I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[18768]
Open Access
Abstract: The most widely used method to measure the transport properties of dense polymeric membranes is the time lag method in a constant volume/pressure increase instrument. Although simple and quick, this method provides only relatively superficial, averaged data of the permeability, diffusivity, and solubility of gas or vapor species in the membrane. The present manuscript discusses a more sophisticated computational method to determine the transport properties on the basis of a fit of the entire permeation curve, including the transient period. The traditional tangent method and the fitting procedure were compared for the transport of six light gases (H2, He, O2, N2, CH4, and CO2) and ethane and ethylene in mixed matrix membranes (MMM) based on Pebax®1657 and the metal–organic framework (MOF) CuII2(S,S)-hismox·5H2O. Deviations of the experimental data from the theoretical curve could be attributed to the particular MOF structure, with cavities of different sizes. The fitting procedure revealed two different effective diffusion coefficients for the same gas in the case of methane and ethylene, due to the unusual void morphology in the MOFs. The method was furthermore applied to mixed gas permeation in an innovative constant-pressure/variable-volume setup with continuous analysis of the permeate composition by an on-line mass-spectrometric residual gas analyzer. This method can provide the diffusion coefficient of individual gas species in a mixture, during mixed gas permeation experiments. Such information was previously inaccessible, and it will greatly enhance insight into the mixed gas transport in polymeric or mixed matrix membranes.
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Apr 2020
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[22411]
Abstract: A bio-metal-organic framework (bio-MOF) derived from the amino acid L-serine has been prepared in bulk form and evaluated
as sorbent for the molecular recognition and extraction of B-vitamins. The functional pores of bio-MOF exhibit high amounts of
hydroxyl groups jointly directing other supramolecular host-guest interactions thus providing the recognition of B-vitamins in
fruit juices and energy drinks. Single-crystal X-ray diffraction studies reveal the specific B-vitamin binding sites and the existence
of multiple hydrogen bonds between these target molecules and the framework. It offered unique snapshots to accomplish an
efficient capture of these solutes in complex aqueous matrices. Four B-vitamins (thiamin, nicotinic acid, nicotinamide, and
pyridoxine) were investigated. They were eluted from the sorbent with phosphate buffer at pH 7 and analyzed by HPLC with
UV detection. The sorbent was compared with commercial C18 cartridges. Following the procedure, acceptable reproducibility
(RSD values < 14%) was achieved, and the detection limits were in the range 0.4 to 1.4 ng mL−1. The method was applied to the
analysis of energy drink and juice samples and the recoveries were between 75 and 123% in spiked beverage samples.
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Mar 2020
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[18768]
Abstract: Since the advent of the first metal–organic frameworks (MOFs), we have witnessed an explosion of captivating architectures with exciting physicochemical properties and applications in a wide range of fields. This, in part, can be understood under the light of their rich host–guest chemistry and the possibility to use single-crystal X-ray diffraction (SC-XRD) as a basic characterization tool. Moreover, chemistry on preformed MOFs, applying recent developments in template-directed synthesis and postsynthetic methodologies (PSMs), has shown to be a powerful synthetic tool to (i) tailor MOFs channels of known topology via single-crystal to single-crystal (SC-SC) processes, (ii) impart higher degrees of complexity and heterogeneity within them, and most importantly, (iii) improve their capabilities toward applications with respect to the parent MOFs. However, the unique properties of MOFs have been, somehow, limited and underestimated. This is clearly reflected on the use of MOFs as chemical nanoreactors, which has been barely uncovered. In this Account, we bring together our recent advances on the construction of MOFs with appealing properties to act as chemical nanoreactors and be used to synthesize and stabilize, within their channels, catalytically active species that otherwise could be hardly accessible. First, through two relevant examples, we present the potential of the metalloligand approach to build highly robust and crystalline oxamato- and oxamidato-MOFs with tailored channels, in terms of size, charge and functionality. These are initial requisites to have a playground where we can develop and fully take advantage of singular properties of MOFs as well as visualize/understand the processes that take place within MOFs pores and somehow make structure–functionalities correlations and develop more performant MOFs nanoreactors. Then, we describe how to exploit the unique and singular features that offer each of these MOFs confined space for (i) the incorporation and stabilization of metals salts and complexes, (ii) the in situ stepwise synthesis of subnanometric metal clusters (SNMCs), and (iii) the confined-space self-assembly of supramolecular coordination complexes (SCCs), by means of PSMs and underpinned by SC-XRD. The strategy outlined here has led to unique rewards such as the highly challenging gram-scale preparation of stable and well-defined ligand-free SNMCs, exhibiting outstanding catalytic activities, and the preparation of unique SCCs, different to those assembled in solution, with enhanced stabilities, catalytic activities, recyclabilities, and selectivities. The results presented in this Accounts are just a few recent examples, but highly encouraging, of the large potential way of MOFs acting as chemical nanoreactors. More work is needed to found the boundaries and fully understand the chemistry in the confined space. In this sense, mastering the synthetic chemistry of discrete organic molecules and inorganic complexes has basically changed our way of live. Thus, achieving the same degree of control on extended hybrid networks will open new frontiers of knowledge with unforeseen possibilities. We aim to stimulate the interest of researchers working in broadly different fields to fully unleash the host–guest chemistry in MOFs as chemical nanoreactors with exclusive functional species.
