IN PRESS - Selected, just-accepted articles

  Formation of metal-organic ligand complexes affects solubility of metals in airborne particles at an urban site in the Po Valley

Andrea Tapparo, Valerio Di Marco, Denis Badocco, Sara D’Aronco, Lidia Soldà, Paolo Pastore, Brendan M. Mahon, Markus Kalberer, and Chiara Giorio

Chemosphere (IF = 5.108)

DOI: 10.1016/j.chemosphere.2019.125025

Metals in atmospheric aerosols play potentially an important role in human health and ocean primary productivity. However, the lack of knowledge about solubility and speciation of metal ions in the particles or after solubilisation in aqueous media (sea or surface waters, cloud or rain droplets, biological fluids) limits our understanding of the underlying physico-chemical processes. In this work, a wide range of metals, their soluble fractions, and inorganic/organic compounds contained in urban particulate matter (PM) from Padua (Italy) were determined. Metal solubility tests have been performed by dissolving the PM in water and in solutions simulating rain droplet composition. The water-soluble fractions of the metal ions and of the organic compounds having ligand properties have been subjected to a multivariate statistical procedure, in order to elucidate associations among the aqueous concentrations of these PM components in simulated rain droplets. In parallel, a multi-dimensional speciation calculation has been performed to identify the stoichiometry and the amount of metal-ligand complexes theoretically expected in aqueous solutions. Both approaches showed that the solubility and the aqueous speciation of metal ions were differently affected by the presence of inorganic and organic ligands in the PM. The solubility of Al, Cr, and Fe was strongly correlated to the concentrations of oxalic acid, as their oxalate complexes represented the expected dominant species in aqueous solutions. Oxalates of Al represented ~98% of soluble Al, while oxalates of Cu represented 34-75% of the soluble Cu, and oxalates of Fe represented 76% of soluble Fe. The oxidation state of Fe can strongly impact the speciation picture. If Fe is present as Fe(II) rather than Fe(III), the amount of Cr and Cu complexed with diacids can increase from 75% to 94%, and from 32% to 53%, respectively. For other metals, the solubility depended on the formation of soluble aquo-complexes, hence with a scarce effect of the organic ligands. An iron-oxalate complex was also directly detected in aerosol sample extracts.

  Combined high degree of carboxylation and electronic conduction in graphene acid set new limits for metal free catalysis in alcohol oxidation

Matías Blanco, Dario Mosconi, Michal Otyepka, Miroslav Medveď, Aristides Bakandritsos, Stefano Agnoli and Gaetano Granozzi

Chem. Sci., 2019, (IF: 9.556)

DOI: 10.1039/C9SC02954K

Graphene oxide, the most prominent carbocatalyst for several oxidation reactions, has severe limitations due to the overstoichiometric amounts required to achieve practical conversions. Graphene Acid, a well-defined graphene derivative selectively and homogeneously covered by carboxylic groups but maintaining the high electronic conductivity of pristine graphene, sets new activity limits in the selective and general oxidation of a large gamut of alcohols, even working at 5 wt% loading for at least 10 reaction cycles without any influence from  metal impurities. According to experimental data and first principle calculations, the selective and dense functionalization with carboxyl groups, combined with excellent electron transfer properties, accounts for the unprecedented catalytic activity of this graphene derivative. Moreover, the controlled structure of graphene acid allows shedding light upon the critical steps of the reaction and regulating precisely its selectivity toward different oxidation products.

  Exploring the phase-selective, green hydrothermal synthesis of upconverting doped sodium yttrium fluoride: effects of temperature, time and precursors

Nora Jannsen, Stefano Diodati, Nicola Dengo, Francesca Tajoli, Nicola Vicentini, Giacomo Lucchini, Adolfo Speghini, Denis Badocco, Paolo Pastore, Silvia Gross

