One-Dimensional Supramolecular Organization of Single-Molecule Magnets

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• 作者：Lollita Lecren ; Wolfgang Wernsdorfer ; Yang-Guang Li ; Alessandro Vindigni ; Hitoshi Miyasaka ; Rodolphe Cl&eacute ; rac
• 刊名：Journal of the American Chemical Society
• 出版年：2007
• 出版时间：April 25, 2007
• 年：2007
• 卷：129
• 期：16
• 页码：5045 - 5051
• 全文大小：357K
• 年卷期：v.129,no.16(April 25, 2007)
• ISSN：1520-5126

文摘

An out-of-plane dimeric Mn^III quadridentate Schiff-base compound, [Mn₂(salpn)₂(H₂O)₂](ClO₄)₂(salpn^2- = N,N'-(propane)bis(salicylideneiminate)), has been synthesized and structurally characterized. The crystal structure reveals that the [Mn₂(salpn)₂(H₂O)₂]²⁺ units are linked through weak H-bonds(OH_water···O_Ph) in one dimension along the c-axis, forming supramolecular chains. The exchange interactionbetween Mn^III ions via the biphenolate bridge is ferromagnetic (J/k_B = +1.8 K), inducing an S_T = 4 groundstate. This dinuclear unit possesses uni-axial anisotropy observed in the out-of-plane direction withD_Mn2/k_B = -1.65 K. At low temperatures, this complex exhibits slow relaxation of its magnetization inagreement with a single-molecule magnet (SMM) behavior. Interestingly, the intermolecular magneticinteractions along the one-dimensional organization, albeit weak (J'/k_B = -0.03 K), influence significantlythe thermally activated and quantum dynamics of this complex. Thus, unique features such as M vs Hdata with multiple steps, hysteresis effects, and peculiar relaxation time have been explained consideringSMMs in small exchange-field perturbations and finite-size effects intrinsic to the chain arrangement. Themagnetic properties of this new complex can be regarded as an intermediate behavior between SMM andsingle-chain magnet (SCM) properties.