Photoresponsive crown ethers. 1. Cis-trans isomerism of azobenzene as a tool to enforce conformational changes of crown ethers and polymers

Shinkai, Seiji; Nakaji, Takahiro; Nishida, Yoshihiro; Ogawa, Tetsuro; Manabe, Osamu

doi:10.1021/ja00538a026

Cited by 259 publications

(113 citation statements)

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“…The azobenzene-bridged crown ether 3a was synthesized by Shinkai and collaborators. 17 In this analogue the diazastilbene phenyl rings are linked to the same crown ether.…”

Section: Photoswitchable Receptors Based On Diazastilbenesmentioning

confidence: 99%

Molecular switches as photocontrollable “smart” receptors

2012

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This critical review focuses on the development of photochromic compounds as sensors for cations, anions, and biologically important molecules. The review commences with a brief description of photochromism and the strategies to exploit photochromic molecular switches' properties for sensing application. This is followed by a summary of photoswitchable receptors emerged to date and classified according to the photochromic structure they are based on. These include azobenzenes, fulgides, dithienylethenes, dihydroindolizines, chromenes and spiropyrans.

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“…The azobenzene-bridged crown ether 3a was synthesized by Shinkai and collaborators. 17 In this analogue the diazastilbene phenyl rings are linked to the same crown ether.…”

Section: Photoswitchable Receptors Based On Diazastilbenesmentioning

confidence: 99%

Molecular switches as photocontrollable “smart” receptors

2012

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“…2 The isomerization of azobenzenes has been recently exploited for the preparation of several molecular machines 3 used as both biological 4 and photonic 5 devices. The strong geometrical difference between the extended trans form and the compact cis form in the gas phase and in solution may provide important details on the distribution and the dynamics of the azobenzene guest into hosts such as cyclodextrins 6 and crown ethers 7 or on the conformational changes of polypeptide chains. 8 The mechanism by which the Z-E isomerization takes place is not unequivocally established since two opposing pathways have been proposed: the reaction may proceed either by rotation about the N=N double bond or by flip-flop inversion of one of the nitrogen atoms.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of the Z-E isomerization of monosubstituted azobenzenes in polar organic and aqueous micellar solvents

Maria¹,

Fontana²,

Gasbarri³

et al. 2008

Arkivoc

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The rates of Z-E isomerization of azobenzene and seven 4-substituted derivatives (CH3, CF3, OCH3, n-Butyl, Ot-Butyl, Br, F) have been investigated at 25 °C in ethanol, in methanol, in methanol/water mixtures and in aqueous solutions of ionic and non-ionic micelles by recording in the dark the spectral changes observed after exposure to UV light of the samples. The competitive contributions of the rotation vs. inversion mechanisms by which the isomerization of azobenzenes can occur have emerged from V-shaped Hammett plots. The obtained rate constants can be used as polarity indicators of the different micro-heterogeneous media with two main advantages with respect to other probes. Firstly they are not affected by hydrogen bonding between the substrate and the environment, as in the case of push-pull azobenzenes. Secondly, the derived substrate-independent Hammett  values allow to separate the effects of orientation of the probe from the polarity of the supramolecular aggregate.

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“…For instance, switches based on azobenzene have been used to control ion complexation (4,5), electronic properties (6), catalysis (7), and the folding of peptides (8)(9)(10)(11)(12)(13) whereas diarylidenes have provided the framework for the construction of rotary motors and transmissions (14). The computer modeling of switches that differ in size, polarity, and isomerization mechanism represents an attractive research target (15) yielding building blocks to be used in diverse molecular environments.…”

mentioning

confidence: 99%

An artificial molecular switch that mimics the visual pigment and completes its photocycle in picoseconds

Sinicropi

Martin

Ryazantsev

et al. 2008

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

161

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Single molecules that act as light-energy transducers (e.g., converting the energy of a photon into atomic-level mechanical motion) are examples of minimal molecular devices. Here, we focus on a molecular switch designed by merging a conformationally locked diarylidene skeleton with a retinal-like Schiff base and capable of mimicking, in solution, different aspects of the transduction of the visual pigment Rhodopsin. Complementary ab initio multiconfigurational quantum chemistry-based computations and time-resolved spectroscopy are used to follow the light-induced isomerization of the switch in methanol. The results show that, similar to rhodopsin, the isomerization occurs on a 0.3-ps time scale and is followed by <10-ps cooling and solvation. The entire (2-photon-powered) switch cycle was traced by following the evolution of its infrared spectrum. These measurements indicate that a full cycle can be completed within 20 ps.CASPT2//CASSCF ͉ mid-IR ͉ photochemical switch ͉ time resolved spectroscopy ͉ UV-vis M olecular switches based on photochemical E/Z isomerizations have been used in different contexts to convert light energy into ''mechanical'' motion at the molecular level (1-3). For instance, switches based on azobenzene have been used to control ion complexation (4, 5), electronic properties (6), catalysis (7), and the folding of peptides (8-13) whereas diarylidenes have provided the framework for the construction of rotary motors and transmissions (14). The computer modeling of switches that differ in size, polarity, and isomerization mechanism represents an attractive research target (15) yielding building blocks to be used in diverse molecular environments. However, this cannot be limited to the computation of equilibrium properties but requires the description of the entire photocycle. In other words, one needs to compute the potential energy surfaces controlling the switch E 3 Z and Z 3 E excited-state evolution, its decay and ground state relaxation, and the competing thermal E/Z isomerization in the proper environment (e.g., in solution or in a biomolecule backbone). The complexity of these calculations impedes the study of candidates that are intractable with accurate quantum chemical methods (allowing comparison with spectroscopic data) or that feature, as for azobenzene and diarylidenes (16), more than 1 low-lying excited state, leading to a plethora of reaction paths to be computed.The retinal protonated Schiff-base chromophore of rhodopsins (17-19) constitutes an example of an E/Z switch shaped by biological evolution that can be modeled with quantitative computations (20). In bovine rhodopsin (Rh), a selective photoisomerization of the 11-cis chromophore (PSB11) occurs via evolution of a single 3 * excited state (S 1 ) that survives for only 150 fs and yields, upon decay, the all-trans ground state (S 0 ) product with a 67% quantum yield (16,20). Although these properties make Rh an excellent reference for the design of E/Z switches, irradiation of PSB11 in solution (26, 27) features an unselec...

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Photoresponsive crown ethers. 1. Cis-trans isomerism of azobenzene as a tool to enforce conformational changes of crown ethers and polymers

Cited by 259 publications

References 0 publications

Molecular switches as photocontrollable “smart” receptors

Molecular switches as photocontrollable “smart” receptors

Kinetics of the Z-E isomerization of monosubstituted azobenzenes in polar organic and aqueous micellar solvents

An artificial molecular switch that mimics the visual pigment and completes its photocycle in picoseconds

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