Chem. Eur. J., Just Accepted Manuscript

DOI: 10.1002/chem.201903261

I. F.: 5.160

Upconverting materials are materials capable, when excited with radiation of a suitable wavelength, of emitting light at a lower wavelength (and therefore at higher energy) than the incident radiation. This characteristic makes them effective candidates for many technological applications, for instance in photonics, optical codification and sensing applications. Among upconverting materials, NaYF4 is one of the most efficient.
In this paper, an easy, green low-temperature route was optimized for the synthesis of upconverting doped NaYF4, allowing to tune, through variations of the experimental parameters, the prevalence and co-occurrence of the two main crystalline phases displayed by the species. Instead of using carcinogen or toxic solvents, the synthesis was performed in water at relatively low temperatures via the hydrothermal approach. The effect of temperature, treatment time and precursors on the crystal structure, morphology and composition of the resulting materials was furthermore investigated via a plethora of techniques (XRD, XPS, SEM, ICP-MS) and the optimal parameters to yield hexagonal sodium yttrium fluoride were determined.

  The mechanism of concentric HfO2/Co3O4/TiO2 nanotubes investigated by intensity modulated photocurrent spectroscopy (IMPS) and electrochemical impedance spectroscopy (EIS) for photoelectrochemical activity

Xiaochen Huai, Leonardo Girardi, Ran Lu, Shang Gao, Yu Zhao, Yunhan Ling, Gian Andrea Rizzi, Gaetano Granozzi, Zhengjun Zhang

NanoEnergy 2019, (IF: 15.548)

In this work, we describe the preparation and photoelectrochemical (PEC) properties of concentric HfO2/Co3O4/TiO2 nanotubes (NTs). From a methodological point of view, we demonstrated, for the first time, that intensity modulated photocurrent spectroscopy (IMPS) and electrochemical impedance spectroscopy (EIS) efficiently complement and can be highly valuable to optimize PEC water-splitting devices. We verified that the CSC and CH values (the capacitance of space charge region and Helmholtz layer, derived from a phenomenological equivalent circuits model, ECM) are of similar magnitude and that the CH can be affected by applied bias, the nature of the catalytic material and the passivation layer. The calculated CH/(CH+CSC) are in agreement with the high frequency intercept (HFI) derived by the IMPS experimental data.
The charge transfer efficiencies (ղtr) were obtained from the IMPS and ECM data: the ղtr values for HfO2/Co3O4/TiO2-NTs increased to 80.4% (0 V vs Ag/AgCl) compared to those in Co3O4/TiO2-NTs (56.9%,0 V vs Ag/AgCl) and in TiO2-NT (25.6%, 0 V vs Ag/AgCl).
We proved that the excellent PEC properties of HfO2/Co3O4/TiO2-NTs are due to i) the band alignment between small bad gap of Co3O4 and TiO2 semiconductors, ii) increased hole transfer efficiency ղtr caused by excellent catalytic properties of Co3O4 and iii) the passivation effect on surface defects of a HfO2 layer with appropriate thickness.

  Carbon dots from citric acid and its intermediates formed by thermal decomposition

Plinio Innocenzi, Luca Malfatti, Sergio Marras, Carlo Maria Carbonaro, Gaetano Granozzi, Robert ludmerczki, Laura Calvillo, Stefania Mura, Istvan Mandity, Sebastiamo Garroni, Massimo Carraro, Nina Senes

Chem. Eur. J.2019, (IF: 5.16)

Thermal decomposition of citric acid is one of the most common syntheses of fluorescent C-dots; the reaction pathway is,however, quite complex and the details are still far from being understood. For instance, several intermediates formduring the processand they alsogive risetofluorescent species. In the present work, the formation of fluorescent C-dots fromcitric acid has been studied as a function of reaction time by coupling infrared analysis, X-ray photoelectron spectroscopy, liquid chromatography/mass spectroscopy (LC/MS) with the change ofthe optical properties, absorption and emission. The reaction intermediates, which have been identifiedat different stages,producetwo main emissive species, in the green andblue, as also indicated by the decay time analysis. C-dots from the intermediateshave also beensynthesised via thermal decomposition observingan emission maximum around 450 nm. The citric acid C-dots in water have shown shorttemporal stability,but their functionalization with 3-aminopropyltriethoxysilane has reduced thequenching.The understanding of the citric acid thermal decomposition reaction is expected toimprove the control and reproducibility of C-dotssynthesis.

