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1. Optimization of the preparation procedure of cobalt modified silicas as catalysts in methanol decomposition

Author

Bulgarian Academy of Sciences - Sofia, ISTM-CNR, Milano - Italy, L. Malatesta University of Milan, Italy - Dept CIMA, UCL - SST/IMCN/MOST - Molecules, Solids and Reactivity, Tsoncheva, T., Gallo, A., Scotti, N., Dimitrov, M., Delaigle, Romain, Gaigneaux, Eric M., Bulgarian Academy of Sciences - Sofia, ISTM-CNR, Milano - Italy, L. Malatesta University of Milan, Italy - Dept CIMA, UCL - SST/IMCN/MOST - Molecules, Solids and Reactivity, Tsoncheva, T., Gallo, A., Scotti, N., Dimitrov, M., Delaigle, Romain, and Gaigneaux, Eric M.

Abstract

Novel modified “chemisorption–hydrolysis” technique and conventional “incipient wetness impregnation” procedure were compared for loading of cobalt species on mesoporous silica supports. Effect of cobalt amount, pH of the precursor solution, duration of the “chemisorption” procedure and pre-treatment medium, as well as topological characteristics of the mesoporous silica support were investigated. The state of the loaded cobalt species was studied by XRD, FTIR, FTIR of adsorbed pyridine, UV–vis, XPS and TPR methods and their catalytic properties were elucidated in methanol decomposition to hydrogen and carbon monoxide. The “incipient wetness impregnation” technique facilitates the formation of finely dispersed spinel cobalt oxide species. Their catalytic activity could be significantly increased by hydrogen pretreatment, but the effect is more pronounced when mesoporous silica with ordered pseudo 1D pore structure (SBA-15) is used as a support. The modified “chemisorption–hydrolysis” procedure facilitates the formation of strongly interacting with the support cobalt species, which are stable under the reduction conditions. Their properties could be regulated during the modification procedure, by varying the cobalt content and pH of the impregnated solution as well as by the duration of the “chemisorption” procedure.

Published
2012

2. Photochromic DTE-Substituted-1,3-di(2-pyridyl)benzene Platinum(II) Complexes: Photo-modulation of Luminescence and Second-order Nonlinear Optical Properties

Author

Eleonora Garoni, Alessia Colombo, Julien Boixel, Daniele Marinotto, Véronique Guerchais, Dominique Roberto, Stefania Righetto, Hong Zhao, Denis Jacquemin, Claudia Dragonetti, Thierry Roisnel, Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Dipartimento di Chimica, Università degli Studi di Milano [Milano] (UNIMI), ISTM CNR, Milano, Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation (CEISAM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Centre National de la Recherche Scientifique, INSTMMI012, National Interuniversity Consortium of Materials Science and Technology, Institut des Sciences Chimiques de Rennes ( ISCR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Ecole Nationale Supérieure de Chimie de Rennes-Institut National des Sciences Appliquées ( INSA ) -Centre National de la Recherche Scientifique ( CNRS ), Università degli studi di Milano [Milano], ISTM CNR, Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation ( CEISAM ), Université de Nantes ( UN ) -Centre National de la Recherche Scientifique ( CNRS ), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Milano = University of Milan (UNIMI), and Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Photoluminescence, Photoisomerization, 010405 organic chemistry, chemistry.chemical_element, 010402 general chemistry, Ring (chemistry), Photochemistry, Photochromism, 01 natural sciences, [ CHIM ] Chemical Sciences, Fluorescence, 3. Good health, 0104 chemical sciences, Inorganic Chemistry, closed-ring isomer, chemistry, Moiety, [CHIM]Chemical Sciences, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Physical and Theoretical Chemistry, Platinum, Luminescence, Isomerization
Abstract

International audience; We disclose a new family of photochromic cyclometalated platinum(II) complexes (PtDTE1 and PtDTE2), where a dithienylethene (DTE) unit is connected at the para-position of the central phenyl ring of (N^C^N) cyclometalated ligand, through two different linkages. Their syntheses are presented along with the X-ray characterizations of both the open and closed isomers of PtDTE1. The investigation of their photophysical properties is made, including absorption, photochromism, emission, and second-order nonlinear properties. We report a quantitative photo-isomerization for both PtDTE1 and PtDTE2, irrespective of the nature of the connecting mode between the DTE unit and the platinum(II) moiety. The efficient photochromism allows a significant NLO photo-modulation, both in solution and in thin films. In addition, we show that the photoluminescence of the PtDTE1 and PtDTE2 can be controlled by the open/closed isomerization of the DTE unit.

