I. O. Shklyarevskiy

Anharmonic Magnetic Deformation of Self-Assembled Molecular Nanocapsules

High magnetic fields were used to deform spherical nanocapsules, self-assembled from bolaamphiphilic 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. A 43, 409 (1973)10.1016/0375-9601(73)90396-4], and permit the determination of the bending rigidity of the capsules as (2.6+/-0.8) x 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 behavior, and allows discussion of the formation and stability of nanocapsules in solution.

Magnetic field induced alignment of cyanine dye J-aggregates

High magnetic fields were used for the alignment of J-aggregates of cyanine dyes in solution leading to strongly polarized optical properties, yielding a maximum dichroic ratio of 13. The aligned aggregates were fixed by gelation resulting in samples that are stable at room temperature and exhibit strongly polarized absorption and emission spectra.

Using magnetic birefringence to determine the molecular arrangement of supramolecular nanostructures

Abstract Supramolecular aggregates can be aligned in solution using a magnetic field. Because of the optical anisotropy of the molecular building blocks, the alignment results in an anisotropic refractive index of the solution parallel and perpendicular to the magnetic field. We present a model for calculating the magnetic birefringence, using solely the magnetic susceptibilities and optical polarizabilities of the molecules, for any molecular arrangement. We demonstrate that magnetic birefringence is a very sensitive tool for determining the molecular organization within supramolecular aggregates.

Magnetic Field Alignment of Liquid Crystalline Pentathiophene

Liquid crystalline α,α′-disubstituted pentathiophene was aligned using high magnetic fields (>5 T) resulting in macroscopically oriented samples. The pentathiophene crystallites were found to be aligned perpendicular to the magnetic field direction, as is evidenced by microscopy images. The samples are stable at room temperature and will be used for further investigations such as the determination of the (anisotropic) mobility and the polarization of the light emission.