Luminescent thermometer based on Eu3+/Tb3+-organic-functionalized mesoporous silica

In this work we investigate a mesoporous silica (MS) decorated with dipyridyl-pyridazine (dppz) ligands and further grafted with a mixture of Eu3+/Tb3+ ions (28.45%:71.55%), which was investigated as a potential thermometer in the 10-360K temperature range. The MS material was prepared employing a hetero Diels-Alder reaction: 3,6-di(2-pyridyl)-1,2,4,5-tetrazine was reacted with the double bonds of vinyl-silica (vSilica) followed by an oxidation procedure. We explore using the dppz-vSilica material to obtain visible emitting luminescent materials and for obtaining a luminescent thermometer when grafted with Eu3+/Tb3+ ions. For the dppz-vSilica@Eu,Tb material absolute sensitivityS(a) of 0.011K(-1) (210K) and relative sensitivityS(r) of 1.32 %K-1 (260K) were calculated showing good sensing capability of the material. Upon temperature change from 10K to 360K the emission color of the material changed gradually from yellow to red

Exploring the System Lanthanide/Succinate in the Formation of Porous Metal–Organic Frameworks: Experimental and Theoretical Study

Exploring the Ln/succinate system and the template effect in hydrothermal synthesis made it possible to obtain [La₂(Succ)₃(H₂O)₃]·2H₂O and [Ln₂(Succ)₃(H₂O)₂] where Ln = La, Pr, Nd, Sm, Eu, Gd, and Tb. The first case is a 2D network with a sql plane net topology. The 3D supramolecular network is formed by strong hydrogen bonds, which give rise to a pcu network. In the second case, a family of 3D compounds with a bnn topology could be synthesized. Both compounds can be obtained in the presence of 5-sulfosalicylate (5-SSA^3–) as a template agent, and the presence of toluene in the reaction enables formation only of [Ln₂(Succ)₃(H₂O)₂] compounds. This paper addresses a systematic synthetic and theoretical study of the formation equilibrium of the molecules reported. The influence of the template agent on the formation of porous MOFs and the luminescent behavior are addressed

Synthesis, Characterization and Structural Analysis of Two New Biguanide Complexes

This study reports on the synthesis and characterization of two new coordination compounds of the active pharmaceutical ingredient metformin and transition metals. The cobalt compound with the formula [Co(Met)3][CoCl4]Cl·3H2O is a complex salt formed by a cationic Co(III) octahedral and anionic Co(II) tetrahedral subunits. The Cu(II) complex is represented by the formula [(Cu(Met)Cl)2-μ-Cl2] and is a dimeric compound with two chloride anions acting as a bridge, forming shared-edge square pyramidal units. Both compounds were characterized by single crystal X-ray diffraction, FT-IR spectroscopy and thermal analysis

Ln-MOF pseudo-merohedral twinned crystalline family as solvent-free heterogeneous catalysts

Hydrothermally promoted assembly of the multifunctional 3,5-disulfobenzoic acid (3,5-DSB) ligand with the lanthanide series and the 1,10-phenanthroline as a secondary ligand gives rise to the formation of 2D coordination polymers. The isostructural RPF-20-Ln series, with formula [Ln(3,5-DSB)(Phen)(H 2O)]·H2O (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb), present pseudomerohedral twinned crystals. The polymeric network consists of uninodal 2D net (43·63) layers perpendicular to the [010] direction. π-π Stacking interactions between them gives rise to the tridimensional supramolecular framework. The new compounds were tested as catalysts in acid Lewis reactions. A comparative study with other lanthanide MOFs inside the systems Ln/DSB and Ln/DSB/Phen reveals some structural facts that could improve the catalytic behavior of this kind of material. © 2014 American Chemical Society.R.D. acknowledges a FPI scholarship from Spanish Ministry of Science and Innovation (MICIN) and Fondo Social Europeo from the EU. This work has been supported by the Spanish MCYT Project MAT2010-17571, Consolider-Ingenio CSD2006-2010, MAT2011-29020-C02-02, PHAMA S2009/MAT-1756 Comunidad Autónoma de Madrid.Peer Reviewe

Lanthanide Metal–Organic Frameworks: Searching for Efficient Solvent-Free Catalysts

Three Ln-based 2D metal–organic frameworks with the formula [Ln­(3,5-DSB)­(Phen)] (Ln = La, Pr, Nd; 3,5-DSB = 3,5-disulfobenzoate; Phen = 1,10-phenathroline) were hydrothermally synthesized. They belong to two 2D structural types, and their nets own different topologies. The isostructural La and Pr compounds possess a uninodal 5-connected SP 2-periodic net (6,3). The Nd compound has a binodal 3- and 6-connected kgd net. The novel compounds exhibit excellent catalytic activities toward the cyanosilylation reaction under solvent-free conditions