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Feb 2020
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[22411]
Abstract: We report a new water-stable multivariate (MTV) Metal-Organic Framework (MOF) prepared by combining two different oxamide-based metalloligands derived from the natural amino acids L-serine and L-methionine. This unique material features hexagonal channels decorated with two types of flexible and functional “arms” (–CH2OH and –CH2CH2SCH3) capa-ble to act, synergistically, for the simultaneous and efficient removal of both inorganic (heavy metals like Hg2+, Pb2+ and Tl+) and organic (dyes such as Pyronin Y, Auramine O, Brilliant Green and Methylene Blue) contaminants and, in addi-tion, this MTV-MOF is completely reusable. Single-crystal X-ray diffraction (SCXRD) measurements allowed to solve the crystal structure of a host-guest adsorbate, containing both HgCl2 and Methylene Blue, and offered unprecedented snap-shots about this unique dual capture process. This is the very first time that a MOF can be used for the removal of all sorts of pollutants from water resources, thus opening new perspectives for this emerging type of MTV-MOFs.
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Aug 2019
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I19-Small Molecule Single Crystal Diffraction
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Jesus
Ferrando-soria
,
Antonio
Fernandez
,
Deepak
Asthana
,
Selina
Nawaz
,
Iñigo J.
Vitorica-yrezabal
,
George F. S.
Whitehead
,
Christopher A.
Muryn
,
Floriana
Tuna
,
Grigore A.
Timco
,
Neil D.
Burton
,
Richard E. P.
Winpenny
Open Access
Abstract: Molecules that are the size of small proteins are difficult to make. The most frequently examined route is via self-assembly, and one particular approach involves molecular nanocapsules, where ligands are designed that will enforce the formation of specific polyhedra of metals within the core of the structure. Here we show that this approach can be combined with mechanically interlocking molecules to produce nanocapsules that are decorated on their exterior. This could be a general route to very large molecules, and is exemplified here by the synthesis and structural characterization of a [13]rotaxane, containing 150 metal centres. Small angle X-ray scattering combined with atomistic molecular dynamics simulations demonstrate the compound is intact in solution.
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Aug 2019
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I19-Small Molecule Single Crystal Diffraction
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Marta
Mon
,
Rosaria
Bruno
,
Estefanía
Tiburcio
,
Aida
Grau-atienza
,
Antonio
Sepulveda-escribano
,
Enrique V
Ramos-fernandez
,
Alessio
Fuoco
,
Elisa
Esposito
,
Marcello
Monteleone
,
Johannes Carolus
Jansen
,
Joan
Cano
,
Jesus
Ferrando-soria
,
Donatella
Armentano
,
Emilio
Pardo
Diamond Proposal Number(s):
[18768]
Abstract: Understand/visualize the established interactions between gases and adsorbents is mandatory to implement better per-formant materials in adsorption/separation processes. Here we report the unique behavior of a rare example of a hemila-bile chiral three-dimensional metal-organic framework (MOF) with an unprecedented qtz-e-type topology, with formula CuII2(S,S)-hismox . 5H2O (1) (hismox = bis[(S)-histidine]oxalyl diamide). 1 exhibits a continuous and reversible breath-ing behavior, based on the hemilability of carboxylate groups from L-histidine. In-situ powder (PXRD) and single crystal X-ray diffraction (SCXRD) using synchrotron radiation allowed to unveil the crystal structures of 4 different host-guest adsorbates (Ar, N2, CO2 and C3H6@1), the rationalization of the breathing motion and unravel the mechanisms govern-ing the adsorption of these gases. Then, this information has been transferred to implement efficient separations of mix-tures of industrial and environmental relevance –CO2/N2, CO2/CH4 and C3H8/C3H6 using 1 in packed columns as the sta-tionary phase and dispersed in a mixed matrix membrane.
