Allocation of Ambipolar Charges on an Organic Diradical with a Vinylene–Phenylenediyne Bridge

Two redox and magnetically active perchlorotriphenylmethyl (•PTM) radical units have been connected as end-capping groups to a bis(phenylene)diyne chain through vinylene linkers. Negative and positive charged species have been generated, and the influence of the bridge on their stabilization is discussed. Partial reduction of the electron-withdrawing •PTM radicals results in a class-II mixed-valence system with the negative charge located on the terminal PTM units, proving the efficiency of the conjugated chain for the electron transport between the two terminal sites. Counterintuitively, the oxidation process does not occur along the electron-rich bridge but on the vinylene units. The •PTM radicals play a key role in the stabilization of the cationic species, promoting the generation of quinoidal ring segments

GPR56/ADGRG1 Inhibits Mesenchymal Differentiation and Radioresistance in Glioblastoma

A mesenchymal transition occurs both during the natural evolution of glioblastoma (GBM) and in response to therapy. Here, we report that the adhesion G-protein-coupled receptor, GPR56/ADGRG1, inhibits GBM mesenchymal differentiation and radioresistance. GPR56 is enriched in proneural and classical GBMs and is lost during their transition toward a mesenchymal subtype. GPR56 loss of function promotes mesenchymal differentiation and radioresistance of glioma initiating cells both in vitro and in vivo. Accordingly, a low GPR56-associated signature is prognostic of a poor outcome in GBM patients even within non-G-CIMP GBMs. Mechanistically, we reveal GPR56 as an inhibitor of the nuclear factor kappa B (NF-κB) signaling pathway, thereby providing the rationale by which this receptor prevents mesenchymal differentiation and radioresistance. A pan-cancer analysis suggests that GPR56 might be an inhibitor of the mesenchymal transition across multiple tumor types beyond GBM

GPR56/ADGRG1 inhibits mesenchymal differentiation and radioresistance in glioblastoma

A mesenchymal transition occurs both during the natural evolution of glioblastoma (GBM) and in response to therapy. Here, we report that the adhesion G-protein-coupled receptor, GPR56/ADGRG1, inhibits GBM mesenchymal differentiation and radioresistance. GPR56 is enriched in proneural and classical GBMs and is lost during their transition toward a mesenchymal subtype. GPR56 loss of function promotes mesenchymal differentiation and radioresistance of glioma initiating cells both in vitro and in vivo. Accordingly, a low GPR56-associated signature is prognostic of a poor outcome in GBM patients even within non-G-CIMP GBMs. Mechanistically, we reveal GPR56 as an inhibitor of the nuclear factor kappa B (NF-κB) signaling pathway, thereby providing the rationale by which this receptor prevents mesenchymal differentiation and radioresistance. A pan-cancer analysis suggests that GPR56 might be an inhibitor of the mesenchymal transition across multiple tumor types beyond GBM

Robust Organic Radical Molecular Junctions Using Acetylene Terminated Groups for C−Au Bond Formation

Bejarano, Francesc et al.Organic paramagnetic and electroactive molecules are attracting interest as core components of molecular electronic and spintronic devices. Currently, further progress is hindered by the modest stability and reproducibility of the molecule/electrode contact. We report the synthesis of a persistent organic radical bearing one and two terminal alkyne groups to form Au-C σ bonds. The formation and stability of self-assembled monolayers and the electron transport through single-molecule junctions at room temperature have been studied. The combined analysis of both systems demonstrates that this linker forms a robust covalent bond with gold and a better-defined contact when compared to traditional sulfur-based linkers. Density functional theory and quantum transport calculations support the experimental observation highlighting a reduced variability of conductance values for the C-Au based junction. Our findings advance the quest for robustness and reproducibility of devices based on electroactive molecules.We acknowledge Dr. G. Sauthier from the ICN2 for the XPS measurements, Prof. Carlos Gomez from IcMOL for the SQUID measurements, A. Bernabé and Dr. V. Lloveras from ICMAB for the LDI-ToF and EPR measurements, respectively. This work was supported by FET ACMOL project (GA no. 618082), CIBER-BBN, the DGI (Spain) project FANCY CTQ2016-80030-R, the Generalitat de Catalunya (2014-SGR-17) and the MINECO, through the “Severo Ochoa” Programme for Centers of Excel-lence in R&D (SEV-2015-0496). F.B he is enrolled in the Materi-als Science Ph.D. program of UAB. We thank the Dutch science foundation NWO/FOM for financial support.Peer reviewe

Study of the E–Z stilbene isomerisation in perchlorotriphenyl-methane (PTM) derivatives

