Aliphatic organoimido derivatives of polyoxometalates containing a bioactive ligand.

A series of aliphatic organoimido derivatives of hexamolybdate based on amantadine, namely (nBu4 N)2 [Mo6 O18 (NC10 H15 )] (1), (nBu4 N)2 {cis-[Mo6 O17 (NC10 H15 )2 ]} (2), (nBu4 N)2 {trans-[Mo6 O17 (NC10 H15 )2 ]} (3), and (nBu4 N)2 [Mo6 O16 (NC10 H15 )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 trans-disubstituted 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.