Chelation of UO 2þ 2 and Th IV by N,N 0 -bis(pyridoxylideneiminato)R (R = n-propyl, diethylamine), new dianionic Schiff bases derived from vitamin B6: Synthesis and structural features of [Th(pyr 2 pen) 2 ] (pen = 1,3-propylendiamine), [UO 2 (pyr 2 pen)(CH 3 OH)] and [UO 2 (pyr 2 dien)] Æ 2H 2 O (dien = diethylenetriamine). Searching further modelings for heavy metals damage inhibition in living beings Davi Fernando Back, Gelson Manzoni de Oliveira * , Jaqueline Pinto Vargas, Ernesto Schulz Lang, Greice Tabarelli Departamento de Quı ´mica, Laborato ´ rio de Materiais Inorga ˆnicos, Universidade Federal de Santa Marı ´a, 97105–900 Santa Maria, RS, Brazil Received 28 June 2007; received in revised form 28 September 2007; accepted 17 October 2007 Available online 30 October 2007 Abstract Th(NO 3 ) 4 Æ 5H 2 O reacts with H 2 pyr 2 pen {propylenediamine-bis(pyridoxylideneimine)}, UO 2 (NO 3 ) 2 Æ 6H 2 O reacts with H 2 pyr 2 pen and H 2 pyr 2 dien {diethylenetriamine-bis(pyridoxylideneimine)} under deprotonation of the endo hydroxyl groups of the Schiff bases rings to give the chelate complexes [Th(pyr 2 pen) 2 ](1), [UO 2 (pyr 2 pen)(CH 3 OH)] (2) and [UO 2 (pyr 2 dien)] Æ 2H 2 O(3). In 1 the thorium center is the common vertex of two square pyramids displaced on 45° to each other. In 2 and 3 the uranium atoms are the centers of distorted pentagonal bipyramides. In 2 a methanol molecule achieves the coordination number 7 of the uranium(VI) ion, in 3 the central N atom of the dien section of the ligand accomplishes the coordination polyhedra, resulting a chelate complex with remarkable higher symmetry. Some radiological factors are also discussed, correlating the knowledges of new chemical properties of uranium and thorium with the understanding of its metabolism in living beings, what, in principle, should give support for clinical studies about prevention, diagnosis and treatment of uranium, thorium and/or heavy metals poisoning. Ó 2007 Elsevier Inc. All rights reserved. Keywords: Complex chelates of uranium(VI) and thorium(IV); Bioinorganic chemistry of uranium and thorium; Metallation of biological ligands 1. Introduction 1.1. Vitamin B6 complex as chelating agents It is fairly known that the compounds deriving from the vitamin B6 complex (A), pyridoxal (PL), pyridoxamine (PM) and pyridoxine (PN) display a reasonable variety of coordination sites with different charges and hard/soft character [1], allowing the assumption of a rich coordina- tion chemistry. N CH 3 OH HO L PL: L = CHO; PM: L = CH 2 NH 2 ; PN: L = CH 2 OH A 0162-0134/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jinorgbio.2007.10.009 * Corresponding author. Tel.: +55 55 3220 8757; fax: +55 55 3220 8031. E-mail address: manzoni@quimica.ufsm.br (G. Manzoni de Oliveira). www.elsevier.com/locate/jinorgbio Available online at www.sciencedirect.com Journal of Inorganic Biochemistry 102 (2008) 666–672 JOURNAL OF Inorganic Biochemistry