Proton-Transfer and Photo-Deamination Reactive Mechanisms Studies of Amines Compounds

Yang, Yunfan

doi:10.4208/cicc.2017.v5.n2.2

Cited by 7 publications

(2 citation statements)

References 24 publications

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“…Similar experimental results were obtained upon photolysis at 355 and 223.1 nm, demonstrating that the reaction rate decreases in the order 355 > 266 > 223.1 nm for the photolysis wavelengths and in the order cyclohexane ≈ acetonitrile > water for the type of solvent. Thus, it appears that the tautomeric hydrogen transfer process in DMMP occurs at lower excited states (i.e., S 2 , S 1 , and/or T n excited states), in agreement with previously reported ESIPT reaction systems due to the hydrogen-bonding chain between solute and solvents. − …”

Section: Resultssupporting

confidence: 89%

UV and Resonance Raman Spectroscopic and Theoretical Studies on the Solvent-Dependent Ground and Excited-State Thione → Thiol Tautomerization of 4,6-Dimethyl-2-mercaptopyrimidine (DMMP)

et al. 2018

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The vibrational spectra of 4,6-dimethyl-2-mercaptopyrimidine (DMMP) in acetonitrile, methanol, and water were assigned by resonance Raman spectroscopy through a combination of Fourier-transform infrared spectroscopy (FT-IR), FT-Raman UV-vis spectroscopy, and density functional theoretical (DFT) calculations. The FT-Raman spectra show that the neat solid DMMP is formed as a dimer due to intermolecular hydrogen bonding. In methanol and water, however, the majority of the Raman spectra were assigned to the vibrational modes of DMMP(solvent) ( n = 1-4) clusters containing NH···O hydrogen bonds. The intermolecular NH···O hydrogen bond interactions, which are key constituents of the stable DMMP thione structure, revealed significant structural differences in acetonitrile, methanol, and water. In addition, UV-induced hydrogen transfer isomeric reactions between the thione and thiol forms of DMMP were detected in water and acetonitrile. DFT calculations indicate that the observed thione → thiol tautomerization should occur easily in lower excited states in acetonitrile and water.

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Section: Resultssupporting

confidence: 89%

UV and Resonance Raman Spectroscopic and Theoretical Studies on the Solvent-Dependent Ground and Excited-State Thione → Thiol Tautomerization of 4,6-Dimethyl-2-mercaptopyrimidine (DMMP)

et al. 2018

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“…These highly electronegative atoms interact through electrostatic and dispersive forces, which contributes to the formation of HBs. Many studies have shown that upon photoexcitation of HB systems, the donor and acceptor molecules reorganized due to the significant difference in charge distribution of different electronic states, which made for the occurrence of the excited-state intramolecular proton transfer (ESIPT) reaction. − …”

Section: Introductionmentioning

confidence: 99%

Effects of Twisted Intramolecular Charge Transfer Behavior on Excited-State Intramolecular Proton Transfer Reactions of Methyl Benzoate Derivatives in Water Solution

et al. 2022

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Many methyl benzoate derivatives were found to show intramolecular charge transfer (ICT), intramolecular proton transfer, and other properties, which have extensive applications in lasing media, metal ion sensors, active materials, and fluorescence probe fields. However, the intrinsic relationship and reaction mechanism between the excited-state intramolecular proton transfer (ESIPT) and ICT between methyl benzoate derivatives with different substituents have not been explained. In this paper, the density functional theory and time-dependent density functional theory methods were used to study the ESIPT and ICT behaviors of p-aminosalicylic acid methyl ester and p-dimethylaminosalicylic acid methyl ester in water and obtain the intrinsic interaction between the two behaviors. The bond parameters, infrared spectra, reduced density gradient scatter plots, and topological analyses of these two molecules in the ground state and excited state were analyzed to confirm the enhancement of the excited-state intramolecular hydrogen bonds (IHBs). The simulated absorption and fluorescence spectra of these molecules agreed well with the experimental values. Based on the optimized structure, we also plotted the natural transition orbitals, electron density difference maps, and frontier molecular orbitals (FMOs), which showed the changes of the charge distribution of these molecules intuitively upon photoexcitation. In addition, we also found that the degree of IHB enhancement with −N(CH3)2 substituents was less than that with −NH2, reflecting an inhibition effect of twisted intramolecular charge transfer (TICT) on ESIPT reaction. This conclusion was confirmed by our calculated potential energy curves. This work may better deepen the comprehension of the intrinsic relationship between ESIPT and TICT behavior and sequentially provide better theoretical guidance for the synthesis of fluorescent molecules related to these two behaviors.

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Why the lowest electronic excitations of rhodamines are overestimated by time‐dependent density functional theory

Zhou

2018

Int J of Quantum Chemistry

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Rhodamines are widely used as laser dyes and fluorescent probes due to their excellent photophysical and photochemical properties. Previous theoretical studies have shown that the lowest excitation energies of rhodamines are overestimated systematically by time‐dependent density functional theory (TDDFT). In this study, we first perform a TDDFT benchmark study with 21 exchange‐correlation functionals (XCFs) on a series of rhodamines and assess the performance of different types of functional in predicting the lowest excitation energies of rhodamines. Statistical results reveal that the fraction of Hartree–Fock exchange (HFX) included in the XCF is a key parameter. Pure functionals without HFX offer the best performance, with the mean absolute error (MAE) of approximately 0.1 eV. However, they provide a wrong order of the lowest nπ* and ππ* states and suffer from charge‐transfer contamination problem for rhodamine dyes (RDs) in zwitterionic form. Among the other tested functionals, popular global hybrid functional B3LYP delivers the smallest MAE of 0.36 eV. We then perform calculations with second‐order algebraic diagrammatic construction and extended multiconfiguration quasi‐degenerate perturbation theory at second‐order of PT expansion methods. Remarkably accurate results are obtained. We confirm that the reason for the overestimation of the lowest excitation energies of RDs by TDDFT method should be similar to that of cyanine dyes, and that double excitations contribute to this systematic deviation.

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Proton-Transfer and Photo-Deamination Reactive Mechanisms Studies of Amines Compounds

Cited by 7 publications

References 24 publications

UV and Resonance Raman Spectroscopic and Theoretical Studies on the Solvent-Dependent Ground and Excited-State Thione → Thiol Tautomerization of 4,6-Dimethyl-2-mercaptopyrimidine (DMMP)

UV and Resonance Raman Spectroscopic and Theoretical Studies on the Solvent-Dependent Ground and Excited-State Thione → Thiol Tautomerization of 4,6-Dimethyl-2-mercaptopyrimidine (DMMP)

Effects of Twisted Intramolecular Charge Transfer Behavior on Excited-State Intramolecular Proton Transfer Reactions of Methyl Benzoate Derivatives in Water Solution

Why the lowest electronic excitations of rhodamines are overestimated by time‐dependent density functional theory

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