De Novo Design Approach Based on Nanorecognition: Functional Molecules/Materials and Nanosensors/Nanodevices

Kwang S. Kim 

Pohang University of Science and Technology (POSTECH), San 31, Hoyja-dong, Nam-gu, Pohang 790-784, Korea, South

Abstract

Design of functional molecules and nanodevices has been a fascinating issue in these days. To develop innovative nanomaterial systems, it is necessary to create a new paradigm for the design approach because the systems involved in quantum phenomena are hardly comprehensible by intuition and simple experiences. For practical utility, functional materials need to be self-assembled, and nanodevices would be self-engineered. To this end, the nanorecognition should play an important role. The nanorecognition is governed mainly by interaction forces such as hydrogen bonding, ionic interaction, π-H/π-π interactions, and metallic interactions as well as the capture / transport/ release of electrons /photons/ protons. The manifestation of these interaction forces has led us to the design and realization of diverse ionophores/receptors, organic nanotubes, nanowires, molecular mechanical devices, molecular switches, enzyme mimetics, protein folding/unfolding, etc. In this talk, we focus on the following topics. (i) We discuss ionophores/receptors with chemo-sensing capability for biologically important cations (ammonium cations and acetylcholine by utilizing cation-π interactions, directional hydrogen bonding, charge-charge/charge-dipole interactions) and anions (F-, Cl-, Br-, I-, phosphate, pyrophospate, ATP, GTP, etc., by utilizing the CH+-X- ionic hydrogen bonds,based on tweezer structures to accommodate a nearly free excess electron in a large empty space as a surface bound form). (ii) We discuss how the understanding of hydrogen bonding and pi-interactions has led to the design of nanotubes from calix[4]hydroquinone (CHQ). The CHQ tubes are self-assembled to form long tubular structures in the presence of water with the formation of one dimensional short H-bonds relay. The bundles are formed with the intertubular π-π stacking interactions. The binding situations of neutral and cationic transition metals with the redox system of hydroquinone and quinone predicts what kind of nanostructures (nanoclusters, nanowires, and nanofilns) would form. (iii) We observed that the conformational change between stacked and edge-to-face conformers in p-benzoquinone-benzene complexes is controlled by electrochemical potential. This flapping motion illustrates a promising pathway toward the design of mobile nanomechanical devices.

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Presentation: plenary lecture at 18th Conference on Physical Organic Chemistry, Plenary session, by Kwang S. Kim
See On-line Journal of 18th Conference on Physical Organic Chemistry

Submitted: 2006-06-01 05:30
Revised:   2006-08-04 17:24