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  • 1.
    Ai, Yuejie
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Theoretical studies on photophysics and photochemistry of DNA2010Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Theoretical studies on biological systems like nucleic acid and protein have been widely developed in the past 50 years and will continue to be a topic of interest in forefronts of natural science. In addition to experimental science, computational modeling can give useful information and help us to understand biochemical issues at molecular, atomic and even electronic levels.

    Deoxyribonucleic acid (DNA), the hereditary basis of life’s genetic identity, has always been major topic of discussions since its structure was built in 1953. However, harmful UV radiation from sunlight can make damage to DNA molecules and eventually give rise to DNA damaging biological consequences, like mutagenesis, carcinogenesis, and cell death. Photostability, photodamage, and photorepair are of vital importance in the photophysics and photochemistry of DNA. In this thesis, we have applied high level computer-aided theoretical methods to explore the underlying mechanisms for these three critical issues of DNA. Special attentions are paid to the following aspects: the properties of the excited states, the design of relevant computational models and the effects of biological environments.

    We have systematically studied the excited state properties of DNA from single base to base pair and oligonucleotides, where the concerted base pairing and base stacking effects was found to play important roles in DNA photostability. The UV-light induced isomerization mechanism between two photoproducts of DNA photodamage has been revealed in different biological environments. In association with DNA photodamage, the related photorepair processes have been proposed for different lesions in photolyase which is a catalytic enzyme for DNA, and the calculated results well explained the experimental observations. In particular, the internal and external properties of flavin cofactors have been extensively studied by combining the electronic structure and spectroscopic calculations. We have examined the effects of the intramolecular hydrogen bond on spectroscopic properties of flavins. The good agreements with the experimental spectra indicated that the biological self-regulation acted critical role in these biological systems.

  • 2.
    Ai, Yuejie
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Cui, Ganglong
    Beijing Normal University.
    Fang, Qiu
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Fang, Weihai
    Beijing Normal University.
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Exploring concerted effects of base pairing and stacking on the excited-state nature of DNA oligonucleotides by DFT and TD-DFT studies2011Ingår i: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 111, nr 10, s. 2366-2377Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have taken (dA)5, (dT)5, and (dA)5•(dT)5 as model systems to study concerted effects of base pairing and stacking on excited-state nature of DNA oligonucleotides using density functional theory (DFT) and time dependent DFTmethods. The spectroscopic states are determined to be of a partial A →A charge transfernature in the A•T oligonucleotides. The T → T charge-transfer transitionsproduce dark states, which are hidden in the energy region of the steady-stateabsorption spectra. This is different from the previous assignment that the T → Tcharge-transfer transition is responsible for a shoulder at the red side of the first strongabsorption band. The A →T charge-transfer states were predicted to have relativelyhigh energies in the A•T oligonucleotides. The present calculations predict that the T→A charge-transfer states are not involved in the spectra and excited-state dynamics ofthe A•T oligonucleotides. In addition, the influence of base pairing and stacking on thenature of the 1nΠ* and 1ΠΠ* states are discussed in detail.

  • 3.
    Ai, Yue-Jie
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Liao, Rongzhen
    Stockholm University.
    Chen, Shilu
    Beijing Institute of Technology.
    Hua, Wei-Jie
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Fang, Wei-Hai
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Repair of DNA Dewar Photoproduct to (6-4) photoproduct in (6-4) Photolyase2011Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 115, nr 37, s. 10976-10982Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dewar photoproduct (Dewar PP) is the valence isomer of (6-4) photoproduct ((6-4)PP) in photodamaged DNA. Compared to the extensive studied CPD photoproducts, the underlying repair mechanisms for the (6-4)PP, and especially for the Dewar PP, are not well-established to date. In this paper, the repair mechanism of DNA Dewar photoproduct T(dew)C in (6-4) photolyase was elucidated using hybrid density functional theory. Our results showed that, during the repair process, the T(dew)C has to isomerize to T(6-4)C photolesion first via direct C6'-N3' bond cleavage facilitated by electron injection. This isomerization mechanism is energetically much more efficient than other possible rearrangement pathways. The calculations provide a theoretical interpretation to recent experimental observations.

