Although the relationship between molecular and supramolecular chirality remains elusive,the existing results have demonstrated the vital role of hydrophilic motifs in controlling the supramolecular handedness of pept...Although the relationship between molecular and supramolecular chirality remains elusive,the existing results have demonstrated the vital role of hydrophilic motifs in controlling the supramolecular handedness of peptide nanofibrils compared with hydrophobic ones.However,unlike conventional hydrophobic residues,we speculate that aromatic hydrophobic residues are mostly likely to play a unique role in regulating the supramolecular handedness because theπ–πstacking interactions of their side chains are directional like hydrogen bonding and can direct high levels of self-assembly due to the geometric confining of aromatic rings.To confirm this hypothesis,we here design a series of amphiphilic short peptides,with their hydrophobic motifs being composed of aromatic residues.Their short lengths not only favor their structural stability,synthesis,and sequence variation but also enable us to readily link their molecular and supramolecular structures.Through the combination of experiments and theoretical simulations,we demonstrate that the peptides containing L-form aromatic residues form left-handed nanofibrils while those containing D-form aromatic residues assemble into right-handed ones,irrespective of the chirality of their C-terminal hydrophilic residue.Theoretical calculations revealed that the stacking of aromatic side chains betweenβ-strands directed the twisting direction of theβ-sheets formed,with L-and D-form phenylalanine side chains stacking in a clockwise and anti-clockwise way,and more ordered and stronger aromatic stacking for homochiral peptides facilitated the formation of nanofibrils with a marked tubular feature.This study has bridged the knowledge gap in our understanding of how aromatic residues affect the supramolecular chirality of short peptides.展开更多
Efficient heterojunction organic photovoltaic （OPV） cells are fabricated based on copper tetra-methyl phthalocyanine （CuMePc） as donor and fullerene （C60） as acceptor. The power conversion efficiency of CuMePc/C...Efficient heterojunction organic photovoltaic （OPV） cells are fabricated based on copper tetra-methyl phthalocyanine （CuMePc） as donor and fullerene （C60） as acceptor. The power conversion efficiency of CuMePc/C60 OPV cell （2.52%） is increased by 88% compared with that of the non-peripheral substituted copper phthalocyanine （CuPc）/C60 OPV cell （1.34%）. The introduction of methyl substituent leads to stronger π–π interaction of CuMePc （～ 3.5 ？） than that of CuPc （～ 3.8 ？）. The efficiency improvement is attributed to the enhanced carrier mobility of CuMePc thin film （1.1×10-3 cm2/V·s） and better film morphology by introducing methyl groups into the periphery of CuPc molecule.展开更多
The microstructures of as-cast and as-solution Mg–12Gd–2Er–1Zn–0.6Zr alloys were investigated by optical microscopy（OM）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, highresoluti...The microstructures of as-cast and as-solution Mg–12Gd–2Er–1Zn–0.6Zr alloys were investigated by optical microscopy（OM）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, highresolution transmission electron microscopy（HRTEM）X-ray diffraction（XRD） and selected-area electron diffraction（SAED） in the present investigation. The results show that the primary eutectic phase Mg5（Gd, Er, Zn） and some flocculent features are found in the as-cast alloy; the SAED pattern indicates that these flocculent features are the dense areas of stacking faults. The 14H-LPSO structure precipitates in the temperature range of 673–793 K, and the volume fraction of 14H-LPSO structure increases with the extension of heating time; however, there is no precipitation of 14H-LPSO structure when the temperature reaches up to 803 K. In addition, the Mg5（Gd, Er, Zn） phase dissolves gradually along with the precipitation of 14H-LPSO structure.展开更多
基金the National Natural Science Foundation of China(Nos.22172193,22072181,and U1832108)a joint Innovate UK-Syngenta funded project under knowledge transfer partnership(No.KTP12697)an EPSRC IAA 377 grant(No.R128362)with Arxada.We acknowledge the use of the resources of the China Spallation Neutron Source in Dongguan of Guangdong Province of China.
文摘Although the relationship between molecular and supramolecular chirality remains elusive,the existing results have demonstrated the vital role of hydrophilic motifs in controlling the supramolecular handedness of peptide nanofibrils compared with hydrophobic ones.However,unlike conventional hydrophobic residues,we speculate that aromatic hydrophobic residues are mostly likely to play a unique role in regulating the supramolecular handedness because theπ–πstacking interactions of their side chains are directional like hydrogen bonding and can direct high levels of self-assembly due to the geometric confining of aromatic rings.To confirm this hypothesis,we here design a series of amphiphilic short peptides,with their hydrophobic motifs being composed of aromatic residues.Their short lengths not only favor their structural stability,synthesis,and sequence variation but also enable us to readily link their molecular and supramolecular structures.Through the combination of experiments and theoretical simulations,we demonstrate that the peptides containing L-form aromatic residues form left-handed nanofibrils while those containing D-form aromatic residues assemble into right-handed ones,irrespective of the chirality of their C-terminal hydrophilic residue.Theoretical calculations revealed that the stacking of aromatic side chains betweenβ-strands directed the twisting direction of theβ-sheets formed,with L-and D-form phenylalanine side chains stacking in a clockwise and anti-clockwise way,and more ordered and stronger aromatic stacking for homochiral peptides facilitated the formation of nanofibrils with a marked tubular feature.This study has bridged the knowledge gap in our understanding of how aromatic residues affect the supramolecular chirality of short peptides.
基金Project supported by the Special Funds for the Development of Strategic Emerging Industries in Shenzhen City,China(Grant No.JCYJ20120830154526537)Start-up Funding of the South University of Science and Technology of China,and the Strategic Research Grant of the City University of Hong Kong(Grant No.7002724)
文摘Efficient heterojunction organic photovoltaic （OPV） cells are fabricated based on copper tetra-methyl phthalocyanine （CuMePc） as donor and fullerene （C60） as acceptor. The power conversion efficiency of CuMePc/C60 OPV cell （2.52%） is increased by 88% compared with that of the non-peripheral substituted copper phthalocyanine （CuPc）/C60 OPV cell （1.34%）. The introduction of methyl substituent leads to stronger π–π interaction of CuMePc （～ 3.5 ？） than that of CuPc （～ 3.8 ？）. The efficiency improvement is attributed to the enhanced carrier mobility of CuMePc thin film （1.1×10-3 cm2/V·s） and better film morphology by introducing methyl groups into the periphery of CuPc molecule.
基金financially supported by the Projects of Beijing Municipal Science and Technology Commission (No. Z131100003213019)the Projects of Beijing Municipal Commission of Education (Nos. KM201110005001 and KM201310005001)Beijing Natural Science Foundation (No. 2144043)
文摘The microstructures of as-cast and as-solution Mg–12Gd–2Er–1Zn–0.6Zr alloys were investigated by optical microscopy（OM）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, highresolution transmission electron microscopy（HRTEM）X-ray diffraction（XRD） and selected-area electron diffraction（SAED） in the present investigation. The results show that the primary eutectic phase Mg5（Gd, Er, Zn） and some flocculent features are found in the as-cast alloy; the SAED pattern indicates that these flocculent features are the dense areas of stacking faults. The 14H-LPSO structure precipitates in the temperature range of 673–793 K, and the volume fraction of 14H-LPSO structure increases with the extension of heating time; however, there is no precipitation of 14H-LPSO structure when the temperature reaches up to 803 K. In addition, the Mg5（Gd, Er, Zn） phase dissolves gradually along with the precipitation of 14H-LPSO structure.
