Excited-state Intermolecular Proton Transfer Research Articles

Development of Controllable Hetero-Pauson-Khand Polymerization to Functional Stimuli-Responsive Poly(γ-lactam)s.

Polymers containing lactam structures play a crucial role in both natural biological systems and human life, and their synthesis, functions and applications are of utmost importance for biomimetics and the creation of new materials. In this study, we developed an efficient heterogeneous Pauson-Khand polymerization (h-PKP) method for the controlled synthesis of main-chain poly(γ-lactam)s containing α, β-unsaturated γ-lactam functionalities using readily available internal alkynes and imines. The molecular weights of the resulting poly(N-Ts/γ-lactam)s can be precisely controlled by adjusting the ratio of phenyl formate and nickel. These polymers exhibit high solid-state luminescence and demonstrate rapid and sensitive dual responsiveness to light and acid stimuli. They further demonstrate strong reactive oxygen species (ROS) generation capability. The unique dual-emission peaks observed in poly(N-H/γ-lactam)s obtained through post-treatment under acidic conditions demonstrate a mechanism of aggregation-induced intermolecular excited-state proton transfer specific to lactam structures. The efficient one-pot synthetic method for poly(γ-lactam) provides a novel strategy for constructing polymers with γ-lactam structures in the main chain and the simple and efficient post-modification method offer a versatile toolbox for functionalizing poly(γ-lactam)s to expand their potential applications.

Harvesting the tuning mechanism of strategic polychrome and white light emission in NapH dye based on excited state intermolecular proton transfer

Organic white light emitting (WLE) materials have sparked a research boom due to their promising applications in display devices, artificial lighting, and molecular sensors. However, the complex luminescence mechanism of full-spectra emitting materials has limited the development of white light materials with high stability and reproducibility. In this study, building on the full-spectra luminescent naphthimide dye (NapH) introduced by Xu et al., (Chin. Chem. Lett. 35(2024), 108348), we report the solvent-sensitive excited state proton transfer (ESPT) properties and white light emission mechanism in NapH. Our theoretical research results show that the ESPT process of NapH molecule is hindered in the low-polar solvent tetrahydrofuran (THF), so only the blue fluorescence from the Enol* is observed in the experiment. In contrast, in polar solvents such as water (H2O) and methanol (MeOH), the formation of strong intermolecular hydrogen bonds successfully initiates the ESPT process, leading to the dual fluorescence observed in experiments, with blue emission from the Enol* and red emission from the Nap anion. In essence, different solvent environments can adjust several emission colors. Furthermore, we theoretically verify that the optimal white light emission can be achieved when the mixed solvent ratio of dimethyl sulfoxide (DMSO) and dioxane (DIOX) is 5:5, which aligns well with experimental results. More importantly, we elucidate the specific WLE mechanism from multiple perspectives, including potential energy curves and electron spectra. Our work not only displays the interaction models of NapH molecule in various solvents, but also reveals the underlying luminescence mechanism, thus providing a valuable theoretical reference for the development and advancement of new white light materials.

Comparative Study of Fluorescence Emission of Fisetin, Luteolin and Quercetin Powders and Solutions: Further Evidence of the ESIPT Process.

Fisetin and Luteolin are important flavonoids produced in plants and known for their antioxidant, anti-inflammatory, neuroprotective, and analgesic properties. They are also good candidates for different types of biosensors. The model used to describe the fluorescence (FL) emission of these flavonoids involves an excited-state intermolecular proton transfer (ESIPT) process that causes a change in the molecule configuration and a corresponding decrease in the emission energy. Due to the different molecular structures of Fisetin and Luteolin, only one possible proton transfer within the molecule is allowed for each of them: transfer of the H3 proton for Fisetin and of the H5 for Luteolin. Here, we compare their calculated emission wavelengths, obtained using TDDFT/M06-2X/6-31++G(d,p), with their FL emission spectra measured on the corresponding powders and solutions and show that the experimental data are consistent with the presence of the ESIPT process. We also compare the emission wavelengths found for Fisetin and Luteolin with those calculated and measured for Quercetin, where, under photoexcitation, the transfers of both H3 and H5 protons are possible. We analyze the difference in the processes associated with the H3 and H5 proton transfers and discuss the reason for the predominance of the H5 proton transfer in Quercetin. Additionally, a new system of notation for flavonoid molecules is developed.

Substituent effects of halogens on the excited-state intermolecular proton transfer reactions.