  • 4.
    Ai, Yue-Jie
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Liao, Rong-zhen
    Chen, Shu-feng
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Fang, Wei-Hai
    Theoretical Studies on Photoisomerizations of (6-4) and Dewar Photolesions in DNA2010Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 114, nr 44, s. 14096-14102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The (6-4) photoproduct ((6-4) PP) is one of the main lesions in UV-induced DNA damage. The (6-4) PP and its valence isomer Dewar photoproduct (Dewar PP) can have a great threat of mutation and cancer but gained much less attention to date. In this study, with density functional theory (DFT) and the complete active space self-consistent field (CASSCF) methods, the photoisomerization processes between the (6-4) PP and the Dewar PP in the gas phase, the aqueous solution, and the photolyase have been carefully examined. Noticeably, the solvent effect is treated with the CASPT2//CASSCF/Amber (QM/MM) method. Our calculations show that the conical intersection (Cl) points play a crucial role in the photoisomerization reaction between the (6-4) PP and the Dewar PP in the gas and the aqueous solution. The ultrafast internal conversion between the S-2 ((1)pi pi*) and the So states via a distorted intersection point is found to be responsible for the formation of the Dewar PP lesion at 313 nm, as observed experimentally. For the reversed isomeric process, two channels involving the "dark" excited states have been identified. In addition to the above passages, in the photolyase, a new electron-injection isomerization process as an efficient way for the photorepair of the Dewar PP is revealed.

  • 5.
    Ai, Yue-Jie
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Liao, Rong-Zhen
    Fang, Wei-Hai
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Theoretical studies on the isomerization mechanism of the ortho-green fluorescent protein chromophore2012Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 14, nr 38, s. 13409-13414Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a systematic theoretical investigation on the overall ground state and excited-state isomerization reaction mechanism of ortho-green fluorescent protein chromophore (o-HBDI) using the density functional theory and the multireference methods. The calculated results and subsequent analysis suggest the possible isomerization mechanism for o-HBDI. By comparison with experimental observation and detailed analysis, it is concluded that as initiated by the excited-state intramolecular proton transfer reaction, the conical intersection between the ground state and the excited state along the C4-C5 single-bond rotational coordinate is responsible for the rapid deactivation of o-HBDI.

  • 6.
    Ai, Yuejie
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Tian, Guangjun
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Liao, Rongzhen
    Stockholm University.
    Zhang, Qiong
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Fang, Weihai
    Beijing Normal University.
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Intrinsic property of flavin mononucleotide controls its optical spectra in three redox states2011Ingår i: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 12, nr 16, s. 2899-2902Artikel i tidskrift (Refereegranskat)
  • 7.
    Ai, Yue-Jie
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Tian, Guangjun
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Role of non-Condon vibronic coupling and conformation change on two-photon absorption spectra of green fluorescent protein2013Ingår i: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 111, nr 9-11, s. 1316-1321Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two-photon absorption spectra of green fluorescent proteins (GFPs) often show a blue-shift band compared to their conventional one-photon absorption spectra, which is an intriguing feature that has not been well understood. We present here a systematic study on one- and two-photon spectra of GFP chromophore by means of the density functional response theory and complete active space self-consistent field (CASSCF) methods. It shows that the popular density functional fails to provide correct vibrational progression for the spectra. The non-Condon vibronic coupling, through the localised intrinsic vibrational modes of the chromophore, is responsible for the blue-shift in the TPA spectra. The cis to trans isomerisation can be identified in high-resolution TPA spectra. Our calculations demonstrate that the high level ab initio multiconfigurational CASSCF method, rather than the conventional density functional theory is required for investigating the essential excited-state properties of the GFP chromophore.

  • 8.
    Ai, Yuejie
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Zhang, Feng
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Chen, Shufeng
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Fang, Weihai
    Importance of the Intramolecular Hydrogen Bond on the Photochemistry of Anionic Hydroquinone (FADH-) in DNA Photolyase2010Ingår i: Journal of Physical Chemisty Letters, ISSN 1948-7185, Vol. 1, s. 743-747Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The design of a proper molecular model with a good balance between the size of the model system and the computational capacity is essential for theoretical modeling of biological systems. We have shown in this letter that the often used model system, a lumiflavin (7,8-dimethy-10-methyl-isoalloxazine), can not correctly describe geometrical and electronic structures of FADHin DNA photolyase. The intramolecular hydrogen bond between the isoalloxazine ring and the ribityl moiety is found to play a significant role in controlling photochemical properties of FADHin DNA photolyase

  • 9.
    Ai, Yue-Jie
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Zhang, Feng
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Cui, Gang-Long
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Fang, Wei-Hai
    Ultrafast deactivation processes in the 2-aminopyridine dimer and the adenine-thymine base pair: Similarities and differences2010Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 133, nr 6, s. 064302-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    2-aminopyridine dimer has frequently been used as a model system for studying photochemistry of DNA base pairs. We examine here the relevance of 2-aminopyridine dimer for a Watson-Crick adenine-thymine base pair by studying UV-light induced photodynamics along two main hydrogen bridges after the excitation to the localized (1)pi pi(*) excited-state. The respective two-dimensional potential-energy surfaces have been determined by time-dependent density functional theory with Coulomb-attenuated hybrid exchange-correlation functional (CAM-B3LYP). Different mechanistic aspects of the deactivation pathway have been analyzed and compared in detail for both systems, while the related reaction rates have also be obtained from Monte Carlo kinetic simulations. The limitations of the 2-aminopyridine dimer as a model system for the adenine-thymine base pair are discussed. (C) 2010 American Institute of Physics. [doi:10.1063/1.3464485]