Published
2018

3. Helium-induced electronic transitions in photo-excited BA+ –HEn exciplexes

Author

Martí Pi, Marcel Drabbels, Nadine Halberstadt, Fausto Cargnoni, Patricia Vindel Zandbergen, Manuel Barranco, Théorie (LCAR), Laboratoire Collisions Agrégats Réactivité (LCAR), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Departament de Física Fonamental, Facultat de Física, Universitat de Barcelona (UB), Institut de Nanociència i Nanotecnologia (IN2UB), ISTM CNR, ISTM CNR, Milano, Swiss Federal Institute of Technology at Lausanne (EPFL), Universitat de Barcelona, Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse)

Subjects
Materials science, General Physics and Astronomy, 010402 general chemistry, Helium, 01 natural sciences, Molecular physics, Ion, 0103 physical sciences, Atom, Heli, Physics::Atomic and Molecular Clusters, Química quàntica, Physics::Atomic Physics, Symmetry breaking, Physical and Theoretical Chemistry, Wave functions, ComputingMilieux_MISCELLANEOUS, 010304 chemical physics, Avoided crossing, 0104 chemical sciences, Photoexcitation, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Atomic electron transition, Excited state, Relaxation (physics), Quantum chemistry, Funcions d'ona
Abstract

The possibility for helium-induced electronic transitions in a photo-excited atom is investigated using Ba+ excited to the 6p P-2 state as a prototypical example. A diabatization scheme has been designed to obtain the necessary potential energy surfaces and couplings for complexes of Ba+ with an arbitrary number of helium atoms. It involves computing new He-Ba+ electronic wave functions and expanding them in determinants of the non-interacting complex. The 6p P-2

Published
2018

4. Intriguing C-H center dot center dot center dot Cu interactions in bis-(phenanthroline)Cu(I) redox mediators for dye-sensitized solar cells

Author

Colombo, Alessia, Ossola, Rachele, Magni, Mirko, Roberto, Dominique, Jacquemin, Denis, Castellano, Carlo, Demartin, Francesco, Dragonetti, Claudia, Dipartimento di Chimica, Università degli Studi di Milano [Milano] (UNIMI), ISTM CNR, Milano, Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation (CEISAM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
[CHIM]Chemical Sciences
Abstract

We have synthesized and characterized a series of bis-(phenanthroline)Cu(I) complexes of interest as redox mediators for dyesensitized solar cells. This study led to the discovery of intriguing anagostic interactions between the hydrogen atom and the copper center as evidenced by X-ray diffraction studies on a single crystal. Remarkably, an anagostic interaction was found between a H atom of a methyl group and a copper site.

Published
2018

5. Highly active nanostructured palladium-ceria electrocatalysts for the hydrogen oxidation reaction in alkaline medium

Author

Hamish A. Miller, Anicet Zadick, Laetitia Dubau, Serhiy Cherevko, Huong Doan, Marcello Marelli, Marian Chatenet, Dario R. Dekel, Francesco Vizza, Sanjeev Mukerjee, Simon Geiger, Ryan Pavlicek, Istituto di Chimica dei Composti Organometallici (ICCOM), Consiglio Nazionale delle Ricerche (CNR), ISTM CNR, Milano, Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Gesellschaft, Helmholtz Institute Erlangen Nürnberg for Renewable Energy (IEK-11), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association-Helmholtz-Gemeinschaft = Helmholtz Association, Northeastern University [Boston], Technion - Israel Institute of Technology [Haifa], European Union’s Horizon 2020 research and innovation programme, European Project: 721065,CREATE, and National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)

