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1.
Nat Commun ; 10(1): 1612, 2019 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-30962436

RESUMO

Biologically derived metal-organic frameworks (bio-MOFs) are of great importance as they can be used as models for bio-mimicking and in catalysis, allowing us to gain insights into how large biological molecules function. Through rational design, here we report the synthesis of a novel bio-MOF featuring unobstructed Watson-Crick faces of adenine (Ade) pointing towards the MOF cavities. We show, through a combined experimental and computational approach, that thymine (Thy) molecules diffuse through the pores of the MOF and become base-paired with Ade. The Ade-Thy pair binding at 40-45% loading reveals that Thy molecules are packed within the channels in a way that fulfill both the Woodward-Hoffmann and Schmidt rules, and upon UV irradiation, Thy molecules dimerize into Thy<>Thy. This study highlights the utility of accessible functional groups within the pores of MOFs, and their ability to 'lock' molecules in specific positions that can be subsequently dimerized upon light irradiation, extending the use of MOFs as nanoreactors for the synthesis of molecules that are otherwise challenging to isolate.

2.
Chem Commun (Camb) ; 54(61): 8506-8509, 2018 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-30003213

RESUMO

We report a one-pot emulsion-templating strategy for the preparation of ZIF-8 microcapsules both in the presence and absence of surfactants. Capsule diameter is tuneable in the range 1-10 µm, and they can be post-synthetically etched with excess imidazole to form hierarchical architectures resembling Oleaceae pollen grains.

3.
Acc Chem Res ; 50(6): 1423-1432, 2017 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-28489346

RESUMO

Many living organisms are capable of producing inorganic materials of precisely controlled structure and morphology. This ubiquitous process is termed biomineralization and is observed in nature from the macroscale (e.g., formation of exoskeletons) down to the nanoscale (e.g., mineral storage and transportation in proteins). Extensive research efforts have pursued replicating this chemistry with the overarching aims of synthesizing new materials of unprecedented physical properties and understanding the complex mechanisms that occur at the biological-inorganic interface. Recently, we demonstrated that a class of porous materials termed metal-organic frameworks (MOFs) can spontaneously form on protein-based hydrogels via a process analogous to natural matrix-mediated biomineralization. Subsequently, this strategy was extended to functional biomacromolecules, including proteins and DNA, which have been shown to seed and accelerate crystallization of MOFs. Alternative strategies exploit co-precipitating agents such as polymers to induce MOF particle formation thus facilitating protein encapsulation within the porous crystals. In these examples the rigid molecular architecture of the MOF was found to form a protective coating around the biomacromolecule offering improved stability to external environments that would normally lead to its degradation. In this way, the MOF shell mimics the protective function of a biomineralized exoskeleton. Other methodologies have also been explored to encapsulate enzymes within MOF structures, including the fabrication of polycrystalline hollow MOF microcapsules that preserve the original enzyme functionality over several batch reaction cycles. The potential to design MOFs of varied pore size and chemical functionality has underpinned studies describing the postsynthesis infiltration of enzymes into MOF pore networks and bioconjugation strategies for the decoration of the MOF outer surface, respectively. These methods and configurations allow for customized biocomposites. MOF biocomposites have been extended from simple proteins to complex biological systems including viruses, living yeast cells, and bacteria. Indeed, a noteworthy result was that cells encapsulated within a crystalline MOF shell remain viable after exposure to a medium containing lytic enzymes. Furthermore, the cells can adsorb nutrients (glucose) through the MOF shell but cease reproducing until the MOF casing is removed, at which point normal cellular activity is fully restored. The field of MOF biocomposites is expansive and rapidly developing toward different applied research fields including protection and delivery of biopharmaceuticals, biosensing, biocatalysis, biobanking, and cell and virus manipulation. This Account describes the current progress of MOFs toward biotechnological applications highlighting the different strategies for the preparation of biocomposites, the developmental milestones, the challenges, and the potential impact of MOFs to the field.


