Spontaneous Assembly of a Polymeric Helicate of Sodium with LVO2 Units Forming the Strand: Photoinduced Transformation into a Mixed-Valence Product

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• 作者：Subodh Kanti Dutta ; Satyabrata Samanta ; Suman Mukhopadhyay ; Pannee Burckel ; A. Alan Pinkerton ; and Muktimoy Chaudhury
• 刊名：Inorganic Chemistry
• 出版年：2002
• 出版时间：June 3, 2002
• 年：2002
• 卷：41
• 期：11
• 页码：2946 - 2952
• 全文大小：200K
• 年卷期：v.41,no.11(June 3, 2002)
• ISSN：1520-510X

文摘

The anionic cis-dioxovanadium(V) complex species LVO₂^- of a tridentate ONS ligand (H₂L) can bind sodium ionin a bis-monodentate fashion like a bridging carboxylate group. The product [LVO₂Na(H₂O)₂] (1) is a water solublepolymeric compound in which the complementary units are held together by the simultaneous use of hydrogenbonding and Coulombic interactions. Crystallographic characterization reveals that 1 is a single stranded helicatewith LVO₂^- units forming the strand which surrounds the labile sodium ions that occupy the positions on the axis.In solution of protic solvents, viz. water and methanol, 1 is quite stable as indicated by electrical conductivity and¹H NMR measurements. In aprotic solvents, viz. CH₃CN, DMF, or DMSO, however, the extended hydrogen bondednetwork in 1 breaks apart and the helical structure collapses when irradiated with visible light. The product is amixed-oxidation vanadium(IV/V) species obtained by photoinduced reduction as confirmed by EPR, time dependent¹H NMR, and electronic spectroscopy. Compound 1 is a rare example of a nonnatural helix where hydrogen bondinginteractions play a crucial role in stabilizing the single stranded polymeric structure such as that frequently observedin the biological world.