The OpenAIRE Research Community Dashboard: On blending scientific workflows and scientific publishing

First Online 30 August 2019Despite the hype, the effective implementation of Open Science is hindered by several cultural and technical barriers. Researchers embraced digital science, use “digital laboratories” (e.g. research infrastructures, thematic services) to conduct their research and publish research data, but practices and tools are still far from achieving the expectations of transparency and reproducibility of Open Science. The places where science is performed and the places where science is published are still regarded as different realms. Publishing is still a post-experimental, tedious, manual process, too often limited to articles, in some contexts semantically linked to datasets, rarely to software, generally disregarding digital representations of experiments. In this work we present the OpenAIRE Research Community Dashboard (RCD), designed to overcome some of these barriers for a given research community, minimizing the technical efforts and without renouncing any of the community services or practices. The RCD flanks digital laboratories of research communities with scholarly communication tools for discovering and publishing interlinked scientific products such as literature, datasets, and software. The benefits of the RCD are show-cased by means of two real-case scenarios: the European Marine Science community and the European Plate Observing System (EPOS) research infrastructure.This work is partly funded by the OpenAIRE-Advance H2020 project (grant number: 777541; call: H2020-EINFRA-2017) and the OpenAIREConnect H2020 project (grant number: 731011; call: H2020-EINFRA-2016-1). Moreover, we would like to thank our colleagues Michele Manunta, Francesco Casu, and Claudio De Luca (Institute for the Electromagnetic Sensing of the Environment, CNR, Italy) for their work on the EPOS infrastructure RCD; and Stephane Pesant (University of Bremen, Germany) his work on the European Marine Science RCD

Basicity as a Thermodynamic Descriptor of Carbanions Reactivity with Carbon Dioxide: Application to the Carboxylation of α,β-Unsaturated Ketones

The utilization of carbon dioxide as a raw material represents nowadays an appealing strategy in the renewable energy, organic synthesis, and green chemistry fields. Besides reduction strategies, carbon dioxide can be exploited as a single-carbon-atom building block through its fixation into organic scaffolds with the formation of new C-C bonds (carboxylation processes). In this case, activation of the organic substrate is commonly required, upon formation of a carbanion C−, being sufficiently reactive toward the addition of CO2. However, the prediction of the reactivity of C− with CO2 is often problematic with the process being possibly associated with unfavorable thermodynamics. In this contribution, we present a thermodynamic analysis combined with density functional theory calculations on 50 organic molecules enabling the achievement of a linear correlation of the standard free energy (ΔG0) of the carboxylation reaction with the basicity of the carbanion C−, expressed as the pKa of the CH/C− couple. The analysis identifies a threshold pKa of ca 36 (in CH3CN) for the CH/C− couple, above which the ΔG0 of the carboxylation reaction is negative and indicative of a favorable process. We then apply the model to a real case involving electrochemical carboxylation of flavone and chalcone as model compounds of α,β-unsaturated ketones. Carboxylation occurs in the β-position from the doubly reduced dianion intermediates of flavone and chalcone (calculated ΔG0 of carboxylation in β = −12.8 and −20.0 Kcalmol-1 for flavone and chalcone, respectively, associated with pKa values for the conjugate acids of 50.6 and 51.8, respectively). Conversely, the one-electron reduced radical anions are not reactive toward carboxylation (ΔG0 > +20 Kcalmol-1 for both substrates, in either α or β position, consistent with pKa of the conjugate acids < 18.5). For all the possible intermediates, the plot of calculated ΔG0 of carboxylation vs. pKa is consistent with the linear correlation model developed. The application of the ΔG0 vs. pKa correlation is finally discussed for alternative reaction mechanisms and for carboxylation of other C=C and C=O double bonds. These results offer a new mechanistic tool for the interpretation of the reactivity of CO2 with organic intermediates

A Proton-Coupled Electron Transfer Strategy to the Redox-Neutral Photocatalytic CO2 Fixation

Herein, we report our study on the design and development of a novel photocarboxylation method. We have used an organic photoredox catalyst (PC, 4CzIPN) and differently substituted dihydropyridines (DHPs) in combination with an organic base (1,5,7-triazabicyclodec-5-ene, TBD) to access a proton-coupled electron transfer (PCET) based manifold. In depth mechanistic investigations merging experimental analysis (NMR, IR, cyclic voltammetry) and density-functional theory (DFT) calculations reveal the key activity of a H-bonding complex between the DHP and the base. The thermodynamic and kinetic benefits of the PCET mechanism allowed the implementation of a redox-neutral fixation process leading to synthetically relevant carboxylic acids (18 examples with isolated yields up to 75%) under very mild reaction conditions. Finally, diverse product manipulations were performed to demonstrate the synthetic versatility of the obtained products

Unveiling the impact of the light source and steric factors on [2 + 2] heterocycloaddition reactions

