Photo-response assisted enantiomer separations on an azobenzene-modified gamma-cyclodextrin stationary phase in micro-HPLC.
The photo-responses of the retention and enantioseparation of several optical isomers were evaluated using an azobenzene-modified gamma-cyclodextrin stationary phase (Az gamma-CDSP) in micro-HPLC. UV light irradiation induced a decrease in the retention and the chiral selectivity for N-(3,5-dinitrobenzoyl)-1-phenylethylamine (DNBPEA) and N-(3,5-dinitrobenzoyl)-1-(1-naphtylethyl)amine (DNBNEA), while an increase was induced for dansylphenylalanine (DnsPhe) using a mixture of methanol and aqueous phosphate buffer as the mobile phase. No changes in the retention and the enantiomer separation of benzoin were observed with UV light irradiation. The retention behaviors were recovered by visible-light irradiation. It was speculated that the main factor of the change in the retention behavior was a change in the pi-pi interaction due to the azobenzene moiety of the stationary phase with photo-irradiation. Comparing the retention behavior before and after UV light irradiation, a suitable condition for obtaining a better resolution and enantiomer separation would be chosen using Az gamma-CDSP.
Photocontrolled adsorption chromatography for lysozyme using azoaromatic polymer
Photoresponsive polymeric adsorbents containing an azobenzene moiety were prepared, and adsorption behavior of lysozyme onto the adsorbents was studied. In the dark the amount of lysozyme adsorbed increased with increasing hydrophobicity of the surface of the adsorbents. Therefore, it is suggested that hydrophobic interaction between lysozyme and the adsorbents plays an important role in their adsorption behavior. On irradiation with UV light, the amount of lysozyme adsorbed decreased. This result is due to increased polarity of the surface of the adsorbent induced by UV irradiation and the resultant reduction in hydrophobic interaction with lysozyme. When a column chromatography of lysozyme was carried out using the photoresponsive polymeric adsorbent as a packing material, lysozyme was eluted by photoirradiation in a system using water as the single solvent.
Self-assembly of pyridinium-tailored anthracene amphiphiles into supramolecular hydrogels.
The mixing of a polyacid cross-linker with a pyridinium-functionalized anthracene amphiphile afforded a supramolecular hydrogel through a self-assembly process that was primarily driven by π-stacking and electrostatic interactions.