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Jul 2019
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I19-Small Molecule Single Crystal Diffraction
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Rosa
Adam
,
Marta
Mon
,
Lucas H. G.
Kalinke
,
Alejandro
Vidal-moya
,
Antonio
Fernandez
,
Richard E. P.
Winpenny
,
Antonio
Domenech-carbo
,
Antonio
Leyva-perez
,
Donatella
Armentano
,
Emilio
Pardo
,
Jesus
Ferrando-soria
Diamond Proposal Number(s):
[18768]
Abstract: Supramolecular Coordination Compounds (SCCs) represent the power of Coordination Chemistry methodologies to self-assemble discrete architectures with targeted properties. SCCs are generally synthesised in solution, with isolat-ed 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 preformed MOF (SCCs@MOF) and its post-assembly metalation to give a PdII-AuIII supramolecular assembly, crys-tallography underpinned. These SCCs@MOF catalyse the coupling of boronic acids and/or alkynes, representative multisite metallic-catalysed reactions in which traditional SCCs tend to decompose, and retain its structural integrity as consequence of the synergetic hybridization between SCCs and MOF. These results open new avenues in both the synthesis of novel SCCs and their use on heterogeneous metal-based Supramolecular Catalysis.
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Jun 2019
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I19-Small Molecule Single Crystal Diffraction
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Abstract: Here we show that a structure containing a polymeric interlocking daisy chain is obtained from the reaction of an inorganic–organic [2]rotaxane [HB{CrIII7NiII(μ-F)8(O2CtBu)16}], where B is an organic thread terminated with a bi-pyridyl unit, with an oxo-centered metal carboxylate triangle [FeIII2CoII(μ3-O)(O2CtBu)6(HO2CtBu)3].
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Feb 2019
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I19-Small Molecule Single Crystal Diffraction
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Emilio
Pardo
,
Donatella
Armentano
,
Miguel A.
Rivero–crespo
,
Marta
Mon Conejero
,
Jesus
Ferrando-soria
,
Christian W.
Lopes
,
Mercedes
Boronat
,
Antonio
Leyva–pérez
,
Avelino
Corma
,
Juan C.
Hernández–garrido
,
Miguel
López–haro
,
Jose J.
Calvino
,
Enrique V.
Ramos–fernandez
Diamond Proposal Number(s):
[16033, 18768]
Abstract: The synthesis and reactivity of single metal atoms in low–valence state bound to just water, rather than to organic ligands or surfaces, is conceptually relevant and a major experimental challenge. Here, we show a gram–scale wet synthesis of a Pt11+ complex stabilized in a confined space by a water cluster, formed by a well–defined crystallographic first water sphere and a second coordination sphere linked to a Metal–Organic Framework (MOF) through electrostatic and H–bonding interactions. The role of the water cluster is not only isolating and stabilizing the Pt atoms, but also regulating the charge of the metal and the adsorption of reactants. This is shown for the low–temperature water–gas shift reaction (WGSR: CO + H2O → CO2 + H2), where both metal coordinated and H–bonded water molecules trigger a double water attack mechanism to CO and give CO2 with both oxygen atoms coming from water. The stabilized Pt1+ single sites in confined water clusters allow performing the WGSR at temperatures as low as 50 ºC.
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Nov 2018
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[15244]
Abstract: Offsetting the impact of human activities on the biogeochemical cycle of mercury has become necessary for a sustainable planet. Herein, we report the development of a water-stable and eco-friendly metal–organic framework, which has the formula {Cu4
II[(S,S)-methox]2}.
5H2O (1), where methox is bis[(S)-methionine]oxalyl diamide. Its
features include narrow functional channels decorated with thioalkyl
chains, which are able to capture HgCl2 from aqueous media in an
efficient, selective, and rapid manner. The conscious design effort in terms of size, shape, and reactivity of the channels results in extremely efficient immobilization of HgCl2 guest species in a very stable
conformation, similar to that of the enzyme mercury reductase. Thus,
1 enables the highly efficient removal of toxic HgCl2 from aqueous media and reduces the [Hg2+] concentration from the dangerous level of 10 ppm to acceptable limits of below 2 ppb in drinking water. The unusual combination of a low-cost straightforward synthetic procedure
and high stability under environmental conditions, together with its ability to efficiently and rapidly remove poisonous mercury ions, places 1 among themost attractive adsorbents reported to date for the purification of contaminated water.
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Aug 2017
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