Utilization of nondestructive techniques for analysis of the Martian meteorite NWA 6963 and its implications for astrobiology

Martian meteorites are excellent study materials for understanding the present and past of Mars, as they are important historical astrophysical artifacts because they possess information about Martian geological evolution and physical and chemical characteristics. In our case, we analyzed the NWA 6963 Martian meteorite classified as basaltic shergottite because of its chemical structure. A computerized microtomography (μCT) study in the NWA 6963 Martian meteorite provided us with 2D and 3D images that were extremely useful for ascertaining the internal structure of the analyzed sample and gave us the opportunity to find a crumpled material with a very peculiar structural format. In addition, it was possible to observe through the μCT that this encrusted material also has a completely different density of the meteorite. Calcium, strontium, and potassium were detected qualitatively, among others through the technique of X‐ray fluorescence.     

Synthesis and X‐ray Structural Characterization of the Polymeric Cluster Compound [Hg3(O2SePh)(SePh)5]n

Two synthetic routes to prepare [Hg₃(O₂SePh)(SePh)₅]_n and its structural characterization are presented in this paper. This compound results either from the partial oxidation of mercury phenylselenolate clusters or from a mixture of its components with defined stoichiometry. This compound was observed in almost all of our reactions as a by‐product, during the development of the synthesis of new mercury selenolate clusters. It was now characterized by single‐crystal X‐ray diffractometry, elemental analysis, and infrared spectroscopy.     

Metallation of Ligands with Biological Activity: Synthesis and X‐Ray Characterization of [UO2(PN)2(H2O)]Cl2{PN = vitamin B6 pyridoxine[2‐methyl‐3‐hydroxy‐4, 5‐bis(hydroxymethyl) pyridine]}

Chloridrate of pyridoxine (vitamin B₆) reacts with UO₂(NO₃)₂·6H₂O in acetonitril containing triethylamine to give the complex salt [UO₂(PN)₂(H₂O)]Cl₂. The structure of the novel compound was analyzed by single crystal X‐ray diffraction affording the centrosymmetric triclinic space group . In [UO₂(PN)₂(H₂O)]²⁺ two zwitterionic pyridoxine molecules complex the uranium atom in a planar manner with a water molecule achieving the coordination of a semi planar pentagon. The two uranyl oxo ligands set the axis of a distorted pentagonal bipyramide. The ability of vitamin B₆ pyridoxine to react with UO₂²⁺ allowing the chelation of one uranium atom represents a very specific model of assimilation of uranium by living beings. It could also explain the serious damages caused by heavy or radioactive metals like uranium since their complexation “in vivo” by enzymatic systems like pyridoxal phosphate‐containing enzymes would lead to a modification of the prosthetic groups of the metalloenzymes with loss of their catalytic activities.     

Synthesis and Structural Features of New Schiff Base Complexes of Mononuclear MnIV,Dinuclear CoIICoIII,and Tetranuclear CuII

2‐(((2‐Hydroxy‐3‐methoxyphenyl)methylene)amino)‐2(hydroxymethyl)‐1,3‐propanediol (LH₄, as abbreviation) reacts with MnCl₂ · 4H₂O, CoCl₂ · 6H₂O, and Cu(ClO₄)₂ · 6H₂O to give the new complexes [Mn(LH₂)₂] ( 1 ), [Co₂Cl(H₂O)(LH₂)₂] · 4H₂O ( 2 ), and [Cu₄(LH₂)₄(H₂O)₄] ( 3 ). Complex 1 is formed by the assembly of two molecules of the ligand with one manganese(IV) ion. In the mixed‐valence cobalt complex 2 there is an asymmetry between the coordination spheres of cobalt(II) and cobalt(III). In the tetramer 3 four copper(II) ions attain a distorted tetrahedral configuration surrounded by four molecules of the ligand.