Fluorescent aromatic urea compounds undergo excited-state intermolecular proton transfer (ESPT) in the presence of acetate anions to produce an excited state of the tautomer (T*) from the excited state of the complex (N*), resulting in dual fluorescence. Herein, we performed spectroscopic measurements of anthracen-1-yl-3-phenylurea derivatives with substituents, -CF3, -F, or -Cl, at the p-position of the phenyl group in the presence of acetate to investigate the substituent effects on the ESPT reaction and the deactivation processes of N* and T*. Kinetic analysis showed that the reverse ESPT rate constant (k-PT) depended on the respective substituents, suggesting that each substituent may influence the reverse ESPT process differently. In particular, since the electron-withdrawing properties of -F are estimated by the - I and + Iπ effects, it is plausible that -F has a slight electron-donating property and influences the reverse process from T* to N* in the excited state. This study shows that it is possible to control emission by selecting specific substituents in the ESPT system.

Tautomeric enhancement of 2-(1H-pyrazol-5-yl)pyridine in photoinduced proton transfer by water-assisted molecules

Theoretical insight of excited state proton transfer (ESPT) in 2-(1H-pyrazol-5-yl)pyridine abbreviated as PPP interacting with water wires: PPP(H2O)n where n = 13 has been presented in both static and dynamics studies. Explicit water molecules placed around PPP have been simulated to elucidate the intermolecular hydrogen bonding interactions between them. Hydrogen bond strengthening in the excited state (S1) has been verified by shorter bond distances and redshift of IR vibrational spectra involving the proton transfer (PT) process. Furthermore, on-the-fly excited state dynamics simulations of all complexes have been performed to provide detailed information on the PT mechanism. The dynamic results show that one water molecule added to the neighboring PPP as an intermolecular hydrogen bonding bridge can promote double excited state intermolecular proton transfer up to 36% compared with its intrinsic intramolecular hydrogen bond of the PPP system. Meanwhile adding a second or third water molecule could decrease the probabilities of PT. Especially in PPP(H2O)3, a rearrangement of water molecules is observed that PT occurs via one water molecule. Hence, the models with explicit water molecules interacting with PPP as intermolecular hydrogen bonding bridge are a great representative role played by water molecules of the PT process at the molecular level.

Comparative Analysis of Fluorescence Emission in Myricetin, Kaempferol, and Quercetin Powders and Solutions.

Myricetin is a flavonol with high antioxidant properties. In this research, the fluorescence emission of myricetin powder and its solutions in different solvents were measured and analyzed by comparing with the results of calculations. Comparison of the calculated and measured characteristic wavelengths allowed the identification of all the spectral features in the fluorescence spectra of myricetin powder and solutions with different concentrations. The computation was based on modeling the process of the excited state intermolecular proton transfer, which predicts the formation of tautomeric forms of the flavonol molecule. Characteristic emission wavelengths were obtained using TDDFT/M06-2X/6-31++G(d,p). To understand the influence of the hydroxyl groups in the B-ring of the flavonol molecule on the emission spectrum, we also compared the fluorescence spectra of myricetin with those of kaempferol and quercetin. Moreover, based on the analysis of the changes in the shape of the FL spectra with the concentration of the solution, a criterion for the complete dissolution of the flavonol powders was established, which is important for bioavailability of flavonoids.

Recognition of specific monosaccharides by fluorescence change through the suppression effect on excited-state intermolecular proton transfer reactions.

Pyrene-urea derivatives and acetate anions were used to investigate the excited-state intermolecular proton transfer (ESPT) reaction, where a molecule undergoes intermolecular proton transfer to form a tautomer species in the excited state. Since ESPT occurs when intermolecular hydrogen bonds exist between urea compounds and acetate species, we hypothesize that this reaction might be influenced by compounds with hydroxy groups. In this study, cyclodextrins, saccharides, and ethanol were examined to assess the effects of hydroxy groups on the ESPT reaction. After introducing various hydroxy compounds into the urea-acetate system in dimethylformamide, we observed differences in the fluorescence spectra and fluorescence decay curves. These differences indicate varying interactions between the hydroxy compounds and complexes, leading to distinct fluorescence lifetime behaviors, which makes fluorescence lifetime imaging technology particularly suitable.

Photochromism of phenazine-2,3-diol derivatives through excited state intermolecular proton transfer based on keto-enol tautomerization.

