Preparation and Evaluation of a Pyridinediamide Bridged Bis (β-cyclodextrin) Chiral Stationary Phase

Based on the dehydration condensation reaction between 2, 3-pyridinedicarboxylic acid and 6-amino-beta-cyclodextrin , a pyridinediamide bridged bis(beta-cyclodextrin) was synthesized and then bonded onto silica gel to obtain a novel pyridinediamide bridged bis(beta-cyclodextrin) chiral stationary phase (PyCDP) . A total of 38 chiral drugs and pesticides including flavanones , triazoles , amino acids and beta-blockers were used as chiral probes to systematically evaluate the chiral high performance liquid chromatography (HPLC) performance of the new stationary phase. Additionally, a common native cyclodextrin stationary phase (CDCSP) was also prepared by the similar method for comparsion purpose. The research results showed that the new bridged cyclodextrin stationary phase could resolve all 38 chiral analytes in both reversed-phase and polar organic modes. Among them, the enantiomeric resolution (R-s) of 2'-hydroxyflavanone , flutriaftil , phenylalanine and esmolol were 2. 36 , 1. 98 , 1. 86 and 1. 62 within 30 min , respectively. In reversed-phase chromatographic mode, PyCDP could realize the baseline separations of triazole pesticides by adjusting the volume fraction of acetonitrile (20% -35%) in the mobile phase in the temperature range of 15-30 degrees C , and could resolve triadimenol and bitertanol with two chiral centers into four peaks, respectively. PyCDP achieved the complete separations of easily ionized acidic , basic and polar amino acids in the pH range (5. 0-6. 5) of the mobile phases. In addition, PyCDP was also suitable for polar organic mode. For example, carvedilol (R-s =1. 42) with larger steric hindrance could also be resolved , and it was the first time to realize the separation of bevanolol on cyclodextrin stationary phases. However, under the optimized conditions, CDCSP could only resolve 20 chiral substances with lower resolutions. Obviously , the synergistic inclusion of two adjacent cavities on bridged cyclodextrin and the hydrogen bond and pi-pi effect provided by pyridinediamide bridging group were conducive to chiral separations. PyCDP was a kind of multifunctional chiral separation materials.

Automated summary

A novel pyridinediamide bridged bis(beta-cyclodextrin) chiral stationary phase (PyCDP) was synthesized and evaluated for chiral high performance liquid chromatography (HPLC) performance. The results showed that PyCDP could separate a variety of chiral analytes in both reversed-phase and polar organic modes, outperforming the common native cyclodextrin stationary phase (CDCSP).