Information gained from in-depth mechanistic investigations can be used to control the selectivity of reactions, leading to expansion of the generality of synthetic processes and discovery of new reactivity. Here, we investigate the mechanism of light-driven [2 + 2] heterocycloadditions (Paternò–Büchi reactions) between indoles and ketones to develop insight into these processes. Using ground-state ultraviolet–visible absorption and transient absorption spectroscopy, together with density functional theory calculations, we found that the reactions can proceed via an exciplex or electron–donor–acceptor complex, which are key intermediates in determining the stereoselectivity of the reactions. We used this discovery to control the diastereoselectivity of the reactions, gaining access to previously inaccessible diastereoisomeric variants. When moving from 370 to 456 nm irradiation, the electron– donor–acceptor complex is increasingly favoured, and the diastereomeric ratio (d.r.) of the product moves from >99:<1 to 47:53. In contrast, switching from methyl to ipropyl substitution favours the exciplex intermediate, reversing the d.r. from 89:11 to 16:84. Our study shows how light and steric parameters can be rationally used to control the diastereoselectivity of photoreactions, creating mechanistic pathways to previously inaccessible stereochemical variants

Exploring the Vinylogous Reactivity of Cyclohexenylidene Malononitriles: Switchable Regioselectivity in the Organocatalytic Asymmetric Addition to Enals Giving Highly Enantioenriched Carbabicyclic Structures

Modulation of the complex reactivity of cyclohexenylidene malononitriles using diverse β-aryl-substituted enals and proper organocatalytic modalities resulted in divergent asymmetric reaction patterns to furnish angularly fused or bridged carbabicyclic frameworks. In particular, use of remotely enolizable dicyanodienes <b>1</b>, under one-pot sequential amine/NHC catalysis, led to [3 + 2] cycloaddition to afford ε,δ-bonded spiro[4.5]­decanone structures <b>5</b>. Alternatively, modifying the standard amine catalysis by adding a suitable chemical stimulus (<i>p</i>-nitrophenol cocatalyst) switched the reactivity decidedly toward a domino [4 + 2] cycloaddition to afford γ′,δ-bonded bicyclo[2.2.2]­octane carbaldehydes <b>8</b>. Products invariably formed in good yields, with rigorous chemo-, regio-, diastereo-, and enantiocontrol. Experimental evidence, including carbon isotope effects measured by ¹³C NMR, were indicative of the rate (and stereochemistry) determining step of these transformations and suggested a stepwise mechanism for the [4 + 2] cycloadditive pathway

Photoelectrochemical C-H Activation Through a Quinacridone Dye Enabling Proton-Coupled Electron Transfer

Dye-sensitized photoanodes for C-H activation in organic substrates are assembled by vacuum sublimation of a commercially available quinacridone (QNC) dye in the form of nanosized rods onto fluorine-doped tin oxide (FTO), TiO2, and SnO2 slides. The photoanodes display extended absorption in the visible range (450-600 nm) and ultrafast photoinduced electron injection (&lt;1 ps, as revealed by transient absorption spectroscopy) of the QNC dye into the semiconductor. The proton-coupled electron-transfer reactivity of QNC is exploited for generating a nitrogen-based radical as its oxidized form, which is competent in C-H bond activation. The key reactivity parameter is the bond-dissociation free energy (BDFE) associated with the N center dot/N-H couple in QNC of 80.5 +/- 2.3 kcal mol(-1), which enables hydrogen atom abstraction from allylic or benzylic C-H moieties. A photoelectrochemical response is indeed observed for organic substrates characterized by C-H bonds with BDFE below the 80.5 kcal mol(-1) threshold, such as gamma-terpinene, xanthene, or dihydroanthracene. This work provides a rational, mechanistically oriented route to the design of dye-sensitized photoelectrodes for selective organic transformations

Exploring the Vinylogous Reactivity of Cyclohexenylidene Malononitriles: Switchable Regioselectivity in the Organocatalytic Asymmetric Addition to Enals Giving Highly Enantioenriched Carbabicyclic Structures

Modulation of the complex reactivity of cyclohexenylidene malononitriles using diverse β-aryl-substituted enals and proper organocatalytic modalities resulted in divergent asymmetric reaction patterns to furnish angularly fused or bridged carbabicyclic frameworks. In particular, use of remotely enolizable dicyanodienes <b>1</b>, under one-pot sequential amine/NHC catalysis, led to [3 + 2] cycloaddition to afford ε,δ-bonded spiro[4.5]­decanone structures <b>5</b>. Alternatively, modifying the standard amine catalysis by adding a suitable chemical stimulus (<i>p</i>-nitrophenol cocatalyst) switched the reactivity decidedly toward a domino [4 + 2] cycloaddition to afford γ′,δ-bonded bicyclo[2.2.2]­octane carbaldehydes <b>8</b>. Products invariably formed in good yields, with rigorous chemo-, regio-, diastereo-, and enantiocontrol. Experimental evidence, including carbon isotope effects measured by ¹³C NMR, were indicative of the rate (and stereochemistry) determining step of these transformations and suggested a stepwise mechanism for the [4 + 2] cycloadditive pathway