Mono- and binuclear chloridecomplexes of bismuth (III) with 2-aminopyrimidine cations depending on specific synthetic route
Mono- and binuclear chloridecomplexes of bismuth (III) with 2-aminopyrimidine cations depending on specific synthetic route. Trofimova T., Orlova M., Tafeenko V., Proshin A., Glazkova I., Pankratov D. //Mendeleev Communications. 2020. V.30. №2. P.202-204.
Complexes of BiIII with 2-aminopyrimidine cations with metal-to-ligand ratios of 1:3 or 2:4 (depending on reaction conditions) were synthesized and characterized by elemental analysis, 1H NMR spectroscopy, and single crystal X-ray crystallography. The possibility of conversion of the latter complex into the former one was demonstrated. The determined cytotoxicity depended on the structure of these complexes.
Developments in the antitumor therapy have resulted in active studies of transition and heavy metal compounds, which significantly improved understanding of their properties. A substantial impetus to this was given by the successful clinical administration of cisplatin and its subsequent derivatives. There is another reason for the intent attention to metals and their complexes: the design of radiopharmaceuticals of new generation. In both cases, bismuth is of extreme interest since it has demonstrated remarkable results in oncological studies, although the mechanism of action for its compounds is still unclear. Moreover, there are attractive radionuclides of bismuth. In medicine, the most popular are BiIII complexes, however they remain less explored for cytotoxicity and antitumor potential as compared with the complexes of other metals. The potent antitumor activity of some BiIII compounds has already been reported.
In the present work, two new BiIII complexes with 2-aminopyrimidine (2-AP) have been synthesized, which may be of interest for radiomedical research. Herein, their structures and features depending on the synthetic routes are reported. The chemistry of organic-inorganic hybrid bismuth compounds is currently of considerable interest also in advanced materials studies. Among hybrid tetraiodobismuthates, single and double charged cations were found in derivatives of aliphatic and aromatic heterocyclic compounds. In the case of isomeric 2-, 3- and 4-aminopyridinium cations, the increased positive charge on the amino group for 4-substituted isomer leads to the formation of stronger N–H∙∙∙I hydrogen bonds. Mixed products were formed in solutions containing simultaneously two halide ions, e.g., solid products enriched with iodine were isolated in the case of both Br– and I– ions. For chlorine and iodine pair, a compound possessing the halogen ratio of 2 : 3 was precipitated from the solution. At high pH values, partial hydrolysis of BiIII occurs with the formation of polymer cations and Bi–O–Bi bridges.
We have found that obtained bismuth complexes are low-toxic towards normal lymphocytes but more toxic towards Jurkat cell line according to the data of MTT-test. Compound 2 was an order of magnitude more cytotoxic towards leukemic cells as compared to 1 due to the higher relative concentration of contained bismuth, which is a strong cytotoxic agent.
In conclusion, we have demonstrated the dependence of structure of formed bismuth complexes on the differences in the synthetic route, which causes a change in the pH value, solubility of bismuth compounds, acid concentration and, consequently, the formation or breaking of bridging bonds.