Room Temperature Magnetic Switchability Assisted by Hysteretic Valence Tautomerism in a Layered Two-Dimensional Manganese Radical Coordination Framework
Room Temperature Magnetic Switchability Assisted by Hysteretic Valence Tautomerism in a Layered Two-Dimensional Manganese Radical Coordination Framework
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DOI：
10.1021/jacs.6b10544
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发表时间：
2016-12-21
影响因子：
15
通讯作者：
Luneau, Dominique
中科院分区：
文献类型：
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作者：
Lannes, Anthony;Suffren, Yan;Luneau, Dominique
锰-硝酰基-氮氧二维配位聚合物{[Mn-2（NITIm）（3）] ClO 4}（n）（1）（NITImH = 2-（2-咪唑基）-4，4，5，5-四甲基-4，5-二氢-1H-3-氧化物-1-氧基）在室温附近经历不寻常的滞后热诱导价态互变异构转变，在此期间锰（II）离子被氧化成锰（III），三个去质子化的自由基中的两个（NITIm（-））被还原成它们的抗磁性氨基氧基形式（表示为NITRed 2-）。在冷却时，高温物质{[Mn-2（II）（NITIm）（3）] ClO 4}，（1（HT））在约274 K转变为低温物质{[Mn-2（III）（NITRed）（2）（NITIM）] ClO 4}（n）（1（LT）），而在加热时，该过程在约287 K反转。这种价态互变异构现象得到了温度依赖性磁化率测量、差示扫描量热法（DSC）、晶体结构测定、紫外-可见吸收、X射线吸收（XAS）和发射（XES）以及固态电子顺磁共振（EPR）光谱的支持。
The manganese-nitronyl-nitroxide two-dimensional coordination polymer {[Mn-2(NITIm)(3)]ClO4}(n) (1) (NITImH = 2-(2-imidazoly1)-4,4,5,5-tetramethyl-4,5-dihydro-1H-3-oxide-1-oxyl) undergoes an unusual hysteretic thermo-induced valence tautomeric transition near room temperature, during which the manganese(II) ions are oxidized to manganese(III) and two of the three deprotonated radicals (NITIm(-)) are reduced to their diamagnetic aminoxyl form (denoted NITRed2-). Upon cooling, the high temperature species {[Mn-2(II)(NITIm)(3)]ClO4}, (1(HT)) turns into the low-temperature species {[Mn-2(III)(NITRed)(2)(NITIM)] ClO4}(n) (1(LT)) around 274 K, while on heating the process is reversed at about 287 K. This valence tautomeric phenomenon is supported by temperature-dependent magnetic susceptibility measurements, differential scanning calorimetry (DSC), crystal structure determination, UV-vis absorption, X-ray absorption (XAS), and emission (XES) and electron paramagnetic resonance (EPR) spectroscopies in the solid state.