离子型芘衍生物同聚电解质键合平衡的模拟

利用平衡键合模型模拟了聚电解质同荧光探针离子键合过程的计量关系 ,以及添加盐竞争键合时的计量关系 .计算的结果能够描述荧光实验结果 .芘离子探针PyMeA·HCl的IE IM 随着探针浓度的增加 ,会出现一个极大值 ,此极大值能够定量地给出饱和键合计量关系 .当盐浓度和聚电解质荷电单元浓度相当时 ,盐离子和芘离子探针发生明显的竞争键合 ,部分离子探针被排挤入水相 ,实验的IE IM 随盐浓度增大急剧减小

SIMULATION FOR BINDING EQUILIBRIUM OF IONIC DERIVATIVE OF PYRENE WITH POLYELECTROLYTE

Binding of cationic derivative of pyrene,pyrenemethylamine hydrochloride (PyMeA·HCl) to a polyanion,poly(2-(acrylamido)-2-methylpropanesulfonic acid) (PAMPS) in aqueous solutions was probed by the excimer fluorescence and simulated with a competitive binding equilibrium model.The relative emission intensity I E/I M of excimer to monomer displays a maximum with increasing PyMeA·HCl concentration and the binding stoichiometry for saturation binding is determined from the concentrations of PAMPS and PyMeA·HCl at the maximum.I E/I M obviously decreases with adding sodium chloride of about 10 -4 mol/L into the solution due to the competitive binding of sodium and probe cations.In our binding equilibrium model,the binding of different cations on anionic polymer is considered as an equilibrated reversible process governed by the equilibrium constant.I E and I M are assumed to be proportional to the probe concentrations forming excimer and remaining individually,respectively.Calculated bound probe concentration c DL increases with total probe concentration c D0 before binding saturation and the increasing rate becomes higher with higher value of the equilibrium constant.The simulated I E/I M,as the above probe concentration ratio,also shows a maximum with increasing c D0 at the same position as experimentally observed.By assuming a comparable binding equilibrium constant for the cation of added salt,the abrupt decrease in I E/I M observed with adding salt is reproduced by the simulation.These results indicate that the competitive binding of ionic pyrene probe on polyelectrolyte can be reasonably described by the binding equilibrium model.