Syntheses, Structures, and Photochemistry of Manganese Nitrosyls Derived from Designed Schiff Base Ligands: Potential NO Donors That Can Be Activated by Near-Infrared Light

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• 作者：C. Gianna Hoffman-Luca ; Aura A. Eroy-Reveles ; Jose Alvarenga ; Pradip K. Mascharak
• 刊名：Inorganic Chemistry
• 出版年：2009
• 出版时间：October 5, 2009
• 年：2009
• 卷：48
• 期：19
• 页码：9104-9111
• 全文大小：887K
• 年卷期：v.48,no.19(October 5, 2009)
• ISSN：1520-510X

文摘

Two manganese nitrosyls, namely, [Mn(SBPy₃)(NO)](ClO₄)₂ (1) and [Mn(SBPy₂Q)(NO)](ClO₄)₂ (2), have been synthesized by using designed pentadentate Schiff base ligands N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-pyridine-2-aldimine (SBPy₃) and N,N-bis(2-pyridyl methyl)amine-N-ethyl-2-quinoline-2-aldimine (SBPy₂Q). Reaction of NO(g) with [Mn(SBPy₃)(MeOH)](ClO₄)₂ and [Mn(SBPy₂Q)(EtOH)](ClO₄)₂ in MeCN affords 1 and 2, respectively, in good yields. Narrow-width peaks in the ¹H NMR spectra and strong ν_NO at 1773 cm⁻¹ (of 1) and 1759 cm⁻¹ (of 2) confirm a strongly coupled {low-spin Mn(II)-NO•}formulation for both these {Mn-NO}⁶ nitrosyls. In MeCN, 1 exhibits two strong absorption bands with λ_max at 500 and 720 nm. These bands red shift to 550 and 785 nm in case of 2 because of substitution of the pyridyl-imine moiety of SBPy₃ with quinolyl-imine moiety in the SBPy₂Q ligand frame. Exposure of solutions 1 and 2 to near-infrared (NIR) light (780 nm, 5 mW) results in rapid bleaching of the orange and fuchsia solutions, and free NO is detected in the solutions by an NO-sensitive electrode. The high quantum yield values (Φ) of 1 (0.580 ± 0.010, λ_irr = 550 nm, MeCN) and 2 (0.434 ± 0.010, λ_irr = 550 nm, MeCN) and in particular their sensitivity to NIR light of 800−950 nm range strongly suggest that these designed manganese nitrosyls could be used as NIR light-triggered NO donors.