Publications by authors named "Natalia Padial"

18 Publications

  • Page 1 of 1

Impact of Pore Size and Defects on the Selective Adsorption of Acetylene in Alkyne-Functionalized Nickel(II)-Pyrazolate-Based MOFs.

Chemistry 2021 Jun 11. Epub 2021 Jun 11.

Departamento de Química, Universidad de Granada, Av. Fuentenueva S/N, 18071, Granada, Spain.

C H /CO separation is a highly challenging process as a consequence of their similar physicochemical properties. In this work we have explored, by static and dynamic gas sorption techniques and computational modelling, the suitability of a series of two isoreticular robust Ni(II)pyrazolate-based MOFs, bearing alkyne moieties on the ligand backbones, for C H /CO separation. The results are consistent with high adsorption capacity and selectivity of the essayed systems towards C H molecules. Furthermore, a post-synthetic treatment with KOH ethanolic solution gives rise to linker vacancy defects and incorporation of extraframework potassium ions. Creation of defects is responsible for increased adsorption capacity for both gases, however, strong interactions of the cluster basic sites and extraframework potassium cations with CO molecules are responsible for a lowering of C H over CO selectivity.
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http://dx.doi.org/10.1002/chem.202100821DOI Listing
June 2021

Selective Implantation of Diamines for Cooperative Catalysis in Isoreticular Heterometallic Titanium-Organic Frameworks.

Angew Chem Int Ed Engl 2021 May 26;60(21):11868-11873. Epub 2021 Mar 26.

Functional Inorganic Materials team, Instituto de Ciencia Molecular, Universidad de Valencia, Catedrático Jose Beltrán-2, 46980, Paterna, Spain.

We introduce the first example of isoreticular titanium-organic frameworks, MUV-10 and MUV-12, to show how the different affinity of hard Ti(IV) and soft Ca(II) metal sites can be used to direct selective grafting of amines. This enables the combination of Lewis acid titanium centers and available -NH sites in two sizeable pores for cooperative cycloaddition of CO to epoxides at room temperature and atmospheric pressure. The selective grafting of molecules to heterometallic clusters adds up to the pool of methodologies available for controlling the positioning and distribution of chemical functions in precise positions of the framework required for definitive control of pore chemistry.
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http://dx.doi.org/10.1002/anie.202100176DOI Listing
May 2021

Serine-Selective Bioconjugation.

J Am Chem Soc 2020 10 5;142(41):17236-17242. Epub 2020 Oct 5.

Department of Chemistry, Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States.

This Communication reports the first general method for rapid, chemoselective, and modular functionalization of serine residues in native polypeptides, which uses a reagent platform based on the P(V) oxidation state. This redox-economical approach can be used to append nearly any kind of cargo onto serine, generating a stable, benign, and hydrophilic phosphorothioate linkage. The method tolerates all other known nucleophilic functional groups of naturally occurring proteinogenic amino acids. A variety of applications can be envisaged by this expansion of the toolbox of site-selective bioconjugation methods.
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http://dx.doi.org/10.1021/jacs.0c05595DOI Listing
October 2020

Heterometallic Titanium-Organic Frameworks by Metal-Induced Dynamic Topological Transformations.

J Am Chem Soc 2020 Apr 30;142(14):6638-6648. Epub 2020 Mar 30.

Functional Inorganic Materials Team, Instituto de Ciencia Molecular (ICMol), Universitat de València, Paterna 46980, València, Spain.

