Ultrafast excited-state dynamics in photochromic <i>N</i>-salicylideneaniline studied by femtosecond time-resolved REMPI spectroscopy

Okabe, Chie; Nakabayashi, Takakazu; Inokuchi, Yoshiya; Nishi, Nobuyuki; Sekiya, Hiroshi

doi:10.1063/1.1801991

Cited by 70 publications

(99 citation statements)

References 45 publications

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“…9,[14][15][16][17]22,24,28,29 Theory predicts a ground-state torsion angle of 36°about the anil twist angle α (C 7 NC 6 C 5 dihedral angle; see Figure 1c for a definition of the critical angles considered in this study) at the B3LYP/6-31G* level of theory 28 and 44°at the HF/6-31G* level. 29 An angle of 49°was found by X-ray diffraction of crystalline SA.…”

Section: Introductionmentioning

confidence: 91%

Initial Processes of Proton Transfer in Salicylideneaniline Studied by Time-Resolved Photoelectron Spectroscopy

Sekikawa

Schalk

et al. 2013

J. Phys. Chem. A

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Excited-state intramolecular proton transfer (ESIPT) in salicylideneaniline (SA) and selected derivatives substituted in the para position of the anilino group have been investigated by femtosecond time-resolved photoelectron spectroscopy (TRPES) and time-dependent density functional theory (TDDFT). SA has a twisted structure at the energetic minimum of the ground state, but ESIPT is assumed to take place through a planar structure, although this has not been fully established. The TRPES studies revealed that the excited-state dynamics within the S 1 band varied significantly with excitation wavelength. At finite temperatures, the ground state was found to sample a broad range of torsional angles, from planar to twisted. At lower photon energies (370 nm), only the planar groundstate molecules were excited, and the excited-state reaction took place within 50 fs. At higher energies (350 and 330 nm), predominantly twisted ground-state molecules were excited: they had to planarize before ESIPT could occur. This process was found to be slower in methylated SA but did not change significantly in the brominated and nitrated SAs. These substitution effects on the decay dynamics can be explained by modifications of the potential barriers, as predicted by the TDDFT calculations, and support the mechanism of a twisting motion of the anilino ring prior to ESIPT. The contribution of another pathway leading to internal conversion within the enol form was found to be minor at the excitation wavelengths considered here.

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Section: Introductionmentioning

confidence: 91%

Initial Processes of Proton Transfer in Salicylideneaniline Studied by Time-Resolved Photoelectron Spectroscopy

Sekikawa

Schalk

et al. 2013

J. Phys. Chem. A

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“…Our experimental system for picosecond time-resolved study is described in several references. 45,63,64 Figure 4 displays the principle of picosecond time-resolved resonance-enhanced multiphoton ionization (REMPI) spectroscopy to measure the decays of the excited normal 7AI 2 dimer. The pump laser excites 7AI 2 in a specific single vibronic state of the normal dimer, subsequently the probe laser ionizes the normal dimer.…”

Section: Experimental Methodsmentioning

confidence: 99%

Excited-State Double-Proton Transfer in the 7-Azaindole Dimer in the Gas Phase. Resolution of the Stepwise versus Concerted Mechanism Controversy and a New Paradigm

