IN PRESS - Selected, just-accepted articles

Martin Pilarski, Roland Marschall, Silvia Gross, Michael Wark

Appl. Cat. B: Environmental, Just accepted manuscript

I. F.: 9.446

Layered cesium copper titanate as well as the unmodified cesium titanate Cs0.68Ti1.830.17O4 (□: vacancy) were synthesized by a solution-based approach. The insertion of small amounts of copper into the vacancies of Cs0.68Ti1.830.17O4 led to a significant red shift of the band gap energy from 3.4 eV to 2.9 eV. During photocatalytic H2 production experiments, a steady increase in the evolution rate was detected, which can be referred to the in-situ reduction of incorporated copper ions to metallic Cu. As shown by XPS, the reduced copper ions leach out of the lattice to the catalyst surface and act as co-catalyst for H2 formation, considerably exceeding the activity achieved with Cs0.68Ti1.830.17O4 modified with 0.075 wt.-% of Rh as co-catalyst.

Tomasz Kosmala, Laura Calvillo, Stefano Agnoli and Gaetano Granozzi

ACS Catalysis 2018, DOI: 10.1021/acscatal.7b02690 (I.F.= 10.614)

Electron transfer is the most crucial step in several electrochemical reactions, therefore finding alternative ways for its control represents a huge step toward the design of advanced electrocatalytic materials. We demonstrate that the electrons from an oxide-buried metal interface can be efficiently exploited in electrochemical reactions. This is proven by studying the electrochemical activity of model systems constituted by cobalt oxide ultrathin (<2nm) films epitaxially grown on Pd(100). Metal/metal oxide interfacial hybridization and electron tunnelling from the metal substrate through the oxide endow CoOx ultrathin films with exceptional electrochemical activity and improved methanol poison tolerance. In situ XPS and Raman measurements indicate that during the oxygen reduction reaction, CoOx films are oxidized by oxygen: Co3O4/CoO is fully converted to a spinel phase, whereas CoO is transformed via the transient formation of Co(OH)2 to a mixed Co3O4/CoOOH phase. The study of different oxide film thickness shows the crucial role of the substrate. At the UT regime, the performance of cobalt oxide is essentially analogous to that of Pd(100), because the electrons from the metal substrate can tunnel through the oxide and reduce the oxygen on the electrode surface. On the other hand, as the oxide thickness increases, tunnelling is suppressed and the ORR activity is significantly reduced. Therefore, UT oxide films supported on metals represent an innovative class of materials for electrochemistry applications that show properties not available in a single material. These results demonstrate that the in situ study of ultrathin films on single crystals is a powerful method for the identification of materials active phase and of novel phenomena such as electron tunnelling.

 

T. Gatti, E. Menna, M. Meneghetti, M. Maggini, A. Petrozza, F. Lamberti

Journal: Nano Energy (IF: 12.343)

DOI: 10.1016/j.nanoen.2017.09.016

Fullerenes have been extensively used for more than two decades for the development of organic photovoltaics (OPV). While OPV seems to be a technology almost ready for the market, in the last few years fullerenes are attracting a big interest for the improvement they afford on the already well-performing perovskite solar cells (PSCs). Thanks to PSC integration, interest in fullerenes is rising again, opening up new exciting perspectives for photovoltaics. This review article aims at analyzing the landmark contributions that gave birth to the novel application of fullerenes in PSCs and to the technological solutions that are emerging with them.

 

T. Gatti, N. Manfredi, C. Boldrini, F. Lamberti, A. Abbotto, E. Menna

Journal: Carbon (IF: 6.337)

DOI: 10.1016/j.carbon.2017.01.081

We report here the first example of a covalent functional nanocarbon hybrid based on a benchmark metal-free donor-π-acceptor (D-π-A) dye and reduced graphene oxide (RGO). The dyad, prepared by direct arylation of the RGO surface by means an aniline derivative of the D-π-A species, has been thoroughly characterized in terms of dye loading percentage and spectroscopic properties, in comparison with the reference free dye, pristine RGO, and with an analogous non-covalent dye-RGO hybrid. When used as a photosensitizing agent in dye-sensitized solar cells (DSSC), the covalent hybrid demonstrated lower photovoltaic performances compared to the cell with the reference dye, a result that was mostly ascribed to the lower dye content of the former. Furthermore, the RGO based sensitizer showed stronger binding to the semiconductor oxide in comparison to the reference dye, paving the way to a new generation of DSSC photoanodes with improved chemical stability. This work demonstrates the full potential of the new class of hybrid sensitizers to equal or even exceed the photovoltaic performances achieved by standard organic photovoltaic sensitizers once molecular engineering of the functional nanocarbon hybrid has been refined.

