Chiral Crystals of Cd(II) and Mn(II) Isostructural Complexes with Lapacholate, a Natural Pharmaceutical

O. E. PIRO; E. E. CASTELLANO; R. A. FARFÁN ; J. A. ESPÍNDOLA

Santa Fe

Congreso; VIII Reunión de la Asociación Argentina de Cristalografía (AACr); 2012

Asociación Argentina de Cristalografía (AACr)

Lapachol (LapH) is a natural pharmaceutical extracted from the wood of lapacho (Tabebuia avellanedeae) trees and other tropical plants. Since Inca's times, it is employed as a folk remedy to treat several diseases in South America. It is believed that coordination of Lap ligand to transition metals may improve its therapeutic activity. The crystal and molecular architecture of the isostructural lapacholate (Lap) complexes with cadmium and manganese ions were determined by X-ray diffraction methods. [M(Lap)2]n (M: Cd, Mn) crystallize in the tetragonal space group P43212 with Z=4 molecules per unit cell. The M(II) ion is in a distorted octahedral environment coordinated to four symmetry-related Lap ligands acting as bidentate ligands through their adjacent carbonyl and phenol oxygen atoms. The other two ligands occupy the remaining binding positions through their other, para carbonyl, oxygen atoms. This give rise to a 3-D supra-molecular arrangement of [M(Lap)2]n complexes that extends throughout the crystal lattice. The Mn complex is the chiral counterpart of a [Mn(Lap)2]n complex reported previously (S.G. P41212), a fact that suggests that the corresponding crystal samples could be racemic conglomerates generated by spontaneous resolution, a rare phenomenon first discovered by L. Pasteur in 1848.