Assuntos
DNA/química , Estruturas Metalorgânicas/química , Proteínas/química , Hidrogéis/química , Estruturas Metalorgânicas/síntese química , Propriedades de Superfície
4.
Chem Sci ; 6(3): 1938-1943, 2015 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-28717454

RESUMO

In this contribution we report a synthetic strategy for the encapsulation of functional biomolecules within MOF-based microcapsules. We employ an agarose hydrogel droplet Pickering-stabilised by UiO-66 and magnetite nanoparticles as a template around which to deposit a hierarchically structured ZIF-8 shell. The resulting microcapsules are robust, highly microporous and readily attracted to a magnet, where the hydrogel core provides a facile means to encapsulate enzymes for recyclable size-selective biocatalysis.

5.
Chem Commun (Camb) ; 50(97): 15453-6, 2014 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-25352373

RESUMO

We describe the direct post-synthetic hydroxylation of UiO-66 through the photogeneration of hydroxyl radicals. Three approaches have been investigated, and levels of conversion up to 77% have been observed within 48 h.

6.
Chem Soc Rev ; 43(16): 5431-43, 2014 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-24811778

RESUMO

This tutorial review summarises recent advances in the direct supramolecular templating of metal-organic frameworks (MOFs) with hierarchical porosity across the micro- and mesoporous regimes. These are set against the important synthetic considerations that need to be addressed to ensure that strong interactions between the MOF precursors and a stable template assembly allow the highest chance of success. The article is grouped by template type and each category is illustrated with key examples and, where reported, an evaluation of their enhanced properties arising from the hierarchical structuring of the porous networks.

7.
Angew Chem Int Ed Engl ; 53(15): 4001-5, 2014 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-24604879

RESUMO

Herein, bipolar electrochemistry is applied in a straightforward way to the site-selective in situ synthesis of metal-organic framework (MOF) structures, which have attracted tremendous interest in recent years because of their significant application potential, ranging from sensing to gas storage and catalysis. The novelty of the presented work is that the deposit can be intentionally confined to a defined area of a substrate without using masks or templates. The intrinsic site-selectivity of bipolar electrochemistry makes it a method of choice to generate, in a highly controlled way, hybrid particles that may have different functionalities combined on the same particle. The wireless nature of electrodeposition allows the potential for mass production of such Janus-type objects.


Assuntos
Metais/química , Compostos Organometálicos/química , Catálise , Eletroquímica , Modelos Moleculares , Estrutura Molecular
8.
Chem Commun (Camb) ; 50(36): 4711-3, 2014 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-24675992

RESUMO

We report for the first time the pH-dependent fluorescence of UiO-66-NH2 across the wide range from 1 to 9. By application of a post-synthetic modification (PSM) diazotisation strategy, we synthesized a new material, UiO-66-N=N-ind, which shows increased chemical stability and enhanced sensing up to pH 12.


Assuntos
Coloides/química , Corantes Fluorescentes/química , Água/química , Zircônio/química , Concentração de Íons de Hidrogênio
9.
Adv Mater ; 25(19): 2717-22, 2013 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-23554180

RESUMO

Hollow composite microcapsules are prepared by the assembly of pre-formed nanocrystals of metal-organic frameworks (MOFs) around emulsion droplets, followed by interfacial polymerisation of the interior. The micropores of the MOF crystals embedded within a semipermeable hierarchically structured polymeric membrane are an effective combination for the retention of encapsulated dye molecules. Release can be triggered however by acid dissolution of the MOF component.


