PREPARATION AND ENANTIOSEPARATION OF COPOLYMER CHIRAL STATIONARY PHASES WITH (1R,2R)-(+)-1,2-DIPHENYLETHYLENEDIAMINE AS THE CHIRAL BUILDING BLOCK

Abstract

(1 R,2 R)-(+)-1,2-Diphenylethylenediamine was copolymerized with terephthaloyl chloride and toluene 2,4-diisocyanate at different fed ratios to give two polymeric chiral selectors. The selectors were immobilized onto 3-aminopropyl silica gel to afford corresponding chiral stationary phases. The enantioseparation evaluation reveals the shorter-chain polymeric selector possesses better enantioseparation ability. In normal phase mode, tert-butanol is advantageous for enantioseparation when it is used as one of the mobile phase compositions. The influence of other aspects including selector structure, sample loading and temperature on the enantioseparation ability of these chiral stationary phases was also studied.

Keywords:

• chiral stationary phase
• copolymer
• enantioseparation
• high-performance liquid chromatography

ACKNOWLEDGMENT

Funding from National Natural Science Foundation of China (grant number: 20675061) is gratefully acknowledged.

Notes

Retention factor (k₁): (t₁-t₀)/t₀, where t₁ is the retention time of the first-eluted enantiomer, and t₀ was determined by measuring the retention time of the solvent, which was used to prepared the samples; Separation factor (α): k₂/k₁, where k₂ was calculated from (t₂-t₀)/t₀, and t₂ refers to the retention time of the second-eluted enantiomer; Resolution (R_s): 2(t₂-t₁)/(w₁+w₂), in which w₁ and w₂ refer to, respectively, the bandwidth of the first-eluted enantiomer and the second-eluted enantiomer. pH value of the buffer solution: ^a 8.67; ^b 5.06; ^c 4.00.