Nickel,an important transi-tion metal element,is one of the trace elements for hu-man body and has a crucial impact on life and health.Some evidences show the excess exposure to metal ions might be associated with neu...Nickel,an important transi-tion metal element,is one of the trace elements for hu-man body and has a crucial impact on life and health.Some evidences show the excess exposure to metal ions might be associated with neurological diseases.Herein,we applied Raman spectroscopy to study the Ni(II)ion effect on kinetics of amyloid fibrillation of hen egg white lysozyme(HEWL)in thermal and acidic conditions.Using the well-known Raman indicators for protein tertiary and secondary structures,we monitored and analyzed the concentration effect of Ni(II)ions on the unfolding of tertiary structures and the transformation of sec-ondary structures.The experimental evidence validates the accelerator role of the metal ion in the kinetics.Notably,the additional analysis of the amide I band profile,combined with thioflavin-T fluorescence assays,clearly indicates the inhibitory effect of Ni(II)ions on the formation of amyloid fibrils with organizedβ-sheets structures.Instead,a more significant promotion influence is affirmed on the assembly into other aggregates with disordered struc-tures.The present results provide rich information about the specific metal-mediated protein fibrillation.展开更多
Threshold photoelectron spectrum of CH_(2)F_(2)in the photon energy range of 12.45-14.10 eV was re-investigated by means of a combination of photo-electron-photoion coincidence experiments and density functional theor...Threshold photoelectron spectrum of CH_(2)F_(2)in the photon energy range of 12.45-14.10 eV was re-investigated by means of a combination of photo-electron-photoion coincidence experiments and density functional theory calculations.A series of vibrational peaks were distinctly observed in this range.Using optimized geometries and vibrational frequencies of the CH_(2)F_(2)neutral and its cation in ground state at the M06-2X/cc-pVTZ level of theory,Franck-Condon factor simulations were conducted.Taking into account anharmonicity influences,a perfect agreement between the simulated and experimental spectra has been achieved.From the reliable vibrational assignments,adiabatic and vertical ionization energies of CH_(2)F_(2)are derived as 12.371±0.010 eV and 13.281±0.010 eV,respectively.In addition,the experimental frequencies of four vibrational modes with ai symmetry for CH_(2)F_(2)+(X^(2)B_(1))ions are determined.展开更多
Time-sliced velocity map ion imaging(VMI)experiments were performed to investigate the photodissociation of H_(2)S^(+)X^(2)B_(1),via the excitation to the A^(2)A_(1)(0,11,0)state.Experimental images of the S^(+)(^(4)S...Time-sliced velocity map ion imaging(VMI)experiments were performed to investigate the photodissociation of H_(2)S^(+)X^(2)B_(1),via the excitation to the A^(2)A_(1)(0,11,0)state.Experimental images of the S^(+)(^(4)Su)products were recorded near 349.60 nm for the K=1 band,and near 344.30 nm for the K=2 band.The derived product total kinetic energy release(TKER)spectra exhibit partially rotationally resolved structures corresponding to the H_(2)(X^(1)∑_(g)^(+))co-products.The observed product state and angular distributions both exhibit sensitive dependence on the photolysis wavelength at near 349.60 nm and 344.30 nm.These phenomena indicate the underlying rich dynamic details and the role of the rotational excitation of H_(2)S^(+).展开更多
Dimethyl sulfoxide(DMSO)plays an important role in chemistry,biology and industry.The S=O stretching vibration serves as a sensitive probe of its structure under different chemical environments.However,spectral assign...Dimethyl sulfoxide(DMSO)plays an important role in chemistry,biology and industry.The S=O stretching vibration serves as a sensitive probe of its structure under different chemical environments.However,spectral assignment for the S=O stretching vibration of liquid DMSO remains unclear due to the interference of CH_(3)antisymmetric rocking and different aggregates,leading to the confusion in explaining the microstructures of liquid DMSO.Here,the S=O stretching spectra in pure DMSO and in extremely diluted CCl_(4)solution were investigated with temperaturedependent Raman spectroscopy.It is shown that CH_(3)antisymmetric rocking does not significantly interfere with the S=O band profile due to its low Raman intensity.Three decomposed peaks at 1027,1042 and 1055 cm^(-1)in liquid DMSO show obviously different intensity variety upon the temperature increasing.Combined with quantum chemistry calculation on(DMSO)_(n)(n=1-4)clusters,Raman spectra in the S=O stretching region were assigned and the simultaneous presence of the monomer,dimer and trimmer in liquid DMSO were concluded.These results contribute to a more detailed molecular understanding of the structure of DMSO in the liquid state.展开更多
