Cationic Mn2+/H+ exchange leading a slow solid-state transformation of a 2D porphyrinic network at ambient conditions

Metalloporphyrins exhibit outstanding chemical, physical and biological properties in dissolution, however, it is a challenge to synthesize them as stable solid frameworks. Long-time stability is crucial for future applications of these materials, and we have detected a slow, solid-state transformation of a 2D MnII-porphyrin at RT. The remarkable point is that this transformation showed up as a result of Electronic Paramagnetic Resonance measurements. Otherwise, the evolution of the system could have remained undetected. Thus, 2D [Mn3(TCPP)(H2O)4]•nD (1) (where TCPP is meso-tetra(4-carboxyphenyl)porphyrin and D is the sovent) has been synthesized hydrothermally, and characterised by means of X-ray diffraction (XRD), Thermogravimetry and X-ray thermodiffractometry (XRTD). This compound slowly transforms into [Mn(H4TCPP)(H2O)2]•nD (2) according to the equilibrium [Mn3(TCPP)]+4H+ ↔ [Mn(H4TCPP)]+2Mn2+. The evolution of the system has been studied through analysis of the distortion (both of the coordination sphere and the tetrapyrrolic macrocycle) and Density Functional Theory (DFT) quantum mechanical calculations.Ministerio de Economia y Competitividad (MAT2013-42092-R), Gobierno Vasco (Basque University System Research Groups, IT-630-13) and UPV/EHU (UFI11/15

Water-induced phased transformation of a CuII-coordination framework with pyridine-2,5-dicarboxylate and di-2-pyridyl ketone: synchrotron radiation analysis

Phase transformations in solid coordination frameworks (SCFs) are of interest for several applications, and this work reports on a crystal-to-crystal transformation found for a CuII-based SCF. Thus, combination of PDC and (py)2C(OH)2 ligands, where PDC is pyridine-2,5-dicarboxylate and (py)2C(OH)2 is the derivative gem-diol of di-2-pyridyl ketone ((py)2CO), produces [Cu(PDC)((py)2C(OH)2)(H2O)] (1). Compound 1 transforms into [Cu(PDC)((py)2C(OH)2)] (2) by thermally-induced loss of water. Characterization of both compounds has been carried out by means of IR spectroscopy, single crystal and powdered sample X-ray diffraction (XRD) through conventional and synchrotron radiation, thermogravimetry (TG), X-ray thermodiffractometry (TDX), and scanning electron microscopy (SEM). Since the molecules of water in 1 are coordinated to the metal ions, their removal provokes local distortions on the coordination sphere (square pyramidal for 1 and square planar for 2), which extend through the whole framework affecting the hydrogen bond system and the packing (2D for 1 and 0D for 2). In fact, the wavy nature of the planes in 1 becomes sharper in 2, producing an oscillation of the framework: i.e., open (1) and close (2) accordion. The crystal-to-crystal transformation is reversible (1↔2) and hysteresis has been observed associated to it. Quantum-mechanical calculations based on the density functional theory (DFT) show that the 1↔2 structural rearrangement involves a high amount of energy, meaning that the role of the coordinated molecule of water exceeds the mere formation of hydrogen bonds.Ministerio de Economía y Competitividad(MAT2013-42092-R), Gobierno Vasco (Basque University System Research Group, IT-630-13) and UPV/EHU (UFI 11/15) and Ministerio de Ciencia e Innovación (BES-2011-045781)

Highly thermally stable heterogeneous catalysts: study of 0D and 3D porphyrinic MOFs