  Palladium nanoparticles supported on graphene acid: a stable and eco-friendly bifunctional C–C homo- and cross-coupling catalyst

Matías Blanco, Dario Mosconi, Cristina Tubaro, Andrea Biffis, Denis Badocco, Paolo Pastore, Michal Otyepka, Aristides Bakandritsos, Zhibo Liu, Wencai Ren, Stefano Agnoli and Gaetano Granozzi

Green Chem., 2019, (IF: 9.405)

DOI: 10.1039/c9gc01436e

A mild impregnation of graphene acid (GA) with Pd(OAc)2 yields Pd nanoparticles with a size that can be easily controlled by the amount of the Pd precursor, and with a sharp and tunable size distribution ranging from 1 nm up to 9 nm. The spectroscopic and microscopic characterization of the GA–Pd composites reveals a strong interaction between the metal and the carboxyl groups of the GA support, and suggests a nanoparticle growth mechanism entailing counterion metathesis followed by a GA promoted reduction. The GA–Pd nanohybrids are highly active catalysts in the Suzuki–Miyaura cross coupling reaction under environmentally-friendly conditions. TOF values exceeding 30 000 h−1, high selectivity toward the coupling product and versatility for a large variety of substrates are reported.
Given the large amount of carboxyl groups, the catalysts are exceptionally stable, and no appreciable metal leaching is observed during the reaction. Notably, at variance with conventional carbon and graphene supports, the GA supported Pd nanoparticles show a bifunctional activity and can yield biphenyl adducts upon oxidative homocoupling of arylboronic acids.

  Surface functionalization of grown-on-tip ZnO nanopyramids: from fabrication to light-triggered applications

Alberto Gasparotto,* Chiara Maccato, Giorgio Carraro, Cinzia Sada, Urška Lavrenčič Štangar, Bruno Alessi, Conor Rocks, Davide Mariotti, Andrea La Porta, Thomas Altantzis, Davide Barreca

ACS Applied Materials & Interfaces (I.F. 8.097)

DOI: 10.1021/acsami.8b22744

We report on a combined chemical vapor deposition (CVD)/radio frequency (RF) sputtering synthetic strategy for the controlled surface modification of ZnO nanostructures by Ti-containing species. Specifically, the proposed approach consists in the CVD of grown-on-tip ZnO nanopyramids, followed by titanium RF sputtering under mild conditions. The results obtained by a thorough characterization demonstrate the successful ZnO surface functionalization with dispersed Ti-containing species in low amounts. This phenomenon, in turn, yields a remarkable enhancement of photoactivated superhydrophilic behavior, self-cleaning ability, and photocatalytic performances in comparison to bare ZnO. The reasons accounting for such an improvement are unravelled by a multitechnique analysis, elucidating the interplay between material chemico-physical properties and the corresponding functional behavior. Overall, the proposed strategy stands as an amenable tool for the mastering of semiconductor-based functional nanoarchitectures through ad-hoc engineering of the system surface.

  Direct depolymerization coupled to liquid extraction surface analysis high-resolution mass spectrometry for the characterization of the surface of plant tissues

Chiara Giorio, Edwige Moyroud, Beverley J. Glover, and Markus Kalberer

Analytical Chemistry (IF: 6.042)

DOI: 10.1021/acs.analchem.9b01094

The cuticle, the outermost layer covering the epidermis of most aerial organs of land plants, can have a heterogenous composition even on the surface of the same organ. The main cuticle component is the polymer cutin which, depending on its chemical composition and structure, can have different biophysical properties. In this study, we introduce a new on-surface depolymerization method coupled to liquid extraction surface analysis (LESA) high-resolution mass spectrometry (HRMS) for a fast and spatially resolved chemical characterization of the cuticle of plant tissues. The method is composed of an on-surface saponification, followed by extraction with LESA using a chloroform-acetonitrile-water (49:49:2) mixture and direct HRMS detection. The method is also compared with LESA-HRMS without prior depolymerization for the analysis of the surface of the petals of Hibiscus richardsonii flowers, which have a ridged cuticle in the proximal region and a smooth cuticle in the distal region. We found that on-surface saponification is effective enough to depolymerize the cutin into its monomeric constituents thus allowing detection of compounds that were not otherwise accessible without a depolymerization step. The effect of the depolymerization procedure was more pronounced for the ridged/proximal cuticle, which is thicker and richer in epicuticular waxes compared with the cuticle in the smooth/distal region of the petal.