 

T. Gatti, S. Casaluci, M. Prato, M. Salerno, F. Di Stasio, A. Ansaldo, E. Menna, A. Di Carlo, F. Bonaccorso

Adv. Funct. Mater. (IF: 12.124)

DOI: 10.1002/adfm.201602803

Perovskite solar cells (PSCs) are demonstrating great potential to compete with second generation photovoltaics. Nevertheless, the key issue hindering PSCs full exploitation relies on their stability. Amongst the strategies devised to overcome this problem, the use of carbon nanostructures (CNSs) as hole transporting materials (HTMs) has given impressive results in terms of solar cells stability to moisture, air oxygen and heat. In this work, we propose the use of a HTM based on a poly(3-hexylthiophene) (P3HT) matrix doped with organic functionalized single walled carbon nanotubes (SWCNTs) and reduced graphene oxide in PSCs to achieve higher η (11% and 7.3%, respectively) and prolonged shelf-life stabilities (480 h) in comparison with a benchmark PSC fabricated with a bare P3HT HTM (η = 4.3% at 480 h). Further endurance test, i.e., up to 3240 h, have shown the failure of all the PSCs based on un-doped P3HT, while, on the contrary, a η of ~ 8.7% is still detected from devices containing 2wt% SWCNT-doped P3HT as HTM. We attribute the increase in photovoltaic performances and stabilities of the P3HT-CNSs-based solar cell with respect to the standard P3HT-based one to the improved interfacial contacts between the doped HTM and the adjacent layers.

N. Vicentini, T. Gatti, P. Salice, G. Scapin, C. Marega, F. Filippini, E. Menna

Journal: Carbon (IF: 6.337)

DOI: 10.1016/j.carbon.2015.08.094

A biocompatible porous scaffold obtained via electrospinning a nanocomposite solution of poly(L-lactic acid) and 4-methoxyphenyl functionalized multi-walled carbon nanotubes is presented here for the first time for the enhancement of neurite outgrowth. Optimization of blend preparation and deposition parameters paves the way to the obtainment of defect-free random networks of nanofibers with homogeneous diameters in the hundreds of nanometers length scale. The tailored covalent functionalization of nanotube surfaces allows a homogeneous dispersion of the nanofillers within the polymer matrix, diminishing their natural tendency to aggregate and form bundles. This results in a remarkable effect on the crystallization temperature, as evidenced through differential scanning calorimetry. Furthermore, transmission electron microscopy shows carbon nanotubes anisotropically aligned along the fiber axes, a feature believed to enhance neurite adhesion and growth. Indeed, microscopy images show neurites extension along the direction of nanofibers, highlighting the extreme relevance of scaffold morphology in engineering complex tissue environments. Furthermore, a remarkable effect on increasing the neurite outgrowth results when using the fibrous scaffold containing dispersed carbon nanotubes in comparison with an analogous one made of only polymer, providing further evidence of the key role played by carbon nanostructures in inducing neuronal differentiation.

Elisabetta Schievano, Marco Tonoli, and Federico Rastrelli

Analytical Chemistry (I.F. 6.320)
DOI: 10.1021/acs.analchem.7b03656
Publication Date (Web): November 7, 2017

The knowledge on carbohydrates composition is of great importance to determine the properties of natural matrices such as food-stuff and food ingredients. However, due to the structural similarity and the multiple isomeric forms of carbohydrates in solution, their analysis is often a complex task. Here we propose an NMR analytical procedure based on highly selective chemical shift fil-ters followed by TOCSY, which allows to acquire specific background-free signals for each sugar. The method was tested on raw honey samples dissolved in water with no other pre-treatment. Twenty two sugars typically found in honey were quantified: four monosaccharides (glucose, fructose, mannose, rhamnose), eleven disaccharides (sucrose, trehalose, turanose, maltose, maltulose, palatinose, melibiose and melezitose, isomaltose, gentiobiose nigerose and kojibiose) and seven trisaccharides (raffinose, isomalto-triose, erlose, melezitose, maltotriose, panose and 1-kestose). Satisfactory results in terms of limit of quantification (0.03 – 0.4 g/100g honey), precision (% RSD: 0.99 – 4.03), trueness (bias % 0.4 – 4.2) and recovery (97 – 104 %) were obtained. An accurate control of the instrumental temperature and of the sample pH endows an optimal chemical shift reproducibility, making the proce-dure amenable to automation and suitable to routine analysis. While validated on honey, which is one of the most complex natural matrices in terms of saccharides composition, this innovative approach can be easily transferred to other natural matrices.