Assuntos
Cápsulas/síntese química , Corantes/química , Cristalização/métodos , Emulsões/química , Metais/química , Nanotecnologia/métodos , Polímeros/química , Teste de Materiais
10.
J Am Chem Soc ; 134(50): 20466-78, 2012 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-23121122

RESUMO

The reaction between Zn and a pyrene-based ligand decorated with benzoate fragments (H(4)TBAPy) yields a 2D layered porous network with the metal coordination based on a paddlewheel motif. Upon desolvation, the structure undergoes a significant and reversible structural adjustment with a corresponding reduction in crystallinity. The combination of computationally assisted structure determination and experimental data analysis of the desolvated phase revealed a structural change in the metal coordination geometry from square-pyramidal to tetrahedral. Simulations of desolvation showed that the local distortion of the ligand geometry followed by the rotation and displacement of the pyrene core permits the breakup of the metal-paddlewheel motifs and the formation of 1D Zn-O chains that cross-link adjacent layers, resulting in a dimensionality change from the 2D layered structure to a 3D structure. Constrained Rietveld refinement of the powder X-ray diffraction pattern of the desolvated phase and the use of other analytical techniques such as porosity measurements, (13)C CP MAS NMR spectroscopy, and fluorescence spectroscopy strongly supported the observed structural transformation. The 3D network is stable up to 425 °C and is permanently porous to CO(2) with an apparent BET surface area of 523(8) m(2)/g (p/p° = 0.02-0.22). Because of the hydrophobic nature, size, and shape of the pores of the 3D framework, the adsorption behavior of the structure toward p-xylene and m-xylene was studied, and the results indicated that the shape of the isotherm and the kinetics of the adsorption process are determined mainly by the shape of the xylene isomers, with each xylene isomer interacting with the host framework in a different manner.


Assuntos
Compostos Orgânicos/química , Zinco/química , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Espectrometria de Fluorescência
11.
Chem Soc Rev ; 41(6): 2344-81, 2012 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-22182916

RESUMO

Porous metal-organic frameworks (MOFs) are highly ordered crystalline materials prepared by the self-assembly of metal ions with organic linkers to yield low density network structures of diverse topology. MOFs have attracted considerable attention over the last decade due to their facile preparation, tunable pore metrics and the ease of functionalisation of their internal surfaces, such that designer frameworks with exceptional properties for application in gas-storage, separation of small molecules, heterogeneous catalysis and drug delivery are becoming commonplace. For any material to find practical utility however, there is a need for processing and formulation into application-specific configurations. One way to do this is to prepare composite materials where the MOF is supported on a planar substrate or some other shaped body through interaction with functional groups at the support interface. This is a rapidly developing research area, and this review provides an overview of the diverse MOF composite materials prepared up to now, organised by interface type. The importance of the interface is explored within each section and while the overall emphasis is on applications of the composites, coatings and MOF-based devices, the most widely-used and successful synthetic strategies for composite formation are also presented. (183 references).


Assuntos
Membranas Artificiais , Compostos Organometálicos/química , Compostos Organometálicos/síntese química , Tamanho da Partícula , Porosidade , Propriedades de Superfície
12.
Chem Commun (Camb) ; 47(12): 3389-91, 2011 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-21331397

RESUMO

The coordination of adenine to Ni(2+) forms a dimer unit which can be linked by 3,5-pyrazoledicarboxylic acid into chains which assemble under hydrothermal conditions via hydrogen bonding into a robust porous network. The material displays selectivity for CO(2) over CH(4) and an isosteric heat which increases with guest loading.

13.
J Am Chem Soc ; 132(12): 4119-30, 2010 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-20201518

RESUMO

The carboxylate ligand 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy)-based on the strongly fluorescent long-lifetime pyrene core-affords a permanently microporous fluorescent metal-organic framework, [In(2)(OH)(2)(TBAPy)].(guests) (1), displaying 54% total accessible volume and excellent thermal stability. Fluorescence studies reveal that both 1 and TBAPy display strong emission bands at 471 and 529 nm, respectively, upon excitation at 390 nm, with framework coordination of the TBAPy ligands significantly increasing the emission lifetime from 0.089 to 0.110 ms. Upon desolvation, the emission band for the framework is shifted to lower energy: however, upon re-exposure to DMF the as-made material is regenerated with reversible fluorescence behavior. Together with the lifetime, the emission intensity is strongly enhanced by spatial separation of the optically active ligand molecules within the MOF structure and is found to be dependent on the amount and chemical nature of the guest species in the pores. The quantum yield of the material is found to be 6.7% and, coupled with the fluorescence lifetime on the millisecond time scale, begins to approach the values observed for Eu(III)-cryptate-derived commercial sensors.

