The intramolecular H-bonding effect on the growth and stability of Schiff-base surface covalent organic frameworks
The intramolecular H-bonding effect on the growth and stability of Schiff-base surface covalent organic frameworks
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分子内氢键对希夫碱表面共价有机骨架生长和稳定性的影响
DOI：
10.1039/c6cp06894d
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发表时间：
2017
影响因子：
3.3
通讯作者：
Wan Li-Jun
中科院分区：
文献类型：
--
作者：
Mo Yi-Ping;Liu Xuan-He;Sun Bing;Yan Hui-Juan;Wang Dong;Wan Li-Jun
通过在席夫碱中心附近添加-OH官能团来引入分子内氢键被认为是一种有用的策略，以提高本体共价有机框架（COFs）的稳定性和结晶性。然而，分子内氢键对表面COFs（SCOFs）合成的影响几乎没有探索。本文设计了基于1，3，5-三（4-氨基苯基）苯（TAPB）与具有对称或不对称取代羟基官能团的乙醛之间的Schiff碱反应的SCOFs。在没有溶剂的情况下，羟基取代基可以容易地被氧化;因此需要氩气保护以获得高质量的SCOF。此外，尽管取代基具有对称性，但可以获得具有均匀孔的扩展网络。实验结果和理论计算都表明，分子内氢键对表面合成的影响不如体相合成中的重要，这是因为基底本身可以导致吸附分子的平面化。分子内氢键的存在可以增强网络在酸和碱环境中的稳定性。
The introduction of intramolecular H-bonding by adding –OH functionalities adjacent to the Schiff base centers is considered to be a useful strategy to enhance the stability and crystallinity of bulk covalent organic frameworks (COFs). However, the influence of intramolecular H-bonding on the synthesis of surface COFs (SCOFs) have been barely explored. Herein, SCOFs based on the Schiff-base reaction between 1,3,5-tris(4-aminophenyl)benzene (TAPB) and terephthalaldehydes with symmetry or asymmetrically substituted hydroxyl functional groups are designed. In the absence of a solvent, hydroxyl substituents can be easily oxidized; thus argon protection is required to obtain high-quality SCOFs. Besides, an extended network with uniform pores can be achieved in spite of the symmetry of substituents. Both experimental results and theoretical calculations show that the influence of intramolecular hydrogen bonding on surface synthesis is not as important as that in bulk phase synthesis because the substrate itself can lead to the complanation of adsorbed molecules. The existence of intramolecular H-bonding can enhance the stability of the network in both acid and alkali environments.