Yun Luo, Björn Kirchhoff, Donato Fantauzzi, Laura Calvillo, Luis Alberto Estudillo-Wong, Gaetano Granozzi, Timo Jacob, and Nicolas Alonso-Vante

ChemSusChem 2017, DOI: 10.1002/cssc.201701822 (I.F.= 7.226)

Improving the efficiency of Pt-based oxygen reduction reaction (ORR) catalysts while also reducing costs remains an important challenge in energy research. To this end, we synthesized highly stable and active carbon-supported Mo-doped PtCu (Mo-PtCu/C) nanoparticles (NPs) from readily available precursors in a facile one-pot reaction. Mo-PtCu/C displays two- to four-fold higher ORR half-cell kinetics than reference PtCu/C and Pt/C materials – a trend which was confirmed in proof-of-concept experiments using a H2/O2 micro-laminar fuel cell. This Mo-induced activity increase mirrors observations for Mo-PtNi/C NPs and possibly suggests an emerging trend. Electrochemical accelerated stability tests revealed that dealloying is greatly reduced in Mo-PtCu/C in contrast to the binaries PtCu/C and PtMo/C. Supporting DFT studies suggest that Mo-PtCu’s exceptional stability can be attributed to oxidative resistance of Mo-doped atoms. Furthermore, our calculations revealed that oxygen can induce segregation of Mo to the catalytic surface where it effects beneficial changes to the surface’s oxygen adsorption energetics in context of the Sabatier principle. 

Pandiaraj Sekar, Laura Calvillo, Cristina Tubaro, Marco Baron, Anuj Pokle, Francesco Carraro, Alex Martucci and Stefano Agnoli

ACS Catalysis 2017, DOI: 10.1021/acscatal.7b02166 (I.F.= 10.614)

Carbon dioxide reduction into useful chemical products is a key technology to address urgent climate and energy challenges. In this study, a nanohybrid made by Co3O4 and graphene is proposed as an efficient electrocatalyst for the selective reduction of CO2 to formate at low overpotential. The comparison between samples with different metal oxide to carbon ratio and with or without doping of the graphene moiety, indicates that the most active catalyst is formed by highly dispersed and crystalline nanocubes exposing {001} oriented surfaces, whereas the nitrogen doping is critical to obtain a controlled morphology and to facilitate a topotactic transformation during electrocatalytic conditions to CoO, which results to be the true active phase. The nanohybrid made up by intermediate loading of Co3O4 supported on Nitrogen doped graphene is the most active catalyst, being able to produce 3.14 mmol of formate in 8 h at -0.95 V vs SCE with a faradic efficiency of 83% 

 

Valerio Matozzo a, Jacopo Fabrello, Luciano Masiero, Federico Ferraccioli, Livio Finos, Paolo Pastore, Iole Maria Di Gangi, Sara Bogialli

IF 5.099

Accepted 25 October 2017

DOI: https://doi.org/10.1016/j.envpol.2017.10.100

Glyphosate (GLY) is one of the most used herbicide worldwide. Considering that information concerning the impact of GLY on bivalves is scarce, in this study we evaluated for the first time the effects of environmentally realistic concentrations of GLY (10, 100 and 1000 mg/L) to the mussel Mytilus galloprovincialis. Mussels were exposed for 7, 14 and 21 days and several biomarkers were measured in haemocytes/haemolymph (total haemocyte counts, haemocyte diameter and volume, haemolymph pH, haemolymph lactate dehydrogenase activity, haemocyte lysate lysozyme and acid phosphatase activities), as well as in gills and digestive gland (antioxidant enzyme and acetylcholinesterase activities). The concentrations of GLY and its main metabolite aminomethylphosphonic acid in the experimental tanks were also measured. The MANOVA analysis demonstrated that the experimental variables considered (exposure concentration, exposure duration, and their interaction) affected significantly biomarker responses. In addition, the two-way ANOVA analysis indicated that GLY was able to affect most of the cellular parameters measured, whereas antioxidant enzyme activities resulted to be influenced moderately. Interestingly, exposure to GLY reduced significantly acetylcholinesterase activity in gills. Although preliminary, the results of this study demonstrated that GLY can affect both cellular and biochemical parameters in mussels, highlighting a potential risk for aquatic invertebrates.

