Chirality hold broad applications in life sciences,quantum devices,and various other areas.Traditionally,molecular chirality can be characterized by using steady-state circular dichroism spectroscopy.However,the techn...Chirality hold broad applications in life sciences,quantum devices,and various other areas.Traditionally,molecular chirality can be characterized by using steady-state circular dichroism spectroscopy.However,the techniques that can characterize excited state chirality are progressively capturing the public interest as it can provide the dynamic information for chirality generation and transfer.In this review,we focus on the theoretical background and the developmental history of femtosecond time-resolved circular dichroism spectroscopy(TRCD)techniques around the world.Additionally,we provide examples to showcase the utility of these techniques in the analysis of the dynamical molecular chemical structures,the investigation of molecular chirality generation,and the detection of electron spin dynamics in semiconductor quantum dots.展开更多
Enantiomer separation is one of the most important prerequisites for the investigation of environmental enantioselective behavior for chiral pesticides.The enantiomeric separation of three chiral pesticides,indoxacarb...Enantiomer separation is one of the most important prerequisites for the investigation of environmental enantioselective behavior for chiral pesticides.The enantiomeric separation of three chiral pesticides,indoxacarb,lambda-cyhalothrin,and simeconazole,were studied on cellulose tris-(3,5-dimethylphenyl-carbamate)-coated chiral stationary phase(CDMPC-CSP) using high-performance liquid chromatography under normal phase condition.The effects of chromatographic conditions,such as the mobile phase composition including the concentration and type of alcohol modifiers in hexane,flow rate and column temperature,on enantiomer separation were examined.The thermodynamical mechanism of enantioseparation and chiral recognition mechanism were discussed.Better separation were achieved using 20% n-propanol for indoxacarb,2% iso-butanol for lambda-cyhalothrin,and 20% iso-propanol for simeconazole as modifiers in hexane at 25℃ with the selectivity factor(a) of 1.69,1.82 and 1.70,respectively.The resolution factor(Rs) decreased as the flow rate increased from 0.4 to 1.1 ml·min-1.The retention factor(k') and selectivity factor for the enantiomers of analytes decreased as temperature increased.The lna-1/T plots for racemic chiral pesticides were linear in the range of 15-35℃ in hexane/iso-propanol and the chiral separation was controlled by enthalpy.Hydrogen bonding,π-π and dipole-dipole interactions between enantiomers and CDMPC-CSP play an important role in chiral identification,and the fitting of the asymmetric portion of solutes in a chiral cavity or channel of the CSP is also important.展开更多
We have prepared new chiral Schiff base complexes, and copper（Ⅱ） （2） to investigate steric effect of ligands for 1 and bis（N-R-l-phenylethyl-5- methoxysalicydenaminato） nickel（Ⅱ） （1） 2 and known bis（N-R-l...We have prepared new chiral Schiff base complexes, and copper（Ⅱ） （2） to investigate steric effect of ligands for 1 and bis（N-R-l-phenylethyl-5- methoxysalicydenaminato） nickel（Ⅱ） （1） 2 and known bis（N-R-l-phenylethyl-3,5-dichlorosalicydenaminato） nickel（Ⅱ） （3） and copper（Ⅱ） （4）. By using two kinds of photochromic dyes, disperse red 1 （DRI） and azobenzene （AZ）, we investigated the efficiency of increasing optical anisotropy of organic/inorganic hybrid materials of 1 through 4＋AZ or DRI＋PMMA in polymethylmethacrylate （PMMA） cast films by Weigert effect （and compared with cis-trans isomerization by alternate UV and visible light for 3 and 4 to previous study）. Gradual increase of optical anisotropy was observed for all the hybrid materials regardless of flexibility of Schiff base complexes, and the degree of dichroism and weak intermolecular interactions were discussed based on polarized absorption electronic spectra.展开更多
基金funded by the National Natural Science FoundationofChina(No.92156024and No.92356307 to Jinquan Chen)Menghui Jia thanks the Materials Characterization Center and the Office of Laboratory and Equipment of East China Normal University for funding support(ECNUETR2023-13).
文摘Chirality hold broad applications in life sciences,quantum devices,and various other areas.Traditionally,molecular chirality can be characterized by using steady-state circular dichroism spectroscopy.However,the techniques that can characterize excited state chirality are progressively capturing the public interest as it can provide the dynamic information for chirality generation and transfer.In this review,we focus on the theoretical background and the developmental history of femtosecond time-resolved circular dichroism spectroscopy(TRCD)techniques around the world.Additionally,we provide examples to showcase the utility of these techniques in the analysis of the dynamical molecular chemical structures,the investigation of molecular chirality generation,and the detection of electron spin dynamics in semiconductor quantum dots.
基金Supported by China Postdoctoral Science Fund (20090461007)Postdoctoral Research Funding Special Plans of Hunan(2010RC4025)Graduate Innovation Research Project of Hunan (CX2010B295)
文摘Enantiomer separation is one of the most important prerequisites for the investigation of environmental enantioselective behavior for chiral pesticides.The enantiomeric separation of three chiral pesticides,indoxacarb,lambda-cyhalothrin,and simeconazole,were studied on cellulose tris-(3,5-dimethylphenyl-carbamate)-coated chiral stationary phase(CDMPC-CSP) using high-performance liquid chromatography under normal phase condition.The effects of chromatographic conditions,such as the mobile phase composition including the concentration and type of alcohol modifiers in hexane,flow rate and column temperature,on enantiomer separation were examined.The thermodynamical mechanism of enantioseparation and chiral recognition mechanism were discussed.Better separation were achieved using 20% n-propanol for indoxacarb,2% iso-butanol for lambda-cyhalothrin,and 20% iso-propanol for simeconazole as modifiers in hexane at 25℃ with the selectivity factor(a) of 1.69,1.82 and 1.70,respectively.The resolution factor(Rs) decreased as the flow rate increased from 0.4 to 1.1 ml·min-1.The retention factor(k') and selectivity factor for the enantiomers of analytes decreased as temperature increased.The lna-1/T plots for racemic chiral pesticides were linear in the range of 15-35℃ in hexane/iso-propanol and the chiral separation was controlled by enthalpy.Hydrogen bonding,π-π and dipole-dipole interactions between enantiomers and CDMPC-CSP play an important role in chiral identification,and the fitting of the asymmetric portion of solutes in a chiral cavity or channel of the CSP is also important.
文摘We have prepared new chiral Schiff base complexes, and copper（Ⅱ） （2） to investigate steric effect of ligands for 1 and bis（N-R-l-phenylethyl-5- methoxysalicydenaminato） nickel（Ⅱ） （1） 2 and known bis（N-R-l-phenylethyl-3,5-dichlorosalicydenaminato） nickel（Ⅱ） （3） and copper（Ⅱ） （4）. By using two kinds of photochromic dyes, disperse red 1 （DRI） and azobenzene （AZ）, we investigated the efficiency of increasing optical anisotropy of organic/inorganic hybrid materials of 1 through 4＋AZ or DRI＋PMMA in polymethylmethacrylate （PMMA） cast films by Weigert effect （and compared with cis-trans isomerization by alternate UV and visible light for 3 and 4 to previous study）. Gradual increase of optical anisotropy was observed for all the hybrid materials regardless of flexibility of Schiff base complexes, and the degree of dichroism and weak intermolecular interactions were discussed based on polarized absorption electronic spectra.
