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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Photoisomerization induced scission of rod-like micelles unravelled with multiscale modeling

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Heerdt, Gabriel [1] ; Tranca, Ionut [2] ; Markvoort, Albert J. [3, 4] ; Szyja, Bartlomiej M. [5] ; Morgon, Nelson H. [1] ; Hensen, Emiel J. M. [2]
Total Authors: 6
[1] Univ Estadual Campinas, Dept Phys Chem, Inst Chem, POB 6154, BR-13083970 Campinas, SP - Brazil
[2] Eindhoven Univ Technol, Lab Inorgan Mat Chem, Dept Chem Engn & Chem, POB 513, NL-5600 MB Eindhoven - Netherlands
[3] Eindhoven Univ Technol, Computat Biol Grp, Dept Biomed Engn, POB 513, NL-5600 MB Eindhoven - Netherlands
[4] Eindhoven Univ Technol, Inst Complex Mol Syst, POB 513, NL-5600 MB Eindhoven - Netherlands
[5] Wroclaw Univ Sci & Technol, Div Fuels Chem & Technol, Fac Chem, Gdanska 7-9, PL-50344 Wroclaw - Poland
Total Affiliations: 5
Document type: Journal article
Source: Journal of Colloid and Interface Science; v. 510, p. 357-367, JAN 15 2018.
Web of Science Citations: 0

Hypothesis: In photorheological fluids, subtle molecular changes caused by light lead to abrupt macroscopic alterations. Upon UV irradiation of an aqueous cetyltrimethylammonium bromide (CTAB) and trans-ortho-methoxycinnamic acid (trans-OMCA) solution, for instance, the viscosity drops over orders of magnitude. Multiscale modeling allows to elucidate the mechanisms behind these photorheological effects. Experiments: We use time-dependent DFT calculations to study the photoisomerization, and a combination of atomistic molecular dynamics (MD) and DFT to probe the influence of both OMCA isomers on the micellar solutions. Findings: The time-dependent DFT calculations show that the isomerization pathway occurs in the first triplet excited state with a minimum energy conformation closest to the after photoisomerization predominant cis configuration. In the MD simulations, with sub-microsecond timescales much shorter than the experimental morphological transition, already a clear difference is observed in the packing of the two OMCA isomers: contrary to trans-OMCA, cis-OMCA exposes notable part of its hydrophobic aromatic rings at the micelle surface. This can explain why trans-OMCA adopts rod-like micellar packing (high viscosity) while cis-OMCA spherical micellar packing (low viscosity). Moreover, lowering of the OMCA co-solute concentration allowed us to perform full simulation of the breakup process of the rod-like micelles which are stable prior to isomerization. (C) 2017 Elsevier Inc. All rights reserved. (AU)

FAPESP's process: 16/04963-6 - Molecular dynamics of cellulose enzymatic hydrolysis and QM / MM simulations of chemical reactions in biomolecular systems
Grantee:Gabriel Heerdt
Support type: Scholarships in Brazil - Post-Doctorate