Néstor Merino-Díez, Aran Garcia-Lekue, Eduard Carbonell-Sanromà, Jingcheng Li, Martina Corso, Luciano Colazzo, Francesco Sedona, Daniel Sánchez-Portal, Jose Ignacio Pascual, and Dimas G. de Oteyza

ACS Nano (IF: 13.942)
DOI: 10.1021/acsnano.7b06765

We report on the energy level alignment evolution of valence and conduction bands of armchair-oriented graphene nanoribbons (aGNR) as their band gap shrinks with increasing width. We use 4,4’’-dibromo-para-terphenyl as molecular precursor on Au(111) to form extended poly-para-phenylene nanowires, which can be fused sideways to form atomically precise aGNRs of varying widths. We measure the frontier bands by means of scanning tunneling spectroscopy, corroborating that the nanoribbon’s band gap is inversely proportional to their width. Interestingly, valence bands are found to show Fermi level pinning as the band gap decreases below a threshold value around 1.7 eV. Such behavior is of critical importance to understand the properties of potential contacts in graphene nanoribbon-based devices. Our measurements further reveal a relatively unique system for studying Fermi level pinning by modifying an adsorbate´s band gap while maintaining an almost unchanged interface chemistry defined by substrate and adsorbate. 

Sven Urban, Igor Djerdj, Paolo Dolcet, Limei Chen, Maren Möller, Omeir Khalid, Hava Camuka, Rüdiger Ellinghaus, Chenwei Li, Silvia Gross, Peter J. Klar, Bernd Smarsly, Herbert Over

Chem. Mater., Just Accepted Manuscript
DOI: 10.1021/acs.chemmater.7b03091
I. F.: 9.466

The temporary storage of oxygen in a solid catalyst is imperative for many important industrial oxidation reactions in the gas phase, for instance the post-treatment of automotive exhaust gas. A peculiar mixed Ce-Zr (1:1) oxide, the ordered κ-Ce2Zr2O8 phase, is a promising catalytic material exhibiting an extraordinarily high oxygen storage capacity (OSC) and high thermal and chemical stability. In this paper, we elucidate the temperature-dependent transformation between the pyrochlore pyr-Ce2Zr2O7+x and κ-Ce2Zr2O8 phase upon oxygen uptake by in-situ X-ray diffraction, X-ray absorption and in-situ Raman spectroscopy, providing insights into the electronic and structural changes on the atomic level, which are at the heart of the extraordinarily high OSC. We demonstrate that the Ce3+ concentration can be followed in-situ by Raman spectroscopy of the electronic spin flip in the f-shell of trivalent cerium. The catalytic activity of the κ- e2Zr2O8 phase has been investigated without an additional active component such as Pt: While the high OSC of the kappa phase is beneficial for the oxidation of CO, the oxidation of HCl turns out to be not affected by the high OSC. 

Valentina Caputi, Ilaria Marsilio, Viviana Filpa, Silvia Cerantola, Genny Orso, Michela Bistoletti, Nicola Paccagnella, Sara De Martin, Monica Montopoli, Stefano Dall’Acqua, Francesca Crema, Iole-Maria Di Gangi, Francesca Galuppini, Isabella Lante, Sara Bogialli, Massimo Rugge, Patrizia Debetto, Cristina Giaroni and Maria Cecilia Giron

British Journal of Pharmacology

DOI: 10.1111/bph.13965

Impact factor: 5.773

First published: 30 August 2017

Background and Purpose. Gut microbiota is essential for the development of the gastrointestinal system, including the enteric nervous system (ENS). Perturbations of gut microbiota in early life have the potential to alter neurodevelopment leading to functional bowel disorders later in life. We examined the hypothesis that gut dysbiosis impairs the structural and functional integrity of the ENS, leading to gut dysmotility in juvenile mice.

