Bisdithiophosphonic acids and their derivatives are strong sulphur- and phosphorus-containing acids with complexing, membranotropic properties and anticipated bioactivity. These acids contain two dithiophosphoryl groups that can associate with basic compounds and metal ions to form organic salts with potential biocidal effects against pathological cells and organisms. In this work, resorcinol and 4,4'-propane-2,2-diyldiphenol were used in the reactions with Lawesson's reagent to synthesize O,O'-(benzene-1,3-diyl)-1,3-bis(4-methoxyphenyl)dithiophosphonic) and O,O'-[propane-2,2-diyl-bis(4,1-phenylene)-bis(4,4'-methoxyphenyl)dithiophosphonic) acids, respectively. The synthesized bisdithiophosphonic acids were converted into disodium and dipotassium salts as well as salts on the basis of (S)-(–)-nicotine, (8R,9S)-quinine, and (8R,9S)-quinidine. Structural characterization of the resulting compounds was carried out using ³¹Р{¹H} and FTIR spectroscopies.

Antibacterial properties of these compounds were assessed in vitro using broth microdilution method. Disodium and dipotassium bisdithiophosphonates were found to be low active against Staphylococcus aureus with minimal inhibitory concentration (MIC) of 1250 μg mL⁻¹. O,O'-(benzene-1,3-diyl)-1,3-bis(4-methoxyphenyl)dithiophosphonic) acid and its salt with (S)-(–)-nicotine showed increased antibacterial effect toward Bacillus cereus with MIC of ca. 78 μg mL⁻¹. Cytotoxicity of the compounds toward human prostate adenocarcinoma (PC-3) cells was additionally studied using resazurin assay upon 24- and 72-hour culture. The synthesized compounds decreased growth of the cancer cells with inhibitory concentrations in micromolar/submillimolar range. The results can be used for further structure evolution of bisdithiophosphonates with antibacterial and cytotoxic activities. This work was funded by the Academy of Sciences of the Republic of Tatarstan in 2024 according to the grant on conducting fundamental and applied research in scientific and educational organizations and enterprises of the real sector of the Republic of Tatarstan.