Synthetic, Structural, Spectroscopic, Electrochemical Studies and Self-assembly of Nanoscale Polyoxometalate−Organic Hybrid Molecular Dumbbells

Three rigid-rod conjugated organic−inorganic hybrid nanodumbbells (Bu4N)4[O18Mo6N(C6H4)NMo6O18] (1), (Bu4N)4[O18Mo6N(C12H8)NMo6O18] (2), and (Bu4N)4[O18Mo6N(C14H12)NMo6O18] (3) bearing terminal polyoxometalate (POM) cages, with different lengths of approximately 2−3 nm and different substituents on the rod, have been synthesized via one-pot reaction of octamolybdate and the appropriate aromatic diamine dihydrochloride with N,N′-dicyclohexylcarbodiimide (DCC) as a dehydrating agent. These complexes have been characterized with UV−vis, IR, 1H NMR, ESI mass spectrometry, cyclic voltammetry, differential pulse voltammetry, and X-ray single-crystal diffraction techniques. The influence of the rod length and substituents on properties of these complexes has been investigated. In addition, the self-assembly of these nanorods has also been explored.