Abstract
This work presents three new experimental methods for studying molecular imprinting. The electric conductivity measurements of the pre-polymerization mixture of amine templates in an aprotic solvent provide evidence of ionic dissociation of the pre-polymerization complexes. The displacement measurement of the template propranolol from its molecularly imprinted polymer (MIP) using a quaternary ammonium ion in toluene, shows that this MIP behaves as an ion exchanger even in a non-polar solvent. The same experiment also shows that template binding to the MIP from toluene involves ionic interaction. The third experimental method introduced here serves to study the models of template binding on MIPs. To this end the binding isotherm of propranolol (PR) has been measured on a polymer mixture consisting of non-imprinted control polymer (NIP) and a stronger binding acidic polymer, respectively. All three methods are suitable for studying several other imprinting systems.
Highlights
Molecular imprinting is a vigorous field of research [1,2,3,4,5,6,7,8,9]
If a quaternary ammonium salt is used instead of an amine competitor, replacement of the template appears unlikely because the quaternary ammonium ions are not likely to form a hydrogen bond. Against this expectation we have found that a quaternary ammonium salt, tetrabutylammonium bromide can displace the amine template, propranolol, from its molecularly imprinted polymer (MIP) in the non-polar medium of toluene
Competition by the quaternary ammonium ion releases the amine template in its cationic form, not in the amine form, in which it had been adsorbed. These results show that the binding of propranolol from toluene occurs at least partly in ionic form, i.e., the carboxylic group of the MIP donates a hydrogen ion to the template in the course of binding
Summary
Molecular imprinting is a vigorous field of research [1,2,3,4,5,6,7,8,9]. Each year more than a thousand new papers are registered in the molecularly imprinted polymer (MIP) database [10]. There are many potential applications of MIPs, including analytical ones. MIPs for small molecules and macromolecules, like proteins, are made in great variety [1,2,3,4,5,6,7,8,9,10].
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call