Applications in environmental bioinorganic: Nutritional and ultrastructural evaluation and calculus of thermodynamic and structural properties of metal-oxalate complexes

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 150; pp. 750 - 757
• Main Authors: Tolentino, Terezinha Alves, Bertoli, Alexandre Carvalho, dos Santos Pires, Maíra, Carvalho, Ruy, Labory, Claudia Regina Gontijo, Nunes, Janaira Santana, Bastos, Ana Rosa Ribeiro, de Freitas, Matheus Puggina
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 05-11-2015
• Subjects: Brachiaria - metabolism; Brachiaria - ultrastructure; Calcium - metabolism; Coordination Complexes - metabolism; Lead - metabolism; Lead - toxicity; Models, Molecular; Oxalate crystals; Oxalates - metabolism; Plant Leaves - metabolism; Plant Leaves - ultrastructure; Plant Roots - metabolism; Plant Roots - ultrastructure; Raphids; Structural analysis; Thermodynamics; Raphids; Pb; Oxalate crystals; Structural analysis
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2015.06.016

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•Theoretical analysis together with the techniques of atomic absorption spectroscopy and transmission electron microscopy.•Oxalate-metal complexes (Ca2+ and Pb2+) were studied by theoretical calculations.•The thermodynamic stability of the metal complex was analyzed.
Lead (Pb) is known by its toxicity both for animals and plants. In order to evaluate its toxicity, plants of Brachiaria brizantha were cultivated on nutritive solution of Hoagland during 90days and submitted to different concentrations of Pb. The content of macro and micronutrients was evaluated and there was a reduction on root content of Ca, besides the lowest dosages of Pb had induced an increase of N, S, Mn, Cu, Zn and Fe. The cell ultrastructure of leaves and roots were analyzed by transmission electronic microscopy (TEM). Among the main alterations occurred there were invaginations on cell walls, the presence of crystals on the root cells, accumulation of material on the interior of cells and vacuolar compartmentalization. On the leaves the degradation of chloroplasts was observed, as well as the increase of vacuoles. Structures for the formation of oxalate crystals were proposed through molecular modeling and thermodynamic stability. Calculi suggest the formation of highly stable metal-oxalate complexes.