The E–Z isomerisation of two perchlorotriphenylmethane derivatives containing stilbene units has been investigated, both thermally and photochemically. The irreversibility of the E / Z isomerisation in both compounds is experimentally demonstrated and supported by density functional calculations.We thank Carlos Franco for his help with the HPLC analysis and Amable Bernab´e CTQ2016-80030-R for the MALDI-ToF characterizations. We thank the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN); DGI (Spain) with projects BE-WELL CTQ2013-40480-R and MAT2012-30924, and Generalitat de Catalunya (grant 2009SGR00516, 2014SGR97 and XRQTC). We also thank the EU projects ERC StG 2012-306826 e-GAMES, ITN iSwitch (GA no. 642196), ACMOL (GA no. 618082) and CIG-ELECTROMAGIC (PCIG10-GA-2011-303989). Spanish Ministry of Economy and Competitiveness, through the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (SEV-2015-0496). N. C. thanks the RyC contract. F. B. acknowledges the FPU fellowship. F. B. is enrolled in the Materials Science PhD program of UAB.Peer reviewe

Photoswitching activation of a ferrocenyl-stilbene analogue by its covalent grafting to gold

Until now, surface-deposited stilbenes have been much less studied than other photochromic systems. Here, an asymmetrically substituted styrene incorporating a redox-active ferrocene moiety and a terminal alkyne group has been synthesised to investigate its photoisomerization in solution, and upon the formation of chemisorbed self-assembled monolayers through a carbon-gold bond formation. Charge transport measurements across the monolayers reveal that upon chemical linkage to the gold substrate there is an alteration of the isomerization pathway, which favours the trans to cis conversion, which is not observed in solution. The experimental observations are interpreted based on quantum chemistry calculations.This work was funded by the Spanish Ministry project GENESIS PID2019-111682RB-I00, the Generalitat de Catalunya (2017-SGR-918) and the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centers of Excellence in R&D (FUNFUTURE CEX2019-000917-S and CIBER-BBN. The work in Valencia and Madrid is supported by the MINECO-FEDER project CTQ2017-87054. The work in Madrid is further supported by the Spanish Science Ministry through the SEV-2016-0686 and CEX2020-001039-S grants and by the Campus of International Excellence (CEI) UAM + CSIC. D. R.-S. acknowledges the MINECO Ramón y Cajal grant (RYC-2015-19234) and the MDM-2015-0538 María de Maeztu Programme. J. C.-T. thanks (DOC-FAM fellowship, grant agreement Nr.754397 through H2020-MSCA-COFUND-2016). F. B. and J. C -T. are enrolled in the Materials Science PhD program of UAB. F. B. thanks the Spanish Ministry for the FPU fellowship.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe

Robust organic radical molecular junctions using acetylene terminated groups for c-au bond formation

Organic paramagnetic and electroactive molecules are attracting interest as core components of molecular electronic and spintronic devices. Currently, further progress is hindered by the modest stability and reproducibility of the molecule/electrode contact. We report the synthesis of a persistent organic radical bearing one and two terminal alkyne groups to form Au-C σ bonds. The formation and stability of self-assembled monolayers and the electron transport through single-molecule junctions at room temperature have been studied. The combined analysis of both systems demonstrates that this linker forms a robust covalent bond with gold and a better-defined contact when compared to traditional sulfur-based linkers. Density functional theory and quantum transport calculations support the experimental observation highlighting a reduced variability of conductance values for the C-Au based junction. Our findings advance the quest for robustness and reproducibility of devices based on electroactive molecules.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.QN/van der Zant LabQN/Afdelingsburea

Exploiting the versatile alkyne-based chemistry for expanding the applications of a stable triphenylmethyl organic radical on surfaces

International audienceThe incorporation of terminal alkynes into the chemical structure of persistent organic perchlorotriphenylmethyl (PTM) radicals provides new chemical tools to expand their potential applications. In this work, this is demonstrated by the chemical functionalization of two types of substrates, hydrogenated SiO2-free silicon (Si-H) and gold, and, by exploiting the click chemistry, scarcely used with organic radicals, to synthesise multifunctional systems. On one hand, the one-step functionalization of Si-H allows a light-triggered capacitance switch to be successfully achieved under electrochemical conditions. On the other hand, the click reaction between the alkyne-terminated PTM radical and a ferrocene azide derivative, used here as a model azide system, leads to a multistate electrochemical switch. The successful post-surface modification makes the self-assembled monolayers reported here an appealing platform to synthesise multifunctional systems grafted on surfaces

Robust Organic Radical Molecular Junctions Using Acetylene Terminated Groups for C–Au Bond Formation

Organic paramagnetic and electroactive molecules are attracting interest as core components of molecular electronic and spintronic devices. Currently, further progress is hindered by the modest stability and reproducibility of the molecule/electrode contact. We report the synthesis of a persistent organic radical bearing one and two terminal alkyne groups to form Au–C σ bonds. The formation and stability of self-assembled monolayers and the electron transport through single-molecule junctions at room temperature have been studied. The combined analysis of both systems demonstrates that this linker forms a robust covalent bond with gold and a better-defined contact when compared to traditional sulfur-based linkers. Density functional theory and quantum transport calculations support the experimental observation highlighting a reduced variability of conductance values for the C–Au based junction. Our findings advance the quest for robustness and reproducibility of devices based on electroactive molecules