Polymeric architectures of bismuth citrate based on dimeric building blocks

Area of Science:

• Coordination Chemistry
• Materials Science
• Medicinal Chemistry

Background:

• Bismuth compounds are utilized in pharmaceuticals, particularly for treating ulcers.
• Understanding the structural diversity of bismuth complexes is crucial for drug development.

Purpose of the Study:

• To synthesize and characterize novel bismuth citrate complexes.
• To investigate the structural features and potential applications of these complexes.
• To generate a structural model for ranitidine bismuth citrate (RBC).

Main Methods:

• Single-crystal X-ray diffraction for structural determination.
• Solid-state cross polarization/magic angle spinning (CP/MAS) 13C NMR for structural identification.
• Electrospray ionization-mass spectrometry (ESI-MS) for solution behavior analysis.

Main Results:

• Four bismuth complexes, [(H2En)[Bi2(cit)2(H2O)4/3]·(H2O)], [(H2En)3[Bi2(cit)2Cl4]·(H2O)], [(HPy)2[Bi2(cit)2(H2O)8/5]·(H2O)], and [(H2En)[Bi2(cit)2](H2O)], were successfully synthesized and crystallized.
• Crystal structures revealed dimeric bismuth citrate units forming polymeric frameworks with embedded protonated ethylenediamine (En) and pyridine (Py) moieties.
• A structural model for ranitidine bismuth citrate (RBC) was generated based on the framework of complex 1.

Conclusions:

• The synthesized bismuth complexes exhibit diverse polymeric structures based on dimeric bismuth citrate units.
• The study provides valuable structural insights relevant to the antiulcer drug ranitidine bismuth citrate.
• Further investigation into the behavior of these complexes in solution is warranted.