Preparation and Evaluation of an Azobenzenediamide Bridged bis(β-Cyclodextrin)-Bonded Chiral Stationary Phase for HPLC

An azobenzenediamide bridged bis(beta-cyclodextrin) chiral stationary phase (AZCDP) was prepared, and its high-performance liquid chromatography performance in reversed-phase and polar organic modes was evaluated by chiral probes, including triazoles, flavanones, amino acids and beta-blockers. The results showed that AZCDP had strong chiral separation ability and the 40 chiral compounds were successfully resolved, of which 32 were completely separated (Rs >= 1.5) and the best enantioresolution was up to 3.93 within 20 min under a wide range of pH value and temperature. The separation ability of AZCDP with double cavities was significantly better than common CD-CSPs with single cavity, which was related to the synergistic inclusion effect. Compared with the previously reported stilbene (C=C)-bridged CSP, AZCDP with azobenzene (N=N)-bridged had a wider resolution range. For example, it could resolve myclobutanil, pindolol, carteolol, betaxolol, bevanolol and bitertanol, which could not be resolved before, and should be related to the fact that the flexible N=N was more compatible with the synergistic inclusion between cavities than the rigid C=C bridge group. The azobenzenediamide bridging group could also provide hydrogen bond, pi-pi and other sites, which was conducive to chiral separations.

Automated summary

An azobenzenediamide bridged bis(beta-cyclodextrin) chiral stationary phase (AZCDP) was prepared and showed strong chiral separation ability, successfully resolving 32 out of 40 chiral compounds with a resolution up to 3.93 within 20 minutes. The AZCDP with double cavities had better separation performance compared to the commonly used CD-CSPs with single cavity, thanks to the synergistic inclusion effect. The unique bridging group of azobenzenediamide also provided hydrogen bond, pi-pi and other sites, facilitating chiral separations.