Synthetic light-activated molecular switches and motors on surfaces

Katsonis, Nathalie; Lubomska, Monika; Pollard, Michael M.; Feringa, Bernard; Rudolf, Petra

doi:10.1016/j.progsurf.2007.03.011

Cited by 223 publications

(178 citation statements)

References 93 publications

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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)

219

262

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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)

219

262

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“…In their functionalized forms, the lower-half "stator" is immobilized on a surface 32,[35][36][37][38] and the upper-half "rotator" rotates around the double-bond "axle". Due to steric overcrowding in the so-called fjord regions, the motor halves deviate from planarity to adopt helical structures, denoted P or M to indicate right-handed or left-handed helicity, respectively.…”

Section: Introductionmentioning

confidence: 99%

Computational design of faster rotating second-generation light-driven molecular motors by control of steric effects

Oruganti

Fang

Durbeej

2015

Phys. Chem. Chem. Phys.

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We report a systematic computational investigation of the possibility to accelerate the rate-limiting thermal isomerizations of the rotary cycles of synthetic light-driven overcrowded alkene-based molecular motors through modulation of steric interactions.Choosing as reference system a second-generation motor known to accomplish rotary motion in the MHz regime and using density functional theory methods, we propose a three-step mechanism for the thermal isomerizations of this motor and show that variation of the steric bulkiness of the substituent at the stereocenter can reduce the (already small) free-energy barrier of the rate-determining step by a further 15−17 kJ mol -1 . This finding holds promise for future motors of this kind to reach beyond the MHz regime. Furthermore, we demonstrate and explain why one particular step is kinetically favored by decreasing and another step is kinetically favored by increasing the steric bulkiness of this substituent, and identify a possible back reaction capable of impeding the rotary rate.3

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“…Briefly, photoisomerization is a process in which molecular structural change between isomers is caused by photoexcitation. Therefore, because isomerization causes a conformational change that can change the overall structure of a molecule, cis-trans isomerization is an intriguing mechanism that can be used to regulate mechanical devices and biological reactions (5)(6)(7)(8).…”

mentioning

confidence: 99%

Using photons to manipulate enzyme inhibition by an azobenzene-modified nucleic acid probe

Kim

Phillips

Liu

et al. 2009

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

141

115

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The ability to inhibit an enzyme in a specific tissue with high spatial resolution combined with a readily available antidote should find many biomedical applications. We have accomplished this by taking advantage of the cis-trans photoisomerization of azobenzene molecules. Specifically, we positioned azobenzene moieties within the DNA sequence complementary to a 15-base-long thrombin aptamer and then linked the azobenzene-modified cDNA to the aptamer by a polyethylene glycol (PEG) linker to make a unimolecular conjugate. During the photoisomerization of azobenzene by visible light, the inhibition of thrombin is disabled because the probe hybridizes with the cDNA in the trans-azobenzene conformation so that the aptamer cannot bind its target thrombin. However, when UV light is applied, melting of the hairpin structure (duplex) is induced via trans-to-cis conversion, thereby changing conformation of the aptamer and making the aptamer free to bind to and inhibit its target thrombin. By using standard clotting assays, we measured the IC 200 of various probe designs in both states and concluded the feasibility of using photon energy to temporally and spatially regulate these enzymatic reactions. Thus, we can report the development of DNA probes in the form of photon-controllable (thrombin) inhibitors, termed PCIs, and we expect that this approach will be highly beneficial in future biomedical and pharmaceutical applications.anticoagulation ͉ aptamer ͉ enzyme inhibitor ͉ photo controllable ͉ thrombine O ver the last decade, extensive research has been devoted to the study of phototransformable molecules based on photochromism chemistry. This science has been applied to photooptical technology and such photomodulated devices as eyeglasses called Transitions (1-4). A photochromic compound has 2 molecular states: stable and relatively unstable. The 2 states are interchangeable by the effect of irradiation using different wavelengths and differ from one another in terms of both physical and chemical properties. The photoconversion mechanism can largely be divided into 3 transformation types: photochromic tautomerism, cis-trans isomerization, and photocyclization. Briefly, photoisomerization is a process in which molecular structural change between isomers is caused by photoexcitation. Therefore, because isomerization causes a conformational change that can change the overall structure of a molecule, cis-trans isomerization is an intriguing mechanism that can be used to regulate mechanical devices and biological reactions (5-8).As one of the most popular phototransformable molecules in use today, azobenzene and its derivatives belong to the cis-trans isomerization category and are composed of 2 phenyl rings linked by a NAN double bond (Fig. 1) (9). The 2 isomers can be switched with particular wavelengths of light: UV light at 365 nm, corresponding to the trans-to-cis conversion, and visible light at 465 nm, corresponding to the cis-to-trans isomerization. There are reports that demonstrate the possible applications of su...

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Synthetic light-activated molecular switches and motors on surfaces

Cited by 223 publications

References 93 publications

Molecular chirality at surfaces

Molecular chirality at surfaces

Computational design of faster rotating second-generation light-driven molecular motors by control of steric effects

Using photons to manipulate enzyme inhibition by an azobenzene-modified nucleic acid probe

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