Molina D. Advanced Functional Materials; 25 (26): 4129 - 4134. 2015. 10.1002/adfm.201501166. IF: 11.805

    The integration of stimuli-responsive valence tautomeric (VT) molecular systems into solid materials without compromising their functionality is a major bottleneck for the use of these compounds in high-added value applications. In this work, an innovative, simple, and universal approach is described to tackle this challenge based on the confinement of the active species into liquid-filled polymeric capsules. A microstructured solid with optimized solution-like behavior is obtained in this way, whose VT properties can be rationally tuned upon variation of the encapsulated solvent. Incorporation of the resulting capsules into thin films or other matrices of interest allows successful transfer of valence tautomerism from the liquid phase to solid materials, thus paving the way to the fabrication of functional devices based on spin transition compounds. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


2013

  • Liquid-filled capsules as fast responsive photochromic materials

    Vázquez-Mera, N.; Roscini, C.; Hernando, J.; Ruiz-Molina, D. Advanced Optical Materials; 1: 631 - 636. 2013. 10.1002/adom.201300121. IF: 0.000