Oxamato/Oxamidato-Based Multifunctional Porous Coordination Polymers

El principal objetivo de esta presente Tesis concierne el diseño y la síntesis de materiales multifuncionales, una línea de investigación de creciente interés dentro del campo de la Química de Materiales. Para llevar a cabo dicho objetivo, hemos aprovechado los avances que ha experimentado la química metalosupramolecular en los últimos años. Concretamente pretendemos hacer uso de los métodos de auto-ensamblaje programado basado en las diferentes preferencias que muestran los iones metálicos en sus entornos de coordinación y en la funcionalización de ligandos orgánicos. Para ello, hemos sintetizado ligandos derivados de grupos oxamato y oxamidato, que actuarán como moléculas de partida para la obtención de estructuras de alta dimensionalidad con diversas propiedades, siendo el control de la porosidad la más relevante. Nuestros esfuerzos se centran, por tanto, en la obtención de polímeros de coordinación porosos (PCPs) y en dotarles de propiedades físicas tales como quiralidad, adsorción y separación de gases o propiedades magnéticas, entre otras. La Tesis, a su vez, se divide en dos líneas de investigación cuyos resultados se muestran en las Partes 1 y 2. La Parte 1 se basa en el diseño de una nueva estrategia sintética para obtener materiales porosos quirales de una forma sencilla y efectiva. La aproximación consiste en el uso de metaloligandos enantiopuros que han sido sintetizados a partir de la funcionalización de aminoácidos (alanina, valina, leucina y fenilglicina) con los grupos oxamato y oxamidato. La quiralidad intrínseca de los aminoácidos se transmite de manera efectiva a sus derivados y los diferentes residuos alifáticos y aromáticos juegan un papel fundamental en el proceso de ensamblaje de las estructuras de mayor dimensionalidad. A su vez, la Parte 1 está divida en las Partes 1.A y 1.B que se centran en los derivados de oxamato y oxamidato, respectivamente. Resulta interesante que a partir de ambas familias de proligandos se obtuvieron metaloligandos quirales de estructuras complejas que dieron lugar a una amplia variedad de fascinantes redes tridimensionales quirales. En la Parte 1.A se demuestra el éxito de la estrategia del metaloligando para transmitir la quiralidad de unos sistemas a otros siendo uno de los resultados más sorprendentes y sin precedentes la obtención de un MOF quiral sintetizado a partir del auto-ensamblaje de cadenas quirales con complejos catiónicos actuando como nodos. En la Parte 1.B, de entre todas las familias de PCPs que se han obtenido, destacan especialmente los PCPs derivados de calcio(II). Esta familia representa una plataforma excelente para el estudio de cómo las propiedades de adsorción y separación de gases pueden ser moduladas basándose en la diferente funcionalización de los poros de los PCPs. De esta forma, se consiguió separar metano de otros hidrocarburos de mayor cadena carbonada. La Parte 2 consiste en el uso de algunos métodos post-sintéticos (MPSs) para insertar nuevas propiedades en materiales que ya están formados y así obtener PCPs multifuncionales. En este capítulo de la Tesis se han explorado tres aproximaciones diferentes que se muestran en las Partes 2.A, 2.B, y 2.C. Haciendo uso de un MOF aniónico poroso, cuya estructura 3D presenta contra-cationes distribuidos a lo largo de los canales, hemos llevado a cabo la sustitución de dichos cationes por otros de distinta naturaleza e investigado las propiedades físicas que los nuevos materiales así preparados pueden exhibir. De esta manera, la Parte 2.A muestra como el intercambio de los iones sodio(I) de un PCP preformado por iones litio(I) y potasio(I) da lugar a dos nuevos materiales más robustos que muestran capacidades de adsorción de gases y propiedades magnéticas mejoradas. En la Parte 2.B, hemos encapsulado de forma efectiva un complejo catiónico de hierro(III) en los poros de un PCP a través de un intercambio catiónico con los iones sodio(I). La estabilidad estructural del nuevo material se ve reforzada y las propiedades magnéticas tanto del PCP como del complejo de hierro(III) mejoran. Por último, en la Parte 2.C, llevamos a cabo el método post-sintético más exigente ya que implica el reemplazo no sólo de los contra-cationes sino también el de los iones metálicos que actúan como