Web Release Date: October 25,
Molecular Recognition and Conductance in Crown Ethers
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095
Institute of Chemistry, and the Lise Meitner center the Hebrew University of Jerusalem, Jerusalem, 91904 Israel
Received October 24, 2002
Abstract:
Crown ethers have the remarkable property of recognizing and binding specific metal cations in complex mixtures. We propose to combine molecular recognition with molecular electric conductance. The question we address is: can the event of binding a cation be sensed by a change in conductance? Specifically, we study a short molecular wire (MW) containing a crown-6 molecule connected via sulfur atoms to two gold atomic wires acting as metallic leads. Upon binding a cation, the density of states of the system is only slightly affected. This reflects the fact that the cation binding is largely electrostatic in nature and is accompanied by little electronic reorganization. Yet, the cationic binding does significantly lower conductance. We also identify strong interference affecting the conductance. A striking feature is the insensitivity of conductance to the type of ligand with the exception of the proton.
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