Effect of Different Substituted Groups on Excited-State

Article pubs.acs.org/JPCC

Effect of Different Substituted Groups on Excited-State Intramolecular Proton Transfer of 1‑(Acylamino)-anthraquinons Yanzhen Ma,† Yunfan Yang,†,‡ Ruifang Lan,† and Yongqing Li*,†,‡ †

Department of Physics, Liaoning University, Shenyang 110036, People’s Republic of China State Key Lab of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China

‡

ABSTRACT: This study uses density functional and timedependent density functional theory to investigate excited-state intramolecular proton transfer (ESIPT) reactions of 1-(acylamino)-anthraquinons (AYAAQs). We report that hydrogen-bond intensity in excited states is affected by the different AYAAQs substituted groups in ethanol for the first time. Absorption and emission spectra were also calculated and show that the changed AYAAQs spectra can be explained perfectly by combining the AYAAQs potential energy curves. The theoretical spectral values show good agreement with experimental results. The theoretical calculations indicate that proton transfer reactions can be implemented in the first excited (S1) state. The hydrogen-bond strengthening mechanism was confirmed, where hydrogen-bond interaction acts as the driving force for the ESIPT reactions. Therefore, ESIPT reactions are more likely to occur from AAAQ → CAAQ → DCAQ → TFAQ molecules, which are different substituted derivatives. occurring in some organic molecules, such as flavanols, chromones, and benzazoles.38 The reaction process can be considered as the four-level circle model shown in Scheme 1. The 1-(acylamino)-anthraquinons (AYAAQs) compounds are steady normal structures in the ground-state S0(N), and photo induced process causes S1(N) to undergo an ultrafast ESIPT

1. INTRODUCTION Hydrogen bonds occur in many natural substances and are an extremely common and important interaction. The hydrogen bond (X−H···Y) comprises the proton donor group, X, and the proton acceptor group, Y. Generally, X−H is acidic, whereas Y is basic. Hydrogen bonds are widely found in many important substances, such as amino acids, water, alcohols, proteins, acids, etc.1−5 Hydrogen-bond interactions have received extensive research attention, because they play a crucial role in chemistry, biology, and biochemistry.6−12 Excited-state proton transfer (ESPT) was first observed in 1956 in an experimental study of salicylic acid.13 Subsequently, both intramolecular and intermolecular photo induced proton transfer reactions have been widely investigated using theoretical and experimental methods.14−23 The ESIPT reaction is an ultrafast process occurring in the subpicosecond time scale, where the proton transfer pathway is linked by a hydrogen bond, and the proton donor and acceptor groups are in close proximity.24 The driving force for ESIPT reactions can be provided by hydrogen-bonding interaction,25,26 and different substituents have important effects on the ESIPT process potential barriers and fluorescent radiation of the molecules, which in turn changes the photochemical and photophysical properties of the molecules.27−29 These property changes can be extensively applied to fluorescent sensing technologies, fluorescence imaging, and organic light emitting diodes (OLEDs).30−35 ESIPT processes have been extensively investigated, due to their importance in chemistry, biology, and biochemistry,36,37 with ESIPT reactions frequently © XXXX American Chemical Society

Scheme 1. Potential Curves for AYAAQs S0 and S1 States along the ESIPT Coordinatea

The KS0 and KS1 denote keto forms in the ground and first excited states, respectively. a

Received: February 22, 2017 Revised: June 29, 2017 Published: June 29, 2017 A

DOI: 10.1021/acs.jpcc.7b01726 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C

Figure 1. Normal and keto forms of AAAQ, CAAQ, DCAQ, and TFAQ. “−” represents that AAAQ and CAAQ do not exist in keto forms.

reaction along with dual fluorescence radiative transition. In general, ESIPT reactions show intramolecular charge transfer (ICT), which will give rise to a distinct fluorescent bathochromic. However, some ESIPT mechanism reactions are complicated. The mechanisms of proton transfer, such as the sequence for a two-proton transfer system, the mode of proton transfer, etc., cannot be obtained by spectrum technology alone.39−44 Therefore, we provide a detailed examination of ESIPT dynamical mechanisms of ESIPT reactions based on theoretical calculations. Previous studies have shown AYAAQs double fluorescence, and the effect of different solvents on the short singlet excitedstate lifetimes and ESIPT reaction of AYAAQs has been investigated.45−49 The current study explores the effect of different substituted groups on the ESIPT reactions of AYAAQs in ethanol solvent. We believe that the occurrence of ESIPT reactions will depend on the intensity of hydrogen bonds linked with proton transfer reactions. It is significant that these derivatives presented different photochemical information in the corresponding electronic spectra in this experiment. Nagaoka et al. proposed the nodal plane model that delocalized lone π electrons facilitate rearrangement of the bonds, which induced ESIPT reactions in some AYAAQs derivatives.50,51 Different substituents have different effects to the ESIPT reactions. In AYAAQs systems, electron-donating groups are not favorable to delocalize lone π electrons on the benzene ring, such as the methyl group. Rather, contrary electronwithdrawing groups facilitate the delocalization of lone π electrons, such as the trifluoromethyl group. Therefore, to further clearly observe the extent of ESIPT of AYAAQs molecules with different substituents, we investigate how these different substituent groups of derivatives affect proton transfer reactions. To better explain the phenomena, considerable theoretical research was also conducted. In the current work, we use density functional (DFT) and the time-dependent density functional theory (TDDFT) methods combined with B3LYP/6-31+g(d) to optimize AYAAQs molecule structures in the S0 and S1 states, and calculate the vertical excitation energy, vibrational spectra (IR), hole−electron distance, integral of overlap of hole−electron, natural population analysis (NPA) of charges on N atoms, and the potential energy curve. We can derive a reasonable explanation for AYAAQs systems from these results.