  • 10.
    Hua, Weijie
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ai, Yue-Jie
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Gao, Bin
    Univ Tromso, Tromso, Norway.
    Li, Hongbao
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    X-ray spectroscopy of blocked alanine in water solution from supermolecular and supermolecular-continuum solvation models: a first-principles study2012Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 14, nr 27, s. 9666-9675Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The N1s near-edge X-ray absorption fine structure (NEXAFS) and X-ray emission spectra (XES) of blocked alanine in water solution have been investigated at the first-principles level based on cluster models constructed from classical molecular dynamics simulations. The bulk solvent has been described by both supermolecular and combined supermolecular-continuum models. With the former model we show that NEXAFS spectra convergent with respect to system size require at least the inclusion of the second solvation shell and that averaged spectra over several hundreds of snapshots can well represent the statistical effect of different instantaneous configurations of the solvation shells. With the combined model we demonstrate that calculations of a medium-sized peptide-water supermolecule qualitatively predict the NEXAFS spectrum of the solvated peptide even considering a single geometry. Furthermore, sampling over hundreds of snapshots by the combined model, the explicit inclusion of even a few waters yields an averaged spectrum in good quantitative agreement with the discrete model results. In comparison, the XES spectra show little dependence on the structures

  • 11.
    Hua, Weijie
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Ai, Yue-Jie
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Gao, Bin
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    NEXAFS spectroscopies of blocked alanine in water solution from first-principles simulationsManuskript (preprint) (Övrigt vetenskapligt)
  • 12.
    Ma, Yong
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ai, Yuejie
    North China Electric Power University, Beijing, China.
    Song, Xiuneng
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Wang, Chuankui
    Shandong Normal University.
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    The equilibrium geometry of A@C60: A test case for conventional density functional theory2014Ingår i: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 591, s. 312-316Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Potential energy surfaces (PESs) along the reaction pathway towards the center of CC bond between two six membered rings for ten different endohedral fullerenes A@C60 (A = H, C, O, S, N, P, He, Ne, Ar, Kr) have been studied by density functional theory (DFT) and Hartree-Fock (HF) method. The results show that no suitable method can consistently describe the interaction between atom A and carbon cage. The dispersion corrected DFT methods fail to describe the equilibrium geometry and PES of the complexes with light atoms. Nevertheless, the inclusion of the dispersion stabilizes the system as reflected by interaction energies (IEs) between atom A and C60.

  • 13. Tan, Chuang
    et al.
    Guo, Lijun
    Ai, Yuejie
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Li, Jiang
    Wang, Lijuan
    Sancar, Aziz
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Zhong, Dongping
    Direct Determination of Resonance Energy Transfer in Photolyase: Structural Alignment for the Functional State2014Ingår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 118, nr 45, s. 10522-10530Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Photoantenna is essential to energy transduction in photoinduced biological machinery. A photoenzyme, photolyase, has a light-harvesting pigment of methenyltetrahydrofolate (MTHF) that transfers its excitation energy to the catalytic flavin cofactor FADH to enhance DNA-repair efficiency. Here we report our systematic characterization and direct determination of the ultrafast dynamics of resonance energy transfer from excited MTHF to three flavin redox states in E. coli photolyase by capturing the intermediates formed through the energy transfer and thus excluding the electron-transfer quenching pathway. We observed 170 ps for excitation energy transferring to the fully reduced hydroquinone FADH, 20 ps to the fully oxidized FAD, and 18 ps to the neutral semiquinone FADH, and the corresponding orientation factors (kappa(2)) were determined to be 2.84, 1.53 and 1.26, respectively, perfectly matching with our calculated theoretical values. Thus, under physiological conditions and over the course of evolution, photolyase has adopted the optimized orientation of its photopigment to efficiently convert solar energy for repair of damaged DNA.

