Aliphatic Organoimido Derivatives of Polyoxometalates Containing a Bioactive Ligand

A series of aliphatic organoimido derivatives of hexamolybdate based on amantadine, namely (nBu(4)N)(2)[Mo6O18(equivalent to NC10H15)] (1), (nBu(4)N)(2) {cis-[Mo6O17(equivalent to NC10H15)(2)]} (2), (nBu(4)N)(2){trans-[Mo6O17(equivalent to NC10H15)(2)]} (3), and (nBu(4)N)(2)[Mo6O16(equivalent to NC10H15)(3)] (4), was synthesized in reasonable yield by dehydration with N, N'-dicyclohexylcarbodiimide (DCC). They were characterized by IR and UV/ Vis spectroscopy, elemental analysis, ESI mass spectrometry, and single-crystal X-ray structure analysis. The spectral and structural similarities and differences between monosubstituted, cis-disubstituted, and transdisubstituted organoimido derivatives were elucidated and may provide guidance for related work on organoimido-functionalized Lindqvist-type polyoxometalates. In addition, trans-disubstituted and polysubstituted derivatives containing aliphatic organoimido ligands have not yet been reported, and the crystal structure of the trans isomer may lead us to a deeper understanding of disubstituted derivatives. Furthermore, proliferation and morphology of MCF-7 cells were studied with compound 1. The present results show that the DCC-dehydrating protocol could be an efficient approach to covalently graft bioactive ligands such as amantadine onto POMs and enhance their application in clinical cancer treatment.