The Photochemical Isomerization of Azobenzene<sup>1</sup>

Zimmerman, George L.; Chow, Lue-Yung; Paik, Un-Jin

doi:10.1021/ja01547a010

Cited by 527 publications

(357 citation statements)

References 2 publications

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“…The UV-visible absorption spectra of the azobenzene molecule are featured with two major absorption bands corresponding to the S 0 → S 1 and the S 0 → S 2 transitions. The former transition relates to a symmetry-forbidden n − π Ã transition and exhibit a low-intensity peak at 440 nm whereas the latter transition corresponds to a symmetry-allowed π − π Ã transition with the much higher intensity at 320 nm (32). Silver nanospheres having a diameter of 50 nm show a narrow plasmon peak centered at 430 nm, whereas the peak of Ag nanowires (with length of 1 μm) is also around 430 nm.…”

Section: Resultsmentioning

confidence: 99%

Using silver nanowire antennas to enhance the conversion efficiency of photoresponsive DNA nanomotors

Yuan

Zhang²,

Chen³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Plasmonic near-field coupling can induce the enhancement of photoresponsive processes by metal nanoparticles. Advances in nanostructured metal synthesis and theoretical modeling have kept surface plasmons in the spotlight. Previous efforts have resulted in significant intensity enhancement of organic dyes and quantum dots and increased absorption efficiency of optical materials used in solar cells. Here, we report that silver nanostructures can enhance the conversion efficiency of an interesting type of photosensitive DNA nanomotor through coupling with incorporated azobenzene moieties. Spectral overlap between the azobenzene absorption band and plasmonic resonances of silver nanowires increases light absorption of photon-sensitive DNA motor molecules, leading to 85% close-open conversion efficiency. The experimental results are consistent with our theoretical calculations of the electric field distribution. This enhanced conversion of DNA nanomotors holds promise for the development of new types of molecular nanodevices for light manipulative processes and solar energy harvesting.energy conversion | localized surface plasmon | photo-driven nanomotor P lants harvest solar energy by photosynthesis, in which photosensitive biomolecules absorb energy from sunlight and convert it into chemical energy. Human beings utilize solar energy by fossil fuels, solar thermal systems, and, most frequently nowadays, by photovoltaic systems based on optoelectric materials (1). The design of new synthetic materials coupled with a mechanism to capture, convert, and store photon energy will provide new ways to utilize solar energy (2, 3). However, achieving high conversion efficiency remains a challenge in such energy conversion systems.Recently, DNA has received attention in material sciences, especially for the fabrication of nanomachines able to perform nanoscale movements in response to external stimuli (4-11). Experimental and theoretical studies on single DNA nanomachines have led to the development of new energy conversion strategies (12, 13). As one of the most popular phototransformable molecules, azobenzene and its derivatives can change the overall structure by cis-trans isomerisation mechanism. Using the photoisomerization of azobenzene to photo-regulate DNA hybridization, (14) we have designed a single-molecule light-driven DNA nanomotor (15) for the continuous production of energy in the form of mechanical work. This photon-fueled nanomotor is simple and easy to operate, promising a unique approach to harvest photonic energy. Herein, azobenzene derivatives act as element for energy absorption and DNA molecules movement act for mechanical energy export. As we know, solar thermal technology is a technology to harvest solar thermal energy that converts solar energy to movement of molecules and then produces heat caused by molecule thermal moving. In our design, solar energy is converted to close-open movement of DNA molecules. However, few DNA motor molecules can undergo the close-open conversion as a result of the low p...

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Section: Resultsmentioning

confidence: 99%

Using silver nanowire antennas to enhance the conversion efficiency of photoresponsive DNA nanomotors

Yuan

Zhang²,

Chen³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…Table 3. By using the acquired data, the photoisomerization quantum yields ( ) for the trans cis reactions were calculated (see Table 3 according to the procedure reported by Zimmermann et al [215] Figure 23 The cis trans back isomerization was either triggered by light or was observed as a thermal back reaction. For the light induced back reaction, the sample was irradiated at the maximum of the peak of the cis isomer at 450 nm.…”