14.
Nat Mater ; 8(12): 973-8, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19855385

RESUMO

Porous materials are important in a wide range of applications including molecular separations and catalysis. We demonstrate that covalently bonded organic cages can assemble into crystalline microporous materials. The porosity is prefabricated and intrinsic to the molecular cage structure, as opposed to being formed by non-covalent self-assembly of non-porous sub-units. The three-dimensional connectivity between the cage windows is controlled by varying the chemical functionality such that either non-porous or permanently porous assemblies can be produced. Surface areas and gas uptakes for the latter exceed comparable molecular solids. One of the cages can be converted by recrystallization to produce either porous or non-porous polymorphs with apparent Brunauer-Emmett-Teller surface areas of 550 and 23 m2 g(-1), respectively. These results suggest design principles for responsive porous organic solids and for the modular construction of extended materials from prefabricated molecular pores.

15.
Chemistry ; 14(15): 4521-32, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18381717

RESUMO

Substitution of the pillaring ligand in the homochiral open-framework [Ni(2)(L-asp)(2)(bipy)] by extended bipy-type ligands leads to a family of layer-structured, homochiral metal-organic frameworks. The 1D channel topology can be modified by the nature of the organic linker, with shape, cross-section and the chemical functionality tuneable. In addition, the volume of these channels can be increased by up to 36 % compared to the parent [Ni(2)(L-asp)(2)(bipy)]. The linker 1,4-dipyridylbenzene (3rbp) gives access to a new layered homochiral framework [Ni(2)(L-asp)(2)(3rbp)] with channels of a different shape. In specific cases, non-porous analogues with the linker also present as a guest can be activated to give porous materials after sublimation. Their CO(2) uptake shows an increase of up to 30 % with respect to the parent [Ni(2)(L-asp)(2)(bipy)] framework.


Assuntos
Ácido Aspártico/química , Nanoestruturas/química , Compostos Organometálicos/química , 2,2'-Dipiridil/química , Ligantes , Modelos Moleculares , Estrutura Molecular , Níquel/química , Transição de Fase , Porosidade , Difração de Pó , Propriedades de Superfície
17.
Science ; 315(5814): 977-80, 2007 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-17303750

RESUMO

We report a synthetic material, [Co2(bipy)3(SO4)2(H2O)2](bipy) (CH3OH), (1, where bipy = 4,4'-bipyridyl) that contains discrete reactive and inert structural motifs that undergo a reversible substitution reaction involving the concerted and spatially controlled introduction of bipyridine and methanol molecules at the reactive sites. This reaction defines the pore geometry of the resulting open-framework structure and controls the manner in which this structure sorbs small molecules. The molecules involved in the reaction are positioned by an array of well-defined interactions during their path to binding to the metal centers.

19.
Chem Commun (Camb) ; (25): 2670-2, 2006 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-16786082

RESUMO

A microporous hypercrosslinked polymer resin was synthesized and shown to adsorb 3.04 wt.% hydrogen at 77 K and 15 bar; this represents the highest level of hydrogen adsorption yet observed for an organic polymer.

20.
Science ; 306(5698): 1012-5, 2004 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-15486255

RESUMO

Adsorption and desorption of hydrogen from nanoporous materials, such as activated carbon, is usually fully reversible. We have prepared nanoporous metal-organic framework materials with flexible linkers in which the pore openings, as characterized in the static structures, appear to be too small to allow H2 to pass. We observe hysteresis in their adsorption and desorption kinetics above the supercritical temperature of H2 that reflects the dynamical opening of the "windows" between pores. This behavior would allow H2 to be adsorbed at high pressures but stored at lower pressures.

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