Experimental Approach. To induce gut dysbiosis, broad-spectrum antibiotics were administered by gavage to juvenile (3weeks old) male C57Bl/6 mice for 14 days. Bile acid composition in the intestinal lumen was analysed by liquid chromatography-mass spectrometry. Changes in intestinal motility were evaluated by stool frequency, transit of a fluorescent-labelled marker and isometric muscle responses of ileal full-thickness preparations to receptor and non-receptor-mediated stimuli. Alterations in ENS integrity were assessed by immunohistochemistry and Western blot analysis.

Conclusions and Implications. Gut dysbiosis caused complex morpho-functional neuromuscular rearrangements, characterized by structural defects of the ENS and increased tachykininergic neurotransmission. Altogether, our findings support the beneficial role of enteric microbiota for ENS homeostasis instrumental in ensuring proper gut neuromuscular function during critical stages of development.

Paola Lanzafame, Siglinda Perathoner, Gabriele Centi*, Silvia Gross and Emiel J.M. Hensen

Journal: Catalysis Science & Technology

DOI: 10.1039/C7CY01067B

Impact factor: 5.773

Published on line 19.07.2017

This perspective discusses the general concepts that will guide future catalysis and related grand-challenges, based on "The European Roadmap on Science and Technology of Catalysis" prepared by the European Cluster on Catalysis. To adress the changing scenario in refinery and chemical production, and move to a low-carbon sustrainable future, the distinguishing elements of three grand-challenges for catalysis are discussed here: 1) catalysis to address the evolving energy and chemical scenario, 2) catalysis for a cleaner and sustainable future, and 3) addressing catalysis complexity, the latter being organized in three sub-topics: advanced design of novel catalysts, understanding catalysts from molecular to material scale, and expanding catalysis concepts

 

A. Politano, D. Campi, M. Cattelan, I. Ben Amara, S. Jaziri, A. Mazzotti, A. Barinov, B. Gürbulak, S. Duman, S. Agnoli, L. S. Caputi, G. Granozzi, and A. Cupolillo

Scientific Reports (IF= 5.228)

DOI : 10.1038/s41598-017-03186-x

We have investigated the electronic response of single crystals of indium selenide by means of angle-resolved photoemission spectroscopy, electron energy loss spectroscopy and density functional theory. The loss spectrum of indium selenide shows the direct free exciton at ~1.3 eV and several other peaks, which do not exhibit dispersion with the momentum. The joint analysis of the experimental band structure and the density of states indicates that spectral features in the loss function are strictly related to single-particle transitions. These excitations cannot be considered as fully coherent plasmons and they are damped even in the optical limit, i.e. for small momenta. The comparison of the calculated symmetry-projected density of states with electron energy loss spectra enables the assignment of the spectral features to transitions between specific electronic states. Furthermore, the effects of ambient gases on the band structure and on the loss function have been probed.

Vassalini, I., Borgese, L., Mariz, M., Polizzi, S., Aquilanti, G., Ghigna, P., Sartorel, A., Amendola, V. and Alessandri, I.

Chem. Int. Ed., 2017
doi: 10.1002/anie.201703387

Au–Fe nanoparticles synthesized by laser ablation in solution exhibit enhanced activity in the oxygen evolution reaction (see diagram). The results open exciting perspectives for using nanoalloys in catalysis and energy conversion.

C. Suchomski, D. J. Weber, P. Dolcet, A. Hofmann, P. Vöpel, J. Yue, M. Einert, M. Möller, S. Werner, S. Gross, I. Djerdj, T. Brezesinski and B. M. Smarsly

Journal of Material Chemistry A
DOI: 10.1039/c7ta02316b
I. F.: 8.262
First published online 24 April 2017

A cost-effective and tailored synthesis route for the preparation of cubic ZrO2 nanocrystals with high dispersibility was developed. The procedure is straightforward and produces uniform 2–3 nm particles of excellent yield when applying microwave dielectric heating as a “green” method. Furthermore, it can be applied to a wide range of batch sizes (from 0.5 to 20 g ZrO2), which makes it interesting for industrial applications, and also lends itself to the preparation of yttria-stabilized ZrO2 nanocrystals with varying doping levels. The work provides a blueprint for the fabrication of high-quality nanoparticles and structured materials thereof and is likely to trigger further research in the field of solution-processed metal oxides.