Photochromism through excited-state intermolecular proton transfer (ESInterPT) processes based on keto-enol tautomerization was found in phenazine-2,3-diol PD1 and its monoalkoxy derivative PD2 in a glassy matrix at 77 K: the colorless solutions of enol forms PD1-E and PD2-E at 298 K transformed into orange-colored solutions of keto forms PD1-K and PD2-K upon photoirradiation (λ = 385 nm) at 77 K. Furthermore, this report is the first to achieve the single-crystal X-ray structural analyses of phenazine-2,3-diol PD1 and its monoalkoxy derivative PD2, since the report on the synthesis of PD1 70 years ago. Indeed, it was found that PD1 and PD2 molecules exist in the keto form (PD1-K) and the enol form (PD2-E), respectively, in the crystal, and the neighboring PD1-K and PD2-E molecules are linked by one-dimensional intermolecular NH⋯O and OH⋯N hydrogen bonding, respectively. The fact suggests strongly that for PD1 and PD2, the formation of continuous intermolecular hydrogen bonding in aggregates such as in a glassy matrix at 77 K is involved in the keto-enol tautomerization of phenazine-2,3-diol derivatives based on ESInterPT. More interestingly, the color and the photoabsorption spectrum of the solids obtained by sublimation of crystals of PD2-E are similar to those for the crystals of PD1-K, indicating that the PD2 molecule exists in the keto form (PD2-K) in the solid of the sublimate. Therefore, this study provides a valuable insight for a greater understanding of the keto-enol tautomerization of diazaacene-diol derivatives and their photophysical properties in the solution and in the solid state.

π-Conjugation effects on excited-state intermolecular proton-transfer reactions of anthracene-urea derivatives in the presence of acetate anions.

This study investigated emissive urea compounds with an anthryl moiety on one side and a substituent group (biphenyl, naphthyl, benzyl, or cyclohexyl) on the other side across from the urea group. This was performed to determine the contribution of π-conjugation on a substituent group to excited-state intermolecular proton-transfer (ESPT) reactions in the presence of acetate anions. Fluorescence lifetime measurements revealed that the rate constant of the ESPT reaction from the normal form to the tautomer form increased with the length of the π-conjugation. Considering that there were a few differences among the wavelengths of the fluorescence maxima for the anthracene-urea derivatives in the presence of acetate anions, we observed that the extension of π-conjugation promoted tautomer formation. This maintained the energy levels of the normal and tautomer forms in the excited state. Furthermore, an anthracene-urea derivative without π-conjugation did not undergo a reverse ESPT reaction, implying that π-conjugation is considerably involved in the reverse ESPT reaction from the tautomer form to the normal form.

Exploring ESInterPT behaviors of water sensitive probes: 3HF derivative clusters

The fluorescent probe molecules 3-hydroxyflavone derivatives (PPC, EPC and MNC) have been synthesized and for the first time realized the dual color fluorescence imaging of lipid droplets (J. Am. Chem. Soc., 2021, 143, 3169–3179), and PPC and EPC demonstrate the fluorescent sensitivity to water. In this work, the excited-state intermolecular proton transfer (ESInterPT) process in the clusters of 3HF-D with water molecules ((3HF-D-(H2O)n, abbreviated as D-(H2O)n: n = 1, 2, 3, 1 + 2, 2 + 1; D = PPC, EPC, MNC) are investigated by means of the time-dependent density functional theory (TDDFT) method. Based on the calculated potential energy scheme, we found that the dynamics and thermodynamic of excited-state intermolecular proton transfer in D-(H2O)n are different and dependent on the number of water molecules, but all proton transfer processes follow the concerted mechanism. We further reveal the water sensitivity of PPC, EPC and MNC, and theoretically confirm the feasibility of PPC and EPC as water sensitive probes. Besides we found the water sensitivity is correlated with charge transfer degree. This work provides significant insight into fluorescent sensing water using 3HF derivatives which is useful for rational design of new organic fluorescent probes with excellent performance.