  Molecular‐Dynamics‐Simulation‐Directed Rational Design of Nanoreceptors with Targeted Affinity

Xiaohuan Sun, Laura Riccardi, Federico De Biasi, Federico Rastrelli, Marco De Vivo, Fabrizio Mancin

Angew.Chem.Int. Ed. (I.F. 12.102)

DOI: 10.1002/anie.201902316

Published online: May 2, 2019

Here, we demonstrate the possibility of rationally designing nanoparticle receptors with targeted affinity and selectivity for specific small molecules. We used atomistic molecular‐dynamics (MD) simulations to gradually mutate and optimize the chemical structure of the molecules forming the coating monolayer of gold nanoparticles (1.7 nm gold‐core size). The MD‐directed design resulted in nanoreceptors with a 10‐fold improvement in affinity for the target analyte (salicylate) and a 100‐fold decrease of the detection limit by NMR‐chemosensing from the millimolar to the micromolar range. We could define the exact binding mode, which features prolonged contacts and deep penetration of the guest into the monolayer, as well as a distinct shape of the effective binding pockets characterized by exposed interacting points.

  Luminescent sequence-dependent materials through a step by step assembly of RE1-1,4-benzendicarboxylate-RE2 (REx = Y3+, Eu3+ and Tb3+) architectures on a silica surface

Luca Bellucci, Gregorio Bottaro, Luca Labella, Fabio Marchetti, Simona Samaritani, Daniela Belli Dell’Amico, Lidia Armelao


DOI: 10.1039/c9tc00181f

We present an approach toward sequence-dependent materials based on a stepwise assembly on a silica surface of rare earth cations (RE: Y3+, Eu3+ and Tb3+) and the 1,4-benzenedicarboxylate (terephthalate, T2-) ligand, organized in an ordered sequence RE1-T-RE2. The first RE was grafted to silica through a reaction of its N,N-dibutylcarbamato derivative, [RE1(O2CNBu2)(3)], with the surface silanols. The residual carbamato groups in the metal coordination sphere were then substituted by HT- through a reaction with H2T in pyridine. The Brönsted acidity of the pendant COOH groups was successively exploited for the anchorage of the second metal ion (RE1 = Eu, RE2 = Tb; RE1 = Y, RE2 = Tb). The choice of pyridine as the solvent, able to dissolve both H2T and the secondary product [NH2Bu2](2)[T]H2T, was crucial for achieving success with this method. The emission properties of the materials were modulated by modifying the order of the synthetic steps. Metal complexes and materials were characterized by IR, EDX, ICP and photoluminescence. We used Tb3+ to Eu3+ energy transfer (ET) to study the RE3+ spatial distribution and intermetal distances to prove the formation of a RE1-T-RE2 sequence. Photoluminescence was used as a multi-tool technique to characterize the functional properties of the materials and to obtain structural information supporting the sequence growth.

  Tunable E-Z Photo-Isomerization in a,b-Peptide Foldamers Featuring Multiple (E/Z)-3-Aminoprop-2-enoic Acid Units

Giulia Marafon, Marco Crisma, Alessandro Moretto

Org. Lett., DOI: 10.1021/acs.orglett.9b01360, Publication Date (Web): May 15, 2019

impact factor 6.49

Systems in which an external stimulus elicits a response through some sort of modification at the molecular or supramolecular level bear potential for the development of smart materials and devices. This work describes a versatile synthetic approach suitable for the stepwise incorporation of multiple, even consecutive, units of the simplest Ca,b-unsaturated b-amino acid, (E/Z)-3-aminoprop-2-enoic acid, in peptide-based foldamers. The properties of these latter, including photoinduced E/Z isomerizations, were investigated.