Subjects
Materials science, Hydrogen, Inorganic chemistry, hydrogen oxidation, Platinum free, chemistry.chemical_element, 02 engineering and technology, Electrolyte, 010402 general chemistry, 01 natural sciences, 7. Clean energy, Catalysis, Metal, chemistry.chemical_compound, Ceria, General Materials Science, Electrical and Electronic Engineering, Bifunctional, Ion exchange, Renewable Energy, Sustainability and the Environment, Fuel cell, [CHIM.CATA]Chemical Sciences/Catalysis, 021001 nanoscience & nanotechnology, 0104 chemical sciences, chemistry, visual_art, ddc:660, visual_art.visual_art_medium, 0210 nano-technology, Carbon, Anion exchange membrane, Palladium
Abstract

International audience; We report an interesting new class of bifunctional electrocatalysts, Pd/C-CeO 2 , with excellent activity and stability for the hydrogen oxidation reaction (HOR) under alkaline conditions. The unique structure of palladium deposited onto a mixed support of Vulcan XC-72 carbon and CeO 2 consists of Pd metal preferable deposited on the ceria regions of the catalyst. The CeO 2-Pd interaction leads to enhanced HOR kinetics and increased stability. Here we compare catalysts with three different Pd loadings and show that the 10 wt% Pd sample has optimized activity. Hydrogen pumping and fuel cell experiments based on this catalyst show higher activities as compared to a Pd/C sample without ceria. Metal dissolution tests and identical location transmission microscopy experiments show that the catalyst stability under harsh potential cycling experiments in alkaline medium is significantly improved as compared to Pd/C, making this material one of the best options for use as highly active and highly stable electrocatalysts for the HOR in anion exchange membrane fuel cells.

Published
2017

6. Silica 'SHB' chiral Pc-L* copper complexes for halogen-free solvent cyclopropanation reactions

Author

Vladimiro Dal Santo, B. Castano, Emma Gallo, Anne Galarneau, Yvonne C. Hönemann, Alessandro Caselli, Paolo Zardi, Rinaldo Psaro, Universita degli studi di Milano, Chimica, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), ISTM CNR, and ISTM CNR, Milano

Subjects
inorganic chemicals, CU(I) COMPLEXES, Cyclopropanation, General Chemical Engineering, Inorganic chemistry, chemistry.chemical_element, Halogen free, 010402 general chemistry, 01 natural sciences, Catalysis, chemistry.chemical_compound, Polymer chemistry, Pyridine, BIS(OXAZOLINE)-COPPER COMPLEXES, TEMPERATURE, ComputingMilieux_MISCELLANEOUS, ASYMMETRIC CYCLOPROPANATION, Olefin fiber, HETEROGENEOUS CATALYSTS, 010405 organic chemistry, ENANTIOSELECTIVE CATALYSIS, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, Grafting, Copper, 0104 chemical sciences, Solvent, MESOPOROUS SILICA, chemistry, MICROPOROSITY, DIELS-ALDER REACTIONS, CONTAINING MACROCYCLIC LIGANDS
Abstract

The grafting of the preformed Pc-L* (pyridine containing macrocyclic ligands) copper(I) complexes on different ordered and non-ordered silicas, and their use, under heterogeneous batch conditions, as catalysts for the olefin cyclopropanation are reported. High yields (up to 99%) and good recyclability in halogen-free solvent reactions were obtained, together with negligible copper leaching (0.1% of total copper).

