Suchergebnisse

The exact chemical structure of non–crystallising natural products is still one of the main challenges in Natural Sciences. Despite tremendous advances in total synthesis, the absolute structural determination of a myriad of natural products with very sensitive chemical functionalities remains undone. Here, we show that a metal–organic framework (MOF) with alcohol–containing arms and adsorbed water, enables selective hydrolysis of glycosyl bonds, supramolecular order with the so–formed chiral fragments and absolute determination of the organic structure by single–crystal X–ray crystallography in a single operation. This combined strategy based on a biomimetic, cheap, robust and multigram available solid catalyst opens the door to determine the absolute configuration of ketal compounds regardless degradation sensitiveness, and also to design extremely–mild metal–free solid–catalysed processes without formal acid protons. ; This work was supported by the Ministero dell'Istruzione, dell'Università e della Ricerca (Italy) and the MINECO (Spain) (Projects CTQ2016-75671-P, CTQ 2017-86735-P, RTC-2017-6331-5, Severo Ochoa program SEV-2016-0683 and Excellence Unit "Maria de Maeztu" MDM-2015-0538). R.B. thanks the MIUR (Project PON R&I FSE-FESR 2014–2020) for grant. L.B wishes to thank Italian MIUR for grant n. AIM1899391–1 in the framework of the project "Azione I.2, Mobilità dei Ricercatori, PON R&I 2014–2020". Thanks are also extended to the "2019 Post-doctoral Junior Leader-Retaining Fellowship, la Caixa Foundation (ID100010434 and fellowship code LCF/BQ/PR19/11700011" (J. F.- S.). S. S.-N. thanks ITQ for the concession of a contract. D.A. acknowledges the financial support of the Fondazione CARIPLO/"Economia Circolare: ricerca per un futuro sostenibile" 2019, Project code: 2019–2090, MOCA. E.P. acknowledges the financial support of the European Research Council under the European Union's Horizon 2020 research and innovation program/ERC Grant Agreement No. 814804, MOF-reactors.

Supramolecular coordination compounds (SCCs) represent the power of coordination chemistry methodologies to self-assemble discrete architectures with targeted properties. SCCs are generally synthesized in solution, with isolated fully coordinated metal atoms as structural nodes, thus severely limited as metal-based catalysts. Metal-organic frameworks (MOFs) show unique features to act as chemical nanoreactors for the in situ synthesis and stabilization of otherwise not accessible functional species. Here, we present the self-assembly of PdII SCCs within the confined space of a pre-formed MOF (SCCs@MOF) and its post-assembly metalation to give a PdII-AuIII supramolecular assembly, crystallography underpinned. These SCCs@MOFs catalyze the coupling of boronic acids and/or alkynes, representative multi-site metal-catalyzed reactions in which traditional SCCs tend to decompose, and retain their structural integrity as a consequence of the synergetic hybridization between SCCs and MOFs. These results open new avenues in both the synthesis of novel SCCs and their use in heterogeneous metal-based supramolecular catalysis. ; This work was supported by the MINECO (Spain) (Projects CTQ2016-75671-P and 2017-86735-P, and Excellence Units "Severo Ochoa" and "Maria de Maeztu" SEV-2016-0683 and MDM-2015-0538), the Ministero dell'Istruzione, dell'Università e della Ricerca (Italy), and the Engineering and Physical Sciences Research Council (UK). M.M. thanks the MINECO for a predoctoral contract. R.A. thanks UPV and R.G. thanks ITQ for the corresponding contracts. D.A. thanks the "Fondo per il finanziamento delle attività base di ricerca". E.P. acknowledges financial support from the European Research Council under the European Union's Horizon 2020 research and innovation programme/ERC Grant Agreement No. 814804, MOF-reactors. Thanks are also extended to the "Subprograma Atracció de Talent-Contractes Post-doctorals de la Universitat de Valencia" and the "2018 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation" (J.F.-S.). We thank the Diamond Light Source for awarded beamtime (proposal number MT18768) and provision of synchrotron radiation facility, and Dr. David Allan and Dr. Sarah Barnett for their assistance at the I19 beamline.

[EN] Supramolecular coordination compounds (SCCs) represent the power of coordination chemistry methodologies to self-assemble discrete architectures with targeted properties. SCCs are generally synthesized in solution, with isolated fully coordinated metal atoms as structural nodes, thus severely limited as metal-based catalysts. Metal-organic frameworks (MOFs) show unique features to act as chemical nanoreactors for the in situ synthesis and stabilization of otherwise not accessible functional species. Here, we present the self-assembly of Pd-II SCCs within the confined space of a pre-formed MOF (SCCs@MOF) and its post-assembly metalation to give a Pd-II-Au-III supra molecular assembly, crystallography underpinned. These SCCs@MOFs catalyze the coupling of boronic acids and/or alkynes, representative multi-site metal-catalyzed reactions in which traditional SCCs tend to decompose, and retain their structural integrity as a consequence of the synergetic hybridization between SCCs and MOFs. These results open new avenues in both the synthesis of novel SCCs and their use in heterogeneous metal-based supramolecular catalysis. ; This work was supported by the MINECO (Spain) (Projects CTQ2016-75671-P and 2017-86735-P, and Excellence Units "Severn Ochoa" and "Maria de Maeztu" SEV-2016-0683 and MDM-2015-0538), the Ministero dell'Istruzione, dell'Universita e della Ricerca (Italy), and the Engineering and Physical Sciences Research Council (UK). M.M. thanks the MINECO for a predoctoral contract. RA. thanks UPV and R.G. thanks ITQ for the corresponding contracts. D.A. thanks the "Fondo per it finanziamento delle attivita base di ricerca". E.P. acknowledges financial support from the European Research Council under the European Union's Horizon 2020 research and innovation programme/ERC Grant Agreement No. 814804, MOF-reactors. Thanks are also extended to the "Subprograma Atraccio de Talent-Contractes Post-doctorals de la Universitat de Valencia" and the "2018 Leonardo Grant for Researchers and Cultural Creators, BBVA ...