In this work, we theoretically probe into the photo-induced hydrogen bonding effects between S0 state and S1 state as well as the excited state intramolecular proton transfer(ESIPT) behavior for a novel 2-[1,3]dithian...In this work, we theoretically probe into the photo-induced hydrogen bonding effects between S0 state and S1 state as well as the excited state intramolecular proton transfer(ESIPT) behavior for a novel 2-[1,3]dithian-2-yl-6-(7aH-indol-2-yl)-phenol(DIP) probe system. We first study the ground-state hydrogen bonding O–H··· N behavior for DIP. Then we analyze the primary geometrical parameters(i.e., bond length, bond angle, and infrared(IR) stretching vibrational mode)involved in hydrogen bond, and confirm that the O–H··· N of DIP should be strengthened in the first excited state. It is the significant prerequisite for ESIPT reaction. Combining the frontier molecular orbitals(MOs) with vertical excitation analyses, the intramolecular charge transfer(ICT) phenomenon can be found for the DIP system, which reveals that the charge redistribution facilitates ESIPT behavior. By constructing potential energy curves for DIP along the ESIPT reactional orientation, we obtain quite a small energy barrier(3.33 kcal/mol) and affirmed that the DIP molecule undergoes ultrafast ESIPT process once it is excited to the S1 state and quickly transfers its proton, forming DIP-keto tautomer. That is why no fluorescence of DIP can be observed in experiment, which further reveals the ultrafast ESIPT mechanism proposed in this work.展开更多
We theoretically investigate the excited state intramolecular proton transfer(ESIPT) behavior of the novel fluorophore bis-imine derivative molecule HNP which was designed based on the intersection of 1-(hydrazonometh...We theoretically investigate the excited state intramolecular proton transfer(ESIPT) behavior of the novel fluorophore bis-imine derivative molecule HNP which was designed based on the intersection of 1-(hydrazonomethyl)-naphthalene-2-ol and 1-pyrenecarboxaldehyde. Especially, the density functional theory(DFT) and time-dependent density functional theory(TDDFT) methods for HNP monomer are introduced. Moreover, the "our own n-layered integrated molecular orbital and molecular mechanics"(ONIOM) method(TDDFT:universal force field(UFF)) is used to reveal the aggregation-induced emission(AIE) effect on the ESIPT process for HNP in crystal. Our results confirm that the ESIPT process happens upon the photoexcitation for the HNP monomer and HNP in crystal, which is distinctly monitored by the optimized geometric structures and the potential energy curves. In addition, the results of potential energy curves reveal that the ESIPT process in HNP will be promoted by the AIE effect. Furthermore, the highest occupied molecular orbital(HOMO) and lowest unoccupied molecular orbital(LUMO) for the HNP monomer and HNP in crystal have been calculated. The calculation demonstrates that the electron density decrease of proton donor caused by excitation promotes the ESIPT process. In addition, we find that the variation of atomic dipole moment corrected Hirshfeld population(ADCH) charge for proton acceptor induced by the AIE effect facilitates the ESIPT process. The results will be expected to deepen the understanding of ESIPT dynamics for luminophore under the AIE effect and provide insight into future design of high-efficient AIE compounds.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11574083).
文摘In this work, we theoretically probe into the photo-induced hydrogen bonding effects between S0 state and S1 state as well as the excited state intramolecular proton transfer(ESIPT) behavior for a novel 2-[1,3]dithian-2-yl-6-(7aH-indol-2-yl)-phenol(DIP) probe system. We first study the ground-state hydrogen bonding O–H··· N behavior for DIP. Then we analyze the primary geometrical parameters(i.e., bond length, bond angle, and infrared(IR) stretching vibrational mode)involved in hydrogen bond, and confirm that the O–H··· N of DIP should be strengthened in the first excited state. It is the significant prerequisite for ESIPT reaction. Combining the frontier molecular orbitals(MOs) with vertical excitation analyses, the intramolecular charge transfer(ICT) phenomenon can be found for the DIP system, which reveals that the charge redistribution facilitates ESIPT behavior. By constructing potential energy curves for DIP along the ESIPT reactional orientation, we obtain quite a small energy barrier(3.33 kcal/mol) and affirmed that the DIP molecule undergoes ultrafast ESIPT process once it is excited to the S1 state and quickly transfers its proton, forming DIP-keto tautomer. That is why no fluorescence of DIP can be observed in experiment, which further reveals the ultrafast ESIPT mechanism proposed in this work.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574115 and 11704146)
文摘We theoretically investigate the excited state intramolecular proton transfer(ESIPT) behavior of the novel fluorophore bis-imine derivative molecule HNP which was designed based on the intersection of 1-(hydrazonomethyl)-naphthalene-2-ol and 1-pyrenecarboxaldehyde. Especially, the density functional theory(DFT) and time-dependent density functional theory(TDDFT) methods for HNP monomer are introduced. Moreover, the "our own n-layered integrated molecular orbital and molecular mechanics"(ONIOM) method(TDDFT:universal force field(UFF)) is used to reveal the aggregation-induced emission(AIE) effect on the ESIPT process for HNP in crystal. Our results confirm that the ESIPT process happens upon the photoexcitation for the HNP monomer and HNP in crystal, which is distinctly monitored by the optimized geometric structures and the potential energy curves. In addition, the results of potential energy curves reveal that the ESIPT process in HNP will be promoted by the AIE effect. Furthermore, the highest occupied molecular orbital(HOMO) and lowest unoccupied molecular orbital(LUMO) for the HNP monomer and HNP in crystal have been calculated. The calculation demonstrates that the electron density decrease of proton donor caused by excitation promotes the ESIPT process. In addition, we find that the variation of atomic dipole moment corrected Hirshfeld population(ADCH) charge for proton acceptor induced by the AIE effect facilitates the ESIPT process. The results will be expected to deepen the understanding of ESIPT dynamics for luminophore under the AIE effect and provide insight into future design of high-efficient AIE compounds.