 

Sabrina Antonello, Tiziano Dainese, Fangfang Pan, Kari Rissanen, and Flavio Maran

Thiolate-protected metal clusters are materials of ever-growing importance in fundamental and applied research. Knowledge of their single-crystal X-ray structures has been instrumental to enable advanced molecular understanding of their intriguing properties. So far, however, a general, reliable, chemically clean approach to prepare single crystals suitable for accurate crystallographic analysis was missing. Here we show that single crystals of thiolate-protected clusters can be grown in large quantity and very high quality by electrocrystallization.

J. Am. Chem. Soc., Article ASAP 

Open Access

DOI: 10.1021/jacs.7b00568

Publication Date (Web): March 10, 2017

AlphaGalileo University of Jyväskylä (Finland)

 

Arianna Minelli, Paolo Dolcet, Stefano Diodati, Sandra Gardonio, Claudia Innocenti, Denis Badocco, Stefano Gialanella, Paolo Pastore, Luciano Pandolfo, Andrea Caneschi, Angela Trapananti Silvia Gross

Journal of Material Chemistry C

DOI: 10.1039/c6tc05636a

I. F.: 5.066

First published online 23 Feb 2017

A quick, easy and green water-based synthesis protocol involving coprecipitation of oxalates combined with hydrothermal treatment was demonstrated to be very effective in yielding and stabilising, at relatively low temperature (180°C) and in water, the crystallisation of nanostructured manganites. The subcritical hydrothermal approach was in fact shown to play a key role in stabilising phases which are generally achieved at much higher temperatures, and in harsher conditions, thus disclosing an exciting alternative for their synthesis. As a result of this mild wet chemistry approach, the compounds CuMnO2, ZnMn2O4 and ZnMnO3 were synthesised as nanocrystalline powders. Noticeably, the optimised route proved to be effective in stabilising the exotic polymorph cubic spinel ZnMnO3 as a pure compound. This is particularly notable, as very few records concerning this compound are available in literature. The manganites were characterised from a structural (XRPD and SAED, morphological (TEM and SEM) and compositional (XPS, ICP-MS, XAS and CHN analysis) point of view. Since these materials are particularly interesting for functional properties ascribed to their magnetic behaviour, SQUID was employed to study their magnetic properties, yielding a response that could indicate either ferrimagnetic or antiferromagnetic behaviour in CuMnO2 and ZnMnO3.

Ivan Guryanov,    Federico Polo,    Evgeniy Ubyvovk,    Evgenia Vlakh, Tatiana Tennikova,  Armin Tahmasbi Rad, Mu-Ping Nieh and FLAVIO MARAN

Chem. Sci., 2017, Accepted Manuscript

DOI: 10.1039/C6SC05187A  

First published online 02 Feb 2017

Poly(amino acid)-coated gold nanoparticles hold promises in biomedical applications, particularly because they combine unique physicochemical properties of the gold core, excellent biocompatibility, and easy functionalization of the poly(amino acid)-capping shell. Here we report a novel method of the preparation of robust hybrid core-shell nanosystems consisting of a Au144 cluster and a densely grafted polylysine layer. Linear polylysine chains were grown by direct N-carboxyanhydride (NCA) polymerization onto ligands capping the gold nanocluster. The density of the polylysine chains and the thickness of the polymer layer strongly depend on the amount and concentration of the NCA monomer and the initiator. The optical spectra of the so-obtained core-shell nanosystems show a strong surface plasmon resonance (SPR) like band at 531 nm. In fact, despite the gold-cluster size is maintained and the absence of interparticle aggregation, the polylysine-capped clusters behave as if they had a diameter nearly 4 times larger. To the best of our knowledge, this is the first observation of the growth of a fully developed, very stable SPR-like band for a gold nanocluster of such dimension. The robust polylysine protective shell makes the nanoparticles very stable under conditions of chemical etching, in the presence of glutathione, and at different pH values, without gold core deshielding or alteration of the SPR-like band. This polymerization method can be conceivably extended to prepare core-shell nanosystems based on other mono- or co-poly(amino acids). 