Reticular chemistry has boosted the design of thousands of metal and covalent organic frameworks for unlimited chemical compositions, structures, and sizable porosities. The ability to generate porous materials at will on the basis of geometrical design concepts is responsible for the rapid growth of the field and the increasing number of applications derived. Despite their promising features, the synthesis of targeted homo- and heterometallic titanium-organic frameworks amenable to these principles is relentlessly limited by the high reactivity of this metal in solution that impedes the controlled assembly of titanium molecular clusters. We describe an unprecedented methodology for the synthesis of heterometallic titanium frameworks by metal-exchange reactions of MOF crystals at temperatures below those conventionally used in solvothermal synthesis. The combination of hard (titanium) and soft (calcium) metals in the heterometallic nodes of MUV-10(Ca) enables controlled metal exchange in soft positions for the generation of heterometallic secondary building units (SBUs) with variable nuclearity, controlled by the metal incorporated. The structural information encoded in the newly formed SBUs drives an MOF-to-MOF conversion into bipartite nets compatible with the connectivity of the organic linker originally present in the crystal. Our simulations show that this transformation has a thermodynamic origin and is controlled by the terminations of the (111) surfaces of the crystal. The reaction of MUV-10(Ca) with first-row transition metals permits the production of crystals of MUV-101(Fe,Co,Ni,Zn) and MUV-102(Cu), heterometallic titanium MOFs isostructural with archetypical solids such as MIL-100 and HKUST. In comparison to de novo synthesis, this metal-induced topological transformation provides control over the formation of hierarchical micro-/mesopore structures at different reaction times and enables the formation of heterometallic titanium MOFs not accessible under solvothermal conditions at high temperature, thus opening the door for the isolation of additional titanium heterometallic phases not linked exclusively to trimesate linkers.
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http://dx.doi.org/10.1021/jacs.0c00117DOI Listing
April 2020

Enantiodivergent Formation of C-P Bonds: Synthesis of P-Chiral Phosphines and Methylphosphonate Oligonucleotides.

J Am Chem Soc 2020 03 16;142(12):5785-5792. Epub 2020 Mar 16.

Department of Chemistry, Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States.

Phosphorus Incorporation (PI, abbreviated Π) reagents for the modular, scalable, and stereospecific synthesis of chiral phosphines and methylphosphonate nucleotides are reported. Synthesized from limonene oxide, this reagent class displays an unexpected reactivity profile and enables access to chemical space distinct from that of the Phosphorus-Sulfur Incorporation reagents previously disclosed. Here, the adaptable phosphorus(V) scaffold enables sequential addition of carbon nucleophiles to produce a variety of enantiopure C-P building blocks. Addition of three carbon nucleophiles to Π, followed by stereospecific reduction, affords useful P-chiral phosphines; introduction instead of a single methyl group reveals the first stereospecific synthesis of methylphosphonate oligonucleotide precursors. While both Π enantiomers are available, only one isomer is required-the order of nucleophile addition controls the absolute stereochemistry of the final product through a unique enantiodivergent design.
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http://dx.doi.org/10.1021/jacs.9b13898DOI Listing
March 2020

Hydroxamate Titanium-Organic Frameworks and the Effect of Siderophore-Type Linkers over Their Photocatalytic Activity.

J Am Chem Soc 2019 08 1;141(33):13124-13133. Epub 2019 Aug 1.

Universidad de Valencia (ICMol) , Catedrático José Beltrán-2 , 46980 Paterna , Spain.

The chemistry of metal-organic frameworks (MOFs) relies on the controlled linking of organic molecules and inorganic secondary building units to assemble an unlimited number of reticular frameworks. However, the design of porous solids with chemical stability still remains limited to carboxylate or azolate groups. There is a timely opportunity to develop new synthetic platforms that make use of unexplored metal binding groups to produce metal-linker joints with hydrolytic stability. Living organisms use siderophores ( in Greek) to effectively assimilate iron in soluble form. These compounds make use of hard oxo donors as hydroxamate or catecholate groups to coordinate metal Lewis acids such as iron, aluminum, or titanium to form metal complexes very stable in water. Inspired by the chemistry of these microorganisms, we report the first hydroxamate MOF prepared by direct synthesis. MUV-11 (MUV = materials of Universidad de Valencia) is a crystalline, porous material (close to 800 m·g) that combines photoactivity with good chemical stability in acid conditions. By using a high-throughput approach, we also demonstrate that this new chemistry is compatible with the formation of single-crystalline phases for multiple titanium salts, thus expanding the scope of accessible precursors. Titanium frameworks are regarded as promising materials for photocatalytic applications. Our photoelectrochemical and catalytic tests suggest important differences for MUV-11. Compared to other Ti-MOFs, changes in the photoelectrochemical and photocatalytic activity have been rationalized with computational modeling, revealing how the chemistry of siderophores can introduce changes to the electronic structure of the frontier orbitals, relevant to the photocatalytic activity of these solids.
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http://dx.doi.org/10.1021/jacs.9b04915DOI Listing
August 2019

Direct Visualization of Pyrrole Reactivity upon Confinement within a Cyclodextrin Metal-Organic Framework.