Efficient visible-to-ultraviolet(UV)triplet-triplet annihilation upconversion(TTA-UC)with large anti-Stokes shift is highly promising for solar-powered and indoor applications.Nonetheless,the excitationwavelengthis co...Efficient visible-to-ultraviolet(UV)triplet-triplet annihilation upconversion(TTA-UC)with large anti-Stokes shift is highly promising for solar-powered and indoor applications.Nonetheless,the excitationwavelengthis confined to the blue region(<450 nm),mainly due to large energy loss during triplet sensitization,resulting in reduced photon utilization efficiency in practical scenarios.Herein,a series of multiple resonance thermally activated delayed fluorescence(MR-TADF)compounds are developed as purely organic sensitizers for the purpose of energy-loss reduction,which also feature intense absorbance in the visible region,high intersystem crossing efficiencies,and long triplet lifetimes.By pairing the MR-TADF sensitizers with appropriate acceptors,green-to-UV TTA-UC systems were realized with an anti-Stokes shift up to 1.05 eV,upconversion quantum yield up to 8.6%,and threshold excitation intensity as low as 9.2 mW cm^(−2) in solution.The TTA-UC pairs were applied as internal or external sources of UV photons to trigger energy-demanding photopolymerization and photoligation reactions even under excitation of low-power-density green light-emitting diode light,revealing the broad utility of thesemolecular upconverters.This work unlocks the huge potential of MR-TADF-type sensitizers in upconversion applications.展开更多
基金supported by the National Natural Science Foundation of China(No.22125302,No.22173099,No.22288201,No.21873089,and No.21973037)the Guangdong Science and Technology Program(No.2019ZT08L455 and No.2019JC01X091)the Shenzhen Science and Technology Program(No.ZDSYS20200421111001787).
基金supported by the National Natural Science Foundation of China(No.22073088,No.22027801 and No.21873089).
文摘Nickel,an important transi-tion metal element,is one of the trace elements for hu-man body and has a crucial impact on life and health.Some evidences show the excess exposure to metal ions might be associated with neurological diseases.Herein,we applied Raman spectroscopy to study the Ni(II)ion effect on kinetics of amyloid fibrillation of hen egg white lysozyme(HEWL)in thermal and acidic conditions.Using the well-known Raman indicators for protein tertiary and secondary structures,we monitored and analyzed the concentration effect of Ni(II)ions on the unfolding of tertiary structures and the transformation of sec-ondary structures.The experimental evidence validates the accelerator role of the metal ion in the kinetics.Notably,the additional analysis of the amide I band profile,combined with thioflavin-T fluorescence assays,clearly indicates the inhibitory effect of Ni(II)ions on the formation of amyloid fibrils with organizedβ-sheets structures.Instead,a more significant promotion influence is affirmed on the assembly into other aggregates with disordered struc-tures.The present results provide rich information about the specific metal-mediated protein fibrillation.
基金supported by the National Natural Science Foundation of China(Nos.22473104 and 22073088).
文摘Threshold photoelectron spectrum of CH_(2)F_(2)in the photon energy range of 12.45-14.10 eV was re-investigated by means of a combination of photo-electron-photoion coincidence experiments and density functional theory calculations.A series of vibrational peaks were distinctly observed in this range.Using optimized geometries and vibrational frequencies of the CH_(2)F_(2)neutral and its cation in ground state at the M06-2X/cc-pVTZ level of theory,Franck-Condon factor simulations were conducted.Taking into account anharmonicity influences,a perfect agreement between the simulated and experimental spectra has been achieved.From the reliable vibrational assignments,adiabatic and vertical ionization energies of CH_(2)F_(2)are derived as 12.371±0.010 eV and 13.281±0.010 eV,respectively.In addition,the experimental frequencies of four vibrational modes with ai symmetry for CH_(2)F_(2)+(X^(2)B_(1))ions are determined.