  • 14. Yu, Shujun
    et al.
    Wang, Xiangxue
    Ai, Yuejie
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. North China Electric Power University, China.
    Liang, Yu
    Ji, Yongfei
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Li, Jiaxing
    Hayat, Tasawar
    Alsaedi, Ahmed
    Wang, Xiangke
    Spectroscopic and theoretical studies on the counterion effect of Cu(II) ion and graphene oxide interaction with titanium dioxide2016Ingår i: ENVIRONMENTAL SCIENCE-NANO, ISSN 2051-8153, Vol. 3, nr 6, s. 1361-1368Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the widespread use of graphene oxide (GO), it is inevitable that part of GO is released into the environment and co-exist with heavy metal ions as contaminants and is likely to be co-adsorbed on minerals and oxides. This study, for the first time, demonstrates the individual and mutual removal mechanism of GO and Cu(II) on titanium dioxide (TiO2) by batch experiments, spectroscopic analysis and density functional theory (DFT) computations. Electrostatic interaction and hydrogen bonding are the dominant modes of GO sorption onto TiO2, and the interaction of Cu(II) with TiO2 is mainly dominated by inner-sphere surface complexation. The presence of Cu(II) enhances GO coagulation on TiO2 and vice versa. The experimental results are further verified by DFT sorption energy (Es) calculations in the order (TiO2-GO)-Cu > TiO2-GO for GO interaction and (TiO2-GO)-Cu > TiO2-Cu for Cu(II) interaction. The mutual interaction is favorable for the simultaneous removal of GO and heavy metal ions by surface complexation between Cu(II) and oxygen-containing functional groups. These findings might facilitate better understanding of the co-removal behavior of carbon nanomaterials and heavy metal ions on oxides, which is crucial to decreasing the environmental toxicity of pollutants in the natural environment.

  • 15. Yu, Shujun
    et al.
    Wang, Xiangxue
    Yao, Wen
    Wang, Jian
    Ji, Yongfei
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ai, Yuejie
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Alsaedi, Ahmed
    Hayat, Tasawar
    Wang, Xiangke
    Macroscopic, Spectroscopic, and Theoretical Investigation for the Interaction of Phenol and Naphthol on Reduced Graphene Oxide2017Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, nr 6, s. 3278-3286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Interaction of phenol and naphthol with reduced graphene oxide (rGO), and their competitive behavior on rGO were examined by batch experiments, spectroscopic analysis and theoretical calculations. The batch sorption showed that the removal percentage of phenol or naphthol on rGO in bisolute systems was significantly lower than those of phenol or naphthol in single-solute systems. However, the overall sorption capacity of rGO in bisolute system was higher than single-solute system, indicating that the rGO was a very suitable material for the simultaneous elimination of organic pollutants from aqueous solutions. The interaction mechanism was mainly pi-pi interactions and hydrogen bonds, which was evidenced by FTIR, Raman and theoretical calculation. FTIR and Raman showed that a blue shift of C=C and -OH stretching modes and the enhanced intensity ratios of I-D/I-G after phenols sorption. The theoretical calculation indicated that the total hydrogen bond numbers, diffusion constant and solvent accessible surface area of naphthol were higher than those of phenol, indicating higher sorption affinity of rGO for naphthol as compared to phenol. These findings were valuable for elucidating the interaction mechanisms between phenols and graphene-based materials, and provided an essential start in simultaneous removal of organics from wastewater.

  • 16.
    Zhang, Feng
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Ai, Yue-Jie
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Fang, Wei-Hai
    Nonadiabatic histidine dissociation of hexacoordinate heme in neuroglobin protein2010Ingår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present work, density functional theory and canonical nonadiabatic Monte Carlo transition state theory have been used to investigate histidine dissociation process from the hexacoordinate heme in Ngb protein. The potential energy surfaces (PES) of the lowest singlet, triplet, and quintet states are calculated by stepwise optimization along with the histidine dissociation pathway. Based on the calculated two-dimensional PES, the histidine dissociation rates for the spin-forbidden processes via singlet to triplet and singlet to quintet transitions have been calculated by the nonadiabatic Monte Carlo transition state theory in canonical ensemble. The present study provides a quantitative description on spin-forbidden histidine dissociation processes.

  • 17.
    Zhang, Feng
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ai, Yue-Jie
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Fang, Wei-Hai
    Beijing Normal University.
    Nonradiative decay of the lowest excited singlet state of 2-aminopyridine is considerably faster than the radiative decay2009Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 130, nr 14, s. 144315-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ab initio calculations reveal that radiative lifetime of the lowest excited singlet state of 2-aminopyridine (2AP) molecule should be around 20 ns, consistent with the molecules of the same type, but is about one order of magnitude larger than the claimed experimental fluorescent lifetime in recent years. A S1/S0 conical intersection close to the S1 state has been located which could be the possible nonradiative channel that is responsible for the fast decay observed in the experiment.

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