Published
2013

7. Optimization of the preparation procedure of cobalt modified silicas as catalysts in methanol decomposition

Author

Tanya Tsoncheva, Alessandro Gallo, Nicola Scotti, Momtchil Dimitrov, Romain Delaigle, Eric M. Gaigneaux, Daniela Kovacheva, Vladimiro Dal Santo, Nicoletta Ravasio, Bulgarian Academy of Sciences - Sofia, ISTM-CNR, Milano - Italy, L. Malatesta University of Milan, Italy - Dept CIMA, and UCL - SST/IMCN/MOST - Molecules, Solids and Reactivity

Subjects
Post-synthesis modification, Process Chemistry and Technology, Inorganic chemistry, KIT-6, chemistry.chemical_element, Mesoporous silica, cobalt modifications, Methanol decomposition, Catalysis, chemistry.chemical_compound, SBA-15, Adsorption, Pore topology effect, chemistry, Chemisorption, pore topology effect, Cobalt modifications, Methanol, Cobalt, Cobalt oxide, post-synthesis modification, Incipient wetness impregnation
Abstract

Novel modified “chemisorption–hydrolysis” technique and conventional “incipient wetness impregnation” procedure were compared for loading of cobalt species on mesoporous silica supports. Effect of cobalt amount, pH of the precursor solution, duration of the “chemisorption” procedure and pre-treatment medium, as well as topological characteristics of the mesoporous silica support were investigated. The state of the loaded cobalt species was studied by XRD, FTIR, FTIR of adsorbed pyridine, UV–vis, XPS and TPR methods and their catalytic properties were elucidated in methanol decomposition to hydrogen and carbon monoxide. The “incipient wetness impregnation” technique facilitates the formation of finely dispersed spinel cobalt oxide species. Their catalytic activity could be significantly increased by hydrogen pretreatment, but the effect is more pronounced when mesoporous silica with ordered pseudo 1D pore structure (SBA-15) is used as a support. The modified “chemisorption–hydrolysis” procedure facilitates the formation of strongly interacting with the support cobalt species, which are stable under the reduction conditions. Their properties could be regulated during the modification procedure, by varying the cobalt content and pH of the impregnated solution as well as by the duration of the “chemisorption” procedure.

Published
2012

8. Palladium–Ceria Catalysts with Enhanced Alkaline Hydrogen Oxidation Activity for Anion Exchange Membrane Fuel Cells

Author

Hamish A. Miller, Dario R. Dekel, Lianqin Wang, Jasna Jankovic, Chethana B. Krishnamurthy, Francesco Vizza, Sanjeev Mukerjee, Elena S. Davydova, John R. Varcoe, Anna Lenarda, Marco Bellini, Qingying Jia, Maria V. Pagliaro, Massimo Innocenti, Paolo Fornasiero, Ilya Grinberg, Claudio Evangelisti, Marcello Marelli, Bellini, M., Pagliaro, M. V., Lenarda, A., Fornasiero, P., Marelli, M., Evangelisti, C., Innocenti, M., Jia, Q., Mukerjee, S., Jankovic, J., Wang, L., Varcoe, J. R., Krishnamurthy, C. B., Grinberg, I., Davydova, E., Dekel, D. R., Miller, H. A., Vizza, F., ISTM CNR, Milano, CNR-Instituto di Science e tecnologie Moleculari, Northeastern University [Boston], University of Surrey - Department of Chemistry - Centre for Petroleum and Surface Chemistry, Technion - Israel Institute of Technology [Haifa], Istituto di Chimica dei Composti Organometallici (ICCOM), Consiglio Nazionale delle Ricerche (CNR), European Project: 721065,CREATE, University of Surrey (UNIS), and National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)

Subjects
Hydrogen, platinum free, ceria palladium, Energy Engineering and Power Technology, chemistry.chemical_element, Proton exchange membrane fuel cell, 02 engineering and technology, Electrolyte, fuel cells, 010402 general chemistry, anion exchange membrane, ceria, palladium, 01 natural sciences, 7. Clean energy, Catalysis, fuel cell, Materials Chemistry, Electrochemistry, Chemical Engineering (miscellaneous), [CHIM]Chemical Sciences, Electrical and Electronic Engineering, ComputingMilieux_MISCELLANEOUS, Ion exchange, Chemistry, [CHIM.CATA]Chemical Sciences/Catalysis, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Membrane, Chemical engineering, 0210 nano-technology, Platinum, Palladium
Abstract