A fluorescent probe based on modulation of ESIPT signaling for the highly selective detection of N2H4 and cell-imaging

The broad occurrence of the hydrazine (N2H4) residues in aqueousenvironment is a potential threat to human health. Currently, the mainstream strategy for designing N2H4-specific probes is to functionalize a fluorophore with nucleophilic sites for the reductionreaction with N2H4. In this work, we designed and synthesized an excited-state intermolecular proton transfer (inter-ESPT) fluorescent dye(2-amino-4-(4-methoxyphenyl)-7,8-dihydro-5H-spiro[quinoline-6,2′-[1,3]dioxolane]-3-carbonitrilem, DQN) and used it as a probe to sense N2H4. DQN exhibits blue fluorescence in conventional solvents, which is assigned to its normal emission. In the presence of N2H4, the probe DQN can anchor the N2H4 molecule via hydrogen binding, enabling DQN to undergo inter-ESPT process and light up its tautomeric fluorescence. From this basis, an inter-ESPT-based method for N2H4 detection was established, offering high selectivity and sensitivity (11.5 nM). Furthermore, we demonstrated that the probe DQN can recognize the proteins in living cells, affording cell-imaging. This research provides a promising sensing strategy for monitoring N2H4 in water environments and this inter-ESPT dye is a powerful tool for cell-imaging.

Theoretical insights into ultrafast excited state proton transfer coupled with twisted intramolecular charge transfer mechanism in 7-(2ʹ-pyridyl)indole: Effect of hydrogen bonding

The ultrafast proton transfer (PT) process in the excited state of 7-(2′-pyridyl)indole (abbreviated as 7PyIn) has been elucidated by on-the-fly dynamics simulations using the algebraic-diagrammatic construction scheme of second order (ADC(2)) method under the resolution of identity (RI) approximation. The tautomers of 7PyIn alone and associated with an acetonitrile molecule in the 7PyIn-CH3CN complex are most likely found after the excited state intramolecular proton transfer (ESIntraPT) within an ultrafast time scale between 40 and 60 fs. While a methanol molecule in the complex of 7PyIn-CH3OH could establish both ESIntraPT and excited-state intermolecular proton transfer (ESInterPT). ESInterPT of 7PyIn-CH3OH possibly occurs through a concerted process via the intermolecular hydrogen bonding bridge of the methanol molecule almost twice faster than that of ESIntraPT. This slower circumstance of the ESIntraPT process found in 7PyIn-CH3OH may be caused by the competition between formations of the intramolecular and intermolecular hydrogen bonds between 7PyIn and methanol. In addition, after the accomplishment of excited state proton transfer (ESPT), the initiation of conical intersection could be taking place by the structural twist of 7PyIn. The geometries, energies, proton probabilities, and provided mechanisms via the dynamics simulations of 7PyIn and its solvent clusters exhibiting ESIntraPT and ESInterPT are explored to provide the dynamic pictures of the ESPT processes at the molecular level.

Stable white light emission from a single organic molecule via intermolecular hydrogen bond to excited-state intermolecular proton transfer

It is widely recognized that hybrid (organic/inorganic) light emitting diodes (LEDs) are of concern because they use an organic material instead of rare earth phosphors, but extending their lifetime remains challenging. To construct organic luminescent material with high photoluminescence quantum yield (PLQY), a compound named 1-(4-(tert-butyl)phenyl)-2-(4′-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1′-biphenyl]-4-yl)-1H-phenanthro[9,10-d]imidazole (TPBI-BPI) was synthesized by connect two imidazoles units. The PLQY of TPBI-BPI is 0.97 in acetonitrile. The white light emission (WLE) of TPBI-BPI in ethyl acetate solution containing acetic acid was observed, and a solvent-type organic/inorganic hybrid white LED device based on TPBI-BPI was prepared. The luminance efficiency, external quantum efficiency, correlated color temperature, K, and Ra (color rendering index) of the solvent-type WLED are 21.71 lm/W, 12.76%, 6329, and 83.2 at 39.90 mA, respectively. The Commission Internationale de l´Eclairage coordinate of the solvent-type WLED is (0.3135, 0.3507). In addition, the lifetime (T70) of the device can reach 130 h. This is due to the excited state intermolecular proton transfer between TPBI-BPI and acetic acid in ethyl acetate solution after UV illumination. This enables TPBI-BPI to obtain WLE and makes the WLED spectrally stable due to this process's dissipation of UV energy. This work provides a strategy to extend the lifetime of a hybrid LED.