Angew Chem Int Ed Engl 2019 Jul 28;58(27):9179-9183. Epub 2019 May 28.

Instituto de Ciencia Molecular (ICMol), Universitat de València, Paterna, 46980, València, Spain.

Metal-organic frameworks can be used as porous templates to exert control over polymerization reactions. Shown here are the possibilities offered by these crystalline, porous nanoreactors to capture highly-reactive intermediates for a better understanding of the mechanism of polymerization reactions. By using a cyclodextrin framework the polymerization of pyrrole is restricted, capturing the formation of terpyrrole cationic intermediates. Single-crystal X-ray diffraction is used to provide definite information on the supramolecular interactions that induce the formation and stabilization of a conductive array of cationic complexes.
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http://dx.doi.org/10.1002/anie.201904890DOI Listing
July 2019

A Radical Approach to Anionic Chemistry: Synthesis of Ketones, Alcohols, and Amines.

J Am Chem Soc 2019 04 16;141(16):6726-6739. Epub 2019 Apr 16.

Department of Chemistry , Scripps Research , 10550 North Torrey Pines Road , La Jolla , California 92037 , United States.

Historically accessed through two-electron, anionic chemistry, ketones, alcohols, and amines are of foundational importance to the practice of organic synthesis. After placing this work in proper historical context, this Article reports the development, full scope, and a mechanistic picture for a strikingly different way of forging such functional groups. Thus, carboxylic acids, once converted to redox-active esters (RAEs), can be utilized as formally nucleophilic coupling partners with other carboxylic derivatives (to produce ketones), imines (to produce benzylic amines), or aldehydes (to produce alcohols). The reactions are uniformly mild, operationally simple, and, in the case of ketone synthesis, broad in scope (including several applications to the simplification of synthetic problems and to parallel synthesis). Finally, an extensive mechanistic study of the ketone synthesis is performed to trace the elementary steps of the catalytic cycle and provide the end-user with a clear and understandable rationale for the selectivity, role of additives, and underlying driving forces involved.
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http://dx.doi.org/10.1021/jacs.9b02238DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7004484PMC
April 2019

Surface Functionalization of Metal-Organic Frameworks for Improved Moisture Resistance.

J Vis Exp 2018 09 5(139). Epub 2018 Sep 5.

Instituto de Ciencia Molecular (ICMol), Universitat de València;

Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. However, the main issue limiting their applicability is their poor stability in humid conditions. The common methods to overcome this problem involve the formation of strong metal-linker bonds by using highly charged metals, which is limited to a number of structures, the introduction of alkylic groups to the framework by post-synthetic modification (PSM) or chemical vapour deposition (CVD) to enhance overall hydrophobicity of the framework. These last two usually provoke a drastic reduction of the porosity of the material. These strategies do not permit to exploit the properties of the MOF already available and it is imperative to find new methods to enhance the stability of MOFs in water while keeping their properties intact. Herein, we report a novel method to enhance the water stability of MOF crystals featuring Cu2(O2C)4 paddle-wheel units, such as HKUST (where HKUST stands for Hong Kong University of Science & Technology), with the catechols functionalized with alkyl and fluoro-alkyl chains. By taking advantage of the unsaturated metal sites and the catalytic catecholase-like activity of Cu ions, we are able to create robust hydrophobic coatings through the oxidation and subsequent polymerization of the catechol units on the surface of the crystals under anaerobic and water-free conditions without disrupting the underlying structure of the framework. This approach not only affords the material with improved water stability but also provides control over the function of the protective coating, which enables the development of functional coatings for the adsorption and separations of volatile organic compounds. We are confident that this approach could also be extended to other unstable MOFs featuring open metal sites.
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http://dx.doi.org/10.3791/58052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6235109PMC
September 2018

Chemical Engineering of Photoactivity in Heterometallic Titanium-Organic Frameworks by Metal Doping.

