chapter  5
24 Pages

Supramolecular Self-Assembly Governed Molecularly Imprinted Polymers for Selective Chemical Sensing

Introduction ............................................................................................................ 106 Supramolecular Concepts of Molecular Imprinting .......................................... 106 Design of Supramolecular Imprinted Polymer ................................................ 107 Nature of Supramolecular Interactions ............................................................. 108 Removal of Imprinted Template ........................................................................ 110

Covalent Template Binding in MIPs ...................................................................... 111 Noncovalent Template Binding in MIPs ................................................................ 114

Noncovalent Inclusion Complex Formation in MIPs ........................................ 115 Coordinating Template Binding in MIPs ............................................................... 116

Coordinating of Boronic Acid and Its Esters in MIPs....................................... 116 Coordinating via Metal-Porphyrin Complex Formation in MIPs .................... 118

Binding of Templates in MIP Films Prepared by Electropolymerization .............. 120 Formation of Hydrogen Bonds between Functional Monomers and Template for Imprinting via Electropolymerization ......................................... 121 Ditopic Interactions between Functional Monomers and Template for Imprinting via Electropolymerization ............................................................... 122

Conclusions ............................................................................................................ 125 Prospective Research on MIP Chemosensors ........................................................ 125 Acknowledgments .................................................................................................. 126 References .............................................................................................................. 126

Molecularly imprinted polymers (MIPs) are synthetic polymer materials with arti-ˆcially controlled properties.1 Molecular imprinting initially involves complexation in solution of a target compound or its close analogue by suitably selected functional monomers (FMs). These monomers are composed of polymerizing and complexing moieties. Next, the resulting complex is polymerized to yield MIP. At this stage, the imprinted compound plays the role of a template (T). Then, T is removed from the MIP, leaving discrete molecular cavities in it. In this form, MIP is used for a predeˆned application involving accumulation of the compound used for imprinting or its close analogue now as the target analyte. Proper design of interactions between the binding sites of T and the recognition sites of these molecular cavities in the polymer formed is most important in MIP preparation. The technology of molecular imprinting, involving interdisciplinary studies, has recently developed remarkably. This technology, combined with supramolecular, macromolecular, and analytical chemistry, greatly affects the synthesis of MIPs. These polymers, with properly adjusted ¸exibility, excellent mechanical and chemical stability, and biocompatibility, have been applied extensively as stationary phases for chromatographic separations,2 such as chiral separations using SupelMIP,3 as selective absorbents for solid phase microextraction,4 as selective catalysts for pharmaceutically important reactions, for example,5 to mimic the functioning of antibodies in immunoassays (biological receptor mimics);6 and in devices for controlled drug release and drug monitoring.7 Particularly, MIPs have found enormously wide application as recognition units in chemical sensors.1