Light Switching of Molecules on Surfaces

Browne, Wesley R.; Feringa, Ben L.

doi:10.1146/annurev.physchem.040808.090423

Cited by 274 publications

(261 citation statements)

References 95 publications

(81 reference statements)

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“…The designed handedness of the rotor determined the sense of rotation. Furthermore, this research group functionalized surfaces with these rotors and made them rotate upon light exposure [227][228][229]. Finally, this concept has been used to build a molecule with four unidirectional chiral rotor units.…”

Section: Diastereomers and Diastereomeric Recognitionmentioning

confidence: 99%

Molecular chirality at surfaces

Ernst

2012

Physica Status Solidi (b)

221

264

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With the adsorption of larger molecules being increasingly tackled by surface scientists, the aspect of chirality often plays a role. This paper gives a topical review of molecular chirality at surfaces and gives a phenomenological overview of different aspects of adsorption and self‐assembly of chiral and prochiral molecules and the principles of mirror‐symmetry breaking at a surface. After a brief introduction into the history of molecular chirality and the important role it played for understanding the spatial structure of molecules, definitions of chirality are presented. Topics treated here are principle ways to create single chiral adsorbates, chiral ensembles, and monolayers by achiral molecules, adsorption of intrinsically chiral molecules at achiral and chiral surfaces, long‐range symmetry breaking in two‐dimensional (2D) crystals due to additional chiral bias, chiral restructuring of solid surfaces under the influence of chiral molecules, switching the handedness of adsorbates, and chirality at the liquid/air interface. An outlook onto further potential research directions and recommendations for further reading, including nonsurface‐related sources of chiral topics completes this paper.

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Section: Diastereomers and Diastereomeric Recognitionmentioning

confidence: 99%

Molecular chirality at surfaces

Ernst

2012

Physica Status Solidi (b)

221

264

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“…1 Spiropyrans, reported for the first time by Fischer and Hirshberg, 2 are one of the most widely studied classes of photoswitchable compounds.…”

Section: Introductionmentioning

confidence: 99%

A Multiswitchable Poly(terthiophene) Bearing a Spiropyran Functionality: Understanding Photo- and Electrochemical Control

et al. 2011

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An electroactive nitrospiropyran-substituted polyterthiophene, 2-(3,3′′-dimethylindoline-6′-nitrobenzospiropyranyl)ethyl 4,4′′-didecyloxy-2,2′:5′,2′′-terthiophene-3′-acetate, has been synthesized for the first time. The spiropyran, incorporated into the polymer backbone by covalent attachment to the alkoxyterthiophene monomer units, leads to multiple coloured states as a result of both electrochemical isomerization of the spiropyran moiety to merocyanine forms as well as electrochemical oxidation of the polyterthiophene backbone and the merocyanine substituents. While electrochemical polymerization of the terthiophene monomer could occurs without the apparent oxidation of the spiropyran, the subsequent electrochemistry is complex and clearly involves this substituent. In order to understand this complex behaviour, the first detailed electrochemical study of the oxidation of the precursor spiropyran, 1-(2-hydroxyethyl)-3,3-dimethylindoline-6'-nitrobenzospiropyran, was undertaken, showing that, in solution, an irreversible electrochemical oxidation of the spiropyran occurs leading to reversible redox behaviour of at least two merocyanine isomers. With these insights, an extensive electrochemical and spectroelectrochemical study of the nitrospiropyran-substituted polyterthiophene films reveals an initial irreversible electrochemical oxidative ring opening of the spiropyran to oxidized merocyanine. Subsequent reduction and cyclic voltammetry of the resulting nitromerocyanine-substituted polyterthiophene film gives rise to the formation of both merocyanine π-dimers or oligomers and π-radical cation dimers, between polymer chains. Although merocyanine formation is not electrochemically reversible, the spiropyran can be photochemically regenerated, at least in part, through irradiation with visible light. SEM and AFM images support the conclusion that the bulky spiropyran substituent is electrochemically isomerizes to the planar merocyanine moiety affording a smoother polymer film. The conductivity of the freestanding polymer film was found to be 0.4 S cm -1 .3

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“…Among photochromic systems (15)(16)(17)(18), azobenzene derivatives are known to undergo isomerization from trans to cis form, and vice versa, under illumination at a specific wavelength, as well as from cis to trans with temperature (15). In the last few years, we have extensively investigated the thiol-substituted azo-biphenyl (AZO, Fig.…”

mentioning

confidence: 99%

Optically switchable organic field-effect transistors based on photoresponsive gold nanoparticles blended with poly(3-hexylthiophene)

Raimondo

Crivillers

Reinders

et al. 2012

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

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Interface tailoring represents a route for integrating complex functions in systems and materials. Although it is ubiquitous in biological systems-e.g., in membranes-synthetic attempts have not yet reached the same level of sophistication. Here, we report on the fabrication of an organic field-effect transistor featuring dualgate response. Alongside the electric control through the gate electrode, we incorporated photoresponsive nanostructures in the polymeric semiconductor via blending, thereby providing optical switching ability to the device. In particular, we mixed poly(3-hexylthiophene) with gold nanoparticles (AuNP) coated with a chemisorbed azobenzene-based self-assembled monolayer, acting as traps for the charges in the device. The light-induced isomerization between the trans and cis states of the azobenzene molecules coating the AuNP induces a variation of the tunneling barrier, which controls the efficiency of the charge trapping/detrapping process within the semiconducting film. Our approach offers unique solutions to digital commuting between optical and electric signals.O rganic field-effect transistors (OFETs) are basic building blocks for logic applications and for the development of electronic technologies based on soft matter (1-4). Currently, the greatest challenges in the field are the achievement of higher device performance and the development of devices featuring uncommon and multiple functionalities (5). In this regard, hybrid organic-inorganic materials are gaining much attention because, besides their easy processing, they can take advantage of the tunability of the chemical properties of the components, and thus of the material as a whole. Nanoparticles (NPs) of different materials (gold, silver, metal oxides, etc.) can be coated with selfassembled monolayers (SAMs) of a given molecular system, thereby providing them additional functions such as a specific surface energy or optoelectronic properties (6-8). These features can be optimized by achieving control over the packing of SAMs on the NPs (7). When NPs are integrated in a device, they can, for example, act as charge storage sites-i.e., trapping charges centers, allowing the system to act as a memory (9, 10).The incorporation of photochromic molecules into electronic devices to confer them a photoresponsive nature has been recently explored (11)(12)(13)(14). Among photochromic systems (15-18), azobenzene derivatives are known to undergo isomerization from trans to cis form, and vice versa, under illumination at a specific wavelength, as well as from cis to trans with temperature (15). In the last few years, we have extensively investigated the thiol-substituted azo-biphenyl (AZO, Fig. 1A) when chemisorbed on gold surfaces (19)(20)(21)(22). We demonstrated that such a SAM chemisorbed on the planar source and drain electrodes of an OFET can be used to modulate optically the charge injection at the metal-semiconductor interface because of the different tunneling barrier of the cis and trans SAMs (19). However, the observed light-modul...

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Light Switching of Molecules on Surfaces

Cited by 274 publications

References 95 publications

Molecular chirality at surfaces

Molecular chirality at surfaces

A Multiswitchable Poly(terthiophene) Bearing a Spiropyran Functionality: Understanding Photo- and Electrochemical Control

Optically switchable organic field-effect transistors based on photoresponsive gold nanoparticles blended with poly(3-hexylthiophene)

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