Studies On The Syntheses, Structures And Bioactivity Of Rare Earth Complexes With N-(benzenesulfonyl) Glycine

The N-substituted amino acids contain peptide bonds. It has been proved that they are involved in diverse biological processes and display important biological activities. Due to the structures similarities of the N-substituted amino acids with those of the O-terminal end of peptides and proteins, the N-substituted amino acids might be expected to show similiarities with the O-terminal end of peptides and proteins in the respect of coordination behavior, thus, the metal adducts of N-substituted amino acids can act as models for metal-protein interactions. In this sense, the studies of the complexes of the metal ions with N-protected amino acids are very important to understand the biological effect of metal ions and the structure-function relationship of the protein. In this paper, a series of new binary and ternary rare earth complexes of N-(benzenesulfonyl)glycine, which have not been reported ,were synthesized in aqueous solution and characterized by elemental analysis,IR and so on. The crystal structures of the synthesized complexes have been determined by single crystal X-ray diffraction method. All the crystals of binary complexes [La2(BsGlyH)6(H2O)4]·2.65H2O(1), [Pr2(BsGlyH)6(H2O)4]·H2O(2), [Tb2(BsGlyH)6(H2O)4] (3), [Eu2(BsGlyH)6(H2O)4]·DMF(4)and [Y2(BsGlyH)6(H2O)4]·3 H2O(5) belong to triclinic system with space group of Pī, and have the structure of one dimensional poly-nuclear chain. In complexes (1), (2) and (3), the coordination number of the central metal ions is nine and the coordination geometry is a distorted tricapped trigonal prism. The neighboring two metal ions are linked by four bridging carboxylate groups from four BsGlyH-, forming a dimeric unit. Then the dimeric units are connected with each other throughbridging bidentate carboxylate groups, resulting in a polymeric chain. The chains are parallel to each other and pile up into a three-dimensional network structure by means of the intra- and intramolecular hydrogen bonds. The crystal structure of complex (4) has some similarities with those of complexes (1), (2) and (3). The coordination number of Tb3+ ion is also nine, but the coordination polyhedron is a distorted monocapped square antiprism, implying that the transition of the coordination geometry of rare earth ions from tricapped trigonal prism of nine-coordination to square antiprism of eight-coordination .In complex (5), each yttrium ion is eight-coordinated by six oxygen atoms from six caroxyl groups and two oxygen atoms from water molecules, taking a distorted square antiprismatic arrangement. The stucture of complex (5) is also a infinite one-dimensional chain by ByGlyH. Homever, The stucture in (5) is different from those in (1)～(4) in coordination modes of BsGlyH-. In complex (5), all carboxylate groups act as bridging bidentate, so each yttrium ion is invariably connected with each other through bridging bidentate carboxylate groups. In complexes (1)～(4), there are two kinds of coordination modes for the four bridging carboxylate groups in the dimeric units. One is tridentate mode and the other is bidentate mode. All the crystals of ternary complexes [La2(BsGlyH)6 (phen)2 (H2O)2]·2H2O·2C2H5OH (6), [Gd(H2O)2(phen)2(BsGlyH)2]Cl·2H2O(7)and [Er(H2O)2(phen)2(BsGlyH)2]Cl·2H2O (8) belong to triclinic system with space group of Pī. The complex (6) is a dinuclear molecule, and the central point between the two lanthanum ions is the crystallography symmetric centre. Each lanthanum ion is coordinated in a tricapped trigonal prism geometry by nitrogens of 1,10-phenanthroline, oxygen atoms of of carboxylate groups of bsglyH- and oxygen atoms of the coordinated water molecule. The complexes (7) and (8) are novel mononuclear complexes, and both have similar coordination structure. The central metal ions are eight-coordinated by four nitrogen atoms from 1,10-phenanthroline, two oxygen atoms from monodentate carboxyl and two oxygen atoms from coordinated water molecules. The coordination polydedron can be discribed as a distorted square antiprism. Due to t...