The catalytic synthesis of cyclic carbonates via the cycloaddition of CO2 to epoxides is a standard methodology for CO2 fixation.For this purpose,chiral basket-handle porphyrin-Co complexes were devised,prepared,and f...The catalytic synthesis of cyclic carbonates via the cycloaddition of CO2 to epoxides is a standard methodology for CO2 fixation.For this purpose,chiral basket-handle porphyrin-Co complexes were devised,prepared,and fully characterized by nuclear magnetic resonance,mass spectrometry,Fourier transform infrared spectroscopy,ultraviolet-visible spectroscopy,and specific rotation.The proposed metalloporphyrin catalysts were synthesized with either 1,1'-bi-2-naphthol or L-phenylalanine,which have different chirality,and then applied to the coupling of propylene oxide and CO2 for generating chiral cyclic carbonates with good enantioselectivity under extremely mild conditions in the presence of tetrabutyl ammonium chloride as a co-catalyst.The good enantioselectivity in the cycloaddition reaction is attributed to a synergistic interplay between the chiral porphyrin catalysts and the substrate.The mechanism and enantioselectivity of the asymmetric cycloaddition reaction is discussed.展开更多
Hazardous dye substances discharged from the textile and dyestuff industries not only threaten local the surrounding ecosystems but are also hard to degraded.We report the preparation of process for a photocatalytic m...Hazardous dye substances discharged from the textile and dyestuff industries not only threaten local the surrounding ecosystems but are also hard to degraded.We report the preparation of process for a photocatalytic membrane device that can degrade dye pollution under visible light.This filtration membrane,with a well-organized multilayer structure,simultaneously achieves continuous and flow-through separation of degradation products.Cellulose nanofibers(CNFs)were used as a template for nanosheet C_(3)N_(4)(NS C_(3)N_(4))preparation;the performance for the photocatalytic degradation of dyes improved as the morphology changed from bulking to nanosheet.NS C3N4 was then attached to the surface of a prepared CNF membrane via vacuum filtration.This device exhibited high efficiency(the degradation rates of both Rhodamine B and Methylene blue both reached 96%),high flux(above 160 L·h^(-1)·m^(-2)·bar^(-1))and excellent stability(maintaining steady flux and high separation were maintained after 4 h).This easy-preparation,easy-scale-up,and low-cost process provides a new method of fabricating photocatalytic membrane devices for dye wastewater treatment.展开更多
The replacement of synthetic foam materials using natural biological ones is of great significance for saving energy/resources and reducing environmental pollutions.Here we characterized the microstructure and mechani...The replacement of synthetic foam materials using natural biological ones is of great significance for saving energy/resources and reducing environmental pollutions.Here we characterized the microstructure and mechanical properties of natural cornstalk pith,which has a large annual output yet lacks an effective exploitation,and evaluated its feasibility for applications as a substitute for synthetic foam materials.The cornstalk pith was revealed to be a cellular material composed of closed cells elongated along the growth direction of com plant and reinforced by well-aligned vascular bundles penetrating the foam matrix.The compressive behavior is featured by a stable stress plateau which is favorable for energy absorption with its mechanical properties largely dependent on the hydration state and loading configuration.In particular,the initial dimension and mechanical properties of cornstalk pith can be effectively recovered after deformation simply by hydration treatment owing to swelling effect caused by the turgor pressure from osmosis.The cornstalk pith demonstrates an outstanding combination of low density and high energy absorption efficiency among various foam materials,specifically with its plateau stress and energy absorption comparable or even superior to those of some typical synthetic foam materials.These along with the huge resources and good biodegradability make it a promising natural energy absorbing cellular material for replacing synthetic counterparts.展开更多
文摘The catalytic synthesis of cyclic carbonates via the cycloaddition of CO2 to epoxides is a standard methodology for CO2 fixation.For this purpose,chiral basket-handle porphyrin-Co complexes were devised,prepared,and fully characterized by nuclear magnetic resonance,mass spectrometry,Fourier transform infrared spectroscopy,ultraviolet-visible spectroscopy,and specific rotation.The proposed metalloporphyrin catalysts were synthesized with either 1,1'-bi-2-naphthol or L-phenylalanine,which have different chirality,and then applied to the coupling of propylene oxide and CO2 for generating chiral cyclic carbonates with good enantioselectivity under extremely mild conditions in the presence of tetrabutyl ammonium chloride as a co-catalyst.The good enantioselectivity in the cycloaddition reaction is attributed to a synergistic interplay between the chiral porphyrin catalysts and the substrate.The mechanism and enantioselectivity of the asymmetric cycloaddition reaction is discussed.