Angew Chem Int Ed Engl 2018 07 6;57(28):8453-8457. Epub 2018 Jun 6.

Universidad de Valencia (ICMol), Catedrático José Beltrán-2, 46980, Paterna, Spain.

We report a new family of titanium-organic frameworks that enlarges the limited number of crystalline, porous materials available for this metal. They are chemically robust and can be prepared as single crystals at multi-gram scale from multiple precursors. Their heterometallic structure enables engineering of their photoactivity by metal doping rather than by linker functionalization. Compared to other methodologies based on the post-synthetic metallation of MOFs, our approach is well-fitted for controlling the positioning of dopants at an atomic level to gain more precise control over the band-gap and electronic properties of the porous solid. Changes in the band-gap are also rationalized with computational modelling and experimentally confirmed by photocatalytic H production.
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http://dx.doi.org/10.1002/anie.201802089DOI Listing
July 2018

Surface Functionalization of Metal-Organic Framework Crystals with Catechol Coatings for Enhanced Moisture Tolerance.

ACS Appl Mater Interfaces 2017 Dec 12;9(51):44641-44648. Epub 2017 Dec 12.

Instituto de Ciencia Molecular (ICMol), Universitat de València , Catedrático José Beltrán-2 46980, Paterna, Spain.

Robust catechol coatings for enhanced moisture tolerance were produced in one step by direct reaction of Hong Kong University of Science and Technology (HKUST) with synthetic catechols. We ascribe the rapid formation of homogeneous coatings around the metal-organic framework particles to the biomimetic catalytic activity of Cu(II) dimers in the external surface of the crystals. Use of fluorinated catechols results in hydrophobic, permeable coatings that protect HKUST from water degradation while retaining close to 100% of its original sorption capacity.
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http://dx.doi.org/10.1021/acsami.7b15564DOI Listing
December 2017

Chemical Warfare Agents Detoxification Properties of Zirconium Metal-Organic Frameworks by Synergistic Incorporation of Nucleophilic and Basic Sites.

ACS Appl Mater Interfaces 2017 Jul 10;9(28):23967-23973. Epub 2017 Jul 10.

Departamento de Química Inorgánica, Universidad de Granada , Avenida Fuentenueva S/N, 18071 Granada, Spain.

The development of protective self-detoxifying materials is an important societal challenge to counteract risk of attacks employing highly toxic chemical warfare agents (CWAs). In this work, we have developed bifunctional zirconium metal-organic frameworks (MOFs) incorporating variable amounts of nucleophilic amino residues by means of formation of the mixed ligand [ZrO(OH)(bdc)(bdc-NH)] (UiO-66-xNH) and [ZrO(OH)(bpdc)(bpdc-(NH))] (UiO-67-x(NH)) systems where bdc = benzene-1,4-dicarboxylate; bdc-NH= benzene-2-amino-1,4-dicarboxylate; bpdc = 4,4'-biphenyldicarboxylate; bpdc-(NH) = 2,2'-diamino-4,4'-biphenyldicarboxylate and x = 0, 0.25, 0.5, 0.75, 1. In a second step, the UiO-66-xNH and UiO-67-x(NH) systems have been postsynthetically modified by introduction of highly basic lithium tert-butoxide (LiOBu) on the oxohydroxometallic clusters of the mixed ligand MOFs to yield [email protected] and UiO-67-x(NH)@LiOBu materials. The results show that the combination of pre and postsynthetic modifications on these MOF series gives rise to fine-tuning of the catalytic activity toward the hydrolytic degradation of both simulants and real CWAs in unbuffered aqueous solutions. Indeed, [email protected] is able to hydrolyze both CWAs simulants (diisopropylfluorophosphate (DIFP), 2-chloroethylethylsulfide (CEES), and real CWAs (soman (GD), sulfur mustard (HD)) quickly in aqueous solution. These results are related to a suitable combination of robustness, nucleophilicity, basicity, and accessibility to the porous framework.
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http://dx.doi.org/10.1021/acsami.7b06341DOI Listing
July 2017

Synthesis of (±)-aureol by bioinspired rearrangements.