by electrostatic force, DFT and TDDFT methods incorporating dispersion correction were applied to investigate hydrogenbond dynamic behaviors in the S0 and S1 states, respectively. To simulate the experimental conditions, we select the polarizable continuum model (PCM) using the integral equation formalism variant (IEFPCM) solvent model, with dielectric constant of ethanol solvent, ε = 24.3.56−58 The IEFPCM solvent model is a PCM model performed for different mathematical models including consideration of the polar solvent effect. However, the default linear response model cannot precisely estimate the real transition energies. Therefore, the effective state specific method was performed to calculate the solvent nonpolarity. In the process of optimizing AYAAQs geometric structures, the bond length, bond angle, and dihedral angle were not limited. We also calculated AYAAQs frequency and found that virtual frequencies of all of the structures were nonexistent. Therefore, the optimized structures were the most stable structures. Hydrogen-bond interaction changes can be obtained by calculating the bond parameters and IR spectra of the hydrogen-bond moiety. AYAAQs potential energy surfaces in the S0 and S1 states were scanned by increasing the N1−H1 bond length for a fixed step size. The N1−H1 bond length range was 0.92−2.42 Å in the S0 state and 0.96−2.46 Å in the S1 state. To precisely clarify the mechanism strengthening the AYAAQs hydrogen bond, the reduced density gradient (RDG) function was used to analyze nonbonding interaction intensity and type, and RDG isosurfaces were produced using VMD software.59,60 AYAAQs electronic excitation types were confirmed from the hole−electron distribution using the TDDFT/CAM-B3LYP method and 6-31+g(d) basis set.

3. RESULTS AND DISCUSSION 3.1. Geometric Structures of AYAAQs. This study combined DFT and TDDFT methods with the B3LYP function and 6-31+g(d) basis set to optimize AYAAQs in the S0 and S1 states. Figure 1 shows the normal and keto structural forms of AAAQ, CAAQ, DCAQ, and TFAQ. AYAAQs geometric structures were optimized without constraints on bonds, angles, and dihedral angles, and AYAAQs frequency was not virtual. Therefore, all geometric configurations are local minimum points. For descriptive convenience, we labeled specific AYAAQs atoms as shown in Figure 1, and the corresponding hydrogenbond parameters are shown in Table 1. AAAQ and CAAQ changed from S0(N) to S1(N) upon photoexcitation, N1−H1 bond length in the S0 state (1.02 Å) increased significantly in the S1 state (1.05 Å), and O1−H1 bond lengths reduced from 1.84 and 1.83 Å to 1.66 and 1.63 Å, respectively. The shorter intramolecular hydrogen-bond lengths indicate the hydrogen bonds were enhanced in the S1 state. Regarding the bond angles, the O1−H1−N1 bond angle tends to 180°, which

2. COMPUTATIONAL DETAILS This Article calculated all geometrical parameters on the basis of the DFT and TDDFT methods, the Becke’s three-parameter hybrid exchange functional with Lee−Yang−Parr gradientcorrected correlation functional (B3LYP), and the 6-31+g(d) basis set using the Gaussian 09 program suite.52−55 To accurately investigate intramolecular weak interactions induced B


Article


not only strengthened in the S1 state with photoinduced processes, but the hydrogen-bond interaction is also gradually enhanced from AAAQ → TFAQ forms with different substituted groups. 3.2. AYAAQs Vibration and Electronic Spectra. The discrete transition data given by the theoretical calculation and the continuous absorption curve given by the experiment are completely different. Therefore, to correspond to the experimental spectrum, we have broadened the transition data (transition energies, oscillator strengths, and full width at half-maximum (fwhm)) obtained by the theoretical calculation into band shape. In the Gaussview program, the electronic spectra (Figure 3) and vibration spectra (Figure 2) are broadened by the default Gaussian function and Lorentz function. Gaussian function:

Table 1. Main Bond Lengths and Angles for AYAAQs Derivative Structures in the S0 and S1 Statesa AAAQ

CAAQ

DCAQ

TFAQ

S0 S1(N) KS1 S0 S1(N) KS1 S0 S1(N) KS1 S0 S1(N) KS1

H1−N1b

H1−O1b

bond angle

1.02 (1.02) 1.05 (1.05)

1.84 (1.86) 1.66 (1.65)

133.7 (132.1) 145.6 (145.8)

