Imine-linked covalent organic frameworks(COFs)provide distinctive prospects for promoting photocatalytic H_(2)O_(2) production,yet the intricate involvement of imine-derived linkages chemistry under light irradiation ...Imine-linked covalent organic frameworks(COFs)provide distinctive prospects for promoting photocatalytic H_(2)O_(2) production,yet the intricate involvement of imine-derived linkages chemistry under light irradiation remains incompletely elucidated.Here,imine-linked COF-LZU1 demonstrates a visible light-driven H_(2)O_(2) evolution rate of 387μmol g^(-1)h^(-1),particularly,negligible dependence on the sacrificial agents.By virtue of electron paramagnetic spectroscopy and solid-state nuclear magnetic resonance,we experimentally tracked the structure evolution and identified its autooxidation to Wurster's salt mimics under the photocatalytic conditioning.This finding coincides with the radical anion-O_(2)^(-)-governed reaction pathway and is further rationalized with additional theoretical calculations.This study provides insights into both photophysical/photochemical aspects over the imine-linkage structure.展开更多
Autooxidation of five polyphenols representing range of different hydrophobicities(catechin gallate (CG),(-)catechin((-)C),epicatechin(EC),epigallocatechin gallate(EGCG)and epigallocatechin(EGC)) in three different aq...Autooxidation of five polyphenols representing range of different hydrophobicities(catechin gallate (CG),(-)catechin((-)C),epicatechin(EC),epigallocatechin gallate(EGCG)and epigallocatechin(EGC)) in three different aqueous solutions:molecular solution,micellar solution(Tween-20)and liposomal dispersion(soybean lecithin)was monitored by HPLC.The rate of oxidation of the five polyphenols was higher at pH 4.5 than at pH 3.5.Compared with the control,addition of Tween-20(micellar structure)and lecithin(liposomal structure)significantly decreased the degradation of polyphenols.In the presence of lecithin the autooxidation of all the five polyphenols was slower than in the presence of Tween-20. The effective protection of the colloidal structures was compared with the hydrophobicity of the poly- phenols estimated from the partitioning between octanol and water.The protection from oxidation in the presence of the colloidal structures(micellar or liposomal)increased with increasing partitioning of a polyphenol towards the hydrophobic environment.The protecting effect of the colloidal structures was more effective at pH 4.5 than at pH 3.5.展开更多
基金This work was supported by the National Natural Science Foundation of China(22002013)the Fundamental Research Funds for the Central Universities(DUT22LAB602)+1 种基金Liao Ning Revitalization Talents Program(XLYC2008032)China Postdoctoral Science Foundation(Grant No.2023M740496).
文摘Imine-linked covalent organic frameworks(COFs)provide distinctive prospects for promoting photocatalytic H_(2)O_(2) production,yet the intricate involvement of imine-derived linkages chemistry under light irradiation remains incompletely elucidated.Here,imine-linked COF-LZU1 demonstrates a visible light-driven H_(2)O_(2) evolution rate of 387μmol g^(-1)h^(-1),particularly,negligible dependence on the sacrificial agents.By virtue of electron paramagnetic spectroscopy and solid-state nuclear magnetic resonance,we experimentally tracked the structure evolution and identified its autooxidation to Wurster's salt mimics under the photocatalytic conditioning.This finding coincides with the radical anion-O_(2)^(-)-governed reaction pathway and is further rationalized with additional theoretical calculations.This study provides insights into both photophysical/photochemical aspects over the imine-linkage structure.
文摘Autooxidation of five polyphenols representing range of different hydrophobicities(catechin gallate (CG),(-)catechin((-)C),epicatechin(EC),epigallocatechin gallate(EGCG)and epigallocatechin(EGC)) in three different aqueous solutions:molecular solution,micellar solution(Tween-20)and liposomal dispersion(soybean lecithin)was monitored by HPLC.The rate of oxidation of the five polyphenols was higher at pH 4.5 than at pH 3.5.Compared with the control,addition of Tween-20(micellar structure)and lecithin(liposomal structure)significantly decreased the degradation of polyphenols.In the presence of lecithin the autooxidation of all the five polyphenols was slower than in the presence of Tween-20. The effective protection of the colloidal structures was compared with the hydrophobicity of the poly- phenols estimated from the partitioning between octanol and water.The protection from oxidation in the presence of the colloidal structures(micellar or liposomal)increased with increasing partitioning of a polyphenol towards the hydrophobic environment.The protecting effect of the colloidal structures was more effective at pH 4.5 than at pH 3.5.
