Vinaya Siby

• This dissertation presents the synthesis of novel reduced POMs functionalized with dimethylarsinate groups. Chapter 1 introduces POMs, emphasizing polyoxomolybdates. Chapter 2 reviews organofunctionalized POMs and the rationale for this study, building on prior work with dimethylarsinate-functionalized molybdenum POMs. Chapter 3 covers experimental methods, characterization techniques, and synthesis of heterophosphonic and arsonic acid ligands. Chapter 4 describes the synthesis and characterization of eight dimethylarsinate-functionalized phosphomolybdates(V), [RPMoV6O15(OH)3{AsO2(CH3)2}3]2− (R = H, HO, CH3, HO2CCH2, HO2CC2H4, C6H5, 4-FC6H4, 4-F3COC6H4), the monoanionic mixed-valent heptamolybdate [HOMoVIMoV6O15(OH)3{AsO2(CH3)2}3]−, and d-block metal-substituted analogues [MPMoV6O15(OH)3{AsO2(CH3)2}3]2− (M = Fe2+, Ni2+, Mn2+). Chapter 5 focuses on the synthesis, structural features, and antibacterial properties of eleven dimethylarsinate-functionalized arsenomolybdates(V), [RAsMoV6O15(OH)3{AsO2(CH3)2}3]2− (R = HO, CH3, C2H5, C6H5, 3,5-(HOOC)2C6H3, 4-FC6H4, 4-F3CC6H4, 4-F3COC6H4, 4-BrC6H4 and 4-N3C6H4) and [AsIIIMoV6O15(OH)3{AsO2(CH3)2}3]3−. All compounds were synthesized in aqueous media and characterized in the solid state by single-crystal X-ray diffraction, TGA, elemental analysis, FT-IR, and PXRD, while their stability in solution and the gas phase was probed using multinuclear NMR (1H, 31P, 19F, 13C), ESI-MS, ion mobility MS, and MS/MS. Chapter 6 describes the synthesis and characterization of a novel heterometallic, dimethylarsinate-capped wheel-type POM, MoV12WVI18O84{AsO2(CH3)2}18]18− (Mo12W18), prepared under mildly acidic aqueous conditions, with alternating MoV2 and WVI3 units forming a ring with a ~1.5 nm central cavity. Its solid-state and solution behavior were probed using single-crystal XRD, IR, TGA, elemental analysis, MAS and CPMAS NMR, multinuclear solution NMR (1H, 13C, 183W, DOSY), UV-Vis, Raman spectroscopy, and SAXS.