Ln-MOF Pseudo-Merohedral Twinned Crystalline Family as Solvent-Free Heterogeneous Catalysts

Hydrothermally promoted assembly of the multifunctional 3,5-disulfobenzoic acid (3,5-DSB) ligand with the lanthanide series and the 1,10-phenanthroline as a secondary ligand gives rise to the formation of 2D coordination polymers. The isostructural <b>RPF-20-Ln</b> series, with formula <b>[Ln­(3,5-DSB)­(Phen)­(H₂O)]·H₂O</b> (<b>Ln</b> = <b>Sm</b>,<b> Eu</b>,<b> Gd</b>,<b> Tb</b>,<b> Dy</b>,<b> Ho</b>,<b> Er</b>, and <b>Yb</b>), present pseudomerohedral twinned crystals. The polymeric network consists of uninodal 2D net (4³·6³) layers perpendicular to the [010] direction. π–π Stacking interactions between them gives rise to the tridimensional supramolecular framework. The new compounds were tested as catalysts in acid Lewis reactions. A comparative study with other lanthanide MOFs inside the systems Ln/DSB and Ln/DSB/Phen reveals some structural facts that could improve the catalytic behavior of this kind of material

Mechanochemical Synthesis of a Multicomponent Solid Form: The Case of 5‑Fluorocytosine Isoniazid Codrug

Mechanochemistry synthesis was applied to the supramolecular synthesis and green scale-up production of a 1:1 drug–drug cocrystal involving the antimetabolite prodrug 5-Fluorocytosine (5-FC) and the tuberculostatic drug Isoniazid (INH), namely, 5FC-INH. Crystalline material, also obtained by traditional slow evaporation methods, was analyzed by single-crystal X-ray diffraction (XRD). The crystal packing is stabilized by a classical N–H···N hydrogen-bond interaction between the amine moiety of 5-FC and the INH pyridine nitrogen. IR and Raman data provided spectroscopic evidence about the hydrogen atom positions, thereby confirming the neutral nature of the cocrystal. Furthermore, 5FC-INH codrug was also evaluated by a range of analytical techniques such as powder XRD and thermal (thermogravimetric analysis, differential scanning calorimetry, hot stage microscopy) analyses. A physical stability study was performed in high relative humidity conditions to verify possible 5-FC solid-state hydration and/or INH degradation. The equilibrium solubility of this codrug was compared to the anhydrous 5-FC and INH raw materials, in pH 1.2 buffer media, and it was found to be similar to that of 5-FC, a biopharmaceutics classification system class I drug. The results show that the cocrystal has superior phase stability properties against moisture when compared to the starting pharmaceutical ingredients, so it could be considered as a potential candidate for the treatment of concomitant fungal infections, tuberculosis, and cancer

Gossypitrin, A Naturally Occurring Flavonoid, Attenuates Iron-Induced Neuronal and Mitochondrial Damage

The disruption of iron homeostasis is an important factor in the loss of mitochondrial function in neural cells, leading to neurodegeneration. Here, we assessed the protective action of gossypitrin (Gos), a naturally occurring flavonoid, on iron-induced neuronal cell damage using mouse hippocampal HT-22 cells and mitochondria isolated from rat brains. Gos was able to rescue HT22 cells from the damage induced by 100 µM Fe(II)-citrate (EC50 8.6 µM). This protection was linked to the prevention of both iron-induced mitochondrial membrane potential dissipation and ATP depletion. In isolated mitochondria, Gos (50 µM) elicited an almost complete protection against iron-induced mitochondrial swelling, the loss of mitochondrial transmembrane potential and ATP depletion. Gos also prevented Fe(II)-citrate-induced mitochondrial lipid peroxidation with an IC50 value (12.45 µM) that was about nine time lower than that for the tert-butylhydroperoxide-induced oxidation. Furthermore, the flavonoid was effective in inhibiting the degradation of both 15 and 1.5 mM 2-deoxyribose. It also decreased Fe(II) concentration with time, while increasing O2 consumption rate, and impairing the reduction of Fe(III) by ascorbate. Gos–Fe(II) complexes were detected by UV-VIS and IR spectroscopies, with an apparent Gos-iron stoichiometry of 2:1. Results suggest that Gos does not generally act as a classical antioxidant, but it directly affects iron, by maintaining it in its ferric form after stimulating Fe(II) oxidation. Metal ions would therefore be unable to participate in a Fenton-type reaction and the lipid peroxidation propagation phase. Hence, Gos could be used to treat neuronal diseases associated with iron-induced oxidative stress and mitochondrial damage