Theoretical characterization of intramolecular proton transfer in the ground and the lowest-lying triplet excited states of 1-amino-3-propenal: a methodological comparison

In this paper, we described the synthesis and characterization of new diphenylethylene bearing imino group. We concentrated particularly on the investigation of the possibility of the excited state intramolecular charge transfer (ESIPT) of the new dyes experimentally and theoretically. The absorption and fluorescence spectroscopy of the dyes were determined in various solvents. The results showed that the maximal absorption wavelength of 2-[(4'-N,N-dimethylamino-diphenylethylene-4-ylimino)methyl]phenol (C1) and 4-[(4'-N,N-dimethylamino-diphenylethylene-4-ylimino)methyl]phenol (C2) exhibited almost independence on the solvent polarity. While as contrast, the maximal fluorescence wavelength of the dyes showed somewhat dependence on the solvent polarity. In particular, C1 displayed well-separated dual fluorescence spectroscopy. The second fluorescence peak was characterized with an "abnormal" fluorescence emission wavelength in aprotic solvents with large Stokes shift (ca. 140 nm in THF), which was much more than normal Stokes shift (ca. 30 nm in THF). This emission spectroscopy could be assigned to ESIPT emission. On the other hand, the ESIPT fluorescence of C1 was much reduced or lost in the protic solvents. While, only normal fluorescence emission was detected in various solvents. Although the absorption maxima of C1 exhibited about 10 nm red-shift with respect to those of C2, the normal fluorescence maxima of C1 and C2 were almost identical in various solvents. These results suggested that C1 could undergo ESIPT, but C2 was not able to proceed ESIPT. The molecular geometry optimization of phototautomers in the ground electronic state (S 0 ) was carried out with HF method (Hartree-Fock) and at DFT level (Density Functional Theory) using B3LYP both, while the CIS was employed to optimize the geometries of the first singlet excited state (S 1 ) of the phototautomers of C1 and C2 respectively. The properties of the ground state and the excited state of the phototautomers of C1 and C2, including the geometrical parameter, the energy, the frontier orbits, the Mulliken charge and the dipole moment change were performed and compared completely. The data were analyzed further based on our experimental results. Furthermore, the absorption and fluorescence spectra were calculated in theory and compared with the measured ones. The rate constant of internal proton transfer (9.831×10 11 s -1 ) of C1 was much lower than that of salicylidene methylamine (C3, 2.045×10 15 s -1 ), which was a typical Schiff base compound and was well demonstrated to undergo ESIPT easily under photoexcitation.

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Excited State Intramolecular Proton Transfer of New Diphenyl‐ ethylene Derivatives Bearing Imino Group: A Combination of Experimental and Theoretical Investigation

Gao

Zhong

Wang

et al. 2010

Chin. J. Chem.

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A CASSCF/CASPT2 insight into excited‐state intramolecular proton transfer of four imidazole derivatives

Wang

Guo

et al. 2015

J Comput Chem

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Excited-state intramolecular proton transfer (ESIPT) of four imidazole derivatives, 2-(2'-hydroxyphenyl)imidazole (HPI), 2-(2'-hydroxyphenyl)benzimidazole (HPBI), 2-(2'-hydroxyphenyl)-1H-phenanthro[9,10-d]imidazole (HPPI) and 2-(2'-hydroxyphenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole (HPPPI), were studied by the sophisticated CASSCF/CASPT2 methodology. The state-averaged SA-CASSCF method was used to optimize their geometry structures of S0 and S1 electronic states, and the CASPT2 calculations were used for the calibration of all the single-point energies, including the absorption and emission spectra. A reasonable agreement is found between the theoretical predictions and the available experimental spectral data. The forward ESIPT barriers of four target compounds gradually decrease with the increase of molecular size. On the basis of the present calculations, it is a plausible speculation that the larger the size, the faster is the ESIPT rate, and eventually, HPPPI molecule can undergo a completely barrierless ESIPT to the more stable S1 keto form. Additionally, taking HPI as a representative example, the radiationless decays connecting the S0 and S1 /S0 conical intersection structures were also studied by constructing a linearly interpolated internal coordinate (LIIC) reaction path. The qualitative analysis shows that the LIIC barrier of HPI in the keto form is remarkably lower than that of its enol-form, indicating that the former has a big advantage over the latter in the nonradiative process.

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Numerical solving of the vibrational time-independent Schrödinger equation in one and two dimensions using the variational method

Stare

Mavri

2002

Computer Physics Communications

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Theoretical characterization of intramolecular proton transfer in the ground and the lowest-lying triplet excited states of 1-amino-3-propenal: a methodological comparison

Cited by 11 publications

References 93 publications

Excited State Intramolecular Proton Transfer of New Diphenyl‐ ethylene Derivatives Bearing Imino Group: A Combination of Experimental and Theoretical Investigation

Excited State Intramolecular Proton Transfer of New Diphenyl‐ ethylene Derivatives Bearing Imino Group: A Combination of Experimental and Theoretical Investigation

A CASSCF/CASPT2 insight into excited‐state intramolecular proton transfer of four imidazole derivatives

Numerical solving of the vibrational time-independent Schrödinger equation in one and two dimensions using the variational method

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