1.02 1.05

1.83 1.63

133.3 146.3

1.02 1.06 1.58 1.02 1.07 1.63

1.87 1.62 1.04 1.84 1.58 1.02

129.3 145.3 149.9 130.9 147.6 148.4

a

Bond lengths are in angstroms, and bond angles are in degrees. Calculated bond lengths and angles including the dispersion correction are shown in parentheses.

b

G(w) =

2 2 1 e−(w − wi) /2c c 2π

where suggests the hydrogen bond is more stable, in the S1 state, and the O1−H1 bond lengths for of DCAQ and TFAQ reduced from 1.87 and 1.84 Å to 1.62 and 1.58 Å, respectively. Thus, the hydrogen bonds of these structures were strengthened in the S1 state. The O1−H1 bond lengths were in decreasing order AAAQ (1.66 Å) → CAAQ (1.63 Å) → DCAQ (1.62 Å) → TFAQ (1.58 Å) in the S1 state. To verify the calculation, the dispersion correction DFT-D3 was considered in the geometry optimization of the AAAQ molecule, and the H1−N1 and H1− O1 bond lengths and the O1−H1−N1 bond angle are shown in parentheses in Table 1. The dispersion correction is almost negligible. Therefore, the selected methods are reliable, and the hydrogen-bond interaction intensity increases from AAAQ → TFAQ forms, as shown above. The N−H···O hydrogen bond is

c=

FWHM 2 2 ln 2

Lorentz function: L(w) =

fwhm 1 2 2π (w − wi) + 0.25 × fwhm 2

where the w is the abscissa of the spectrum, and wi is the excitation energy corresponding to the electronic excitation of interest. The “i” represents electronic excitation from the first to the nth, and the default value of fwhm (full width at halfmaximum) in Gaussview is 0.4 eV for portrayal of electronic spectra. However, the value of fwhm of drawing infrared vibration spectra should be set as a small enough value (0.017

Figure 2. Infrared vibrational spectra for the N−H bond in the S0 and S1 states of AYAAQs molecules. C


Article


Figure 3. AYAAQs systems absorption and emission spectra based on the TDDFT/B3LYP/6-31+g(d) computation method. Abs. = absorption; Flu. = fluorescence emission of the normal structures; and Flu PT. = fluorescence emission of the keto structures; the vertical lines represent the corresponding experimental value.

435.98 nm) and 425.8 nm, respectively, and the corresponding fluorescence emission peaks are 537.7 (526.56 nm) and 527.8 nm, respectively. Thus, the Stokes’ shifts are 101.1 and 102 nm, respectively. The experimental absorption peaks were approximately 405 and 395 nm, and emission peaks are 525 and 520 nm, respectively. Thus, the chosen calculation method is reliable and shows good agreement with the experimental results. In contrast to TFAQ, AAAQ and CAAQ fluorescence emission spectra are at relatively short wavelengths; hence their Stokes’ shifts are much smaller than that of TFAQ. The DCAQ molecule has an absorption peak at 421 nm, but has two fluorescence emission peaks, 517 and 668 nm. Thus, DCAQ exhibits dual fluorescence emission similar to that of TFAQ. The experimental absorption peak was at approximately 390 nm, and the emission peak was at 510 and 615 nm. The calculated AYAAQs spectra show good agreement with the experimental results, which indicates the feasibility of the theoretical calculation of AYAAQs molecules based on TDDFT/B3LYP/6-31+g(d) calculation. However, the IEFPCM solvent model has some limitations. When the IEFPCM solvent model is used, the linear response model is suitable for the structural optimization, but cannot accurately consider the nonequilibrium solvent effect when calculating the transition energies. Therefore, the state specific method was used to estimate experimental values of transition energies for the AAAQ molecule, which can largely incorporate the solvent effect. The AAAQ calculated absorption peak is at 443.9 nm, and fluorescent emission peak is at 568.2 nm. These are in agreement with the experimental values, which implies that the IEFPCM solvent model is suitable for these systems. 3.3. AYAAQs Hole−Electron Distribution. When photoexcitation occurs, we suppose that electrons transfer from A to

eV), which makes the results of infrared vibration become more precise. The infrared vibrational frequencies of derivatives were calculated, and the stretching vibration frequencies for the AYAAQs derivative’s N−H bonds are shown in Figure 2. The stretching vibrational frequency for the AAAQ N−H bond in the S0 state is at 3441 cm−1 (the frequency considered dispersion correction is 3456 cm−1), and in the S1 state it is at 3003 cm−1 (2985 cm−1), exhibiting a 438 (471) cm−1 red shift in the S1 state; that is, the enhanced hydrogen bond in the S1 state produces a red shift. Similarly, the stretching vibrational frequency of CAAQ, DCAQ, TFAQ N−H bonds for the S0 to S1 state shows a gradual increase in red shift (518, 606, and 708 cm−1, respectively). Thus, hydrogen-bond interaction strengthening can be further investigated using infrared vibrational spectra. To further verify the theoretical calculation reliability, we calculated the absorption and the fluorescence emission spectra of AYAAQ derivatives using the B3LYP/6-31+g(d) method, as shown in Figure 3. The absorption peak for the TFAQ molecule is located at λ = 416.6 nm, which is consistent with the experimental data (approximately λ = 380 nm). The double fluorescence emission peaks are located at λ = 511.5 and 657 nm, severally, with the experimental values of 520 and 620 nm, approximately.50 Thus, the theoretical and experimental values are in good agreement, and TFAQ exhibits dual fluorescence properties in the long and short wave regions, with the long-wavelength region having a larger Stokes’ shift (λ = 240.4 nm) relative to its absorption peak value. The AAAQ and CAAQ spectra have absorption peaks at 436.6 (the absorption peak considered dispersion correction is D


