TY - JOUR

T1 - Voltammetry as a Tool to Monitor the Aggregation Behavior of a Zwitterionic Ferrocene Surfactant

AU - Bitter, Stefan

AU - Schilling, Markus

AU - Brahm, Jan P.

AU - Polarz, Sebastian

AU - Winter, Rainer F.

N1 - Funding Information: The current research was funded by an ERC consolidator grant (I-SURF; project 614606). We gratefully acknowledge the European Research Council for financial support. We also acknowledge the state of Baden-Württemberg for providing us with access to the supercomputing facilities of the bwHPC program. We thank Michael Linseis for his help with the CV measurements and Michael Voggel for his assistance with the ITC measurements. Special thanks go to Dr. Marina Krumova for collecting the cryo-TEM images.

PY - 2021/4/13

Y1 - 2021/4/13

N2 - Amphiphiles are unique in their ability to self-assemble in aqueous solution into aggregates. The control of the self-organization of amphiphiles and the live monitoring of the ensuing structure changes by analytical methods are key challenges in this field. One way to gain control and to trigger the self-assembly/disassembly of amphiphiles is to introduce a redox-active constituent to the amphiphile structure, as is the case with metallosurfactants. In this work, we report a cyclic and square-wave voltammetric study on the multi-stimuli-responsive amphiphile 1-(Z)-heptenyl-1′-dimethylammoniummethyl-(3-sulfopropyl)ferrocene (1). We observe separate waves/peaks for molecules of 1 present as the monomer in its electrode-immobilized, its freely diffusing form, and its aggregated form. This allows for a direct monitoring of how the underlying equilibria depend on the concentration and time. Isothermal titration calorimetry indicates that aggregation is entropically and enthalpically favored. Our findings thus illustrate the utility of voltammetric methods for investigating self-assembly processes of redox-active amphiphiles and their redox switchability.

AB - Amphiphiles are unique in their ability to self-assemble in aqueous solution into aggregates. The control of the self-organization of amphiphiles and the live monitoring of the ensuing structure changes by analytical methods are key challenges in this field. One way to gain control and to trigger the self-assembly/disassembly of amphiphiles is to introduce a redox-active constituent to the amphiphile structure, as is the case with metallosurfactants. In this work, we report a cyclic and square-wave voltammetric study on the multi-stimuli-responsive amphiphile 1-(Z)-heptenyl-1′-dimethylammoniummethyl-(3-sulfopropyl)ferrocene (1). We observe separate waves/peaks for molecules of 1 present as the monomer in its electrode-immobilized, its freely diffusing form, and its aggregated form. This allows for a direct monitoring of how the underlying equilibria depend on the concentration and time. Isothermal titration calorimetry indicates that aggregation is entropically and enthalpically favored. Our findings thus illustrate the utility of voltammetric methods for investigating self-assembly processes of redox-active amphiphiles and their redox switchability.

UR - http://www.scopus.com/inward/record.url?scp=85104275762&partnerID=8YFLogxK

U2 - 10.1021/acs.langmuir.1c00049

DO - 10.1021/acs.langmuir.1c00049

M3 - Article

C2 - 33787275

AN - SCOPUS:85104275762

VL - 37

SP - 4183

EP - 4191

JO - LANGMUIR

JF - LANGMUIR

SN - 0743-7463

IS - 14

ER -