nodos en la red covalente del PCP. Así, conseguimos la sustitución de la totalidad de los iones magnesio(II) diamagnéticos por iones cobalto(II) y níquel(II) paramagnéticos a través de un proceso de transmetalación de monocristal a monocristal, dando lugar a dos nuevos materiales más robustos que su precursor y que no se pudieron obtener mediante síntesis directa. La obtención dos nuevos materiales que presentan un canje magnético de largo alcance a partir de un material paramagnético resulta la característica más fascinante.The main goal of this Ph.D. Thesis concerns the design and synthesis of multifunctional materials which is one of the most challenging topics for chemists and physicists working together in the multidisciplinary field of Materials Chemistry. In order to do so, we have taken advantage of the new developments of the metallosupramolecular chemistry, in particular the molecular-programmed self-assembly methods that exploit the coordination preferences of the metal ions and the versatility of the tailored ligands. In this sense, we have chosen functionalised oxamato and oxamidato derivatives to build extended architectures which can exhibit interesting features, the control of the porosity being one of them. Our efforts have been devoted to prepare porous coordination polymers (PCPs) and investigate the introduction of new physical properties such as chirality, gas sorption and separation or magnetic properties, among others. In this respect, two separated research lines have been explored whose results are shown in Parts 1 and 2. Part 1 deals with the development of a synthetic strategy to obtain chiral porous materials in an easy and effective manner. It consists of the functionalisation of enantiopure amino acids (alanine, valine, leucine and phenylglycine) whose encoded chiral information is efficiently transmitted to their derivatives and their different aliphatic residues play a non-negligible role in the self-assembling processes of the extended structures. In turn, Part 1 has been divided into Parts 1.A and 1.B, focusing on oxamate- and oxamidate-based compounds, respectively. Interestingly, both families of ligands gave rise to very different metalloligands and consequently, to a wide variety of fascinating chiral 3D frameworks which display interesting properties. In Part 1.A, we demonstrate that our metalloligand strategy represents an effective synthetic route to rationally prepare chiral PCPs, one of the unprecedented and striking result being the synthesis of a rod-like MOF from a preformed chiral 1D SBU. Among the oxamidato-derived PCPs shown in Part 1.B, we report a family of calcium(II)-derived PCPs which serves as an excellent platform to study how the gas sorption and selectivity can be tailored by tuning the electron density of the channels of the PCPs, thus achieving an easy manner to separate, for instance, methane from longer hydrocarbons in natural gas. Part 2 concerns the use of several post-synthetic methods (PSMs) to introduce new physical properties into preformed materials and thus to obtain multifunctional PCPs. In this chapter, we have explored three PSMs which are discussed in Parts 2.A, 2.B and 2.C. Taking advantage of the porous and anionic nature of the preformed PCPs and the resulting presence of counter-balancing cations within their 3D frameworks, we have performed the substitution of such cations and investigated the physical properties that the new materials show. In Part 2.A, we show how the exchange of the sodium(I) ions by lithium(I) and potassium(I) cations affords the derived PCPs which exhibit improved structural stability, gas sorption and magnetic properties. In Part 2.B, we are able to encapsulate a preformed iron(III) cationic complex within the pores of a PCP through cation exchange. This encapsulation results into interesting properties for both, the encapsulated complex and the original PCP. We go a step forward in Part 2.C and explore the substitution of not only the counter-balancing cations but also the metal ions constituting the coordination framework. Hence, we satisfactory exchange the diamagnetic magnesium(II) ions by paramagnetic cations from the first-transition row through transmetallation processes, affording two new magnetic materials which could not be prepared by direct synthesis