Article


population redistribution. For AAAQ and CAAQ molecules, NPA charges on the N atoms were −0.678 and −0.677 in the S0 state, and −0.667 and −0.662 in the S1 state, respectively. For DCAQ and TFAQ molecules, the NPA charges were −0.672 and −0.669 in the S0 state, and −0.652 and −0.651 in the S1 state, respectively. Thus, the electron-withdrawing and -donating groups have a significant influence on the NPA charges, decreasing with substitution from CH3 → CH2Cl → CHCl2 → CF3 in the S1 state. 3.4. Potential Energy Profiles. Although Nagaoka et al. used the nodal plane model to illustrate AYAAQ molecules’ ESIPT reactions,50 we calculated potential energy surfaces to assist in visualizing the ESIPT reaction mechanism, as shown in Figure 5. The ground- and excited-state potential energy curves were scanned by increasing the N1−H1 bond length with a fixed 0.1 Å step. Although the TDDFT method is not likely to provide the correct sequence of closely spaced excited states, a large number of previous studies have confirmed the method is reliable for calculating potential energy transfer curves.62−66 The proton transfer reactions cannot occur in the S0 state, because the reaction stationary points are nonexistent, as shown in Figure 5. For AAAQ, with increasing N1−H1 bond step size, the molecule energy increases continuously; that is, the ESIPT reaction does not occur for the AAAQ derivative. Therefore, AAAQ fluorescence emission in the short wavelength region originates from the S1(N) → S0(N) transition. Similarly, for the CAAQ molecule, the ESIPT reaction must surmount the 4.39 kcal/mol potential barrier in the S1 state, but the energy barrier for reverse proton transfer is very small (0.94 kcal/mol), so the reverse proton transfer reaction will occur immediately, before fluorescence is detected. Hence, CAAQ single fluorescence emission can only be detected in the green wavelength range. DCAQ and TFAQ derivatives have potential barriers of 2.56 and 1.78 kcal/mol, respectively. Therefore, the S1 state ESIPT process more easily occurs in TFAQ than in DCAQ. The dual fluorescence signal can be detected in the green and red light ranges, because the reverse proton transfer reaction barriers are not negligible (1.44 and 2.29 kcal/mol, respectively). Therefore, ESIPT reactions occur more easily from AAAQ to TFAQ derivatives, which is consistent with the nodal-plane model proposed by Nagaoka et al.50 To better illustrate the hydrogen-bond strengthening mechanism, Figure 6 shows the RDG isosurfaces, with the hydrogen-bond interactions in the blue areas. The N1−H1··· O1 bond exhibits a distinct hydrogen-bond interaction, but the isosurfaces located in the hydrogen bond are hollow rings, because we set that the electronic density >0.05 is not shown. The hollow rings indicate that these strong enough hydrogenbond interactions exceed the range of a weak interaction. The hollow ring areas gradually contract due to an increasingly strong hydrogen-bond interaction from (a) to (d) in the S1 state. Thus, the N1−H1···O1 bond is enhanced from AAAQ to TFAQ due to the different substituted groups in derivatives.

B. The excitation contribution mainly stems from the molecular orbital transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). However, this single orbital pair model is not suitable in most practical cases, and this study considers the AYAAQs transition processes to include contributions of multiple molecular orbital pairs, and electron transfers are considered as holes and electrons in the following text. Electron and hole distributions obtained using the electron−hole analysis function of the Multiwfn suite are shown in Figure 4, displaying hole, electron, and hole−electron distribution isosurfaces for the AYAAQs derivatives.

Figure 4. Hole, electron, and overlap of hole and electron distributions for AYAAQs derivatives based on the TDDFT/CAM-B3LYP/631+g(d) calculation method. The hole and electron distributions will be represented as blue and green isosurfaces, respectively.