Dynamics simulation of excited-state proton transfer reactions of 8-hydroxyquinoline with water clusters: A TD-DFT study

Detailed pictures of the excited-state proton transfer reactions of 8-hydroxyquinoline (8HQ) and its small clusters of water have been systematically investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods at B3LYP/TZVP and TD-B3LYP/TZVP level of theory, respectively. Intramolecular hydrogen bond (intraHB) and intermolecular hydrogen bond (interHB) interactions between 8HQ and water cluster become stronger in the first excited state (S1), confirmed by hydrogen bond distances and topological analysis. In addition, TD-B3LYP dynamics simulations have been elucidated and revealed that excited-state intramolecular proton transfer (ESIntraPT) and multiply excited-state intermolecular proton transfer (ESInterPT) reactions of these complexes can take place in the ultrafast time scale of femtoseconds. Increasing the number of water molecules may give rise to a barrier energy that is anti-correlated to the probability of tautomer species from phototautomerization, especially in 8HQ-W1 and 8HQ-W1+1. Moreover, water molecules initiate multiple proton transfer occurring through two- and three-step ESInterPT namely excited-state double proton transfer (ESDPT) and excited-state triple proton transfer (ESTPT) in which the interHBs are formed by rearrangement of water molecules of 8HQ-W2. This circumstance takes a longer time (up to 470 fs) compared to that of ESIntraPT. Thus, the simulated results from this study could provide insight into ESIntraPT and ESInterPT of phototautomerization and the significant photodynamics which could not be found from the experimental aspects of 8HQ and its solvent clusters.

White light generation by regulating hydrogen bond-sensitive ESPT of naphthalimide dyes

White light emitting systems of pure organic materials have attracted extensive research interest due to their better compatibility and functional scalability. The reported organic white light materials are mainly based on the multi-channel emission regulation of the compound itself or the mixing of multicolor luminescence materials, but studies on the dependence between multicolor luminescence and the external environment are lacking, which limits the application of these materials in areas such as identification and sensing. This paper reports that the 4- or 3‑hydroxyl-substituted naphthalimides NapH1 and NapH2 form intermolecular hydrogen bonds with adjacent molecules in the environment, and undergo excited-state intermolecular proton transfer under irradiation, resulting in blue-yellow or blue-red dual fluorescence emission, respectively. Since the two compounds have different two-color luminescence channels and the two-color intensity ratio is affected by the environment, and the intermolecular hydrogen bond is determined by the hydrogen bond receptor, polarity, and temperature in the environment, the full spectrum from blue to red light and white light emission can be obtained by adjusting the mixing ratio of the two dyes and the solvent polarity and the ambient temperature. This environmentally sensitive white emission is used to detect the alkalinity of different papers, and the dyed paper can be used as a test strip for acid-base vapor detection.

Excited-state proton transfer reaction of a pyrenylurea derivative in the ionic liquid 1-ethyl-3-methylimidazolium acetate

The present study investigated the effects of 1-ethyl-3-methylimidazolium acetate, an ionic liquid, on the excited-state intermolecular proton transfer reaction between 1-pyrene-1-yl-3-[4-(trifluoromethyl)phenyl]urea and acetate anion. Moreover, the fluorescence properties and kinetics of the excited-state intermolecular proton transfer reaction were examined in different ratios of dimethylsulfoxide and ionic liquid mixtures. Investigations revealed that the proton transfer reaction rate decreased in excess amount of the ionic liquid. Hence, this finding suggests that the slow reaction of urea compounds was related to the slow reorientation of the 1-ethyl-3-methylimidazolium acetate solvent.

A polystyrene-based ESIPT fluorescent polymeric probe for highly sensitive detection of chromium(vi) ions and protein staining.

A "two-step" preparation method of an excited-state intermolecular proton transfer (ESIPT) fluorescent polymer (f-PP) is reported here. The synthesis of f-PP involves the acetylation of polystyrene and a "multicomponent one pot" reaction. The as-prepared polymer bears a group of ESIPT fluorescent units, enabling it to exhibit high brightness, moderate solubility and ESIPT fluorescence. F-PP gives off tautomeric bright green fluorescence under UV-tamp and the dual-emission could be specifically suppressed by Cr(vi). This phenomenon cannot be elicited by other competing species. On this basis, an ESIPT polymeric probe-based method for the determination of Cr(vi) was developed, offering high sensitivity (19.5 nM) and selectivity. The f-PP was successfully used to detect Cr(vi) in real water samples by standard adding methods, indicating its application feasibility.

