Optical Forces at the Nanoscale: Size and Electrostatic Effects

The influence of methanol, ethanol, propan-1-ol, and propan-2-ol on the dissociation of tyrosines of human serum orosomucoid (acid α1-glycoprotein) was studied. The content of alcohols was chosen so that their solutions had the same value of the relative permittivity. Then, the contribution of electrostatic effects was equal in all cases and the observed differences between aqueous and alcoholic solutions reflected other, nonelectrostatic effects in the studied systems. Analysis of the spectrophotometric titration curve revealed three kinds of tyrosine groups (n1, n2, n3), but only the values pK1 and pK2 could be calculated. The observed differences of pK values in aqueous and mixed media are discussed and compared with the structural changes of the orosomucoid molecule.

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Using internal electrostatic fields to manipulate the valence manifolds of copper complexes

Chemical Science ◽

10.1039/d0sc06364a ◽

2021 ◽

Author(s):

Alexander B. Weberg ◽

Samuel P. McCollom ◽

Laura M. Thierer ◽

Michael R. Gau ◽

Patrick J. Carroll ◽

...

Keyword(s):

Coordination Sphere ◽

Copper Complexes ◽

Photophysical Properties ◽

Redox Potentials ◽

Electrostatic Effects ◽

Electrostatic Fields ◽

Secondary Coordination Sphere

Secondary coordination sphere electrostatic effects tune the valence manifolds of copper centers, impacting molecular geometries, photophysical properties, and redox potentials.

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Steric and Electrostatic Effects on the Diffusion of CH4/CH3OH in Copper-Exchanged Zeolites: Insights from Enhanced Sampling Molecular Dynamics and Free Energy Calculations

Langmuir ◽

10.1021/acs.langmuir.1c01078 ◽

2021 ◽

Author(s):

Luis Paulo M. Freitas ◽

Anderson A. Espírito Santo ◽

Tuanan C. Lourenço ◽

Juarez L. F. Da Silva ◽

Gustavo Troiano Feliciano

Keyword(s):

Molecular Dynamics ◽

Free Energy ◽

Free Energy Calculations ◽

Enhanced Sampling ◽

Electrostatic Effects ◽

Energy Calculations

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Plasmonic linear nanomotor using lateral optical forces

Science Advances ◽

10.1126/sciadv.abc3726 ◽

2020 ◽

Vol 6 (45) ◽

pp. eabc3726

Author(s):

Yoshito Y. Tanaka ◽

Pablo Albella ◽

Mohsen Rahmani ◽

Vincenzo Giannini ◽

Stefan A. Maier ◽

...

Keyword(s):

Laser Beam ◽

Incident Light ◽

Lateral Force ◽

Diffraction Limit ◽

Propagation Direction ◽

Optical Force ◽

Optical Forces ◽

Incident Laser ◽

New Class ◽

Force Direction

Optical force is a powerful tool to actuate micromachines. Conventional approaches often require focusing and steering an incident laser beam, resulting in a bottleneck for the integration of the optically actuated machines. Here, we propose a linear nanomotor based on a plasmonic particle that generates, even when illuminated with a plane wave, a lateral optical force due to its directional side scattering. This force direction is determined by the orientation of the nanoparticle rather than a field gradient or propagation direction of the incident light. We demonstrate the arrangements of the particles allow controlling the lateral force distributions with the resolution beyond the diffraction limit, which can produce movements, as designed, of microobjects in which they are embedded without shaping and steering the laser beam. Our nanomotor to engineer the experienced force can open the door to a new class of micro/nanomechanical devices that can be entirely operated by light.

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