Kinetics of photo-isomerization of azobenzene containing surfactants

  • We report on photoisomerization kinetics of azobenzene containing surfactants in aqueous solution. The surfactant molecule consists of a positively charged trimethylammonium bromide head group, a hydrophobic spacer connecting via 6 to 10 CH2 groups to the azobenzene unit, and the hydrophobic tail of 1 and 3CH(2) groups. Under exposure to light, the azobenzene photoisomerizes from more stable trans- to metastable cis-state, which can be switched back either thermally in dark or by illumination with light of a longer wavelength. The surfactant isomerization is described by a kinetic model of a pseudo first order reaction approaching equilibrium, where the intensity controls the rate of isomerization until the equilibrated state. The rate constants of the trans-cis and cis-trans photoisomerization are calculated as a function of several parameters such as wavelength and intensity of light, the surfactant concentration, and the length of the hydrophobic tail. The thermal relaxation rate from cis- to trans-state is studied as well. TheWe report on photoisomerization kinetics of azobenzene containing surfactants in aqueous solution. The surfactant molecule consists of a positively charged trimethylammonium bromide head group, a hydrophobic spacer connecting via 6 to 10 CH2 groups to the azobenzene unit, and the hydrophobic tail of 1 and 3CH(2) groups. Under exposure to light, the azobenzene photoisomerizes from more stable trans- to metastable cis-state, which can be switched back either thermally in dark or by illumination with light of a longer wavelength. The surfactant isomerization is described by a kinetic model of a pseudo first order reaction approaching equilibrium, where the intensity controls the rate of isomerization until the equilibrated state. The rate constants of the trans-cis and cis-trans photoisomerization are calculated as a function of several parameters such as wavelength and intensity of light, the surfactant concentration, and the length of the hydrophobic tail. The thermal relaxation rate from cis- to trans-state is studied as well. The surfactant isomerization shows a different kinetic below and above the critical micellar concentration of the trans isomer due to steric hindrance within the densely packed micelle but does not depend on the spacer length.show moreshow less

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Metadaten
Author details:Pooja AryaORCiDGND, Joachim JelkenORCiDGND, Nino Lomadze, Svetlana SanterORCiDGND, Marek BekirORCiDGND
DOI:https://doi.org/10.1063/1.5135913
ISSN:0021-9606
ISSN:1089-7690
Pubmed ID:https://pubmed.ncbi.nlm.nih.gov/31941331
Title of parent work (English):The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry
Publisher:American Institute of Physics
Place of publishing:Melville
Publication type:Article
Language:English
Date of first publication:2020/01/10
Publication year:2020
Release date:2022/11/23
Tag:driven; genomic DNA conformation; light photocontrol; manipulation; molecules; photoisomerization; water-interface
Volume:152
Issue:2
Article number:024904
Number of pages:10
Funding institution:Priority Program 1726 "Microswimmers-From Single Particle Motion to; Collective Behaviour," Germany; DFGGerman Research Foundation; (DFG)European Commission [SA1657/8-1]; International Max Planck Research; School (IMPRS) on Multiscale BioSystems, Potsdam, Germany
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie
DDC classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Peer review:Referiert
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