J Org Chem 2015 Feb 27;80(3):1866-70. Epub 2015 Jan 27.

Department of Organic Chemistry, Faculty of Sciences, University of Granada , 18071 Granada, Spain.

A bioinspired and sustainable procedure for the straightforward synthesis of (±)-aureol has been achieved in eight steps (14% overall yield) from epoxyfarnesol. The key steps are the titanocene(III)-catalyzed radical cascade cyclization of an epoxyfarnesol derivative and a biosynthetically inspired sequence of 1,2-hydride and methyl shifts.
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http://dx.doi.org/10.1021/jo502841uDOI Listing
February 2015

Selective reduction of aromatic ketones in aqueous medium mediated by Ti(III)/Mn: a revised mechanism.

J Org Chem 2014 Aug 21;79(16):7672-6. Epub 2014 Jul 21.

Departamento Química Orgánica, Facultad de Ciencias, Universidad de Granada , Campus Fuentenueva s/n, 18071 Granada, Spain.

An experimental study on the role played by each of the reagents involved in the selective reduction of aromatic ketones in aqueous medium is reported. In this reaction, the reduction of aromatic ketones is mediated by Cp2TiCl. Moreover, the presence of Mn in the reaction medium is mandatory. To account for these findings, a substantially revised mechanism is proposed.
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http://dx.doi.org/10.1021/jo501141yDOI Listing
August 2014

Ti-catalyzed straightforward synthesis of exocyclic allenes.

Chemistry 2014 Jan 12;20(3):801-10. Epub 2013 Dec 12.

Dpto. Química Orgánica, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva s/n, 18071 Granada (Spain), Fax: (+34) 958248437.

Exocyclic allenes constitute useful building blocks in organic synthesis and have recently been identified as key intermediates in the synthesis of natural products. Here the first general method for the most straightforward synthesis of exocyclic allenes reported to date is presented. This method is based on the Barbier-type cyclization of propargyl halides catalyzed by titanium; a safe, abundant, and ecofriendly metal. The reaction proceeds under mild conditions compatible with different functional groups and provides good yields of five-, six-, and seven-membered carbocycles and nitrogen-containing heterocycles bearing an exocyclic allene group. Experimental evidence supporting the proposed reaction mechanism is also provided. Moreover, this procedure can be carried out in an enantioselective manner by using chiral titanocene(III) catalysts. The utility of this method has been proved in the synthesis of the natural alkaloid stemoamide.
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http://dx.doi.org/10.1002/chem.201304033DOI Listing
January 2014

Study of the incorporation and release of the non-conventional half-sandwich ruthenium(II) metallodrug RAPTA-C on a robust MOF.

Chem Commun (Camb) 2011 Nov 28;47(42):11751-3. Epub 2011 Sep 28.

Universidad de Granada, Departamento de Química Inorganica, 18071 Granada, Spain.

The highly porous and robust [Ni(8)(OH)(4)(OH(2))(2)(4,4'-(buta-1,3-diyne-1,4-diyl)bispyrazolato)(6)](n) MOF can be used as a proof of concept for the incorporation and release of the non-conventional [Ru(p-cymene)Cl(2)(pta)] RAPTA-C metallodrug.
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http://dx.doi.org/10.1039/c1cc14594kDOI Listing
November 2011

Hydrogen atom donors: recent developments.

Top Curr Chem 2012 ;320:93-120

Kekulé Institut für Organische Chemie und Biochemie der Universität Bonn, Germany.

This review highlights recent developments in the field of hydrogen atom transfer (HAT) reagents that circumvent the disadvantages of classical group 14 reagents, such as Bu₃SnH. Special emphasis is laid on the lowering of bond dissociation energies (BDEs) of molecules that could, as yet, not be used as HAT reagents and on the use of organometallic HAT reagents.
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http://dx.doi.org/10.1007/128_2011_124DOI Listing
May 2012
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