Syntheses and characterizations of polyoxometalates containing organic/inorganic hybrid materials

The research presented in this dissertation is focused on the syntheses and characterizations of novel inorganic/organic hybrid materials in which polyoxometalates (POMs) are incorporated into organic conjugated systems. These POM-containing hybrid materials were synthesized using a modular building block approach from imido functionalized Lindqvist clusters and conjugated organic molecules, and characterized by various analytical methods.; The first functionalized arylimido mixed-metal Lindqvist clusters have been synthesized directly from mixed-metal Lindqvist clusters and aromatic amines using dicyclohexylcarbodiimide (DCC) as the activation reagent. Bifunctionalized arylimido hexamolybdates have been selectively prepared from alpha-octamolybdates and aromatic amines in the presence of DCC. These functionalized POMs along with monofunctionalized arylimido hexamolybdates were used as hybrid building blocks to construct hybrid materials.; A series of hybrid dumbbells have been synthesized in good yields in which two POM clusters are connected through an organic conjugated bridge. One of the dumbbells is the first example of hybrid molecules where two different types of POM clusters are linked together through an organic bridge. Electronic interactions in the hybrid dumbbells between the dpi electrons of the clusters and the ppi electrons on the organic conjugated bridge have been investigated by electronic spectroscopy and electrochemistry. The results indicated the electron delocalization between the two clusters through the organic conjugated bridges.; A series of main-chain POM-containing hybrid polymers have been synthesized for the first time from bifunctionalized clusters, in which hexamolybdate clusters are embedded into the main-chain of poly(phenylene ethynylenes) with different conjugation lengths between two adjacent clusters. With good electron accepting ability of the POM clusters and the close interaction between organic conjugated segments and the clusters, photoinduced charge separation were expected to be efficient in this new type of hybrid polymer. A photovoltaic cell has been fabricated using one of these hybrid polymers as the active layer, which shows a respectable power conversion efficiency.; As good electron acceptors, POM clusters have been used to construct two series of multi-dipolar hybrid chromophores for second-order nonlinear optical applications. Hexamolybdates were introduced to different positions of asymmetrical 1,1'-bi-2-naphthol derivatives so that the chiral hybrid chromophores obtained would crystallize in non-centrosymmetric structures.