Polymeric architectures of bismuth citrate based on dimeric building blocks

Abstract

Four bismuth complexes, (H2En)[Bi2(cit) 2(H2O)4/3]•(H2O) x (1), (H2En)3[Bi2(cit)2Cl 4]•(H2O) x (2), (HPy)2[Bi 2(cit)2(H2O)8/5]•(H 2O) x (3) and (H2En)[Bi2(cit) 2](H2O) x (4) [cit = citrate4-; En = ethylenediamine; Py = pyridine] have been synthesized and crystallized. The crystal structures reveal that the basic building blocks in all of these complexes are bismuth citrate dimeric units which combine to form polymeric architectures. The embedded protonated ethylenediamine and pyridine moieties in the polymeric frameworks have been identified by X-ray crystallography and solid-state cross polarization/magic angle spinning (CP/MAS) 13C NMR. Based on the framework of complex 1, a structural model of a clinically used antiulcer drug, ranitidine bismuth citrate (RBC) was generated. The behavior of the protonated amine-bismuth citrate complexes in acidic aqueous solution has been studied by electrospray ionization-mass spectrometry (ESI-MS). © 2010 Science China Press and Springer-Verlag Berlin Heidelberg.