Micellization Turned on Dual Fluorescence and Room Temperature Phosphorescence by Pseudo-ESIPT in Thiadiazole Derivatives

Some luminophores cannot fluoresce from dilute solution, especially those that are highly flexible. By aggregation, the rigidity of these molecules increases allowing for photoluminescence. However, the enhanced rigidity and the intermolecular interactions can give rise to several high-energy excited states, and since they can fluoresce only from the lowest energy excited state, known as the Kasha rule, the energy surplus is lost to the surroundings. In the pursuit of developing efficient light harvesting strategies from the higher energy excited states, it is necessary to look upon the effects not only at the level of nanometric molecules themselves but also of their supramolecular assemblies. Herein, we pinpoint the impact of poor conjugated moieties over the chromophore units, as well as the optical phenomena emerging at the supramolecular level. The molecular design consists of the S-alkylation of 5-amino-1,3,4-thiadiazole-2-thiol with permethylated silicone or hydrocarbons. The synthesized compounds display excited state intermolecular proton transfer (pseudo-ESIPT), blue and green fluorescence, and near-infrared phosphorescence at room temperature.

Protein-activated and FRET enhanced excited-state intermolecular proton transfer fluorescent probes for high-resolution imaging of cilia and tunneling nanotubes in live cells

Excited-state intermolecular proton transfer (inter-ESPT) fluorescent probes responsive to specific bioactive molecules should be greatly promising for protein sensing, DNA mutation simulating and cellular process regulating. However, the inter-ESPT molecules are recessive ESPT fluorophores, which need the assistance of other molecules with both hydrogen-bond accepting and donating abilities to turn on the tautomeric fluorescence. Valid design strategies to create powerful inter-ESPT fluorescent probes are poorly developed, particularly for proteins as targets. We recently reported a unique supramolecular strategy to trigger the inter-ESPT process based on the probe-protein recognition by H-bonding and to image protein-based subcellular structures in live cells. Herein, we found that our inter-ESPT probes (inter-ESPT-01) bearing a 2-amino-3-cyanopyridine scaffold can anchor proteins and light up the “invisible” ESPT state, so as to image the proteins or the protein-based subcellular organelles. More importantly, the inter-ESPT emission of inter-ESPT-01 can be significantly enhanced by the FRET process between amino and imino tautomers, endowing the inter-ESPT-01 probes with super-bright tautomeric fluorescence. The expressed proteins Ecallantide and MarTX were selected as the models to light up the inter-ESPT fluorescence of the probes and revealed that the inter-ESPT process can be triggered by the specific probe-protein recognition events. In the use of the super-bright inter-ESPT fluorescence, not only the proteins, but also the protein-based cilia and tunneling nanotubes (TNTs) can be specifically visualized in living cancer cells. Furthermore, such recognition-driven strategy allows us to construct a unique inter-ESPT probe to track and image specific endogenous proteins in live cells, highlighting the potential of inter-ESPT fluorogens as novel intelligent biomaterials.

Unraveling the Mechanistic Pathway for the Dual Fluorescence in Green Fluorescent Protein (GFP) Chromophore Analogue: A Detailed Theoretical Investigation.

The photophysical properties of the para-sulfonamide (p-TsABDI) analogue of the green fluorescent protein (GFP) chromophore with both proton donating and accepting sites have been exploited in polar solvents to understand the origin of the unusual dual fluorescence nature of the chromophore. In the polar solvents, the compound undergoes structural rearrangement upon photoexcitation, leading to the ultrafast excited-state intermolecular proton transfer (ESIPT) phenomenon at the S1 surface. In this work, we employed both the static electronic structure calculations and on-the-fly molecular dynamics simulation to unravel the underlying reason for this peculiar behavior of the p-TsABDI analogue in polar solvents. To represent this adequately and provide extensive information on the ESIPT mechanism mediated by the solvent molecules, we considered explicit solvent molecules using the integral equation formalism variant of polarizable continuum (IEFPCM) model. From the static calculation analysis, we can conclude that the dual emissive behavior of the compound is ascribed to the proton transfer (PT) phenomena in the excited-state. However, based on the static calculation exclusively, it is hard to ascertain the mechanistic pathway of the PT phenomena. Hence, to investigate the dynamics and reaction mechanism for the ESIPT process, we performed the on-the-fly dynamics simulation for p-TsABDI in solvent clusters. Dynamics simulation results reveal that, based on the time lag between all the proton transfer processes, the ESIPT mechanism occurs in a stepwise manner from the benzylidene moiety of the chromophore to its imidazolinone moiety. However, the nonexistence of crossings between the S1- and S0-states confirms the PT characteristics of the reactions.