  Exploring wet chemistry approaches to ZnFe2O4 spinel ferrite nanoparticles with different inversion degrees: a comparative structural and spectroscopic study

Paolo Dolcet, Kristin Kirchberg, Alice Antonello, Christian Suchomski, Roland Marschall, Stefano Diodati, Rafael Muñoz-Espí, Katharina Landfester, Silvia Gross

Inorg. Chem. Front., Just Accepted Manuscript

I. F.: 5.106

Spinel ferrites (MFe2O4, M being a bivalent metal), are a widely known class of oxides employed in a broad range of applications. It is of the utmost importance to investigate how different synthetic procedures can steer the structural evolution of the target materials, especially with regards to the inversion degree of ZnFe2O4 spinel, since altered properties ascribed to fine (micro)structural differences are common.
In this paper, we synthesised nanocrystalline ZnFe2O4 through three different low-temperature (< 300°C) synthetic approaches: microwave-assisted non-aqueous sol–gel synthesis, hydrothermal synthesis and a combined miniemulsion/hydrothermal approach (these latter two under subcritical conditions). The materials were then thoroughly characterised through complementary analytical methods. Particular attention during this study was focused on the structural evolution over time of the ferrites, in relation to the different employed synthetic approaches, as well as the correlation between different synthetic parameters/methods and the inversion degree of the resulting spinels.

  Direct injection liquid chromatography high-resolution mass spectrometry for determination of primary and secondary terrestrial and marine biomarkers in ice cores

Amy King, Chiara Giorio, Eric Wolff, Elizabeth Thomas, Marco Roverso, Margit Schwikowski, Andrea Tapparo, Sara Bogialli, and Markus Kalberer

Analytical Chemistry (IF: 6.042)

DOI: 10.1021/acs.analchem.8b05224

Many atmospheric organic compounds are long-lived enough to be transported from their sources to polar regions and high mountain environments where they can be trapped in ice archives. While inorganic components in ice archives have been studied extensively to identify past climate changes, organic compounds have rarely been used to assess paleo-environmental changes, mainly due to the lack of suitable analytical methods. This study presents a new method of direct injection HPLC-MS analysis, without the need of pre-concentrating the melted ice, for the determination of a series of novel biomarkers in ice-core samples indicative of primary and secondary terrestrial and marine organic aerosol sources. Eliminating a preconcentration step reduces contamination potential and decreases the required sample volume thus allowing a higher time resolution in the archives. The method is characterised by limits of detections (LODs) in the range of 0.01-15 ppb, depending on the analyte, and accuracy evaluated through an interlaboratory comparison. We find that many components in secondary organic aerosols (SOA) are clearly detectable at concentrations comparable to those previously observed in replicate preconcentrated ice samples from the Belukha glacier, Russian Altai Mountains. Some compounds with low recoveries in preconcentration steps are now detectable in samples with this new direct injection method significantly increasing the range of environmental processes and sources that become accessible for paleo-climate studies.

  The Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) field campaign in Namibia: overview, illustrative observations and way forward

Paola Formenti, Barbara D’Anna, Cyrille Flamant, Marc Mallet, Stuart John Piketh, Kerstin Schepanski, Fabien Waquet, Frédérique Auriol, Gerard Brogniez, Frédéric Burnet, Jean-Pierre Chaboureau, Aurélien Chauvigné, Patrick Chazette, Cyrielle Denjean, Karine Desboeufs, Jean-François Doussin, Nellie Elguindi, Stefanie Feuerstein, Marco Gaetani, Chiara Giorio, Danitza Klopper, Marc Daniel Mallet, Pierre Nabat, Anne Monod, Fabien Solmon, Andreas Namwoonde, Chibo Chikwililwa, Roland Mushi, Ellsworth Judd Welton, and Brent Holben

Bulletin of the American Meteorological Society (IF: 7.804)

