Nickel(II) complexes based on L-amino-acid-derived ligands: Synthesis, characterization and study of the role of the supramolecular structure in carbon dioxide capture

The formation of the symmetrical 3-carbonate-bridged self-assembled trinuclear NiII complex Na2{[Ni(LO)2(H2O)]3(3-CO3)} (LO is the carboxylate anion of a l-tyrosine derivative), involves atmospheric CO2 uptake. The asymmetric unit of the complex comprises an octahedral coordination for the NiII with two l-tyrosine-based ligands, a water molecule and one O atom of the carbonate bridge. The Ni3–3-CO3 core in this compound is the first reported of this kind according to the Cambridge Structural Database (CSD). The supramolecular structure is mainly sustained by hydrogen bonds developed by the phenolic functionality of the l-tyrosine moiety of one ligand and the carboxylate group of a neighbouring ligand. The crystal packing is then characterized by three interpenetrated supramolecular helices associated with a diastereoisomer of the type RsupP, which is essential for the assembly process. Magnetic susceptibility and magnetization data support weak ferromagnetic exchange interactions within the novel Ni3–3-CO3 core. The NiII complex obtained under the same synthetic conditions but using the analogous ligand derived from the amino acid l-phenylalanine instead of l-tyrosine gives rise to to a mononuclear octahedral system. The results obtained for the different complexes demonstrate the role of the supramolecular structure regarding the CO2 uptake property for these NiII–amino-acid-based systems.Fil: Rivas Marquina, Andrea Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; ArgentinaFil: Movilla, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; ArgentinaFil: Sanchez Montilva, Olga Carolina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Rentschler, Eva. Universidad de Mainz; AlemaniaFil: Carrella, Luca. Universidad de Mainz; AlemaniaFil: Alborés, Pablo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Di Salvo, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentin

Amine-Derivatized l -Phenylalanine and l -Tyrosine as Versatile Self-Assembled Platforms of Diverse Supramolecular Architectures: From Mesocrystals to Organogels

Amino-acid-based systems have been specially investigated as potential functional biological or bioinspired materials. In this work, we show the remarkable ability of two small molecules based on the aryl amino acids l-tyrosine and l-phenylalanine to deliver different self-assembled structures, ranging from crystalline materials, such as single crystals and mesocrystals, to organogels. These compounds were obtained through the reaction of the amino acid with the aldehyde piperonal, resulting in not so explored derivatized systems, which conserve the carboxylic and secondary amine groups. The obtaining of each architecture is modulated by the environmental conditions, such as solvent, concentration, pH, temperature, and/or ionic strength, variables easy to control. We study the self-assembly process and features of the resultant materials using a combination of X-ray diffraction, density functional theory, small-angle X-ray scattering, and spectroscopic data. Both, in an organic solution or crystalline state, the self-assembly is governed by ionic intermolecular interactions assisted by H-bonds and, also, with the contribution of contacts involving the π-systems. As observed in related biological systems, we find that the OH function in the l-tyrosine moiety also exerts a tremendous impact over the supramolecular chemistry. In comparison with the free amino acids, the nonpolar moiety and additional short contacts provided by derivatization clearly offer new options and potential applications for more diverse environments. As a clear example, the gelation capability is tested in a crude oil sample, demonstrating a possible use in oil spill recovery.Fil: Movilla, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Rey, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Huck Iriart, Cristián. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Di Salvo, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Low molecular weight amino acid-based derivatives: from organogels to single crystals and mesocrystals

Amino acids are able to self-assemble into ordered superstructures, also called mesocrystals, when they are subjected to certain crystallisation conditions such as, pH, supersaturation level and the use of additives, being the last one the most popular strategy [1, 2]. Besides, self-assembly strategies applied to low-molecular weight building blocks can conduct to supramolecular gels. Their properties can be modulated by variation of temperature or solvent, since these changes directly affect the strength of the non-covalent interactions within the gel network [3]. The obtaining of both, supramolecular gels or crystalline materials, is governed by the presence of non-covalent interactions, resulting in spanning network that can immobilise solvents for the first ones or, the self-assembly between the building blocks, to give place to the others. Thus, there is a delicate balance for a low-weight molecule to behave as a gelator or crystal. Herein, we present a new family of chiral L-amino-acid-based low-weight molecules which behave as excellent building blocks for the construction of supramolecular gels or crystalline structures. Compounds 1-3 are obtained as zwitterions after the reaction between piperonal and L-Alanine, L-Phenylalanine and L-Tyrosine, respectively. Crystallisation experiments using organic solvents are only possible with dilute solutions of the amino acid derivatives due to their low solubility. Compounds 1 and 3 conduct mainly to polycrystalline materials and 2 gives place to crystalline superstructures with spherical morphologies, results attributed to the different solubility and supramolecular properties conferred by the amino acid bone. All derivatives are soluble in basic media after the deprotonation of the zwitterion. After a slow evaporation of the solvent of the basic solutions, spherical-like mesocrystals are obtained. Due to their structural features, compounds 1-3 are also soluble in acids. After slow diffusion of hydrogen chloride vapours in basic solutions of 2, single crystals suitable for XRD studies are obtained. The crystallographic results confirm the presence of the protonated derivative. Although 1 and 3 do not give place to crystals of suitable quality under the same conditions, experiments using other acids are in progress. In order to increase the solubility of compounds 1-3 in their zwitterionic form in organic solvents, the temperature of the solutions can be increased. Only the derivative of phenylalanine is soluble in higher concentrations after increasing the temperature and then after cooling, it gives place to supramolecular gels. The reversibility of the gelification process with temperature is also observed. In conclusion, it is possible to suggest that the presence and directionality of certain functional groups and the intermolecular interactions developed, such as the existence or not of the OH and the phenyl group, are key factors in the mechanism of self-assembly into hierarchical structures, single crystals or even supramolecular organogels. Furthermore, the strong pH dependence allows the obtaining of single crystals or the assembly to crystalline superstructures. This new family of low-molecular-mass derivatives shows a huge versatility regarding supramolecular properties. Varying the aldehyde and/or the amino acid opens a broad perspective for the design of novel self-assembly architectures for the further development of functional soft and/or crystalline materials. Rferences[1] Jiang, H. et al. (2011). Cryst. Growth Des., 11, 3243?3249, and references therein. [2] Ejgenberg, M. & Mastai, Y. (2012). Cryst. Growth Des., 12, 4995−5001. [3] Buerkle, L.E. & Rowan, S.J. (2012). Chem. Soc. Rev., 41, 6089?6102.Fil: Di Salvo, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; ArgentinaFil: Movilla, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; ArgentinaFil: Reynares, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; ArgentinaFil: Sanchez Montilva, Olga Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentin

Synthesis, crystal structure and study of the crystal packing in the complex bis(4-aminopyridine-κN1)dichloridocobalt(II)

Despite the large number of reported crystalline structures of coordination complexes bearing pyridines as ligands, the relevance of π-π interactions among these hereroaromatic systems in the stabilization of their supramolecular structures and properties is not very well documented in the recent literature. The title compound, [CoCl2(C5H6N2)2], was obtained as bright-blue crystals suitable for single-crystal X-ray diffraction analysis from the reaction of 4-aminopyridine with cobalt(II) chloride in ethanol. The new complex was fully characterized by a variety of spectroscopic techniques and single-crystal X-ray diffraction. The crystal structure showed a tetrahedral complex stabilized mainly by bidimensional motifs constructed by π-π interactions with large horizontal displacements between the 4-aminopyridine units, and N - H...Cl hydrogen bonds. Other short contacts, such as C - H...Cl interactions, complete the three-dimensional arrangement. The supramolecular investigation was extended by statistical studies using the Cambridge Structural Database and a Hirshfeld surface analysis.A new cobalt(II) pyridine-based coordination compound showing π-π interactions with large horizontal displacements between the 4-aminopyridine ligands and N - H...Cl and C - H...Cl hydrogen bonds is reported. The molecular and supramolecular structures have been studied in detail and compared with those of similar complexes found in a search of the Cambridge Structural Database. The supramolecular structure was also investigated by Hirshfeld surface analysis.Fil: Sanchez Montilva, Olga Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Movilla, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Rodriguez, Maricel Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Di Salvo, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Guanine crystal formation by bacteria

Abstract Background Guanine crystals are organic biogenic crystals found in many organisms. Due to their exceptionally high refractive index, they contribute to structural color and are responsible for the reflective effect in the skin and visual organs in animals such as fish, reptiles, and spiders. Occurrence of these crystals in animals has been known for many years, and they have also been observed in eukaryotic microorganisms, but not in prokaryotes. Results In this work, we report the discovery of extracellular crystals formed by bacteria and reveal that they are composed of guanine monohydrate. This composition differs from that of biogenic guanine crystals found in other organisms, mostly composed of β anhydrous guanine. We demonstrate the formation of these crystals by Aeromonas and other bacteria and investigate the metabolic traits related to their synthesis. In all cases studied, the presence of the bacterial guanine crystals correlates with the absence of guanine deaminase, which could lead to guanine accumulation providing the substrate for crystal formation. Conclusions Our finding of the hitherto unknown guanine crystal occurrence in prokaryotes extends the range of organisms that produce these crystals to a new domain of life. Bacteria constitute a novel and more accessible model to study the process of guanine crystal formation and assembly. This discovery opens countless chemical and biological questions, including those about the functional and adaptive significance of their production in these microorganisms. It also paves the road for the development of simple and convenient processes to obtain biogenic guanine crystals for diverse applications

Phenylalanine-Based Co²⁺ and Cd²⁺ 1D Coordination Polymers: Structural Properties and Catalytic Application for Solvent-Free Aerobic Oxidation of Cycloalkene

Two 1D coordination polymers (CPs) with general formula [M(L)(H2O)(AcO)]n, (M = Co (1) or Cd (2), AcO = acetate anion and L denotes l-phenylalanine based ligand), were synthesized and fully characterized by various spectroscopies (UV–vis, FTIR, and NMR), thermal techniques, magnetic measurements (for 1), and single-crystal and powder X-ray diffraction studies. They can be described as “ribbon-like” 1D polymers constructed through a zigzag arrangement. The polymeric structure is developed due to the coordination mode adopted by the amino acid ligand, classified as μ3-N1O1:O1:O2, which simultaneously links three metal centers. This moiety also plays an important role as a magnetic coupler between metal centers in the cobalt system, which shows a weak antiferromagnetic interaction. Both CPs have also been used in the catalytic oxidation of cyclohexene with molecular oxygen (O2) as an oxidant. Under mild conditions, both compounds demonstrated remarkable catalytic activity, with the cobalt system being more efficient than the cadmium analogue (conversion: 73 and 58% and selectivity for the major product, 2-cyclohexanone: 63 and 55%, for 1 and 2, respectively). Leaching experiments and the results obtained using a radical quencher are consistent with a radical-mediated mechanism for the Co compound. The presence of the superoxide radical was also confirmed using EPR spectroscopy and DMPO as a spin trap, which was further validated by DFT calculations. The activity observed for the Cd analogue is attributed to the organic scaffold assisted by the templating effect of the metal ion