Simona Neri, Sergio Garcia Martin, Cristian Pezzato and Leonard J. Prins

DOI: 10.1021/jacs.6b12932

Published: January 2017

The activity of a gold nanoparticle-based catalyst can be reversibly up- and down-regulated by light. Light is used to switch a small molecule between cis- and trans-isomers, which inhibits the catalytic activity of the nanoparticles to different extent. The system is functional in aqueous buffer, which paves the way for integrating the system in biological networks.


Fabio Rizzo, Federico Polo, Gregorio Bottaro, Simona Fantacci, Sabrina Antonello, Lidia Armelao, Silvio Quici, and Flavio Maran

DOI: 10.1021/jacs.6b12247

Published: January 15, 2017

We describe the synthesis, computational analysis, photophysics, electrochemistry and electrochemiluminescence (ECL) of a series of compounds formed of two triphenylamines linked by a fluorene or spirobifluorene bridge. The
phenylamine moieties were modified at the para-position of the two external rings by electron-withdrawing or electron-donating substituents. These modifications allowed for fine-tuning of the photoluminescence (PL) and ECL emission from blue to green,
with an overall wavelength span of 73 (PL) and 67 (ECL) nm, respectively. For all compounds, we observed a very high PL quantum yield (79−89%) and formation of stable radical ions. The ECL properties were investigated by direct annihilation of the
electrogenerated radical anion and radical cation. The radical-ion annihilation process is very efficient and causes an intense greenish-blue ECL emission, easily observable even by naked eye, with quantum yield higher than the standard 9,10-
diphenylanthracene. The ECL spectra show one single band that almost matches the PL band. Because the energy of the annihilation reaction is higher than that required to form the singlet excited state, the S-route is considered the favored pathway followed by the ECL process in these
molecules. All these features point to this type of molecular system as promising for ECL applications. 

 Alice Antonello, Gerhard Jakob, Paolo Dolcet, Rebecca Momper, Maria Kokkinopoulou, Katharina Landfester, Rafael Muñoz-Espí, Silvia Gross*

Journal: Chemistry of Materials

IF: 9.407

DOI: 10.1021/acs.chemmater.6b03467

Accepted December 30 2016

Crystalline first row transition metal (Mn, Fe, Co, Ni, Cu and Zn) ferrites were prepared by an unprecedented synergetic combination of miniemulsion synthesis and solvothermal route, pursuing unconventional conditions in terms of space confinement, temperature and pressure. This synergy allowed for obtaining different crystalline ferrites at much lower temperature (i.e., 80 °C) than usually required and without any post-synthesis thermal treatment. X-ray diffraction (XRD) revealed that analogous ferrites synthesized by miniemulsion at ambient pressure or in bulk either at ambient pressure or under solvothermal conditions did not result in comparatively highly crystalline products. To follow the structural evolution at local level as a function of reaction time and depending on the synthesis conditions, X-ray absorption spectroscopy (XAS) was used to determine the cation distribution in these structures. Well-defined nanostructures were observed by transmission electron microscopy (TEM). Concerning their functional behavior, the synthesized ferrites presented superparamagnetism and were found to be active oxidation catalysts, as demonstrated for the oxidation of styrene, taken as a model reaction. Thanks to the magnetic properties, the ferrites can be easily recovered from the reaction medium, after the catalysis, by magnetic separation and reused for several cycles without losing activity.

 Marilena Di Valentin*, Marco Albertini, Maria Giulia Dal Farra, Enrico Zurlo, Laura Orian, Antonino Polimeno, Marina Gobbo and Donatella Carbonera

Journal: Chemistry-A European Journal IF: 5.771

DOI: 10.1002/chem.201603666

First published:9 November 2016

We report a pulsed electron paramagnetic resonance spectroscopic ruler for high-sensitive and accurate measurement of distances and distance distributions based on a novel spin labelling strategy. The ruler consists of a series of α-helical peptides, labeled at the N-terminal end with a porphyrin moiety, which can be excited to the triplet state, and with a nitroxide at various sequence positions, spanning distances in the range 1.8-8 nm. The new methodology has a high potential for measuring nanometer distances in proteins due to the distinctive properties of the porphyrin triplet state. Appropriate spin-labeling protocols can finally extend this novel strategy to any macromolecular system with a general impact in structural (bio)chemistry.