Anion exchange membrane fuel cells (AEMFCs) offer several important advantages with respect to proton exchange membrane fuel cells, including the possibility of avoiding the use of platinum catalysts to help overcome the high cost of fuel cell systems. Despite such potential benefits, the slow kinetics of the hydrogen oxidation reaction (HOR) in alkaline media and limitations in performance stability (because of the degradation of the anion conducting polymer electrolyte components) have generally impeded AEMFC development. Replacing Pt with an active but more sustainable HOR catalyst is a key objective. Herein, we report the synthesis of a Pd–CeO2/C catalyst with engineered Pd-to-CeO2 interfacial contact. The optimized Pd–CeO2 interfacial contact affords an increased HOR activity leading to ˃1.4 W cm–2 peak power densities in AEMFC tests. This is the only Pt-free HOR catalyst yet reported that matches state-of-the-art AEMFC power performances (˃1 W cm–2). Density functional theory calculations suggest that the exceptional HOR activity is attributable to a weakening of the hydrogen binding energy through the interaction of Pd atoms with the oxygen atoms of CeO2. This interaction is facilitated by a structure that consists of oxidized Pd atoms coordinated by four CeO2 oxygen atoms, confirmed by X-ray absorption spectroscopy.

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9. Ulvan as novel reducing and stabilizing agent from renewable algal biomass: Application to green synthesis of silver nanoparticles.

Author

Massironi A, Morelli A, Grassi L, Puppi D, Braccini S, Maisetta G, Esin S, Batoni G, Della Pina C, and Chiellini F

Abstract

Silver nanoparticles (AgNPs) have been intensively investigated in virtue of their optical and antimicrobial properties, although their applications have been limited due to inherent toxicity and to the need of employing harsh chemical reagents for the synthesis. In this work, ulvan, a sulfated polysaccharide extracted from green algae belonging to Ulva armoricana sp., was for the first time investigated and identified as reducing and stabilizing agent for AgNPs synthesis by using milder conditions than those conventionally adopted by chemical methods. The synthesized AgNPs were thoroughly characterized to highlight the structure and the role exerted by ulvan in their synthesis and stabilization. The formation of AgNPs stabilized by a thick ulvan shell was assessed by UV-vis, XRD, TEM, DLS and zeta potential analyses. The developed Ulvan based AgNps showed an IC 50 in the range of 10 μg/ml in Balb/3T3 mouse embryo fibroblasts and antimicrobial activity toward both Gram + and Gram - bacteria., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Published
2019
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10. Author Correction: The Staphylococcus aureus extracellular matrix protein (Emp) has a fibrous structure and binds to different extracellular matrices.

Author

Geraci J, Neubauer S, Pöllath C, Hansen U, Rizzo F, Krafft C, Westermann M, Hussain M, Peters G, Pletz MW, Löffler B, Makarewicz O, and Tuchscherr L

Abstract

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Published
2018
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11. The Staphylococcus aureus extracellular matrix protein (Emp) has a fibrous structure and binds to different extracellular matrices.

Author

Geraci J, Neubauer S, Pöllath C, Hansen U, Rizzo F, Krafft C, Westermann M, Hussain M, Peters G, Pletz MW, Löffler B, Makarewicz O, and Tuchscherr L

Subjects
Amino Acid Sequence, Bacterial Proteins chemistry, Bone and Bones metabolism, Cartilage metabolism, Escherichia coli, Extracellular Matrix ultrastructure, Extracellular Matrix Proteins chemistry, Humans, Kinetics, Protein Binding, Protein Conformation, Protein Domains, Recombinant Proteins, Sequence Alignment, Skin metabolism, Staphylococcus aureus, Bacterial Proteins metabolism, Extracellular Matrix metabolism, Extracellular Matrix Proteins metabolism
Abstract

