Copper(II) Interaction with Mono-, Bis- and Tris-Ring N3O2 Macrocycles: Synthetic, X-ray, Competitive Membrane Transport, and Hypochromic Shift Studies

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• 作者：Joobeom Seo^† ; ; Sunhong Park^† ; ; Shim Sung Lee*^† ; ; Marina Fainerman-Melnikova^‡ ; ; Leonard F. Lindoy*^‡ ;
• 刊名：Inorganic Chemistry
• 出版年：2009
• 出版时间：April 6, 2009
• 年：2009
• 卷：48
• 期：7
• 页码：2770-2779
• 全文大小：379K
• 年卷期：v.48,no.7(April 6, 2009)
• ISSN：1520-510X

文摘

New N-phenyl (L¹), azo-coupled (L²), and tri-linked (L³) substituted derivatives of a parent dibenzo-N₃O₂ macrocycle, 1,12,15-triaza-3,4:9,10-dibenzo-5,8-dioxacycloheptadecane (L⁴), have been synthesized. Competitive seven-metal transport studies across a bulk chloroform membrane employing an aqueous source phase containing equal molar concentrations of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Ag(I), and Pb(II) as their nitrate salts have been performed using both L¹ and L³ as the ionophore, with the results discussed in terms of those obtained previously for related mono-ring (L⁵) and di-linked (L⁶) macrocyclic systems. Sole transport selectivity for Cu(II) was observed in each case. On a per macrocyclic cavity basis the tri-linked analogue L³ gave less efficient Cu(II) transport than its monomeric or di-linked analogues. At least in part, this may reflect the tendency of tri-linked derivative L³ to form a 2:1 complex (metal/ligand) with Cu(II) under the conditions employed; such a stoichiometry was demonstrated to occur in acetonitrile using both spectrophotometric titration and Job plot procedures. The azo-coupled derivative (L²) yields a red solution (λ_max = 495 nm, ε_max = 23000 M⁻¹ cm⁻¹) and undergoes significant hypochromic metal-induced shifts (Δλ_max = 54−174 nm) on metal addition. Cu(II) induces the largest shift (Δλ_max = 174 nm), corresponding to a color change from red to pale-yellow. The X-ray structures of red L²·HNO₃ together with its Cu(II) complexes, [Cu(L²)NO₃]NO₃·CH₂Cl₂ (6) (pale-yellow) and [{Cu(L²)}₂(μ-OH)₂](ClO₄)₂·2CH₂Cl₂·2H₂O (7) (dark-red), are reported. The structural determinations have allowed insight into the structure−function relationships governing the observed color variation between these species.