基金supported by the National Key R&D Program of China(No.2018YFC1902101)the National Natural Science Foundation of China(Nos.21908127,21838006,and 21776159)the project supported by the Foundation(No.KF201810)of Key Laboratory of Pulp and Paper Science and Technology of Ministry of Education/Shandong Province of China and Opening Project of the Key Laboratory of Bionic Engineering(Ministry of Education),Jilin University.
文摘Hazardous dye substances discharged from the textile and dyestuff industries not only threaten local the surrounding ecosystems but are also hard to degraded.We report the preparation of process for a photocatalytic membrane device that can degrade dye pollution under visible light.This filtration membrane,with a well-organized multilayer structure,simultaneously achieves continuous and flow-through separation of degradation products.Cellulose nanofibers(CNFs)were used as a template for nanosheet C_(3)N_(4)(NS C_(3)N_(4))preparation;the performance for the photocatalytic degradation of dyes improved as the morphology changed from bulking to nanosheet.NS C3N4 was then attached to the surface of a prepared CNF membrane via vacuum filtration.This device exhibited high efficiency(the degradation rates of both Rhodamine B and Methylene blue both reached 96%),high flux(above 160 L·h^(-1)·m^(-2)·bar^(-1))and excellent stability(maintaining steady flux and high separation were maintained after 4 h).This easy-preparation,easy-scale-up,and low-cost process provides a new method of fabricating photocatalytic membrane devices for dye wastewater treatment.
基金The authors are grateful for the financial support by National Key R&D Program of China under Grant Number 2020YFA0710404the National Natural Science Foundation of China under grant number 51871216+1 种基金the LiaoNing Revitalization Talents Program,the State Key Laboratory for Modification of Chemical Fibers and Polymer Materials at Donghua Universitythe Opening Project of Jiangsu Province Key Laboratory of High-End Structural Materials under grant number hsm 1801,the Lu Jiaxi International Team Program supported by the K.C.Wong Education Foundation and CAS,and the Youth Innovation Promotion Association CAS.
文摘The replacement of synthetic foam materials using natural biological ones is of great significance for saving energy/resources and reducing environmental pollutions.Here we characterized the microstructure and mechanical properties of natural cornstalk pith,which has a large annual output yet lacks an effective exploitation,and evaluated its feasibility for applications as a substitute for synthetic foam materials.The cornstalk pith was revealed to be a cellular material composed of closed cells elongated along the growth direction of com plant and reinforced by well-aligned vascular bundles penetrating the foam matrix.The compressive behavior is featured by a stable stress plateau which is favorable for energy absorption with its mechanical properties largely dependent on the hydration state and loading configuration.In particular,the initial dimension and mechanical properties of cornstalk pith can be effectively recovered after deformation simply by hydration treatment owing to swelling effect caused by the turgor pressure from osmosis.The cornstalk pith demonstrates an outstanding combination of low density and high energy absorption efficiency among various foam materials,specifically with its plateau stress and energy absorption comparable or even superior to those of some typical synthetic foam materials.These along with the huge resources and good biodegradability make it a promising natural energy absorbing cellular material for replacing synthetic counterparts.