The extracellular matrix protein Emp of Staphylococcus aureus is a secreted adhesin that mediates interactions between the bacterial surface and extracellular host structures. However, its structure and role in staphylococcal pathogenesis remain unknown. Using multidisciplinary approaches, including circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy, transmission electron (TEM) and immunogold transmission electron microscopy, functional ELISA assays and in silico techniques, we characterized the Emp protein. We demonstrated that Emp and its truncated forms bind to suprastructures in human skin, cartilage or bone, among which binding activity seems to be higher for skin compounds. The binding domain is located in the C-terminal part of the protein. CD spectroscopy revealed high contents of β-sheets (39.58%) and natively disordered structures (41.2%), and TEM suggested a fibrous structure consisting of Emp polymers. The N-terminus seems to be essential for polymerization. Due to the uncommonly high histidine content, we suggest that Emp represents a novel type of histidine-rich protein sharing structural similarities to leucine-rich repeats proteins as predicted by the I-TASSER algorithm. These new findings suggest a role of Emp in infections of deeper tissue and open new possibilities for the development of novel therapeutic strategies.

Published
2017
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12. The key intermediate in the amination of saturated C-H bonds: synthesis, X-ray characterization and catalytic activity of Ru(TPP)(NAr)(2) (Ar = 3,5-(CF(3))(2)C(6)H(3)).

Author

Fantauzzi S, Gallo E, Caselli A, Ragaini F, Casati N, Macchi P, and Cenini S

Abstract

The complex Ru(TPP)(NAr)(2) inserts a nitrene group into allylic and benzylic C-H bonds and is the key intermediate in the ruthenium porphyrin-catalyzed amination of hydrocarbons by aryl azides.

Published
2009
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13. Esterification of acidic oils over a versatile amorphous solid catalyst.

Author

Zaccheria F, Brini S, Psaro R, Scotti N, and Ravasio N

Subjects
Catalysis, Energy-Generating Resources, Esterification, Gasoline, Silicon Dioxide, Zirconium, Fatty Acids, Nonesterified chemistry, Green Chemistry Technology methods, Plant Oils chemistry, Triglycerides chemistry
Abstract

An amorphous SiO(2)-ZrO(2) catalyst shows high activity in the esterification of free fatty acids contained in vegetable oils while at the same time promoting the transesterification of triglycerides. The catalyst is hence a good candidate for a low-waste deacidification pretreatment or for a one-pot biodiesel production process starting from oils with a high acid content.

Published
2009
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14. Ground state potential energy surfaces and bound states of M-He dimers (M=Cu,Ag,Au): a theoretical investigation.

Author

Cargnoni F, Kuś T, Mella M, and Bartlett RJ

Abstract

We present an ab initio investigation on the ground state interaction potentials [potential energy surface (PES)] between helium and the group 11 metal atoms: copper, silver, and gold. To the best of our knowledge, there are no previous theoretical PESs proposed for Cu-He and Au-He, and a single one for Ag-He [Z. J. Jakubek and M. Takami, Chem. Phys. Lett. 265, 653 (1997)], computed about 10 years ago at MP2 level and significantly improved by our study. To reach a high degree of accuracy in the determination of the three M-He potentials (M=Cu,Ag,Au), we performed extensive series of test computations to establish the appropriate basis set, the theoretical method, and the computational scheme for these systems. For each M-He dimer we computed the PES at the CCSD(T) level of theory, starting from the reference unrestricted Hartree-Fock wave function. We described the inner shells with relativistic small core pseudopotentials, and we adopted high quality basis sets for the valence electrons. We also performed CCSDT computations in a limited set of M-He internuclear distances, adopting a medium-sized basis set, such as to define for each dimer a CCSD(T) to CCSDT correction term and to improve further the quality of the CCSD(T) interaction potentials. The Cu-He complex has minimum interaction energy (E(min)) of -28.4 microhartree at the internuclear distance of 4.59 A (R(min)), and the short-range repulsive wall starts at 4.04 A (R(E=0)). Quite interestingly, the PES of Ag-He is more attractive (E(min)=-33.8 microhartree) but presents nearly the same R(min) and R(E=0) values, 4.60 and 4.04 A, respectively. The interaction potential for Au-He is markedly deeper and shifted at shorter distances as compared to the lighter complexes, with E(min)=-69.6 microhartree, R(min)=4.09 A and R(E=0)=3.60 A. As a first insight in the structure of M-He(n) aggregates, we determined the rovibrational structure of the three M-He dimers. The Cu-He and Ag-He potentials support just few rotational excitations, while the Au-He PES admits also a bound vibrational excitation.

