Study about quinolone antibacterial agent modifying the Keggin polyoxotungstates

Three new quinolone drug molecules modifying Keggin polyoxometalate compounds have been synthesized under hydrothermal conditions and structurally characterized. Single-crystal X-ray diffraction analysis shows that Keggin clusters modified by [Cu2(Enro)3H2O]4+ subunits result in formation of dimer {[Cu2(Enro)3H2O][SiW12O40]}2 in 1; in 2, Keggin clusters are modified by two [Cu(Norf)2]2+ subunits in the symmetrical coordinated mode, and then, discrete [Cu2(Norf)4][SiW12O40] is obtained; in 3, Keggin clusters are fused together via [Ni(Enro)2]2+ subunits giving the 1D drug-polyoxometalates (POMs) hybrid chain. Antitumor activities in vitro show that 3 exhibits good antitumor activity, while 1 and 2 and their parent SiW12 show no anti-SGC7901 or anti-SMMC7721 activities, indicating that the antitumor activities rest on differences of metal ions, differently affecting electron transfer between quinolone and POMs.