Chiral selection of Troger's base-based macrocycles with different ethylene glycol chains length in crystallization

In the present work,two Troger's base-based macrocycles(TBBMs)with different bridging ethylene glycol chains(T1,n=1;T3,n=3)were successfully synthesized and studied via the crystal analysis.These two TBBMs possess rare rectangular-like cavities and show chiral selection during the crystallization.T1with short glycol chain(n=1)crystallized as racemates,while T3 with long glycol chain(n=3)was found as meso isomer.In contrast to T1 and T3,for T2(n=2)both rac-T2 and meso isomer R2NS2N-T2has been observed in our previous report.Thus,the synthesis of new TBBMs T1 and T3 with different bridging ethylene glycol chains not only makes the study of TBBMs more systematically,but also helps to understand the relationship between the size of the rectangular cavity and the chiral selection of Troger's base-based macrocycles during their crystallization.

Strong circularly polarized luminescence from quantum dots/2D chiral perovskites composites

Chiral perovskites(CPs)have attracted enormous attentions since they have combined chirality and optoelectrical properties well which is promising in circularly polarized luminescence(CPL)application and of great importance for future spin-optoelectronics.However,there is a key contradiction that in chiral perovskites chirality distorts the crystal structure,leading to poor photoluminescence(PL)properties.Achieving the balance between chirality and PL is a major challenge for strong CPL from chiral perovskites.Differently,two-dimensional(2D)chiral perovskite has shown fascinating chiral induced spin selectivity(CISS)effect which can act as spin injector under ambient conditions.Here,we propose an effective strategy to achieve high CPL activity generated from quantum dots(QDs)by introducing 2D chiral perovskite as a chiral source,providing spin polarized carriers through the CISS effect.The as-synthesized QDs/CP composites exhibit dissymmetry factors(glum)up to 9.06×10^(−3).For the first time,we performed grazing incident wide angle X-ray scattering(GIWAXS)measurements,showing the chirality originates from the distorted lattices caused by the large chiral organic cations.Besides,time-resolved PL(TR-PL)measurements verify the enhanced CPL activity should be attributed to the charge transport between two components.These findings provide a useful method to achieve CPL in QDs/2D chiral perovskite heterojunctions which could be promising in spinoptoelectronics application.

Trimetaphosphate-induced chiral selection between amino acid and nucleoside using ^(15)N-^(31)P coupling NMR

Life on Earth uses a common set of L-amino acids(L-aa)to construct proteins and D-nucleosides(D-Nu)to form nucleic acids,which serve as the carrier of genetic information.Herein,we reveal the in-trinsic mechanism of chiral selection of L-aa and D-Nu from the perspective of chemical origin of life.This work employed^(15)N-labeled L-aa and performed one-pot synthesis of nucleotide amidate of amino acid(N-aa-NMP)using equal amounts of L-^(15)N-aa and D-^(14)N-aa with D-/L-Nu in the aqueous solution of trimetaphosphate,generating L-^(15)N-aa-NMP and D-^(14)N-aa-NMP,respectively.The ^(31)P-NMR data indicated that L-aa was preferentially selected during the formation of N-aa-NMP in the presence of D-Nu.Surpris-ingly,D-aa was preferred over L-aa in the presence of L-Nu.Further analysis revealed that L-^(15)N-aa-D-NMP vs.D-^(14)N-aa-L-NMP and D-^(14)N-aa-D-NMP vs.L-^(15)N-aa-L-NMP were mirror isomers of each other,respec-tively.These data suggest that there could be a set of chiral systems opposite to that on Earth,which infers there might be a world of life that is a mirror image of the Earth.

Comparative study of the extraction selectivity of PFO-BPy and PCz for small to large diameter single-walled carbon nanotubes

Semiconducting single-walled carbon nanotubes(s-SWCNTs)are fascinating materials for future electronic and optical applications.Conjugated polymer wrapping is one of the most promising methods for mass production of high purity s-SWCNTs.However,its chiral selectivity is relatively inferior to other s-SWCNT production methods.In this paper,the chiral selectivity of two polymers,poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(6,6′-{2,2′-bipyridine})](PFO-BPy)and poly[9-(1-octylonoyl)-9H-carbazole-2,7-diyl](PCz),which are representatives of widely used polyfluorene and polycarbazole families,respectively,were comparatively studied.Both polymers exhibited high selectivity for a subset of existing chiral species in each of the commercially available raw SWCNT materials(CoMoCAT,HiPco,and arc-discharge)which cover a diameter range of 0.6–1.8 nm.Less chiral species were selected by PFO-BPy from small diameter(<1 nm)raw SWCNT materials,while more from large diameter(>1.2 nm)raw materials.High chiral purity(6,5)(>99%)and(7,5)(>75%)solutions were extracted by PFO-BPy and PCz from CoMoCAT materials,respectively.The different chiral angle and diameter selections for different raw materials by both polymers were ascribed to their different geometrical structures and related polymer-tube interactions.Our work provides indispensable information for better understanding the mechanism of polymer wrapping method and improving extraction of single chirality sSWCNTs.