Different mechanisms of ultrafast excited state deactivation of coumarin 500 in dioxane and methanol solvents: experimental and theoretical study

Zhao

Cheng

et al. 2019

J Chinese Chemical Soc

Given the tremendous potential applications of excited state intramolecular proton transfer (ESIPT) systems, ESIPT molecules have received widespread attention. In this work, based on density functional theory (DFT) and time‐dependent DFT (TDDFT) methods, we theoretically study the excited state dynamical behaviors of salicyladazine (SA) molecules. Our simulated results show that the double intramolecular hydrogen bonds of SA are strengthened in the S1 state via exploring bond distances, bond angles, and infrared (IR) vibrational spectra. Exploring the frontier molecular orbitals (MOs), we confirm that charge redistributions indeed have effects on excited state dynamical behaviors. The increased electronic densities on N atoms and the decreased electronic densities on O atoms imply that charge redistribution may trigger the ESPT process. Analyzing the constructed S0‐state and S1‐state potential energy surfaces (PESs), we confirm that only the excited state single proton transfer reaction can occur although SA possesses two intramolecular hydrogen bonds. In this work, we clarify the specific ESIPT mechanism, which may facilitate developing novel applications based on the SA system in future.

Section: Resultsmentioning

confidence: 99%

A theoretical investigation on the excited state intramolecular single or double proton transfer mechanism of a salicyladazine system

Zhao

Cheng

et al. 2019

J Chinese Chemical Soc

“…43 Unlike all the previous theoretical work of P.Y. Herein, it is worth mentioning that the TDDFT method has become a very useful tool to investigate the hydrogen bonding in the excited states of the hydrogen-bond system theoretically, [47][48][49][50][51][52][53][54][55][56][57][58] even though this kind of calculations are very time-consuming. All the ground-stated geometries of all the relative structures were optimized without constraint based on DFT methodology, in addition, vibrational frequencies were analysed at the optimized forms to conrm that all these congurations corresponds to the local minima on the S 0 potential energy surface (PES).…”

Section: Computational Detailsmentioning

confidence: 99%

“…3) in DCM solvent. [47][48][49][50][51][52][53][54][55][56][57][58] Particularly, the frontier molecular orbitals (MOs) can provide information about properties of excited-stated structures on qualitative discussion of charge distribution. 101 enol-enol form.…”

Section: Electronic Spectra and Frontier Molecular Orbitals (Mos)mentioning

confidence: 99%

Detailed theoretical investigation on ESIPT process of pigment yellow 101

Zhou

et al. 2016

RSC Adv.

Based on density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods, the detailed excited state intramolecular proton transfer (ESIPT) mechanism of 2,2 0 -dihydroxy-1,1 0naphthalazine (P.Y. 101) has been investigated theoretically. Unlike previous theoretical investigation of P.Y. 101, our calculated results not only reproduce the absorption and fluorescence spectra reported in the previous experiment, but also were completed with considering solvent effect. It further demonstrates that the TDDFT theory we adopted is very reasonable and effective. The calculations of main bond lengths and bond angles involving in the hydrogen bondings (O 1 -H 2 /N 3 and O 4 -H 5 /N 6 ) as well as the infrared vibrational spectra and as well as the calculated hydrogen bonding energies demonstrated the intramolecular hydrogen bond was strengthened in the S 1 state. In addition, qualitative and quantitative intramolecular charge transfer based on the frontier molecular orbitals provided the possibility of the ESIPT reaction. The potential energy surfaces of ground state and the first excited state have been constructed to illustrate the ESIPT mechanism. Based on our calculations, the equilibrium ESIPT process exists in the S 1 state. And after the radiative transition, reversed GSIPT can also occur in the S 0 state.

“…Then, in the process of ESIPT reaction, enol* can convert into the keto* via the translocation of proton and the alteration of electronic regions. In experimental phenomenon, the fluorescence band of enol* exhibits the normal Stokes shift, while the emission peak of keto* one owns the larger Stokes shift that can be as large as 6000 to 12 000 cm −1 . In fact, the interest to the ESIPT process is not limited to academic field.…”

Section: Introductionmentioning

confidence: 99%

A detailed theoretical simulation about the excited state dynamical process for the novel (benzo[d]thiazol‐2‐yl)‐5‐(9H‐carbazol‐9‐yl)phenol molecule

J of Physical Organic Chem

Cheng

et al. 2019

Given that molecular excited state dynamical process plays important roles in designing and developing novel applications in recent years. In this work, based on density functional theory (DFT) and time‐dependent density functional theory (TDDFT) methods, we theoretically explored the novel (benzo[d]thiazol‐2‐yl)‐5‐(9H‐carbazol‐9‐yl)phenol (HBT‐Cz) system about its excited state behaviors. Via simulating the electrostatic potential surface (EPS) of HBT‐Cz structure, we confirm the formation of intramolecular hydrogen bond O2—H3···N4 in the S0 state. Our theoretical dominating bond lengths, bond angles, and the infrared (IR) vibrational spectra involved in hydrogen bond demonstrate that O2—H3···N4 should be strengthened in the S1 state. Upon the photoexcitation, we find the charge transfer characteristics around hydrogen bonding moieties play important roles in facilitating excited state intramolecular proton transfer (ESIPT) process. Via constructing potential energy curves, we confirm the ESIPT reaction that further explains previous experimental phenomenon. Moreover, we also search the S1‐state transition state (TS) structure along with ESIPT path, based on which we simulate the intrinsic reaction coordinate (IRC) path. Combing with the atom‐centered density matrix propagation (ADMP) molecular dynamics simulation, we further confirm the ESIPT mechanism presented in this work. We sincerely hope that our theoretical work could guide novel applications based on HBT‐Cz system in future.