New zinc(II), palladium(II) and platinum(II) complexes of DL-piperidine-2-carboxylic acid; X-ray crystal structure of trans-[Zn2([μ-Ca)2(Hpa)2Cl6] and anticancer activity of some complexes

New complexes of DL-piperidine-2-carboxylic acid (DL-H(2)pa), [Zn(Hpa)(AcO)(H2O)(2)], trans-[Zn-2(mu-Ca)(2)(-Hpa)(2)Cl-6], [M(bpy)(Hpa)]Cl and [M(pa)(PPh3)(2)] (M(II) = Pd, Pt) have been prepared and characterized on the basis of elemental analyses, molar conductivity and thermal measurements, IR, Raman, UV-Vis, NMR (H-1 and P-31) and mass spectroscopy. DL-Piperidine-2-carboxylic acids act as bidentate ligands, through the carboxyl oxygen and cyclic nitrogen atoms. The crystal structure of trans-[Zn-2(mu-Ca)(2)(Hpa)(2)- Cl-6], obtained from the addition of ZnCl2 to DL-H(2)pa in either hard tap water or presence of CaCl2, has been determined by X-ray diffraction. It crystallizes in a triclinic lattice with space group symmetry P1. The complex has two zinc atoms in tetrahedral geometry, each ligated by a carboxyl oxygen and three chlorine atoms. The other carboxyl oxygen atoms from the two Hpa(-) ligands are bridged by two calcium atoms, i.e., there are two Zn(Hpa(-))Cl-3 units bridged by two calcium atoms. The free DL-H(2)pa and its complexes, trans-[Zn-2(mu-ca)(2)(Hpa)(2)Cl-6], [Pd(bpy)(Hpa)]Cl and [M(pa)(PPh3)(2)](M(II) = Pd, Pt) have been tested against the serous ovarian cancer ascites, OV 90 cell line. (C) 2012 Elsevier B.V. All rights reserved.