Zigzag Ligands for Transversal Design in Reticular Chemistry: Unveiling New Structural Opportunities for Metal–Organic Frameworks

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Protection strategies for directionally-controlled synthesis of previously inaccessible metal-organic polyhedra (MOPs) : The cases of carboxylate: The amino-functionalised Rh(ii)-MOPs

Herein we report that strategic use of protecting groups in coordination reactions enables directional inhibition that leads to synthesis of highly functionalised metal-organic polyhedra (MOPs), rather than of the extended coordination networks. Using this approach, we functionalised two new porous cuboctahedral Rh(ii)-based MOPs with 24 peripheral carboxylic acid groups or 24 peripheral amino groups

Steric hindrance in metal coordination drives the separation of pyridine regioisomers using rhodium(II)-based metal-organic polyhedra

Altres ajuts: it was also funded by the CERCA Programme/Generalitat de Catalunya.The physicochemical similarity of isomers makes their chemical separation through conventional techniques energy intensive. Herein, we report that, instead of using traditional encapsulation-driven processes, steric hindrance in metal coordination on the outer surface of Rh-based metal-organic polyhedra (Rh-MOPs) can be used to separate pyridine-based regioisomers via liquid-liquid extraction. Through molecular dynamics simulations and wet experiments, we discovered that the capacity of pyridines to coordinatively bind to Rh-MOPs is determined by the positions of the pyridine substituents relative to the pyridine nitrogen and is influenced by steric hindrance. Thus, we exploited the differential solubility of bound and non-bound pyridine regioisomers to engineer liquid-liquid self-sorting systems. As a proof of concept, we separated four different equimolecular mixtures of regioisomers, including a mixture of the industrially relevant compounds 2-chloropyridine and 3-chloropyridine, isolating highly pure compounds in all cases

Zigzag ligands for transversal design in reticular chemistry : unveiling new structural opportunities for metal-organic frameworks

Herein we describe the topological influence of zigzag ligands in the assembly of Zr(IV) metal-organic frameworks (MOFs). Through a transversal design strategy using reticular chemistry, we were able to synthesize a family of isoreticular Zr(IV)-based MOFs exhibiting the bcu - rather than the fcu - topology. Our findings underscore the value of the transversal parameter in organic ligands for dictating MOF architectures

Postsynthetic covalent and coordination functionalization of rhodium(II)-based metal-organic polyhedra

Metal-organic polyhedra (MOP) are ultrasmall (typically 1-4 nm) porous coordination cages made from the self-assembly of metal ions and organic linkers and are amenable to the chemical functionalization of its periphery; however, it has been challenging to implement postsynthetic functionalization due to their chemical instability. Herein, we report the use of coordination chemistries and covalent chemistries to postsynthetically functionalize the external surface of â‰2.5 nm stable Rh(II)-based cuboctahedra through their Rh-Rh paddlewheel units or organic linkers, respectively. We demonstrate that 12 N-donor ligands, including amino acids, can be coordinated on the periphery of Rh-MOPs. We used this reactivity to introduce new functionalities (e.g., chirality) to the MOPs and to tune their hydrophilic/hydrophobic characteristics, which allowed us to modulate their solubility in diverse solvents such as dichloromethane and water. We also demonstrate that all 24 organic linkers can be postsynthetically functionalized with esters via covalent chemistry. In addition, we anticipate that these two types of postsynthetic reactions can be combined to yield doubly functionalized Rh-MOPs, in which a total of 36 new functional molecules can be incorporated on their surfaces. Likewise, these chemistries could be synergistically combined to enable covalent functionalization of MOPs through new linkages such as ethers. We believe that both reported postsynthetic pathways can potentially be used to engineer Rh-MOPs as scaffolds for applications in delivery, sorption, and catalysis

Tuning the selectivity of light hydrocarbons in natural gas in a family of isoreticular MOFs

