Anharmonic magnetic deformation of self-assembled molecular nanocapsules

• Published in: arXiv.org
• Main Authors: Manyuhina, O V, Shklyarevskiy, I O, Jonkheijm, P, Christianen, P C M, Fasolino, A, Katsnelson, M I, A P H J Schenning, Meijer, E W, Henze, O, Kilbinger, A F M, Feast, W J, Maan, J C
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 12.03.2007
• Subjects: Anharmonicity; Birefringence; Deformation mechanisms; Field strength; Free energy; Magnetic fields; Rigidity; Self-assembly
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.0703298

High magnetic fields were used to deform spherical nanocapsules, self-assembled from bola-amphiphilic sexithiophene molecules. At low fields the deformation -- measured through linear birefringence -- scales quadratically with the capsule radius and with the magnetic field strength. These data confirm a long standing theoretical prediction (W. Helfrich, Phys. Lett. {\bf 43A}, 409 (1973)), and permits the determination of the bending rigidity of the capsules as (2.6\(\pm\)0.8)\(\times 10^{-21}\) J. At high fields, an enhanced rigidity is found which cannot be explained within the Helfrich model. We propose a complete form of the free energy functional that accounts for this behaviour, and allows discussion of the formation and stability of nanocapsules in solution.