Heterogeneous catalysts are a great bet for green chemistry in many industrial processes and, in the past decade, promising results have been achieved in order to improve the catalytic activity of Metal Organic Frameworks (MOFs). Accordingly, porphyrins make possible to design new coordination polymers with better properties, taking into account the important functions they develop in nature. In this sense, porphyrin-based MOFs are becoming very relevant in heterogeneous catalysis. Thus, the aim of this work was obtaining metalloporphyrinic MOFs exhibiting catalytic activity. Studying the effect of dimensionality on the MOF properties (including thermal stability and catalytic activity), in this work we study two catalysts with different dimensionalities, 3D [Ni5(H2TCPP)2O(H2O)4]•nS (1) and 0D [Cu(H4TCPP)]•6DMF (2) (where H6TCPP is meso-tetra(4-carboxyphenyl)porphyrin, DMF is N,N-dimethylformamide and S is the solvent). The structural features of both compounds, combined with their high thermal stability and accessible networks, are responsible for the excellent behaviour as heterogeneous catalysts. It is worth mentioning that significant reduction in reaction time compared to other reported catalysts has been observed. The recyclability of one of the herein studied porphyrin-based MOFs is outstanding. Further structural and thermal characterization has been carried out by means of single crystal X-ray diffraction, IR spectroscopy, thermogravimetry (TG), powder X-ray diffraction (XRD) and transmission electron microscopy (TEM).Ministerio de Economia, Industria y Competitividad (MAT2016-76739-R) Gobierno Vasco’’ (Basque University System Research Groups, IT-630-13

Characterization of cobalt based TPP-bipy coordination polymer

Comunicación a congreso: Póster presentado en The 4th EuCheMS Chemistry Congress (4ECC), Prague, Czech Republic, August 26–30, 2012Metalloporphyrin systems are one of the cornerstones on which the existence of life is based, as major biochemical, enzymatic and photochemical functions depend on the special properties of the tetrapyrrolic macrocycle. The possibility of introducing porphyrin units into MOFs (metal-organic frameworks) increases the variety of new materials based on these macrocycles. During the last years, cobalt porphyrins are well-known to be prominent catalysts for oxygen reduction reactions (ORR) and in order to obtain materials which provide new properties our research group is working with different combinations of metalloporphyrins and organic ligands. The work herein presented aims to the characterization of [CoTPP(bipy)]·[CoTPP]0.22·TPP0.78 (TPP= meso-tetraphenylporphyrin and bipy = 4,4´-bipyridine) compound in order to know the thermal, electronic and catalytic properties of these new porphyrin-based coordination polymer.Ministerio de Ciencia e Innovación (MAT2010-15375) y Gobierno Vasco (Basque University System Research Groups, IT-177-07

Self-assembly of metallated TPP porphyrin by external dipyridyl ligands

Póster presentado en: XXII International Congress and General Assembly of the International Union of Crystallography (UICr), 22–30 Agosto 2011. Madrid, EspañaSupramolecular entities based on self-assembly of metalloporphyrins are paradigmatic examples of the great efficiency of the nanodevices used by natural systems in photosynthesis, oxygen transport, electron transfer and catalysis. Therefore, they constitute reference models for the development of new materials that make these, and other yet unexplored, functions. While metalloporphyrin biosystems operate in solution, the preparation of materials based on these macrocycles moves the problem to the solid state synthesis. Thus, obtaining supramolecular entities may be approached by different strategies of synthetic design. One of them consists on the use of external dipyridyl ligands to assemble the metallated porphyrin units. In this aspect, the range of compounds that can be used is endless. In this context, our research group is working with different combinations of organic ligands and metalloporphyrins, and the work herein presented corresponds to the compound [FeTPP(bipy)] (TPP=meso-tetraphenylporphyrin and bipy=4,4´-bipyridine), obtained by solvothermal synthesis. The crystal structure of [FeTPP(bipy)] consists of 1D chains of alternating FeTPP and bipy molecules bonded to the axial positions of the coordination sphere. These chains are sustained by π-π stacking between the phenyl rings at about 5 Å. So far, very few compounds with TPP and bipy have been described, of which only one is really a 1D coordination polymer, being all others isolated dimers. It is also remarkable that, as far as we know, this is the first structure with these ligands based on Fe, one of the most important metals in porphyrin biosystems.Ministerio de Ciencia e Innovación (MAT2010-15375) and the Gobierno Vasco (Basque University System Research Groups, IT-177-07

Metalloporphyrin-based MOFs: First Cobalt Based TPPS-bipy Coordination Network

Poster presentado en el congreso: Third International Conference on Multifunctional, Hybrid and Nanomaterials (3-7 March 2013, Sorrento, Italy)Supramolecular entities based on self-assembly of metalloporphyrins are paradigmatic examples of the great efficiency of the nanodevices used by natural systems in photosynthesis, oxygen transport, electron transfer and catalysis. Thus, porphyrin catalysts are well-known to be highly efficient in many catalytic reactions and, during the last years, a great effort has been devoted to the immobilization of distinct types of catalysts on solids. In this sense, recent strategy consists of the immobilization of catalysts in MOFs (metal-organic frameworks). In our group we have started exploring the possibility of using metalloporphyrins both as structural units in MOFs and catalyst, in the same compound.Ministerio de Ciencia e Innovación (MAT2010-15375) y Gobierno Vasco (Basque University System Research Groups, IT-177-07

