A surface-bound molecule that undergoes optically biased Brownian rotation

James A. Hutchison; Hiroshi Uji-i; Ania Deres; Tom André Jos Vosch; Susana Rocha; Sibylle Müller; Andreas A. Bastian; Jörg Enderlein; Hassan Nourouzi; Chen Li; Andreas Herrmann; Klaus Müllen; Frans De Schryver; Johan Hofkens

doi:10.1038/nnano.2013.285

A surface-bound molecule that undergoes optically biased Brownian rotation

James A. Hutchison, Hiroshi Uji-i, Ania Deres, Tom André Jos Vosch, Susana Rocha, Sibylle Müller, Andreas A. Bastian, Jörg Enderlein, Hassan Nourouzi, Chen Li, Andreas Herrmann, Klaus Müllen, Frans De Schryver, Johan Hofkens

48 Citations (Scopus)

Abstract

Developing molecular systems with functions analogous to those of macroscopic machine components, such as rotors, gyroscopes and valves, is a long-standing goal of nanotechnology. However, macroscopic analogies go only so far in predicting function in nanoscale environments, where friction dominates over inertia. In some instances, ratchet mechanisms have been used to bias the ever-present random, thermally driven (Brownian) motion and drive molecular diffusion in desired directions. Here, we visualize the motions of surface-bound molecular rotors using defocused fluorescence imaging, and observe the transition from hindered to free Brownian rotation by tuning medium viscosity. We show that the otherwise random rotations can be biased by the polarization of the excitation light field, even though the associated optical torque is insufficient to overcome thermal fluctuations. The biased rotation is attributed instead to a fluctuating-friction mechanism in which photoexcitation of the rotor strongly inhibits its diffusion rate.

Original language	English
Journal	Nature Nanotechnology
Volume	9
Issue number	2
Pages (from-to)	131-136
Number of pages	6
ISSN	1748-3387
DOIs	https://doi.org/10.1038/nnano.2013.285
Publication status	Published - Feb 2014

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title = "A surface-bound molecule that undergoes optically biased Brownian rotation",

abstract = "Developing molecular systems with functions analogous to those of macroscopic machine components, such as rotors, gyroscopes and valves, is a long-standing goal of nanotechnology. However, macroscopic analogies go only so far in predicting function in nanoscale environments, where friction dominates over inertia. In some instances, ratchet mechanisms have been used to bias the ever-present random, thermally driven (Brownian) motion and drive molecular diffusion in desired directions. Here, we visualize the motions of surface-bound molecular rotors using defocused fluorescence imaging, and observe the transition from hindered to free Brownian rotation by tuning medium viscosity. We show that the otherwise random rotations can be biased by the polarization of the excitation light field, even though the associated optical torque is insufficient to overcome thermal fluctuations. The biased rotation is attributed instead to a fluctuating-friction mechanism in which photoexcitation of the rotor strongly inhibits its diffusion rate.",

author = "Hutchison, {James A.} and Hiroshi Uji-i and Ania Deres and Vosch, {Tom Andr{\'e} Jos} and Susana Rocha and Sibylle M{\"u}ller and Bastian, {Andreas A.} and J{\"o}rg Enderlein and Hassan Nourouzi and Chen Li and Andreas Herrmann and Klaus M{\"u}llen and {De Schryver}, Frans and Johan Hofkens",

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doi = "10.1038/nnano.2013.285",

language = "English",

volume = "9",

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journal = "Nature Nanotechnology",

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T1 - A surface-bound molecule that undergoes optically biased Brownian rotation

AU - Hutchison, James A.

AU - Uji-i, Hiroshi

AU - Deres, Ania

AU - Vosch, Tom André Jos

AU - Rocha, Susana

AU - Müller, Sibylle

AU - Bastian, Andreas A.

AU - Enderlein, Jörg

AU - Nourouzi, Hassan

AU - Li, Chen

AU - Herrmann, Andreas

AU - Müllen, Klaus

AU - De Schryver, Frans

AU - Hofkens, Johan

PY - 2014/2

Y1 - 2014/2

N2 - Developing molecular systems with functions analogous to those of macroscopic machine components, such as rotors, gyroscopes and valves, is a long-standing goal of nanotechnology. However, macroscopic analogies go only so far in predicting function in nanoscale environments, where friction dominates over inertia. In some instances, ratchet mechanisms have been used to bias the ever-present random, thermally driven (Brownian) motion and drive molecular diffusion in desired directions. Here, we visualize the motions of surface-bound molecular rotors using defocused fluorescence imaging, and observe the transition from hindered to free Brownian rotation by tuning medium viscosity. We show that the otherwise random rotations can be biased by the polarization of the excitation light field, even though the associated optical torque is insufficient to overcome thermal fluctuations. The biased rotation is attributed instead to a fluctuating-friction mechanism in which photoexcitation of the rotor strongly inhibits its diffusion rate.

AB - Developing molecular systems with functions analogous to those of macroscopic machine components, such as rotors, gyroscopes and valves, is a long-standing goal of nanotechnology. However, macroscopic analogies go only so far in predicting function in nanoscale environments, where friction dominates over inertia. In some instances, ratchet mechanisms have been used to bias the ever-present random, thermally driven (Brownian) motion and drive molecular diffusion in desired directions. Here, we visualize the motions of surface-bound molecular rotors using defocused fluorescence imaging, and observe the transition from hindered to free Brownian rotation by tuning medium viscosity. We show that the otherwise random rotations can be biased by the polarization of the excitation light field, even though the associated optical torque is insufficient to overcome thermal fluctuations. The biased rotation is attributed instead to a fluctuating-friction mechanism in which photoexcitation of the rotor strongly inhibits its diffusion rate.

U2 - 10.1038/nnano.2013.285

DO - 10.1038/nnano.2013.285

M3 - Journal article

SN - 1748-3387

VL - 9

SP - 131

EP - 136

JO - Nature Nanotechnology

JF - Nature Nanotechnology

IS - 2

ER -

A surface-bound molecule that undergoes optically biased Brownian rotation

Abstract

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