DOI: 10.1175/BAMS-D-17-0278.1

The AEROCLO-sA (AErosol, RadiatiOn and CLOuds in southern Africa) project investigates the role of aerosols on the regional climate of southern Africa. This is a unique environment where natural and anthropogenic aerosols and a semi-permanent and widespread stratocumulus (Sc) cloud deck are found. The project aims to understand the dynamical, chemical and radiative processes involved in aerosol-cloud-radiation interactions over land and ocean and under various meteorological conditions.
The AEROCLO-sA field campaign was conducted in August and September of 2017 over Namibia. An aircraft equipped with active and passive remote sensors and aerosol in situ probes performed a total of 30 research flight hours. In parallel, a ground-based mobile station with state-of-the-art in situ aerosol probes and remote sensing instrumentation was implemented over coastal Namibia, and complemented by ground-based and balloon-borne observations of the dynamical, thermodynamical and physical properties of the lower troposphere. The focus laid on mineral dust emitted from salty pans and ephemeral riverbeds in northern Namibia, the advection of biomass burning aerosol plumes from Angola subsequently transported over the Atlantic Ocean, and aerosols in the marine boundary layer at the ocean-atmosphere interface.
This article presents an overview of the AEROCLO-sA field campaign with results from the airborne and surface measurements. These observations provide new knowledge of the interactions of aerosols and radiation in cloudy and clear skies in link with the atmospheric dynamics over southern Africa. They will foster new advanced climate simulations and enhance the capability of space-borne sensors, ultimately allowing a better prediction of future climate and weather in southern Africa.

  Nanoparticle-assisted NMR spectroscopy: Enhanced detection of analytes by water mediated saturation transfer

Federico De BiasiDaniele Rosa-Gastaldo, Xiaohuan Sun, Fabrizio Mancin, and Federico Rastrelli

J. Am. Chem. Soc. (I.F. 14.357)

DOI: 10.1021/jacs.8b13225

Accepted: 20 Feb 2019

Nanoparticle-assisted “NMR chemosensing” is an experimental protocol that exploits the selective recognition abilities of nanoparticle receptors to detect and identify small molecules in complex mixtures by NOE magnetization transfer. While the intrinsic sensitivity of the first reported protocols was modest, we have now found that water spins in long-lived association at the nanoparticle monolayer constitute an alternative source of magnetization that can deliver a remarkable boost of sensitivity, especially when combined with saturation transfer experiments. The approach is general and can be applied to analyte-nanoreceptor systems of different compositions. In this work we provide an account of the new method and we propose a generalized procedure based on a joint water-nanoparticle saturation to further upgrade the sensitivity, which ultimately endows selective analyte detection down to the micromolar range on standard instrumentation.

  Hierarchical organization of perylene bisimides and polyoxometalates for photo-assisted water oxidation

Marcella Bonchio, Zois Syrgiannis, Max Burian, Nadia Marino, Erica Pizzolato, Konstantin Dirian, Francesco Rigodanza, Giulia Alice Volpato, Giuseppina La Ganga, Nicola Demitri, Serena Berardi, Heinz Amenitsch, Dirk M. Guldi, Stefano Caramori, Carlo Alberto Bignozzi, Andrea Sartorel & Maurizio Prato

Nature Chemistry (2018)

DOI: 10.1038/s41557-018-0172-y

The oxygen in Earth’s atmosphere is there primarily because of water oxidation performed by photosynthetic organisms using solar light and one specialized protein complex, photosystem II (PSII). High-resolution imaging of the PSII ‘core’ complex shows the ideal co-localization of multi-chromophore light-harvesting antennas with the functional reaction centre. Man-made systems are still far from replicating the complexity of PSII, as the majority of PSII mimetics have been limited to photocatalytic dyads based on a 1:1 ratio of a light absorber, generally a Ru–polypyridine complex, with a water oxidation catalyst. Here we report the self-assembly of multi-perylene-bisimide chromophores (PBI) shaped to function by interaction with a polyoxometalate water-oxidation catalyst (Ru4POM). The resulting [PBI]5Ru4POM complex shows a robust amphiphilic structure and dynamic aggregation into large two-dimensional paracrystalline domains, a redshifted light-harvesting efficiency of >40% and favourable exciton accumulation, with a peak quantum efficiency using ‘green’ photons (λ > 500 nm). The modularity of the building blocks and the simplicity of the non-covalent chemistry offer opportunities for innovation in artificial photosynthesis.