Crystal structure and characterization of a new μ-oxo bridged iron porphyrin

Comunicacion a congreso: Póster presentado en VIII Reunión Científica de Bioinorgánica – Bioburgos 2013 (Burgos, 7 al 10 de julio de 2013)Metalloporphyrin systems are one of the cornerstones on which the existence of life is based, as major biochemical, enzymatic and photochemical functions depend on the special properties of the tetrapyrrolic macrocycle. Supramolecular entities based on self-assembly of those macrocycles are paradigmatic examples of the great efficiency of the nanodevices used by natural systems in photosynthesis, oxygen transport, electron transfer and catalysis, and our group is working with different combinations of metalloporphyrins in order to obtain new compounds that are able to mimicking the functions of those complexes. The work herein presented aims to the characterization of [(FeTCPP)2O] (TCPP= meso-tetracarboxyphenylporphyrin) compound in order to analyse the crystal structure and thermal, spectroscopic and catalytic properties of this new porphyrin-based coordination polymer. Even if there are some other examples of μ-oxo bridged iron porphyrins, this is the first one with TCPP.Ministerio de Ciencia e Innovación (MAT2010-15375) y Gobierno Vasco (Basque University System Research Groups, IT-630-13

Synthesis and structural characterisation of [Cu2[(PDC)2(bpa)(H2O)2]•nH2O•mDMF (n=3 and m=1 for 1, n=7 and m=0 for 2, PDC=2,5-pyrindinedicarboxylate and bpa= 1,2-di(4-pyridil)ethane))

[EN] Combination of polycarboxylate anions and dipyridyl ligands is an effective strategy to produce solid coordination frameworks (SCF) which are crystalline materials based on connections between metal ions through organic ligands. In this sense, combination of polycarboxylate anions and dipyridyl ligands is an effective strategy to produce extended structures. In this context, this work is focused on two novel CuII-based SCFs exhibiting PDC (2,5-pyridinedicarboxylate) and bpa (1,2-di(4-pyridyl)ethane), being the first structures reported in literature containing both ligands. Chemical formula are [Cu2[(PDC)2(bpa)(H2O)2]•3H2O•DMF (1), and [Cu2(PDC)2(bpa)(H2O)2]•7H2O (2), where DMF is dimethylformamide. Compounds 1 and 2 have been characterized by means of XRD, IR, TG/DTG, and DTA analysis.Ministerio de Economía y Competitividad (MAT2013-42092-R, FEDER MAT2010-21342-C02-01), Gobierno Vasco (Basque University System Research Group, IT-630-13, UPV/EHU (UFI 11/15), Ministerio de Ciencia e Innovación(BES-2011-045781)

Coordination and crystallisation molecules: Their interactions affecting the dimensionality of metalloporphyrinic SCFs

Synthetic metalloporphyrin complexes are often used as analogues of natural systems, and they can be used for the preparation of new Solid Coordination Frameworks (SCFs). In this work, a series of six metalloporphyrinic compounds constructed from different meso substituted metalloporphyrins (phenyl, carboxyphenyl and sulfonatophenyl) have been structurally characterized by means of single crystal X-ray diffraction, IR spectroscopy and elemental analysis. The compounds were classified considering the dimensionality of the crystal array, referred just to coordination bonds, into 0D, 1D and 2D compounds. This way, the structural features and relationships of those crystal structures were analyzed, in order to extract conclusions not only about the dimensionality of the networks but also about possible applications of the as-obtained compounds, focusing the interest on the interactions of coordination and crystallization molecules. These interactions provide the coordination bonds and the cohesion forces which produce SCFs with different dimensionalities.Ministerio de Economia y Competitividad (MAT2013-42092-R), Gobierno Vasco (Basque University System Research Groups, IT-630-13) and UPV/EHU (UFI 11/15