Purification of methane from other light hydrocarbons in natural gas is a topic of intense research due to its fundamental importance in the utilization of natural gas fields. Porous materials have emerged as excellent alternative platforms to conventional cryogenic methodologies to perform this task in a cost- and energy-efficient manner. Here we report a new family of isoreticular chiral MOFs, prepared from oxamidato ligands derived from natural amino acids L-alanine, L-valine and L-leucine, where, by increasing the length of the alkyl residue of the amino acid, the charge density of the MOF's channels can be tuned (1 > 2 > 3), decreasing the adsorption preference towards methane over light hydrocarbons thus improving this purification process. The validity of our rational design strategy has been proved by a combination of single-component adsorption isotherms, adsorption kinetics of CH4, C2H6, C3H8 and n-C4H10, and breakthrough experiments of binary CH4/C2H6 and CH4/C3H8 mixtures.This work was supported by the mineco (Spain) (Projects CTQ2013-46362-P, MAT2013-45008-P, MAT2016-81732-ERC, CTQ2016-75671-P and Excellence Unit “Maria de Maeztu” MDM-2015-0538), the Generalitat Valenciana (Spain) (Project PROMETEOII/2014/070, PROMETEOII/2014/004) and the Ministero dell’Istruzione, dell’Università e della Ricerca (Italy). T. G. and M. M. thank the Universitat de València and the mineco for predoctoral contracts. Thanks are also extended to the Ramón y Cajal Program (E. P. and E. V. R.-F. (RYC-2012-11427)). B. S. and J. G. acknowledge the financial support of the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement no. 335746, CrystEng-MOF-MMM

Особливості реалізації графічного конвеєру при візуалізації тривимірних моделей приміщень університету

В більшості систем комп‘ютерної графіки застосовується графічний конвеєр – логічна група послідовно виконуваних обчислень (етапів), які в результаті дають синтезовану сцену на екрані комп‘ютера. Серед основних – етапи геометричних перетворень та візуалізації. Результат виконання кожного з цих етапів впливає на кінцевий вигляд синтезованої сцени, тому їх коректне завершення є необхідною умовою отримання якісного зображення

Synthesis of a chiral rod-like metal–organic framework from a preformed amino acid-based hexanuclear wheel

We report the two-step synthesis of a chiral rod-like metal-organic framework (MOF). The chemical approach consists on the use of a previously prepared oxamato-based homochiral hexanuclear wheel, the ligand being a derivative of the natural amino acid l-alanine, with formula (Me4N)6{CuII6[(S)-alama])6}·10H2O (1) [where (S)-alama=(S)-N-(ethyl oxoacetate)alanine]. The anionic hexacopper(II) wheels, stabilized by the presence of templating tetramethylammonium counter-cations, disassemble in the presence of cationic square-planar [Ni(cyclam)]2+ complexes to yield, after a supramolecular reorganization process that involves axial coordination of the [Ni(cyclam)]2+ cations through the free carbonyl groups of the copper(II) moieties, a neutral chiral rod-like, three-dimensional (3D) MOF with formula [Ni(cyclam)][Cu(S)-alama]2·16H2O (2). The resulting MOF constitutes one of the few examples where such a high-nuclearity metal complex is used as precursor for the construction of rod-like MOFs.T.G. thanks the MINECO for a “Juan de la Cierva” contract. Thanks are also extended to the Ramón y Cajal Program (E.P.), the “Fondo per il finanziamento delle attività base di ricerca” (D.A.), and the “Suprograma atracció de talent-contractes postdoctorals de la Universitat de Valencia” (J.F.-S.). This work was financially supported by the MINECO (Spain) (Ministerio de Economia y Competitividad) (Project CTQ2016-75671-P) and the Ministero dell’Istruzione, dell’Universita e della Ricerca (Italy).Peer reviewe

Zigzag ligands for transversal design in reticular chemistry : unveiling new structural opportunities for metal-organic frameworks

Herein we describe the topological influence of zigzag ligands in the assembly of Zr(IV) metal-organic frameworks (MOFs). Through a transversal design strategy using reticular chemistry, we were able to synthesize a family of isoreticular Zr(IV)-based MOFs exhibiting the bcu - rather than the fcu - topology. Our findings underscore the value of the transversal parameter in organic ligands for dictating MOF architectures