Characterization of polymeric gold(I)-captopril complex using viscosity and various spectroscopic techniques

The characterization of polymeric gold(I)-captopril (Aucap)(n) is carried out using viscosity, electronic, mass, and ¹³C, ¹⁵N NMR spectroscopy. From viscosity measurements, it is observed that the degree of association in (Aucap)(n) is much higher than in (Autm)(n). The (Aucap)(n) was further polymerized in the presence of SCN^- and SeCN^- ions; however, the CN^- ion caused the breakdown of the polymer. After a few hours of the addition of SeCN^- to (Aucap)(n) solution, SeCN^- underwent decomposition to produce CN^- and 'Se' metal which caused dissociation of the polymer. The mass spectroscopic results showed two characteristic routes of fragmentation for (Aucap)(n). Electronic spectroscopy indicated the generation of [Au(CN)₂]^- at a CN^-:(Aucap)(n) ratio ≤ 1, whereas ¹³C, ¹⁵N NMR spectroscopic studies have indicated the detection of [Au(CN)₂]^even at a 1:12 ratio of CN^-:(Aucap)(n). The ¹³C NMR is found to be sensitive to the configuration of the penultimate captopril moiety.