Publication details

Photoswitching of Azobenzene-Based Reverse Micelles above and at Subzero Temperatures As Studied by NMR and Molecular Dynamics Simulations

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Authors

FILIPOVÁ Lenka KOHAGEN Miriam ŠTACKO Peter MUCHOVA Eva SLAVÍČEK Petr KLÁN Petr

Year of publication 2017
Type Article in Periodical
Magazine / Source Langmuir
MU Faculty or unit

Faculty of Science

Citation
Web http://pubs.acs.org/doi/10.1021/acs.langmuir.6b04455
Doi http://dx.doi.org/10.1021/acs.langmuir.6b04455
Field Organic chemistry
Keywords IONIC LIQUIDS; FORCE-FIELD; TRANS ISOMERIZATION; DRUG-DELIVERY; WATER; CRYSTALS; LIGHT; PHOTOISOMERIZATION; VESICLES; SOLVENTS
Description We designed and studied the structure, dynamics, and photochemistry of photoswitchable reverse micelles (RMs) composed of azobenzene-containing ammonium amphiphile 1 and water in chloroform at room and subzero temperatures by NMR spectroscopy and molecular dynamics simulations. The NMR and diffusion coefficient analyses showed that micelles containing either the E or Z configuration of 1 are stable at room temperature. Depending on the water-to-surfactant molar ratio, the size of the RMs remains unchanged or is slightly reduced because of the partial loss of water from the micellar cores upon extensive E -> Z or Z -> E photoisomerization of the azobenzene group in 1. Upon freezing at 253 or 233 K, E-1 RMs partially precipitate from the solution but are redissolved upon warming whereas Z-1 RMs remain fully dissolved at all temperatures. Light-induced isomerization of 1 at low temperatures does not lead to the disintegration of RMs remaining in the solution; however, its scope is influenced by a precipitation process. To obtain a deeper molecular view of RMs, their structure was characterized by MD simulations. It is shown that RMs allow for amphiphile isomerization without causing any immediate significant structural changes in the micelles.
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