Natural Abundance 15N NMR by Dynamic Nuclear Polarization: Fast Analysis of Binding Sites of a Novel Amine-Carboxyl-Linked Immobilized Dirhodium Catalyst
Natural Abundance 15N NMR by Dynamic Nuclear Polarization: Fast Analysis of Binding Sites of a Novel Amine-Carboxyl-Linked Immobilized Dirhodium Catalyst
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DOI：
10.1002/chem.201405043
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发表时间：
2015-02-23
影响因子：
4.3
通讯作者：
Buntkowsky, Gerd
中科院分区：
文献类型：
--
作者：
Gutmann, Torsten;Liu, Jiquan;Buntkowsky, Gerd
合成了一种新型的非均相催化剂。这种稳定的催化剂是由乙酸二聚体(Rh-2(OAc)(4))单元构建的，这些单元共价连接到胺和羧基双官能化介孔二氧化硅(SBA-15NH(2)COOH)。在催化苯乙烯和重氮乙酸乙酯(EDA)生成顺式和反式-1-乙氧基甲酰基-2-苯基环丙烷的环丙烷化反应中表现出良好的催化效果。为了表征该催化剂的结构并确认其成功的固定化，进行了异核固体核磁共振实验。动态核极化(DNP)核磁共振在分析这种新型催化剂的结合位方面具有很高的应用潜力。信号增强型C-13CP MAS和N-15CP MAS技术已被用来在快速时间尺度上检测天然丰度中不同的羧基和胺结合部位。不同结合位的实验化学移动值的解释已通过对镝模型络合物的量子化学计算得到证实。
A novel heterogeneous dirhodium catalyst has been synthesized. This stable catalyst is constructed from dirhodium acetate dimer (Rh-2(OAc)(4)) units, which are covalently linked to amine- and carboxyl-bifunctionalized mesoporous silica (SBA-15NH(2)COOH). It shows good efficiency in catalyzing the cyclopropanation reaction of styrene and ethyl diazoacetate (EDA) forming cis- and trans-1-ethoxycarbonyl-2-phenylcyclopropane. To characterize the structure of this catalyst and to confirm the successful immobilization, heteronuclear solid-state NMR experiments have been performed. The high application potential of dynamic nuclear polarization (DNP) NMR for the analysis of binding sites in this novel catalyst is demonstrated. Signal-enhanced C-13 CP MAS and N-15 CP MAS techniques have been employed to detect different carboxyl and amine binding sites in natural abundance on a fast time scale. The interpretation of the experimental chemical shift values for different binding sites has been corroborated by quantum chemical calculations on dirhodium model complexes.