Kasha's exciton model proposes that T1 energy levels of organic compounds are insensitive to molecular aggregation and microenvironment change because of negligible small transition dipole moments of T1 states.Thi...Kasha's exciton model proposes that T1 energy levels of organic compounds are insensitive to molecular aggregation and microenvironment change because of negligible small transition dipole moments of T1 states.This model holds true in most organic systems till now.Here we report the fabrication of twisted organic phosphors with intramolecular charge transfer characters and flexible molecular structures.When doped into different organic matrices,the twisted phosphor adopts different conformation,exhibits distinct phosphorescence colors and T1 energy levels,which violates Kasha's exciton model in organic system.Given that the change of phosphorescence colors and maxima can be readily distinguished by human eyes and conventional instrument,the twisted phosphors would be exploited as a new type of molecular probe,which would exhibit potential application in optical sensing and stimuli-responsive systems.展开更多
The excited state characters of HY103 have been studied by means of time-resolved photon emission （time-correlated single photon counting） and time dependent density functional theory calculations. The experimental ...The excited state characters of HY103 have been studied by means of time-resolved photon emission （time-correlated single photon counting） and time dependent density functional theory calculations. The experimental and theoretical results demonstrate that HY103 dyes undergo an efficient one-bond-flip motion after photoexicitation at room temperature, which leads to a very short lifetime of the normM fluorescence state, and a weak fluorescence emission around 670 am. However, when HY103 are excited in amorphous glasses at 77 K, the normal fluorescence emission is prolonged to nanoseconds time scale about 2 ns, and the fluorescence emission is enhanced. Furthermore, a new emission state is produced, which is characterized as a volume-conserved twisted （VCT） state. This is the first observation of a VCT state. The experiment indicates that the VCT motion of excited state of π-conjugated molecules in restricted environment can form a stable emission state, and the excited state character of π-conjugated molecules in restricted environment is complex.展开更多
In this paper the results of dynamic NMR studies on ethylmethylamino-tertiary-butyl-phenylborane (EMABPB) with or without light are reported. The NMR data were recorded on a Bruker 400 MHz NMR equipped with our custom...In this paper the results of dynamic NMR studies on ethylmethylamino-tertiary-butyl-phenylborane (EMABPB) with or without light are reported. The NMR data were recorded on a Bruker 400 MHz NMR equipped with our custom-made optical probe and with our custom-made 450 watts (W) monochromatic light sources. The molecular photochemistry including twisted intramolecular charge-transfer-excited-state (TICT) of the EMABPB in several solvents has been investigated. These results indicate that the aminoborane demonstrates multiple configurations in CD3Cl and CD2Cl2 resulting in the shifts of the signals of the alkyl groups on the nitrogen and boron. This indicates that there are some time-dependent changes at constant temperature over the irradiation interval. At ﹣60°C and the presence of light (λ = 265 nm), we observed a large change in the populations of the two sites, and this by itself indicates a modification in the rotation around the boron nitrogen bond in the excited state. By considering the existence of the TICT state, many important energy technologies may be developed with higher efficiency by controlling the back-electron transfer processes.展开更多
基金supports from National Natural Science Foundation of China(22175194)Shanghai Scientific and Technological Innovation Project(20QA1411600,20ZR1469200)+1 种基金Hundred Talents Program from Shanghai Institute of Organic Chemistry(Y121078)Pioneer Hundred Talents Program of Chinese Academy of Sciences(E320021),and Ningbo Natural Science Foundation(2023J243).
文摘Kasha's exciton model proposes that T1 energy levels of organic compounds are insensitive to molecular aggregation and microenvironment change because of negligible small transition dipole moments of T1 states.This model holds true in most organic systems till now.Here we report the fabrication of twisted organic phosphors with intramolecular charge transfer characters and flexible molecular structures.When doped into different organic matrices,the twisted phosphor adopts different conformation,exhibits distinct phosphorescence colors and T1 energy levels,which violates Kasha's exciton model in organic system.Given that the change of phosphorescence colors and maxima can be readily distinguished by human eyes and conventional instrument,the twisted phosphors would be exploited as a new type of molecular probe,which would exhibit potential application in optical sensing and stimuli-responsive systems.
文摘The excited state characters of HY103 have been studied by means of time-resolved photon emission （time-correlated single photon counting） and time dependent density functional theory calculations. The experimental and theoretical results demonstrate that HY103 dyes undergo an efficient one-bond-flip motion after photoexicitation at room temperature, which leads to a very short lifetime of the normM fluorescence state, and a weak fluorescence emission around 670 am. However, when HY103 are excited in amorphous glasses at 77 K, the normal fluorescence emission is prolonged to nanoseconds time scale about 2 ns, and the fluorescence emission is enhanced. Furthermore, a new emission state is produced, which is characterized as a volume-conserved twisted （VCT） state. This is the first observation of a VCT state. The experiment indicates that the VCT motion of excited state of π-conjugated molecules in restricted environment can form a stable emission state, and the excited state character of π-conjugated molecules in restricted environment is complex.
文摘In this paper the results of dynamic NMR studies on ethylmethylamino-tertiary-butyl-phenylborane (EMABPB) with or without light are reported. The NMR data were recorded on a Bruker 400 MHz NMR equipped with our custom-made optical probe and with our custom-made 450 watts (W) monochromatic light sources. The molecular photochemistry including twisted intramolecular charge-transfer-excited-state (TICT) of the EMABPB in several solvents has been investigated. These results indicate that the aminoborane demonstrates multiple configurations in CD3Cl and CD2Cl2 resulting in the shifts of the signals of the alkyl groups on the nitrogen and boron. This indicates that there are some time-dependent changes at constant temperature over the irradiation interval. At ﹣60°C and the presence of light (λ = 265 nm), we observed a large change in the populations of the two sites, and this by itself indicates a modification in the rotation around the boron nitrogen bond in the excited state. By considering the existence of the TICT state, many important energy technologies may be developed with higher efficiency by controlling the back-electron transfer processes.
