Ligation of the quinolone antibacterial agent pipemidic acid to Keggin polyoxotungstates

Abstract Three new drug molecules modifying Keggin polyoxometallate compounds have been synthesized under hydrothermal conditions and structurally characterized by routine techniques. Single-crystal X-ray diffraction analysis shows that compound 1 is constructed by a Keggin cluster and two [Cu(PPA) 2 ] drug complexes, formulated as [Cu(PPA) 2 ] 2 ·[PW 12 O 40 ]·6H 2 O. Compound 2 consists of a Cd substituted Keggin cluster [PW 11 CdO 39 ] and five isolated HPPA drug molecules, formulated as [HPPA] 5 ·[PW 11 CdO 39 ]·2H 2 O. Compound 3 consists of a full oxidised Keggin [PW 12 O 40 ] cluster and three isolated HPPA drug molecules, formulated as [HPPA] 3 ·[PW 12 O 40 ]·2H 2 O. Additionally, the antitumor activity of the three new compounds and their parent components in vitro were studied by a MTT experiment. The results show that introduction of TM-PPA/PPA into the polyoxoanion surface could increase their antitumor activity and make the compounds penetrate into the cells easily. Furthermore, the antitumor activity of the compounds can be modulated by their different structures.