Combined Approach of Mechanochemistry and Electron Crystallography for the Discovery of 1D and 2D Coordination Polymers

Mechanochemical synthesis is an attractive preparative method that combines a green approach with versatility, efficiency, and rapidity of reaction. However, it often yields microcrystalline materials, and their small crystal size is a major hindrance to structure elucidation with conventional single-crystal or powder X-ray diffraction methods. This work presents the novel approach of combining mechanochemistry with electron diffraction techniques to elucidate the crystal structure of metal−organic compounds of zinc(II) and copper(II) with 2,6-pyridinedicarboxylic acid and 4,4′-bipyridine

Coordination Polymers Based on the Trinuclear Triangular Secondary Building Unit [Cu3(\u3bc3-OH)(\u3bc-pz)3]2+(pz = pyrazolate) and Succinate Anion

Reaction conditions (solvent, temperature, pressure) and reagents ratios control the formation of different products from the reactions involving CuII, pyrazole (Hpz), and succinate ion (Suc). Three different coordination polymers (CPs) (one of which porous) based on the trinuclear triangular Cu3(\u3bc3-OH)(\u3bc-pz)3 secondary building unit (SBU), as well as a 1D CP based on the Cu(Hpz)2 SBU were obtained. Moreover, a 3D supramolecular network, formed through quite strong H-bonding interactions involving the mononuclear Cu(HSuc)2(Hpz)4 complex, was also synthesized when an excess of H2Suc was added

Supramolecular Isomerism in Cobalt(II) Coordination Polymers Built from 3,5-Bis(trifluoromethyl)benzoate and 4,4′-Bipyridine

The reaction of [Co2(H2O)(TFMBz)4(py)4] (1) (TFMBz: 3,5-bis(trifluoromethyl)benzoate; py: pyridine) with 4,4′-bipyridine (bpy) in different solvents yields four coordination polymers with unlikely structures but with the same stoichiometry. Three of them contain similar ladder chains consisting of binuclear nodes "Co2(TFMBz)4", in which two of the TFMBz ligands show bidentate bridge coordination, double linked to each adjacent node by bpy but packed in different fashions. The different packing affects the compound porosity; thus, [Co2(TFMBz)4(bpy)2]n(2), precipitated using low-polarity solvents such as supercritical CO2(scCO2), n-butyl acetate, or heptane and also in acetonitrile, is microporous, with a surface area of 330 m2g-1, showing the N2adsorption/desorption isotherm at 77 K with a gate-opening effect at low relative pressures (P/P0= 0.05). The isomer [Co2(TFMBz)4(bpy)2]n(3), synthesized in ethoxyethanol, presents a surface area of 230 m2g-1. A third chain packing isomer, [Co2(TFMBz)4(bpy)2]n(4), is obtained in acetone and has only non-interconnected voids. Finally, precursor 1 is combined with bpy in a highly polar solvent such as water to give [Co(TFMBz)2(bpy)]n(5). In this isomer, all the carboxylate units act as bidentate bridging ligands, generating chains that are interlinked by bpy, leading to a 2D network, which after packing yields a non-porous structure. The resolution of structures 2-5 is only possible with the recently developed 3D electron diffraction method based on the collection of diffraction patterns on sub-micron-sized single crystals. The variation of magnetic susceptibility as a function of temperature is also measured. Overall, our work provides insightful information on the complex landscape of metal-organic framework solids that are formed by crystallization using different solvent media.This work was supported by the Spanish Ministry of Science and Innovation MICINN through the Severo Ochoa Program for Centers of Excellence (CEX2019-000917-S) and the Spanish National Plan of Research with projects PID2020-115631GB-I00. F.P., A.E.L., and M.G. would like to thank Regione Toscana for funding the purchase of the ASI MEDIPIX detector through the FELIX project (POR CREO FERS 2014–2020). The measures for the elucidation of the crystal structure of compound 1 were performed at the XALOC beamline at ALBA Synchrotron with the collaboration of ALBA staff.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe

Structure determination, thermal stability and dissolution rate of δ-indomethacin

The structure solution of the δ-polymorph of indomethacin was obtained using three-dimensional electron diffraction. This form shows a significantly enhanced dissolution rate compared with the more common and better studied α- and γ-polymorphs, indicating better biopharmaceutical properties for medicinal applications. The structure was solved in non-centrosymmetric space group P21 and comprises two molecules in the asymmetric unit. Packing and molecule conformation closely resemble indomethacin methyl ester and indomethacin methanol solvate. Knowledge of the structure allowed the rational interpretation of spectroscopic IR and Raman data for δ-polymorph and a tentative interpretation for still unsolved indomethacin polymorphs. Finally, we observed a solid-solid transition from δ-polymorph to α-polymorph that can be driven by similarities in molecular conformation

Elevated expression of A3 adenosine receptors in human colorectal cancer is reflected in peripheral blood cells.

urpose: Adenosine is a ubiquitous nucleoside that accumulates at high levels in hypoxic regions of solid tumors, and A. adenosine receptors have been recently demonstrated to play a pivotal role in the adenosine-mediated inhibition of tumor cell proliferation. In the present work, we addressed the question of the putative relevance of A3 subtypes in colorectal adenocarcinomas. Experimental Design: Seventy-three paired samples of tumor and surrounding peritumoral normal mucosa at a distance of 2 and 10 cm from the tumor and blood samples obtained from a cohort of 30 patients with colorectal cancer were investigated to determine the presence of A3 receptors by means of binding, immunocytochemistry, and real-time reverse transcription-polymerase chain reaction studies. Results: As measured by receptor binding assays, the density of A3 receptor was higher in colon carcinomas as compared with normal mucosa originating from the same individuals (P < 0.05). Overexpression of A3 receptors at the protein level was confirmed by immunohistochemical studies, whereas no changes in A3 mRNA accumulation in tumors as compared with the corresponding normal tissue were revealed. The overexpression of A3 receptors in tumors was reflected in peripheral blood cells, where the density was approximately 3-fold higher compared with healthy subjects (P < 0.01). In a cohort of 10 patients studied longitudinally, expression of A3 receptors in circulating blood cells returned to normal after surgical resection for colorectal cancer. Conclusions: This study provides the first evidence that A3 receptor plays a role in colon tumorigenesis and, more importantly, can potentially be used as a diagnostic marker or a therapeutic target for colon cancer

Caratterizzazione dell'attivit\ue0 farmacologica dell'iperforina in confronto all'estratto di Hypericum perforatum

Allo scopo di chiarire il meccanismo con cui l'iperforina svolge la sua azione ansiolitica, sono stati eseguiti studi preliminari con antagonisti famcaologici che hanno suggerito un possibile coinvolgimento del sistema serotoninergico e una scarsa implicazione del sistema recettoriale benzodiazepinico