Integrating the overlap of hole−electron (S) distributions provides a measure of the spatial separation between holes and electrons. The distance between the hole and electron centroid, D, provides the charge transfer (CT) length, as shown in Table 2. Although the AYAAQ derivatives’ S values are not large, all D < 1.5 Å. Thus, the transition modes for AAAQ, CAAQ, DCAQ, and TFAQ are local excitation (LE) rather than CT. To show the effect of electron-donating and -withdrawing groups on NPA charges of the atoms in AYAAQs molecules, we calculated the NPA charges in the S0 and S1 states based on the CAM-B3LYP/6-31+g(d) method. As discussed by Yu et al.,61 the CAM-B3LYP method can accurately estimate the electron

4. CONCLUSIONS We investigated the optical phenomena of substituted AYAAQs derivatives based on the theoretical B3LYP function and 631+g(d) basis set for the first time, and calculated the absorption and emission spectra. The calculated spectral and corresponding experimentally measured values were consistent. Therefore, the theoretical method was verified as reliable. Comparing the bond parameters and stretching vibrational

Table 2. Integrated Overlap of Hole−Electron Distributions (S) and the Distance between Hole and Electron Centroids (D)

S D (Å)

AAAQ

CAAQ

DCAQ

TFAQ

0.320 1.158

0.296 0.457

0.270 0.289

0.269 0.439 E


Article


Figure 5. Potential energy curves for AYAAQs derivatives scanned using the TDDFT/B3LYP/6-31+G(d) method for the optimal ground-state and first excited-state geometries.

Figure 6. Reduced density gradient isosurfaces for (a) AAAQ, (b) CAAQ, (c) DCAQ, and (d) TFAQ.

frequencies of the derivatives, we demonstrated that hydrogenbond interactions were strengthened in the S1 state, with hydrogen-bond interaction intensity for the derivatives increasing from AAAQ → CAAQ → DCAQ → TFAQ. The corresponding hydrogen-bond interaction intensities were visually exhibited for the RDG isosurfaces in the S1 state. The derivatives’ potential energy curves were also calculated

and displayed visually. Following the strengthening of the hydrogen bonds, ESIPT reactions were more prone to occur based on the derivatives’ barrier values. Finally, we calculated the NPA charges of the N atoms within the AYAAQs molecules. NPA charges gradually reduced with substitution from CH3 → CH2Cl → CHCl2 → CF3 in the S1 state. Thus, ESIPT reactions of the AYAAQs derivatives more easily occur F


Article


(15) Yi, P. G.; Liang, Y. H. Theoretical Studies of Conjugation and Substituent Effect on Intramolecular Proton Transfer in the Ground and Excited States. Chem. Phys. 2006, 322, 382−386. (16) Li, H. M.; Wang, Y. Q.; Yan, Z. Y.; Feng, H. P.; Hu, Y. Z. Proton Transfer of Magnolol in Ground and Excited States. J. Photochem. Photobiol., A 2007, 186, 202−211. (17) Al-Ansari, I. A. Z. Ground and Excited-State’s Intramolecular Proton Transfer in 2-(2′-Hydroxyphenyl)Iminomethylbenzimidazole and 2-(2′-Hydroxy-4- Bromophenyl) Iminomethylbenzimidazole. J. Lumin. 1997, 71, 83−91. (18) Balón, M.; Muñoz, M. A.; Guardado, P.; Carmona, C. Hydrogen-Bonding Interact between Harmane and Pyridine in the Ground and Lowest Excited Singlet State. Photochem. Photobiol. 1996, 64, 531−536. (19) Vener, M. V.; Scheiner, S.; Sokolov, N. D. Theoretical Study of Hydrogen Bonding and Proton Transfer in the Ground and Lowest Excited Singlet States of Tropolone. J. Chem. Phys. 1994, 101, 9755− 9765. (20) Hemley, R. J.; Dinur, U.; Vaida, V.; Karplus, M. Theoretical Study of the Ground and Excited Singlet States of Styrene. J. Am. Chem. Soc. 1985, 107, 836−844. (21) Krystkowiak, E.; Koput, J.; Maciejewski, A. Hydrogen Bond Effects in the Ground and Excited Singlet States of 4H-1Benzopyrane-4-Thione in Water-Theory and Experiment. Phys. Chem. Chem. Phys. 2012, 14, 8842−8851. (22) Wu, Y. D.; Houk, K. N.; Valentine, J. S.; Nam, W. Is Intramolecular Hydrogen-Bonding Important for Bleomycin Reactivity? A Molecular Mechanics Study. Inorg. Chem. 1992, 31, 718−720. (23) DeChancie, J.; Houk, K. N. The Origins of Femtomolar ProteinLigand Binding: Hydrogen-Bond Cooperativity and Desolvation Energetics in the Biotin-(Strept)Avidin Binding Site. J. Am. Chem. Soc. 2007, 129, 5419−5429. (24) Zhao, J. F.; Yao, H. B.; Liu, J. Y.; Hoffmann, M. R. New ExcitedState Proton Transfer Mechanisms for 1,8-Dihydroxydibenzo[a,h]phenazine. J. Phys. Chem. A 2015, 119, 681−688. (25) Barbara, P. F.; Walsh, P. K.; Brus, L. E. Picosecond Kinetic and Vibrationally Resolved Spectroscopic Studies of Intramolecular Excited-State Hydrogen Atom Transfer. J. Phys. Chem. 1989, 93, 29−34. (26) Douhal, A.; Lahmani, F.; Zewail, A. H. Proton-Transfer Reaction Dynamics. Chem. Phys. 1996, 207, 477−498. (27) Nagaoka, S. I.; Nakamura, A.; Nagashima, U. Nodal-Plane Model for Excited-State Intramolecular Proton Transfer of OHydroxybenzaldehyde: Substituent Effect. J. Photochem. Photobiol., A 2002, 154, 23−32. (28) Wang, R. J.; Liu, D.; Xu, K.; Li, J. Y. Substituent and Solvent Effects on Excited State Intramolecular Proton Transfer in Novel 2(2′-Hydroxyphenyl)Benzothiazole Derivatives. J. Photochem. Photobiol., A 2009, 205, 61−69. (29) Tseng, H. W.; Liu, J. Q.; Chen, Y. A.; Chao, C. M.; Liu, K. M.; Chen, C. L.; Lin, T. C.; Hung, C. H.; Chou, Y. L.; Lin, T. C.; Wang, T. L.; Chou, P. T. Harnessing Excited-State Intramolecular ProtonTransfer Reaction via a Series of Amino-Type Hydrogen-Bonding Molecules. J. Phys. Chem. Lett. 2015, 6, 1477−1486. (30) Kim, T. G.; Kim, Y.; Jang, D. J. Catalytic Roles of Water Protropic Species in the Tautomerization of Excited 6-Hydroxyquinoline: Migration of Hydrated Proton Clusters. J. Phys. Chem. A 2001, 105, 4328−4332. (31) Kanamori, D.; Okamura, T.; Yamamoto, H.; Ueyama, N. Linearto-Turn Conformational Switching Induced by Deprotonation of Unsymmetrically Linked Phenolic Oligoamides. Angew. Chem., Int. Ed. 2005, 44, 969−972. (32) Li, A.; Sun, H. X.; Tan, D. Z.; Fan, W. J.; Wen, S. H.; Qing, X. J.; Li, G. X.; Li, S. Y.; Deng, W. Q. Superhydrophobic Conjugated Microporous Polymers for Separation and Adsorption. Energy Environ. Sci. 2001, 4, 2062−2065. (33) Li, A.; Lu, R. F.; Wang, Y.; Wang, X.; Han, K. L.; Deng, W. Q. Lithium-Doped Conjugated Microporous Polymers for Reversible Hydrogen Storage. Angew. Chem., Int. Ed. 2010, 49, 3330−3333.

