Photocatalytic oxidative organic reactions are important synthetic transformations,and research on reaction selectivity by reactive oxygen species(ROS)is significant.To date,however,there has rarely been any focus on ...Photocatalytic oxidative organic reactions are important synthetic transformations,and research on reaction selectivity by reactive oxygen species(ROS)is significant.To date,however,there has rarely been any focus on the directed generation of ROSs.Herein,we report the first identification of tunable molecular oxygen activation induced by polymeric conjugation in nonmetallic conjugated microporous polymers(CMP).The conjugation between these can be achieved by the introduction of alkynyl groups.CMP-A with an alkynyl bridge facilitates the intramolecular charge mobility while CMP-D,lacking an alkynyl group enhances the photoexcited carrier build-up on the surface from diffusion.These different processes dominate the directed ROS generation of the superoxide radical(·O_(2)^(-))and singlet oxygen(^(1)O_(2)),respectively.This theory is substantiated by the different performances of these CMPs in the aerobic oxidation of sulfides and the dehydrogenative coupling of amines,and could provide insight into the rational design of CMPs for various heterogeneous organic photosynthesis.展开更多
The fruits of Pyracantha fortuneana(Maxim.)Li were fermented with pure fungi to improve their antioxidant capacity.The antioxidant activities of fermented and non-fermented P.fortuneana fruits were estimated by 1,1-di...The fruits of Pyracantha fortuneana(Maxim.)Li were fermented with pure fungi to improve their antioxidant capacity.The antioxidant activities of fermented and non-fermented P.fortuneana fruits were estimated by 1,1-diphenyl-2-picrylhydrazyl(DPPH)and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate)(ABTS)radical scavenging activities,as well as ferric ion reducing antioxidant power(FRAP).The total phenolic content(TPC)and total flavonoid content(TFC)were also determined.Additionally,the changes caused by fermentation were characterized by proton nuclear magnetic resonance spectroscopy(1H NMR).The results showed that P.fortuneana fruits fermented with Rhizopus oryzae and Penicillium commune exhibited stronger antioxidant activity compared with the non-fermented material.Correlation analysis indicated that the increased activity might be ascribed to the improvement of TPC.Chemical characterization of 1H NMR implied that the increased TPC and antioxidant activity might be attributed to some of the phenolic and flavonoid glycosides hydrolyzed to new components during fermentation.The present study was the first report of the fermentation of P.fortuneana fruit with pure fungal strains and suggested that fermentation of P.fortuneana fruits with R.oryzae and P.commune was an effective alternative approach to increase antioxidant,and P.fortuneana fruit fermented by R.oryzae and P.commune might be the new alternative of natural antioxidants.展开更多
基金supported by the National Natural Science Foundation of China(51902121,52073110,22071072,51872107,21975090,and 21801086)the Fundamental Research Funds for the Central Universities of China(2662018QD011,2662018PY052,and 2662019PY023)the Natural Science Foundation of Hubei Province(2019CFB322)。
文摘Photocatalytic oxidative organic reactions are important synthetic transformations,and research on reaction selectivity by reactive oxygen species(ROS)is significant.To date,however,there has rarely been any focus on the directed generation of ROSs.Herein,we report the first identification of tunable molecular oxygen activation induced by polymeric conjugation in nonmetallic conjugated microporous polymers(CMP).The conjugation between these can be achieved by the introduction of alkynyl groups.CMP-A with an alkynyl bridge facilitates the intramolecular charge mobility while CMP-D,lacking an alkynyl group enhances the photoexcited carrier build-up on the surface from diffusion.These different processes dominate the directed ROS generation of the superoxide radical(·O_(2)^(-))and singlet oxygen(^(1)O_(2)),respectively.This theory is substantiated by the different performances of these CMPs in the aerobic oxidation of sulfides and the dehydrogenative coupling of amines,and could provide insight into the rational design of CMPs for various heterogeneous organic photosynthesis.
基金Special Basic Cooperative Research Programs of Yunnan Provincial Undergraduate Universities(Grant No.2019FH001-109)Undergraduates Innovative Experiment Project from MOE(Grant Nos.202010684016,202110684004)。
文摘The fruits of Pyracantha fortuneana(Maxim.)Li were fermented with pure fungi to improve their antioxidant capacity.The antioxidant activities of fermented and non-fermented P.fortuneana fruits were estimated by 1,1-diphenyl-2-picrylhydrazyl(DPPH)and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate)(ABTS)radical scavenging activities,as well as ferric ion reducing antioxidant power(FRAP).The total phenolic content(TPC)and total flavonoid content(TFC)were also determined.Additionally,the changes caused by fermentation were characterized by proton nuclear magnetic resonance spectroscopy(1H NMR).The results showed that P.fortuneana fruits fermented with Rhizopus oryzae and Penicillium commune exhibited stronger antioxidant activity compared with the non-fermented material.Correlation analysis indicated that the increased activity might be ascribed to the improvement of TPC.Chemical characterization of 1H NMR implied that the increased TPC and antioxidant activity might be attributed to some of the phenolic and flavonoid glycosides hydrolyzed to new components during fermentation.The present study was the first report of the fermentation of P.fortuneana fruit with pure fungal strains and suggested that fermentation of P.fortuneana fruits with R.oryzae and P.commune was an effective alternative approach to increase antioxidant,and P.fortuneana fruit fermented by R.oryzae and P.commune might be the new alternative of natural antioxidants.
