Ligation of the quinolone antibacterial agent pipemidic acid to Keggin polyoxotungstates

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)center dot[PW12O40]center dot 6H(2)O. Compound 2 consists of a Cd substituted Keggin cluster [PW11CdO39] and five isolated HPPA drug molecules, formulated as [HPPA](5)center dot[PW11CdO39]center dot 2H(2)O. Compound 3 consists of a full oxidised Keggin[PW12O40] cluster and three isolated HPPA drug molecules, formulated as [HPPA](3)center dot[PW12O40]center dot 2H(2)O. Additionally, the antitumor activity of the three new compounds and their parent components in vitro were studied by a mu 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. (C) 2011 Elsevier Ltd. All rights reserved.