from AAAQ to TFAQ in the S1 state, which confirms the previous outcomes and further validates the chosen theoretical model.

■

AUTHOR INFORMATION

Corresponding Author

*Tel.: +86-24-62202308. E-mail: [email protected]. ORCID

Yongqing Li: 0000-0001-7673-1844 Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (grant no. 11474141), the Natural Science Foundation of Liaoning Province (grant no. 20170540408), and the Program for Liaoning Excellent Talents in University (grant no. LJQ2015040).

■

REFERENCES

(1) Cramer, C. J.; Truhlar, D. G. A Universal Approach to Solvation Modeling. Acc. Chem. Res. 2008, 41, 760−768. (2) Olsen, S.; Smith, S. C. Bond Selection in the Photoisomerization Reaction of Anionic Green Fluorescent Protein and Kindling Fluorescent Protein Chromophore Models. J. Am. Chem. Soc. 2008, 130, 8677−8689. (3) Tung, C. H.; Wu, L. Z.; Zhang, L. P.; Chen, B. Supramolecular Systems as Microreactors: Control of Product Selectivity in Organic Phototransformation. Acc. Chem. Res. 2003, 36, 39−47. (4) Raymo, F. M.; Bartberger, M. D.; Houk, K. N.; Stoddart, J. F. The Magnitude of [C-H···O] Hydrogen Bonding in Molecular and Supramolecular Assemblies. J. Am. Chem. Soc. 2001, 123, 9264−9267. (5) Chu, T. S.; Liu, B. T. Establishing New Mechanisms with Triplet and Singlet Excited-State Hydrogen Bonding Roles in Photoinduced Liquid Dynamics. Int. Rev. Phys. Chem. 2016, 35, 187−208. (6) Konoshima, H.; Nagao, S.; Kiyota, I.; Amimoto, K.; Yamamoto, N.; Sekine, M.; Nakata, M.; Furukawa, K.; Sekiya, H. Excited-State Intramolecular Proton Transfer and Charge Transfer in 2-(2′Hydroxyphenyl)Benzimidazole Crystals Studied by PolymorphsSelected Electronic Spectroscopy. Phys. Chem. Chem. Phys. 2012, 14, 16448−16457. (7) Xie, Y.; Wang, T. T.; Liu, X. H.; Zou, k.; Deng, W. Q. Capture and Conversion of CO2 at Ambient Conditions by a Conjugated Microporous Polymer. Nat. Commun. 2013, 4, 1960. (8) Seo, J. W.; Kim, S. H.; Park, S. H.; Park, S. Y. Tailoring the Excited-State Intramolecular Proton Transfer (ESIPT) Fluorescence of 2-(2′-Hydroxyphenyl)Benzoxazole Derivatives. Bull. Korean Chem. Soc. 2005, 26, 1706−1710. (9) McCarthy, A.; Ruth, A. A. Fluorescence Excitation and Excited State Intramolecular Proton Transfer of Jet-Cooled Naphthol Derivatives: Part 1. 1-Hydroxy-2-Naphthaldehyde. Phys. Chem. Chem. Phys. 2011, 13, 7485−7499. (10) Mordziński, A.; Grabowska, A. Intramolecular Proton Transfer in Excited Benzoxazoles. Chem. Phys. Lett. 1982, 90, 122−127. (11) Enchev, V.; Bakalova, S.; Ivanova, G.; Stoyanov, N. Excited State Intramolecular Proton Transfer in 2-Acetylindan-1, 3-Dione. Chem. Phys. Lett. 1999, 341, 234−238. (12) Nemkovich, N. A.; Kruchenok, J. V.; Rubinov, A. N.; Pivovarenko, V. G.; Baumann, W. Site Selectivity in Excited-State Intramolecular Proton Transfer in Flavonols. J. Photochem. Photobiol., A 2001, 139, 53−62. (13) Weller, A. Innermolekularer Protonenübergang im angeregten Zustand. Z. Elektrochem. 1956, 60, 1144−1147. (14) Friedrich, D. M.; Wang, Z.; Joly, A. G.; Peterson, K. A.; Callis, P. R. Ground-State Proton-Transfer Tautomer of the Salicylate Anion. J. Phys. Chem. A 1999, 103, 9644−9653. G


