Preparation Of Surface Molecularly Imprinted Polymers Coating On Silica-gel For Chiral Separation Of 1,1'-binaphathalene-2.2'-diamine Racemates

The surface molecularly imprinted polymers(SMIPs) were synthesized coating on silica-gel by using R-(-)-l,1'-binaphthalene-2,2'-diamine (R-DABN) as template molecular,methylacrylic acid as functional monomer, ethylene glycol dimethacrylte(EGDMA),2,2'-Azobis(isobutyronitrile) (AIBN) as crosslinkers and initiator, respectively. The SMIPs were applied as chiral stationary phases(CSPs) for chiral separation of DABN racemates.by high-performance liquid chromatography. The influence of some key factors on the chiral recognition ability of SMIPs, such as the type of matrix and functional monomers, the temperature of pre-polymerization, the molar ratio of template to monomer and the type of porogen were systematically investigated. The results displayed that the chiral separation for DABN racemates under the optimum chromatographic conditions by using SMIPs CSPs,prepared with the silica-gel as matrix,22 ? as the suitable temperature of pre-polymerization,R-DABN/MAA ratio =1/4 and used acetonitrile (2 mL) and chloroform (4 mL) as porogen,showed the highest separation factor (3.39) and resolution (1.25). The SMIPs were characterized by 1H NMR, SEM and TEM. The results of 1HNMR shown that there was ion pair exited between template and functional monomer,which had a vital effect on the retention of R-DABN flowing through CSPs. SEM and TEM confirmed molecularly imprinted polymers were successfully covered on the surface of silica-gel.The chromatographic conditions, such as mobile phase composition, sample loading,flow rate,and column temperature were also measured. As the result,the SMIPs got the highest separation factor (3.39) under the chromatographic conditions were as follows: mobile phase, acetonitrile; flow rate, 0.05 mL/min; sample loading, 0.1mg/mL; column temperature,25?.Frontal analysis was used to evaluate affinity to the target molecule of SMIPs.. The binding sites (Lt) of SMIPsr for R-DABN and S-DABN were calculates as 10.05 ?mol/ g and 28.36 ?mol/g,respectively.The dissociation constant (Kdiss) of SMIPs for R-DABN and S-DABN were estimated as 10.05 mmol/L and 29.57 mmol/L, respectively. The results showed SMIPs had greater binding capacity for R-DABN than S-DABN.