Molecular Recognition Principles

Fig. 10.2 (A) Cross-section SEM micrograph of the hybrid membrane containing the receptor 1, (B) membrane transport concentration profiles and (C) molecular recognition principles of acidic I and zwitterionic II L-phenylalanine in the heteropoly-siloxane material membrane (1-hydrogen bonding, 2-charge interaction, 3-Van der Waals forces) [29].

Application of molecular recognition principles allows the design of small molecules able to interact with biological systems for use, e.g. as anticancer drugs. 

Development of Polymer Membrane Anion-Selective Electrodes Based on Molecular Recognition Principles... 

In order to develop selective electrodes, it is necessary to introduce specific interactions between the ionophore and the anion of interest. This can be achieved by designing an ion carrier whose structure is complementary to the anion. This type of design can be based on molecular recognition principles, such as the ones that involve complementarity of shape and charge distribution between the ion and the ionophore. 

In this paper, we report the development of ISEs that have been designed by using molecular recognition principles. Specific examples include the development of polymer membrane anion-selective electrodes based on hydrophobic vitamin B12 derivatives and a cobalt porphyrin. The selectivity patterns observed with these electrodes can be related to differences in the structure of the various ionophores, and to properties of the polymer film. 

In summary, it has been demonstrated that ISEs can be designed by employing molecular recognition principles. In particular, the feasibility of using hydrophobic vitamin B12 derivatives and electropolymerized porphyrin films in the development of polymer membrane anion-selective electrodes has been demonstrated. The studies indicated that the changes in the selectivity of these ISEs can be explained by the difference in structure of the ionophores. In addition, it was shown that by electropolymerization of a cobalt porphyrin, anion-selective electrodes can be prepared that have extended lifetimes compared with PVC-based ISEs, which use a similar compound as the ionophore. 

Herein, we present several examples of the strategies followed in our group few the rational design of new ionophores that can be used in the development of ISEs for environmentally important anions. These strategies are based on molecular recognition principles of biomimetic receptors and preorganized Lewis acid cavity ionophores. 

Crown ether complexation emerged as a versatile molecular recognition principle to realize molecularly-organized thin film assemblies and nanoarehiteetures. Self-assembled monolayers (SAM), for example, were successfully employed to gain control over the organization of a Ceo derivative - bearing a crown ether functionality -and an ammonium-terminated alkanethiolate that was attached... 

R.H. Eish et al. - A New, Aqueous H NMR Shift Reagent Based on Host-Guest Molecular Recognition Principles Using a Supramolecular Host [Cp Rh(2 -deoxyadenosine)]3(OT03, J. Org. Chem. 63, 7151, 1998. 

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