Florencia Di Salvo

Tetrachlorocarbonyliridates: water-soluble carbon monoxide releasing molecules rate-modulated by the sixth ligand.

A new family of compounds is presented as potential carbon monoxide releasing molecules (CORMs). These compounds, based on tetrachlorocarbonyliridate(III) derivatives, were synthesized and fully characterized by X-ray diffraction, electrospray mass spectrometry, IR, NMR, and density functional theory calculations. The rate of CO release was studied via the myoglobin assay. The results showed that the rate depends on the nature of the sixth ligand, trans to CO, and that a significant modulation on the release rate can be produced by changing the ligand. The reported compounds are soluble in aqueous media, and the rates of CO release are comparable with those for known CORMs, releasing CO at a rate of 0.03-0.58 μM min(-1) in a 10 μM solution of myoglobin and 10 μM of the complexes.

Supramolecular architectures in o-carboranyl alcohols bearing N-aromatic rings: syntheses, crystal structures and melting points correlation

The syntheses of new o-carboranyl alcohols bearing N-aromatic rings, 1-[R(hydroxy)methyl]-2-methyl-1,2-dicarba-closo-dodecaborane (R = 6-methyl-2-pyridyl 1b, 3-pyridyl 1c, 2-quinolyl 1e, 4-quinolyl 1f), 1-[R(hydroxy)methyl]-1,2-dicarba-closo-dodecaborane (R = 2-pyridyl 2a, 6-methyl-2-pyridyl 2b, 3-pyridyl 2c, 4-pyridyl 2d, 2-quinolyl 2e, 4-quinolyl 2f)), are reported. The crystal structures of all compounds, except that for 1b, are reported and compared with those related compounds previously synthesized by us (1-[R(hydroxy)methyl]-2-methyl-1,2-dicarba-closo-dodecaborane (R = 2-pyridyl 1a, 4-pyridyl 1d)). We provide an analysis of these compounds by means of X-ray crystallography, NMR/IR spectroscopies, thermal analyses and gas phase calculations in the context of crystal engineering. The results show that the crystal packings of these alcohols are dominated by the supramolecular O–H⋯N heterosynthon, but also include other weaker interactions such as C–H⋯O hydrogen bonds, H⋯H contacts and some degree of (C/B)–H⋯π interactions. There are four types of O–H⋯N hydrogen bonded chains, two giving rise to high melting point compounds (1c, 1d, 1f, 2c, 2d, and 2f) and two affording lower melting point compounds (1a, 2a and 2b). The lowest melting compounds (1e and 2e) show no such infinite O–H⋯N hydrogen bonding networks and only intramolecular O–H⋯N hydrogen bonds. We correlate the presence of the infinite O–H⋯N hydrogen bonding network in the crystal structure for the pyridine derivatives with their melting points. Gas phase calculations show that the energy for the O–H⋯N interactions in hydrogen bonded dimers is in the range 4–8 kcal mol−1.

A Racemic and Enantiopure Unsymmetric Diiron(III) Complex with a Chiral o‐Carborane‐Based Pyridylalcohol Ligand: Combined Chiroptical, Magnetic, and Nonlinear Optical Properties

The design of molecule-based systems combining magnetic, chiroptical and second-order optical nonlinear properties is still very rare. We report an unusually unsymmetric diiron(III) complex 1, in which three bulky chiral carboranylpyridinealkoxide ligands (oCBhmp(-)) bridge both metal ions and the complex shows the above-mentioned properties. The introduction of o-carborane into the 2-(hydroxymethyl)pyridine (hmpH) architecture significantly alters the coordination of the simple or aryl-substituted 2-hmpH. The unusual architecture observed in 1 seems to be triggered by the poor nucleophilicity of our alkoxide ligand (oCBhmp(-)). A very rare case of spontaneous resolution takes place on precipitation or exposure to solvent vapor for the bulk compound, as confirmed by a combination of single-crystal and powder X-ray diffraction, second-harmonic generation, and circular dichroism. The corresponding enantiopure complexes (+)1 and (-)1 have also been synthesized and fully characterized. This research provides a new building block with unique geometry and electronics to construct coordination complexes with multifunctional properties.