  Arene CH insertion catalyzed by ferrocene covalently heterogenized on graphene acid

Dario Mosconi, Matías Blanco, Teresa Gatti, Laura Calvillo, Michal Otyepka, Aristides Bakandritsos, Enzo Menna, Stefano Agnoli and Gaetano Granozzi

Carbon (IF= 7.082)


Accepted on 05th November 2018

The heterogenation of molecular catalysts on solid supports is a viable route for the preparation of hybrid materials that combine the high selectivity and activity of homogeneous active species with the enhanced stability and recyclability imparted by the heterogeneous nature of the support. The paper describes the covalent functionalization with ferrocene (Fc) of two graphene derivatives: graphene acid (GA), a graphene layer whose basal plane is modified with COOH groups but maintaining the electronic and thermal conductivity of pristine graphene, and graphene oxide (GO) as already known oxidized carbon nanomaterial benchmark. The surface modification is performed exploiting the carbodiimide chemistry, which allows introducing up to 3.6 % at. of iron in the GA-based material. Compared to GO, GA owns a superior functionalization degree, which is attributed to its controlled surface chemistry. Both Fc-modified materials are tested as catalysts in the C-H insertion of diazonium salts employing arene substrates. The materials are active, versatile and recyclable catalysts that show a catalytic performance comparable to or even better than molecular Fc, together with a 100% recyclability which does not alter the catalytic performance. The GA-based hybrid catalyst results more active than that based on GO due to the presence of more extended aromatic domains (higher electron conductivity) that facilitate the synergy due to local adsorption phenomena able to sort reagents close to the active sites.

  Substrate-Induced Self-Assembly of Cooperative Catalysts

Pablo Solís Muñana, Giulio Ragazzon, Julien Dupont,Chloe Z.-J. Ren, Leonard J. Prins, Jack L.-Y. Chen

Angewandte Chemie (IF: 12.1)

DOI: 10.1002/anie.201810891

Dissipative self-assembly processes in Nature rely on chemical fuels that activate proteins for assembly through the formation of a noncovalent complex. The catalytic activity of the assemblies causes fuel degradation, resulting in the formation of an assembly in a high-energy, out-of-equilibrium state. Herein, we apply this concept to a synthetic system and demonstrate that a substrate can induce the formation of vesicular assemblies, which act as cooperative catalysts for cleavage of the same substrate. 

  Surface Engineering of Chemically Exfoliated MoS2 in a “Click”: How to Generate Versatile Multifunctional Transition Metal Dichalcogenides-Based Platforms

Giulia Tuci, Dario Mosconi, Andrea Rossin, Lapo Luconi, Stefano Agnoli, Marcello Righetto, Cuong Pham-Huu, Housseinou Ba, Stefano Cicchi, Gaetano Granozzi,* and Giuliano Giambastiani*

Chemistry of Materials (IF= 9.890)

DOI: 10.1021/acs.chemmater.8b03663

Accepted on 11 October 2018

The interest for transition metal dichalcogenides (TMDs) as two-dimensional (2D) analogues of graphene is steadily growing along with the need of efficient and easy tunable protocols for their surface functionalization. This latter aspect holds a key role in the widespread application of TMDs in various technological fields and it represents the missing step to bridge the gap between the more popular Csp2-based networks and their inorganic counterparts. Although significant steps forward have already been made in the field of TMDs functionalization (particularly for MoS2), a rational approach to their surface engineering for the generation of 2D organic-inorganic hybrids capable to accommodate various molecules featured by orthogonal groups has not been reported yet. The paper paves the way towards a new frontier for “click" chemistry in material science. It describes the post-synthetic modification (PSM) of covalently decorated MoS2 nanosheets with phenylazido pendant arms and the successful application of CuAAC chemistry (copper-mediated azide-alkyne cycloaddition) towards the generation of highly homo- and hetero-decorated MoS2 platforms. This contribution goes beyond the proof of evidence of the chemical grafting of organic groups to the surface of exfoliated MoS2 flakes through covalent C-S bonds. It also demonstrates the versatility of the hybrid samples to undergo post-synthetic modifications thus imparting multimodality to these 2D materials.