Article

The Journal of Physical Chemistry C (34) Ma, D. G.; Liang, F. S.; Wang, L. X.; Lee, S. T.; Hung, L. S. Blue Organic Light-Emiting Devices with an Oxidiazole-Containing Emitting Layer Exhibiting Excited State Intramolecular Proton Transfer. Chem. Phys. Lett. 2002, 358, 24−28. (35) Yu, F. B.; Li, P.; Wang, B. S.; Han, K. L. Reversible NearInfrared Fluorescent Probe Introducing Tellurium to Mimetic Glutathione Peroxidase for Monitoring the Redox Cycles between Peroxynitrite and Glutathione in Vivo. J. Am. Chem. Soc. 2013, 135, 7674−7680. (36) Zhao, G. J.; Han, K. L. Early Time Hydrogen-Bonding Dynamics of Photoexcited Coumarin 102 in Hydrogen-Donating Solvents: Theoretical Study. J. Phys. Chem. A 2007, 111, 2469−2474. (37) Zhao, G. J.; Han, K. L. Effects of Hydrogen Bonding on Tuning Photochemistry: Concerted Hydrogen-Bond Strengthening and Weakening. ChemPhysChem 2008, 9, 1842−1846. (38) Henary, M. M.; Fahrni, C. J. Excited State Intramolecular Proton Transfer and Metal Ion Complexation of 2-(2′Hydroxyphenyl)benzazoles in Aqueous Solution. J. Phys. Chem. A 2002, 106, 5210−5220. (39) Li, Y. Q.; Yang, Y. F.; Ding, Y. The New Competitive Mechanism of Hydrogen Bonding Interactions and Transition Process for the Hydroxyphenyl Imidazo [1,2-a] Pyridine in Mixed Liquid Solution. Sci. Rep. 2017, 7, 1574. (40) Wang, Y.; Yin, H.; Shi, Y.; Jin, M. X.; Ding, D. J. Ground-State and Excited-State Multiple Proton Transfer via a Hydrogen-Bonded Water Wire for 3-Hydroxypyridine. New J. Chem. 2014, 38, 4458− 4464. (41) Zhang, Y. J.; Zhao, J. F.; Li, Y. Q. The Investigation of Excited State Proton Transfer Mechanism in Water-Bridged 7-Azaindole. Spectrochim. Acta, Part A 2016, 153, 147−151. (42) Zhang, Y. J.; Sun, M. T.; Li, Y. Q. How was the Proton Transfer Process in Bis-3, 6-(2-Benzoxazolyl)-Pyrocatechol, Single or Double Proton Transfer? Sci. Rep. 2016, 6, 25568. (43) Yang, Y. F.; Zhao, J. F.; Li, Y. Q. Theoretical Study of the ESIPT Process for a New Natural Product Quercetin. Sci. Rep. 2016, 6, 32152. (44) Lan, R. F.; Yang, Y. F.; Ma, Y. Z.; Li, Y. Q. The Theoretical Study of Excited-State Intramolecular Proton Transfer of 2,5Bis(Benzoxazol-2-yl)Thiophene-3,4-Diol. Spectrochim. Acta, Part A 2017, 183, 37−44. (45) Neuwahl, F. V. R.; Bussotti, L.; Righini, R.; Buntinx, G. Ultrafast Proton Transfer in the S1 State of 1-Chloroacetylaminoanthraquinone. Phys. Chem. Chem. Phys. 2001, 3, 1277−1283. (46) Schmidtke, S. J.; Underwood, D. F.; Blank, D. A. Probing Excited-State Dynamics and Intramolecular Proton Transfer in 1Acylaminoanthraquinones via the Intermolecular Solvent Response. J. Phys. Chem. A 2005, 109, 7033−7045. (47) Schmidtke, S. J.; Underwood, D. F.; Blank, D. A. Following the Solvent Directly during Ultrafast Excited State Proton Transfer. J. Am. Chem. Soc. 2004, 126, 8620−8621. (48) Smith, T. P.; Zaklika, K. A.; Thakur, K.; Walker, G. C.; Tominaga, K.; Barbara, P. F. Spectroscopic Studies of Excited-state Intramolecular Proton Transfer in 1-(Acylamino)anthraquinones. J. Phys. Chem. 1991, 95, 10465−10475. (49) Smith, T. P.; Zaklika, K. A.; Thakur, K.; Barbara, P. F. ExcitedState Intramolecular Proton Transfer in 1-(Acylamino)Anthraquinones. J. Am. Chem. Soc. 1991, 113, 4035−4036. (50) Nagaoka, S. I.; Endo, H.; Ohara, K. Correlation Between Excited-State Intramolecular Proton-Transfer and Singlet-Oxygen Quenching Activities in 1-(Acylamino)Anthraquinones. J. Phys. Chem. B 2015, 119, 2525−2532. (51) Nagaoka, S. I.; Nagashima, U. Effects of Node of Wave Function upon Excited-State Intramolecular Proton Transfer of Hydroxyanthraquinones and Aminoanthraquinones. Chem. Phys. 1996, 206, 353− 362. (52) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; et al. Gaussian 09, revision A.02; Gaussian, Inc.: Wallingford, CT, 2009.