Reaction pathways of 2,2,2-trifluoroethylamine and n-butylamine with [Ru(bpy)2(NO)Cl]2+

Abstract The reaction of [Ru(bpy)2(NO)Cl]2+ with 2,2,2-trifluoroethylamine produced [Ru(bpy)2(NO)Cl]+ by electron transfer and a number of organic compounds formed via nucleophilic substitution of the intermediate 2,2,2-trifluoroethyldiazonium ion (free or coordinated). Density functional theory computed results suggest that stabilization of the trifluoroethyldiazonium ion by complexation is much larger than the one corresponding to the butyl ion, in agreement with the fact that no rearrangement products derived from CF3CH2+ were observed.

The reaction of [Ru(bpy)2(NO)Cl]2+ and [Fe(CN)5NO]2− with benzylamine: coordinated nitrosyl as an oxidizing agent

Abstract[Fe(CN)5NO]2−, (1) and [Ru(bpy)2(NO)Cl]2+, (2) react with PhCH2NH2 to produce mainly N-benzylphenyl-methanimine and PhCN as oxidation products. (PhCH2)2NH, PhCH2Cl and PhCH2OH are formed as diazotization products. Products derived from the benzyl radical (such as PhMe), are also formed. Since oxidation products are generated even in the absence of oxygen, a mechanism in which the nitrosyl ligand acts as an oxidant is proposed.

Selenium-containing analogues of WC-9 are extremely potent inhibitors of Trypanosoma cruzi proliferation

The obligate intracellular parasite, Trypanosoma cruzi is the etiologic agent of Chagas disease or American trypanosomiasis, which is the most prevalent parasitic disease in the Americas. The present chemotherapy to control this illness is still deficient particularly in the chronic stage of the disease. The ergosterol biosynthesis pathway has received much attention as a molecular target for the development of new drugs for Chagas disease. Especially, inhibitors of the enzymatic activity of squalene synthase were shown to be effective compounds on T. cruzi proliferation in in vitro assays. In the present study we designed, synthesized and evaluated the effect of a number of isosteric analogues of WC-9 (4-phenoxyphenoxyethyl thiocyanate), a known squalene synthase inhibitor, on T. cruzi growth in tissue culture cells. The selenium-containing derivatives turned out to be extremely potent inhibitors of T. cruzi growth. Certainly, 3-phenoxyphenoxyethyl, 4-phenoxyphenoxyethyl, 4-(3-fluorophenoxy)phenoxyethyl, 3-(3-fluorophenoxy)phenoxyethyl selenocyanates and (±)-5-phenoxy-2-(selenocyanatomethyl)-2,3-dihydrobenzofuran arose as relevant members of this family of compounds, which exhibited effective ED50 values of 0.084 µM, 0.11 µM, 0.083, µM, 0.085, and 0.075 µM, respectively. The results indicate that compounds bearing the selenocyanate moiety are at least two orders of magnitude more potent than the corresponding skeleton counterpart bearing the thiocyanate group. Surprisingly, these compounds exhibited excellent selectively index values ranging from 900 to 1800 making these molecules promising candidates as antiparasitic agents.

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.

Outreach activities at the Argentinian Association of Crystallography (AACr)

Fil: Klinke, Sebastian. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Parque Centenario. Instituto de Investigaciones Bioquimicas de Buenos Aires. Fundacion Instituto Leloir. Instituto de Investigaciones Bioquimicas de Buenos Aires; Argentina

Crystal growing competition for high school students in Argentina

Fil: Di Salvo, Florencia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Quimica, Fisica de los Materiales, Medioambiente y Energia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Quimica, Fisica de los Materiales, Medioambiente y Energia; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Quimica Inorganica, Analitica y Quimica Fisica; Argentina