Sekiya¹,

Sakota²

2006

Bulletin of the Chemical Society of Japan

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The 7-azaindole dimer (7AI 2 ) is a prototype of double hydrogen-bonded molecules. 7AI 2 has been considered as a model DNA base pair and has attracted much attention to the mechanism of the excited-state double-proton transfer (ESDPT). Two ESDPT mechanisms, stepwise and concerted mechanisms, have been proposed so far. Great efforts have been devoted to clarify the mechanism of ESDPT using experimental and theoretical methods. However, the reaction mechanism had been controversial for more than a decade. We provide the resolution of the two mechanisms on the basis of new data obtained from electronic spectroscopy and picosecond time-resolved spectroscopy in the gas phase. The initial state of the ESDPT reaction has been well characterized by investigating the exciton resonance interaction with UV-UV hole-burning spectroscopy for various 7AI 2 isotopomers. The lowest-excited state of 7AI 2 has been classified into the weak coupling case of the exciton theory. We have concluded that the ESDPT reaction in 7AI 2 occurs via the concerted mechanism on the basis of the results of picosecond time-resolved experiments and the H/D kinetic isotope effect on ESDPT studied by measuring the vibronic-state selective dispersed fluorescence spectra. ESDPT of 7AI 2 has a ''dynamic cooperative'' nature that may arise from the coupling of the two moving protons with the reorganization of electrons. We have provided a new paradigm of ESDPT, where two quantum effects, the exciton resonance interaction and the proton tunneling, are concerned with the ESDPT reaction.Proton-transfer reactions are one of the most basic reactions, and they are important in physics, chemistry, and biology. [1][2][3][4][5][6] Spectroscopic studies on various proton-transfer systems combining with theoretical studies have provided rich information about the hydrogen-bonded structure and proton-transfer dynamics. In particular, a very detailed picture has been obtained for intramolecular single-proton transfer in polyatomic molecules, with laser spectroscopic measurements in the gas phase combining with theoretical studies. For example, a proton transfers by quantum mechanical tunneling mechanism when a potential energy barrier exists on a potential energy surface. The proton tunneling was clearly observed in the electronic and vibrational spectra of several polyatomic molecules. [6][7][8][9][10] Spectroscopic data and theoretical studies showed that the proton tunneling has a multi-dimensional nature, i.e., the motion of the moving proton couples with the coordinates of the heavy atoms that constitute the molecule. Such a multi-dimensional nature and quantum mechanical tunneling are important properties that characterize proton-transfer reactions. Now much effort is devoted to obtain a more complete picture for singleproton transfer reactions and also a new picture for more complicated multiproton-transfer reactions. There are many examples of multiproton-transfer reactions such as proton relay systems in enzymes, in hydrogen-bonded water complexes, and prot...

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“…Regarding the ESIPT, fast kinetics experiments previously showed that it occurs both in solid state and in solution within 1 ps and 50 fs, respectively [24][25][26]. Even though the photochromism of anils was extensively studied in the past [24][25][26][27][28][29][30][31], some issues still exist regarding i) the existence of several excited species after the proton transfer (different cis-keto* isomers), ii) the nature of the precursor species of the final trans-keto photo-product and iii) their kinetics. Recently, different UV-visible ultrafast time-resolved experiments (transient absorption, fluorescence) on salicylidene aniline demonstrated that a hot cis-keto* is formed right after the ESIPT first which then relaxes to the fluorescent cold cis-keto* state [14,25,26].…”

Section: Introductionmentioning

confidence: 98%

Chemometric analysis of femtosecond transient absorption spectroscopy data: Study of the photochromism of anils

Ruckebusch

Mouton

Gladytz

et al. 2010

Sci. China Phys. Mech. Astron.

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Chemometric methods are applied for the purpose of extracting relevant information from transient absorption spectroscopy data probing the photochromism of molecules from the family of salicylidene aniline. The process consists of an ultrafast excited state intramolecular proton transfer occurring from an enol form which is then followed by a cis-trans isomerization to finally reach a trans-keto photo-product. This work focuses on the potential of combining multivariate curve resolution for modeling pure profiles and two dimensional correlation spectroscopy data analysis for providing information on the dynamics of spectral features. The results obtained for one derivative of salicylidene aniline provide information regarding the number of species created after the proton transfer and characterization of their absorption spectra and their kinetics in the picosecond time scale. The spectral resolution of two cis-keto* forms is proposed for the first time. It is also found that both cis-keto* species are involved in the formation of the trans-keto photo-product. The main precursor of the trans-keto photo-product is the cis-keto* form which has the shortest characteristic time. multivariate curve resolution, two dimensional correlation spectroscopy, femtosecond absorption, proton transfer, anils, photochromism PACS: 82.53. Eb, 82.53.Hn, 78.47.j

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Ultrafast excited-state dynamics in photochromic N-salicylideneaniline studied by femtosecond time-resolved REMPI spectroscopy

Cited by 70 publications

References 45 publications

Initial Processes of Proton Transfer in Salicylideneaniline Studied by Time-Resolved Photoelectron Spectroscopy

Initial Processes of Proton Transfer in Salicylideneaniline Studied by Time-Resolved Photoelectron Spectroscopy

Excited-State Double-Proton Transfer in the 7-Azaindole Dimer in the Gas Phase. Resolution of the Stepwise versus Concerted Mechanism Controversy and a New Paradigm

Chemometric analysis of femtosecond transient absorption spectroscopy data: Study of the photochromism of anils

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