(53) Becke, A. D. Density Functional Thermochemistry. III. The Role of Exact Exchange. J. Chem. Phys. 1993, 98, 5648−5652. (54) Lee, C.; Yang, W. T.; Parr, R. G. Development of the ColleSalvetti Correlation-Energy Formula into a Functional of the Electron Density. Phys. Rev. B: Condens. Matter Mater. Phys. 1988, 37, 785−789. (55) Miehlich, B.; Savin, A.; Stoll, H.; Preuss, H. Results Obtained with the Correlation Energy Density Functionals of Becke and Lee, Yang and Parr. Chem. Phys. Lett. 1989, 157, 200−206. (56) Cances, E.; Mennucci, B.; Tomasi, J. An New Integral Equation Formalism for the Polarizable Continuum Model: Theoretical Background and Applications to Isotropic and Anisotropic Dielectrics. J. Chem. Phys. 1997, 107, 3032−3041. (57) Cammi, R.; Tomasi, J. Remarks on the Use of the Apparent Surface Charges (ASC) Methods in Solvation Problems: Iterative Versus Matrix-Inversion Procedures and the Renormalization of the Apparent Charges. J. Comput. Chem. 1995, 16, 1449−1458. (58) Miertus, S.; Scrocco, E.; Tomasi, J. Electrostatic Interaction of a Solute with a Continuum. A Direct Utilizaion of Ab initio Molecular Potentials for the Prevision of Solvent Effects. Chem. Phys. 1981, 55, 117−129. (59) Lu, T.; Chen, F. W. Multiwfn: A Multifunctional Wavefunction Analyzer. J. Comput. Chem. 2012, 33, 580−592. (60) Humphrey, W.; Dalke, A.; Schulten, K. VMD-Visnal Molecular Dynamics. J. Mol. Graphics 1996, 14.1, 33−38. (61) Yu, X. F.; Yamazaki, S.; Taketsugu, T. Concerted or Stepwise Mechanism? CASPT2 and LC-TDDFT Study of the Excited-State Double Proton Transfer in the 7-Azaindole Dimer. J. Chem. Theory Comput. 2011, 7, 1006−1015. (62) Zhang, H.; Wang, S. F.; Sun, Q.; Smith, S. C. Kinetic Isotope Effect for Ground State Proton Transfer in the Green Fluorescent Protein: A Quantum-Kinetic Model. Phys. Chem. Chem. Phys. 2009, 11, 8422−8424. (63) Furche, F.; Ahlrichs, R. Erratum: “Time-Dependent Density Functional Methods for Excited State Properties. J. Chem. Phys. 2004, 121, 12772−12773. (64) Saga, Y.; Shibata, Y.; Tamiaki, H. Spectral Properties of Single Light-Harvesting Complexes in Bacterial Photosynthesis. J. Photochem. Photobiol., C 2010, 11, 15−24. (65) Sobolewski, A. L.; Domcke, W. Ab initio Potential-Energy Functions for Excited State Intramolecular Proton Transfer: A Comparative Study of O-Hydroxybenzaldehyde, Salicylic Acid and 7Hydroxy-1-Indanone. Phys. Chem. Chem. Phys. 1999, 1, 3065−3072. (66) Kobayashi, T.; Saito, T.; Ohtani, H. Real-Time Spectroscopy of Transition States in Bacteriorhodopsin During Retinal Isomerization. Nature 2001, 414, 531−534.

H


Effect of Different Substituted Groups on Excited-State

Recommend Documents