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Intramolecular Hydrogen Bond Self-template Synthesis of Some New Robson-type macrocyclic ligands

Chinese Chemical Letters 2001年第9期12卷 757-760页

作者： Jin Cai WU Ning TANG Wei Sheng LIU Min Yu TAN Albert SCCHAN Department of Chemistry Lanzhou UniversityLanzhou 730000 Department of Applied Biology and Chemical technology Hong Kong Polytechnic UniversityHong Kong

The intramolecular hydrogen bond self-template effect was suggested in the process of directly synthesizing the first six chiral metal-free Robson-type macrocyclic ligands. These ligands were characterized by H-1 NMR,... 详细信息

关键词： Self-template macrocyclic ligands

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Potassium Acetate/18-Crown-6 Pair:Robust and Versatile Catalyst for Synthesis of Polyols from Ring-Opening Copolymerization of Epoxides and Cyclic Anhydrides

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Chinese Journal of Chemistry 2023年第1期41卷 83-92页

作者： Xiaoqing Dou Xiao-Hui Liu Bin Wang Yue-Sheng Li School of Materials Science and Engineering Tiangong UniversityTianjin 300387China Tianjin Key Lab of Composite&Functional Materials School of Materials Science and EngineeringTianjin UniversityTianjin 300350China

Efficient synthesis of polyester polyols with tunable molecular weight and microstructures from cyclic anhydride/epoxide mixtures by taking advantage of chain transfer reaction remains a great challenge,because most of the catalysts exhibit poor tolerance to chain transfer agent(CTA).In this contribution,we demonstrated that potassium acetate(KOAc)and 18-crown-6(18-C-6)combination has great potential in the synthesis of diverse polyester polyols with controllable molecular weight and high-end group ***-pared with KOAc,KOAc/18-C-6 pair could induce a much faster chain transfer between the active and dormant chains,and thus produce polyester polyols with narrow and monomodal distribution.In addition,polyester polyols could be efficiently prepared in laboratory by using commercially available cyclic anhydride without further purification(containing about 2%diacid residual as CTA)with an extremely low catalyst loading([catalyst pair]:[anhydride]:[epoxide]=1:50000:250000,[catalyst pair]=0.0004 mol%).KOAc/18-C-6 could also promote the self-switchable copolymerization of cyclic anhydride/epoxide/cyclic ester mixtures.Ring-opening copolymerization of cyclic ester was initiated automatically after the full conversion of cyclic anhydride,finally producing polyester polyols with ABA-type block structure.

关键词： Ring-opening polymerization macrocyclic ligands Block copolymer Cyclic Anhydride Epoxide

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Metal-Ligand Cooperative Effect on Intramolecular Electron Transfer in Macrocycle-Encircled Copper-Oxygen Species

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CCS Chemistry 2023年第9期5卷 2171-2183页

作者： Siqi Zhang Liang Zhao Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology(Ministry of Education) Department of ChemistryTsinghua UniversityBeijing 100084

Reproduction of ubiquitous metal-ligand cooperativity in copper-oxygen enzyme mimics is crucial for the comprehension of catalytic mechanisms in coppercontaining enzymes and copper-catalyzed chemical transformations.Here we describe the synthesis and reduction behavior of a series of encapsulated dinuclear copper-oxygen species by systematically altering the size and geometric structure of peripheral macrocyclic ligands.Along with the occurrence of a single-electron reduction,these macrocycleencircled dicopper complexes show distinct electron transfer pathways as a function of differently sized and substituted macrocyclic ligands.Detailed structural characterization and density functional theory calculations reveal that a coupled metal-ligand and bimetallic cooperativity is involved in the singleelectron reductionof hydroxyl-bridged dicopper species within macrocyclic homologue ligands Py[7]Ph[1]and Py[7]Ph[1]-Me.The highly flexible configurations of macrocyclic ligands are conducive to stabilizing copper-oxygen intermediates with different valence states and facilitating an intramolecular electron transfer between macrocyclic ligands and the central copper-oxygen moiety.Correlation of biased electron transfer behaviors of copper-oxygen species with their peripheral macrocyclic ligands provides a new means of tuning redox properties of metal cluster species and opens a broader prospect on the mechanistic study of copper-containing enzymes and copper-catalyzed transformations.

关键词： metal-ligand cooperativity bimetallic cooperativity macrocyclic ligands copper-oxygen species intramolecular electron transfer

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