Section: Photochemical Switching Investigations Uv/vis Measurementsmentioning

confidence: 99%

Shape‐Switchable Azo‐Macrocycles

et al. 2009

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The synthesis of four shape‐switchable macrocycles comprising different peripheral substituents is described. The macrocycles 1–4 consist of m‐terphenyl semicircles interlinked by two azo joints. These macrocycles were assembled from nitro‐functionalized m‐terphenyl moieties through reductive dimerization. The semicircles were assembled through Suzuki cross‐coupling reactions. The molecular weights of the macrocycles were determined by vapour pressure osmometry, because mass spectrometry failed in the cases of 2 and 3. The E → Z photoisomerization reactions were analysed by UV/Vis spectroscopy complemented by 1H NMR studies. A very slow thermal back‐reaction indicated considerable stabilization of the Z isomer. The reduced efficiency of the thermal back‐reaction probably arises from the reduced degree of freedom due to the mechanical interlinking of the two azo groups. The photostationary state consisted of all‐Z (85 %) and all‐E isomers (15 %). The E → Z transformation induced by irradiation displayed simple exponential kinetics, which indicates pairwise switching of the two azo groups in a macrocycle, at least on the timescale under investigation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] An earlier study on the absorption spectra indicated that the first and second excited states of both cis-and trans-azobenzene were attributed to nπ * and ππ * excitations, respectively. 1,4,11 Quantum yields of the isomerizations for cis-and trans-azobenzene were reported to be different between nπ * and ππ * excitations. 1,2,4 Rau and Luddeke proposed that the photoisomerization of trans-azobenzene should follow different pathways in nπ * and ππ * excitations, through a comparison of the simple azobenzene and the sterically hindered azobenzenes.…”

Section: Introductionmentioning

confidence: 99%

“…1,4,11 Quantum yields of the isomerizations for cis-and trans-azobenzene were reported to be different between nπ * and ππ * excitations. 1,2,4 Rau and Luddeke proposed that the photoisomerization of trans-azobenzene should follow different pathways in nπ * and ππ * excitations, through a comparison of the simple azobenzene and the sterically hindered azobenzenes. 5,7 It was reported that the nπ * excitation invokes the inversion of the NNC bond angle within a planar geometry, while the ππ * excitation invokes the rotation of two phenyl rings around the NN bond ( Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…5,7 It was reported that the nπ * excitation invokes the inversion of the NNC bond angle within a planar geometry, while the ππ * excitation invokes the rotation of two phenyl rings around the NN bond ( Figure 1). Ultrafast UV-visible absorption spectroscopy and time resolved fluorescence experiments on trans-azobenzene suggested that decay in nπ * excitation can be described by three processes: 1, 2, 4, 9, 11 (1) relaxation from the Franck-Condon region to the minimum in the S 1 (nπ * ) state, (2) motion toward S 1 /S 0 conical intersections, and (3) vibrational cooling in the S 0 state through an interaction with solvent molecules.…”

Section: Introductionmentioning

confidence: 99%

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A multireference perturbation study of the NN stretching frequency of trans-azobenzene in nπ* excitation and an implication for the photoisomerization mechanism

Harabuchi

Ishii

Nakayama

et al. 2013

The Journal of Chemical Physics

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A multireference second-order perturbation theory is applied to calculate equilibrium structures and vibrational frequencies of trans-azobenzene in the ground and nπ * excited states, as well as the reaction pathways for rotation and inversion mechanism in the nπ * excited state. It is found that the NN stretching frequency exhibits a slight increase at the minimum energy structure in the nπ * state, which is explained by the mixing of the NN stretching mode with the CN symmetric stretching mode. We also calculate the NN stretching frequency at several selected structures along the rotation and inversion pathways in the nπ * state, and show that the frequency decreases gradually along the rotation pathway while it increases by ca. 300 cm −1 along the inversion pathway. The frequencies and energy variations along the respective pathways indicate that the rotation pathway is more consistent with the experimental observation of the NN stretching frequency in nπ * excitation.

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The Photochemical Isomerization of Azobenzene¹

Cited by 527 publications

References 2 publications

Using silver nanowire antennas to enhance the conversion efficiency of photoresponsive DNA nanomotors

Using silver nanowire antennas to enhance the conversion efficiency of photoresponsive DNA nanomotors

Shape‐Switchable Azo‐Macrocycles

A multireference perturbation study of the NN stretching frequency of trans-azobenzene in nπ* excitation and an implication for the photoisomerization mechanism

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The Photochemical Isomerization of Azobenzene1

Cited by 527 publications

References 2 publications

Using silver nanowire antennas to enhance the conversion efficiency of photoresponsive DNA nanomotors

Using silver nanowire antennas to enhance the conversion efficiency of photoresponsive DNA nanomotors

Shape‐Switchable Azo‐Macrocycles

A multireference perturbation study of the NN stretching frequency of trans-azobenzene in nπ* excitation and an implication for the photoisomerization mechanism

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The Photochemical Isomerization of Azobenzene¹