Published
2008
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15. New structural motifs, unusual quenching of the emission, and second harmonic generation of copper(I) iodide polymeric or oligomeric adducts with para-substituted pyridines or trans-stilbazoles.

Author

Cariati E, Roberto D, Ugo R, Ford PC, Galli S, and Sironi A

Abstract

The structural, emissive, and nonlinear optical properties of new CuI adducts with para-substituted trans-stilbazolic and pyridinic ligands are reported. Single-crystal X-ray diffraction results indicate that the para-substituent on the organic ligand greatly influences the structural motif by its steric (tert-butyl), electronic/steric (dimethylamino), or bridging-donor (cyano) properties so that two absolutely new structural motifs, polymeric and oligomeric, are found when trans-stilbazole and pyridine carry a dimethylamino group in the para-position. In addition, a surprising photoemission behavior is observed, being the solid-state emission of [CuI(trans-4-stilbazole)]n, [CuI(trans-4'-(dimethylamino)-4-stilbazole)]n, and [CuI(4'-tert-butyl-4-stilbazole)]n totally quenched. In the case of the noncentrosymmetric CuI adduct of trans-4'-(dimethylamino)stilbazole a discrete second harmonic generation (SHG) occurs.

Published
2005
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16. Models for biological trinuclear copper clusters. Characterization and enantioselective catalytic oxidation of catechols by the copper(II) complexes of a chiral ligand derived from (S)-(-)-1,1'-binaphthyl-2,2'-diamine.

Author

Mimmi MC, Gullotti M, Santagostini L, Battaini G, Monzani E, Pagliarin R, Zoppellaro G, and Casella L

Subjects
Catalysis, Circular Dichroism, Electron Spin Resonance Spectroscopy, Hydrogen-Ion Concentration, Kinetics, Levodopa chemistry, Ligands, Magnetic Resonance Spectroscopy, Molecular Structure, Oxidation-Reduction, Stereoisomerism, Catechols chemistry, Copper chemistry, Diamines chemistry, Models, Biological, Naphthalenes chemistry
Abstract

The dinuclear and trinuclear Cu(II) complexes of an octadentate ligand derived from (S)-1,1'-binaphthyl-2,2'-diamine have been prepared and characterized by UV/Vis, CD, EPR and NMR spectroscopy. The ligand contains two tridentate aminobis(benzimidazole) donor arms connected to a central bidentate diaminobinaphthyl linker, which hosts the chiral unit. In the dinuclear Cu complex the ligation occurs essentially within the tridentate arms of the ligand. The two Cu centers are EPR nonequivalent and noninteracting. The EPR data suggests that one of the Cu ions additionally interacts with one of the tertiary aminonaphthyl donors. In the trinuclear complex the two aminonaphthyl donors bind the third Cu ion. The EPR spectrum of this complex shows the signal for a mononuclear Cu(II) center bound to a tridentate arm, while the remaining two Cu(II) centers are coupled through hydroxo groups. The CD spectrum shows that in the free ligand a severe reduction of the dihedral angle between the naphthyl groups from the strain free range occurs. This conformation is stabilized by ring stacking interactions with the benzimidazole groups. On complex formation this interaction is removed because the benzimidazole groups are involved in metal binding. In the dinuclear Cu complex the conformation of the binaphthyl chromophore probably approaches the strain free range, while in the trinuclear Cu complex a marked flattening of the dihedral angle between the two naphthyl rings occurs. Both complexes are active catalysts in the oxidation of L-/D-Dopa derivatives to quinones. High enantioselectivity is observed in the oxidation of L-/D-Dopa methyl ester catalyzed by the dinuclear Cu complex, which exhibits strong preference for the d enantiomer. The enantioselectivity is largely lost for the trinuclear Cu complex.

Published
2004
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