基金supported by the National Natural Science Foundation of China(No.22125302 and No.22327801)the Innovation Program for Quantum Science and Technology(No.2021ZD0303304)the University of Science and Technology of China.
文摘Time-sliced velocity map ion imaging(VMI)experiments were performed to investigate the photodissociation of H_(2)S^(+)X^(2)B_(1),via the excitation to the A^(2)A_(1)(0,11,0)state.Experimental images of the S^(+)(^(4)Su)products were recorded near 349.60 nm for the K=1 band,and near 344.30 nm for the K=2 band.The derived product total kinetic energy release(TKER)spectra exhibit partially rotationally resolved structures corresponding to the H_(2)(X^(1)∑_(g)^(+))co-products.The observed product state and angular distributions both exhibit sensitive dependence on the photolysis wavelength at near 349.60 nm and 344.30 nm.These phenomena indicate the underlying rich dynamic details and the role of the rotational excitation of H_(2)S^(+).
基金supported by the National Natural Science Foundation of China(Nos.21873002,22073088,12374001).
文摘Dimethyl sulfoxide(DMSO)plays an important role in chemistry,biology and industry.The S=O stretching vibration serves as a sensitive probe of its structure under different chemical environments.However,spectral assignment for the S=O stretching vibration of liquid DMSO remains unclear due to the interference of CH_(3)antisymmetric rocking and different aggregates,leading to the confusion in explaining the microstructures of liquid DMSO.Here,the S=O stretching spectra in pure DMSO and in extremely diluted CCl_(4)solution were investigated with temperaturedependent Raman spectroscopy.It is shown that CH_(3)antisymmetric rocking does not significantly interfere with the S=O band profile due to its low Raman intensity.Three decomposed peaks at 1027,1042 and 1055 cm^(-1)in liquid DMSO show obviously different intensity variety upon the temperature increasing.Combined with quantum chemistry calculation on(DMSO)_(n)(n=1-4)clusters,Raman spectra in the S=O stretching region were assigned and the simultaneous presence of the monomer,dimer and trimmer in liquid DMSO were concluded.These results contribute to a more detailed molecular understanding of the structure of DMSO in the liquid state.
基金This research was made possible as a result of several generous grants from the National Natural Science Foundation of China(grant nos.51903159 and 91833304)the Shenzhen Science and Technology Program(grant nos.KQTD20170330110107046 and JCYJ20190808151209557).
文摘Efficient visible-to-ultraviolet(UV)triplet-triplet annihilation upconversion(TTA-UC)with large anti-Stokes shift is highly promising for solar-powered and indoor applications.Nonetheless,the excitationwavelengthis confined to the blue region(<450 nm),mainly due to large energy loss during triplet sensitization,resulting in reduced photon utilization efficiency in practical scenarios.Herein,a series of multiple resonance thermally activated delayed fluorescence(MR-TADF)compounds are developed as purely organic sensitizers for the purpose of energy-loss reduction,which also feature intense absorbance in the visible region,high intersystem crossing efficiencies,and long triplet lifetimes.By pairing the MR-TADF sensitizers with appropriate acceptors,green-to-UV TTA-UC systems were realized with an anti-Stokes shift up to 1.05 eV,upconversion quantum yield up to 8.6%,and threshold excitation intensity as low as 9.2 mW cm^(−2) in solution.The TTA-UC pairs were applied as internal or external sources of UV photons to trigger energy-demanding photopolymerization and photoligation reactions even under excitation of low-power-density green light-emitting diode light,revealing the broad utility of thesemolecular upconverters.This work unlocks the huge potential of MR-TADF-type sensitizers in upconversion applications.
