Chiral Shell Research Articles

Shielding effect of hollow chiral sphere

The low-frequency shielding effect of a spherical layer is studied. The layer is made of a chiral material and it is electromagnetically characterized with three material parameters: permittivity, permeability, and chirality. Due to chirality, there is magnetoelectric coupling. The electric and magnetic shielding effects are derived and are shown to be functions of the three material parameters and also the relative thickness of the layer. Illustrations display the effects of the various parameters on the shielding, which is different for the magnetic and electric fields. Among the special effects is that the shielding increases rapidly as the chirality parameter approaches the refractive index of the shell. This makes chiral shells in principle effective shields, and in the future they may offer an alternative to conducting materials for novel shielding applications.

Encapsulation of Guest Molecules into a Dendritic Box

Dendrimers are well-defined, highly branched macromolecules that emanate from a central core and are synthesized through a stepwise, repetitive reaction sequence. The synthesis and characterization of dendritic boxes, based on the construction of a chiral shell of protected amino acids onto poly(propyleneimine) dendrimers with 64 amine end groups, is reported here. Nuclear magnetic resonance-relaxation and optical data show that a dense shell with solid-phase character is formed. Guest molecules were captured within the internal cavities of the boxes when these boxes were constructed in the presence of guest molecules. The diffusion of guest molecules out of the boxes into solution was unmeasurably slow because of the close packing of the shell. These monomolecular dendritic containers of 5-nanometer dimensions with physically locked-in guest molecules were characterized spectroscopically.