通过亚胺自由基引发的1,5-氢原子转移(Hydrogen Atom Transfer,HAT)途径实现C(sp^(3))—H键官能团化,可避免导向基团和当量氧化剂的使用,因而引起了研究人员的广泛关注。近年来,过渡金属和可见光氧化还原体系的发展为高效可控产生亚胺...通过亚胺自由基引发的1,5-氢原子转移(Hydrogen Atom Transfer,HAT)途径实现C(sp^(3))—H键官能团化,可避免导向基团和当量氧化剂的使用,因而引起了研究人员的广泛关注。近年来,过渡金属和可见光氧化还原体系的发展为高效可控产生亚胺自由基提供了可靠的方法。本文根据亚胺自由基的来源分类总结了亚胺自由基引发的1,5-氢原子转移实现C(sp^(3))—H键官能团化反应。展开更多
单原子催化剂(single atom catalysts, SACs)具有热稳定性高、活性中心结构均一、100%的原子效率等特点被广泛应用于各种α,β-不饱和醛结构的催化转移氢化反应。石墨烯作为当前的研究热点之一,具有高比表面积、高化学稳定性、优异的力...单原子催化剂(single atom catalysts, SACs)具有热稳定性高、活性中心结构均一、100%的原子效率等特点被广泛应用于各种α,β-不饱和醛结构的催化转移氢化反应。石墨烯作为当前的研究热点之一,具有高比表面积、高化学稳定性、优异的力学性能和良好导电性等优点,但由于纯石墨烯的带隙为零,并且表面活性位点较少,限制了其作为载体材料的应用。近年来,随着负载型单原子催化剂的兴起,以石墨烯为载体的各种单原子催化剂被合成并在许多催化反应中表现出优异的催化活性,然而对该类催化剂中活性位点的电子性质、形成机理以及金属位点与载体之间的相互作用的微观认识不够深入。因此,本文综述了石墨烯为载体的单原子催化剂的结构稳定性,电子性质,并通过在石墨烯上掺杂杂原子来实现石墨烯改性,采用理论计算方法,探究了金属位点不同配位数对石墨烯为载体的单原子催化剂的催化反应机理和催化性能,从而为设计出性能更好的催化剂提供借鉴与指导意义。展开更多
The hydrogen\|bond defect of water in aqueous solution of a well\|defined poly(2\|hydroxyethyl acrylate)(PHEA) with different molecular weights and concentrations was studied by Raman spectrum analysis. The pre\|desig...The hydrogen\|bond defect of water in aqueous solution of a well\|defined poly(2\|hydroxyethyl acrylate)(PHEA) with different molecular weights and concentrations was studied by Raman spectrum analysis. The pre\|designed molecular weight of PHEAs with narrow polydispersities (<1 20) were synthesized via atom transfer radical polymerization (ATRP). It was found that in a low concentration PHEA aqueous solution(5?wt%), with the increase of molecular weight, the hydrogen bond defect increased markedly, but in a high concentration solution (25?wt%), the hydrogen bond defect was not sensitively affected by the molecular weight of PHEA. At higher temperature, the N value decreased due to the destroying of the hydrogen bond formation between water and the hydrophilic polymer chain in aqueous solutions.展开更多
文摘通过亚胺自由基引发的1,5-氢原子转移(Hydrogen Atom Transfer,HAT)途径实现C(sp^(3))—H键官能团化,可避免导向基团和当量氧化剂的使用,因而引起了研究人员的广泛关注。近年来,过渡金属和可见光氧化还原体系的发展为高效可控产生亚胺自由基提供了可靠的方法。本文根据亚胺自由基的来源分类总结了亚胺自由基引发的1,5-氢原子转移实现C(sp^(3))—H键官能团化反应。
文摘单原子催化剂(single atom catalysts, SACs)具有热稳定性高、活性中心结构均一、100%的原子效率等特点被广泛应用于各种α,β-不饱和醛结构的催化转移氢化反应。石墨烯作为当前的研究热点之一,具有高比表面积、高化学稳定性、优异的力学性能和良好导电性等优点,但由于纯石墨烯的带隙为零,并且表面活性位点较少,限制了其作为载体材料的应用。近年来,随着负载型单原子催化剂的兴起,以石墨烯为载体的各种单原子催化剂被合成并在许多催化反应中表现出优异的催化活性,然而对该类催化剂中活性位点的电子性质、形成机理以及金属位点与载体之间的相互作用的微观认识不够深入。因此,本文综述了石墨烯为载体的单原子催化剂的结构稳定性,电子性质,并通过在石墨烯上掺杂杂原子来实现石墨烯改性,采用理论计算方法,探究了金属位点不同配位数对石墨烯为载体的单原子催化剂的催化反应机理和催化性能,从而为设计出性能更好的催化剂提供借鉴与指导意义。
文摘The hydrogen\|bond defect of water in aqueous solution of a well\|defined poly(2\|hydroxyethyl acrylate)(PHEA) with different molecular weights and concentrations was studied by Raman spectrum analysis. The pre\|designed molecular weight of PHEAs with narrow polydispersities (<1 20) were synthesized via atom transfer radical polymerization (ATRP). It was found that in a low concentration PHEA aqueous solution(5?wt%), with the increase of molecular weight, the hydrogen bond defect increased markedly, but in a high concentration solution (25?wt%), the hydrogen bond defect was not sensitively affected by the molecular weight of PHEA. At higher temperature, the N value decreased due to the destroying of the hydrogen bond formation between water and the hydrophilic polymer chain in aqueous solutions.
基金supported by USTC Research Funds of the Double First-Class Initiative(YD2060002024)Youth Innovation Promotion Association CAS(2020448)+2 种基金National Natur-al Science Foundation of China(22171254)Anhui Provincial Natural Science Foundation(2108085MB58)Start-up Research Fund from University of Science and Technology of China(KY2060000216).
