Characterization of Calcium Bilirubinate Synthesized in Aqueous Solution

Different molar ratios of calcium chloride to sodium bilirubin were mixed to form a series of calcium bilirubinate in aqueous solution. The calcium bilirubinate was characterized by fourier transform infrared, powder X-ray diffraction, and inductively coupled plasma atomic emission spectrometry. The results showed that composition of calcium bilirubinate changed between Ca(C_(33)H_(34)N_4O_6)and Ca_(2.4)(C_(33)H_(32)N_4O_6)(H_2O)_(0.06). There were different coordination states in the complexes of calcium bilirubinate. The complexes with more calcium crystallized well in the experimental condition.