TY  - JOUR
A1  - Loebner, Sarah
A1  - Lomadze, Nino
A1  - Kopyshev, Alexey
A1  - Koch, Markus
A1  - Guskova, Olga
A1  - Saphiannikova, Marina
A1  - Santer, Svetlana
T1  - Light-Induced Deformation of Azobenzene-Containing Colloidal Spheres
BT  - Calculation and Measurement of Opto-Mechanical Stresses
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - We report on light-induced deformation of colloidal spheres consisting of azobenzene-containing polymers. The colloids of the size between 60 nm and 2 mu m in diameter were drop casted on a glass surface and irradiated with linearly polarized light. It was found that colloidal particles can be deformed up to ca. 6 times of their initial diameter. The maximum degree of deformation depends on the irradiation wavelength and intensity, as well as on colloidal particles size. On the basis of recently proposed theory by Toshchevikov et al. [J. Phys. Chem. Lett. 2017, 8, 1094], we calculated the optomechanical stresses (ca. 100 MPa) needed for such giant deformations and compared them with the experimental results.
Y1  - 2018
U6  - https://doi.org/10.1021/acs.jpcb.7b11644
SN  - 1520-6106
VL  - 122
IS  - 6
SP  - 2001
EP  - 2009
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Koch, Markus
A1  - Saphiannikova, Marina
A1  - Santer, Svetlana
A1  - Guskova, Olga
T1  - Photoisomers of Azobenzene Star with a Flat Core: Theoretical Insights into Multiple States from DFT and MD Perspective
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - This study focuses on comparing physical properties of photoisomers of an azobenzene star with benzene-1,3,5-tricarboxamide core. Three azobenzene arms of the molecule undergo a reversible trans-cis isomerization upon UV-vis light illumination giving rise to multiple states from the planar all-trans one, via two mixed states to the kinked all-cis isomer. Employing density functional theory, we characterize the structural and photophysical properties of each state indicating a role the planar core plays in the coupling between azobenzene chromophores. To characterize the light-triggered switching of solvophilicity/solvophobicity of the star, the difference in solvation free energy is calculated for the transfer of an azobenzene star from its gas phase to implicit or explicit solvents. For the latter case, classical all-atom molecular dynamics simulations of aqueous solutions of azobenzene star are performed employing the polymer consistent force field to shed light on the thermodynamics of explicit hydration as a function of the isomerization state and on the structuring of water around the star. From the analysis of two contributions to the free energy of hydration, the nonpolar van der Waals and the electrostatic terms, it is concluded that isomerization specificity largely determines the polarity of the molecule and the solute-solvent electrostatic interactions. This convertible hydrophilicity/hydrophobicity together with readjustable occupied volume and the surface area accessible to water, affects the self-assembly/disassembly of the azobenzene star with a flat core triggered by light.
Y1  - 2017
U6  - https://doi.org/10.1021/acs.jpcb.7b07350
SN  - 1520-6106
VL  - 121
SP  - 8854
EP  - 8867
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Fischer, Markus
A1  - Schütz, Wolfgang
A1  - Bernhardt, Karl-Georg
A1  - Koch, Markus
T1  - Special feature : Plant population biology in al multidisciplinary context
Y1  - 2003
ER  -