Abstract:

A two-dimensional coordination polymer [Zn(L)₂] _{n(Zn-L) was synthesized by the reaction of 1,3-bis(1-carboxyethyl) imidazolium salt (HL) and Zn(NO3)2·6H2O. The product was then reacted with K2PdCl4 in tetrahydrofuran solution to introduce nitrogen heterocyclic carbene-palladium (NHC-Pd) catalytic site to prepare the catalyst NHC-Pd@Zn-L, and the structure was characterized by PXRD, TGA, ICP, SEM, EDS and XPS. The results showed that the catalyst had high thermal stability and the framework structure of the modified Zn-L did not change, and Pd was bound in Zn-L in the form of NHC-Pd and uniformly dispersed in the coordination polymer. NHC-Pd@Zn-L was used to catalyze the Suzuki-Miyaura cross-coupling reaction. When phenylboronic acid and bromobenzene were used as substrates, the catalyst dosage was 15 mg, ethanol was used as solvent, and potassium carbonate was used as base for the reaction at 60℃, 6 h, the yield reaches >99%, and the catalyst is easy to recover and can be recycled for 3 times.}

Key words: N-heterocyclic carbine-Pd, Suzuki-Miyaura cross-coupling reaction, catalysis, coordination polymer, post-synthetic modification

摘要：

以\mathrm{1,3}-二(1-羧乙基)咪唑盐(HL)和Zn(NO₃)₂·6H₂O反应合成二维配位聚合物[Zn(L)₂] _n (Zn-L)，产物再与K₂PdCl₄在四氢呋喃溶液中反应引入氮杂环卡宾-钯（NHC-Pd）催化位点，制得催化剂NHC-Pd@Zn-L，并通过PXRD、TGA、ICP、SEM、EDS和XPS进行表征。结果表明，NHC-Pd@Zn-L具有良好的热稳定性且修饰后晶体的框架结构没有发生变化，Pd以NHC-Pd的形式结合在Zn-L中，并均匀分散在配位聚合物中。将NHC-Pd@Zn-L用于催化Suzuki-Miyaura交叉偶联反应，当以苯硼酸和溴苯为底物，催化剂用量为15 mg，乙醇为溶剂，碳酸钾为碱的条件下60℃反应6 h，产率达到>99%，而且催化剂易于回收并可循环使用3次。

关键词: 氮杂环卡宾-钯, Suzuki-Miyaura交叉偶联反应, 催化, 配位聚合物, 后合成修饰