Synthesis And Characterization Of S-1,1’-Binaphthalene-2,2’-Diamine Molecularly Imprinted Polymer

A series of polymers imprinted with (S)-(-)-1,1’-binaphthalene-2,2’-diamine (S-DABN)had been prepared by non-covalent imprinting technique and been used as stationary phasesby HPLC to separate the racemic DABN. Polymerization conditions, such as the ratio offunctional monomer, porogen and template-monomer, and chromatographic conditions, suchas composition of the mobile phase, column temperature, flow rate and concentration of theanalytes were systematically investigated. The results shown that when synthesized in themixed porogen containing acetonitrile and chloroform (1:2, v/v) and the ratio of functionalmonomer (methacrylic acid, MAA) and template (S-DABN) was1:4, efficient resolution ofracemic (±)-1,1’-binaphthalene-2,2’-diamine with a separation factor of2.14was obtained onthe polymer by HPLC, and the chromatographic conditions were as follows: mobile phase,acetonitrile; flow rate,0.1mL/min; samples concentration,0.1mg/mL; column temperature,25℃. The dissociation constant (Kdiss) and binding sites (Lt) of molecularly imprinted polymersimprinted with S-DABN were evaluated by frontal analysis as1.4mmol/mL and4.56mmol/g,respectively.The adsorption property of the polymers was evaluated using25mg polymers inacetonitrile at25℃. The saturated extents of adsorption for R-DABN and S-DABN were77.5mmol/g and97.5mmol/g respectively. Then adsorption process was evaluated by Scatchardanalysis, dynamic and thermodynamic analysis. Scatchard analysis shown that two classes ofbinding sites were formed in the imprinted polymer, the equilibrium dissociation constant Kd,1and the apparent maximum number Qmax,1of the higher affinity binding sites for S-DABNwere0.14mmol/mL and0.37mmol/g respectively, Kd,2and Qmax,2of the lower affinitybonding sites were0.41mmol/mL and0.81mmol/g respectively. Dynamic analysis shownthat the recognition for S-DABN on polymers could be considered as a second-order reactionwith rate constant and equilibrium adsorption capacity as0.000393and122.39mmol/grespectively. Thermodynamic analysis shown thermodynamic parameters were as follows:ΔH,-8.030kJ/mol; ΔS,-0.0228kJ/(mol·K); ΔG298.15,-1.232kJ/mol; ΔΔH,-4.056kJ/mol; ΔΔS,-0.00329kJ/(mol·K); ΔΔG298.15,-3.075kJ/mol.