Self-assembled organic nanotubes and self-synthesized silver subnanowire arrays in an ambient solution phase

Abstract

We review our recent work on the synthesis and characterization of metallic subnanowire arrays. Previous attempts to synthesize metallic systems of nanodimensions have been fraught with several problems. These include difficulty in synthesis, high temperatures and high pressures involved in the synthesis, low stabilities, susceptibility to external degrading factors, etc. In an attempt to circumvent these problems, our approach involved a novel strategy both of synthesizing and stabilizing the subnanowires. Thus we initially designed unusual organic systems, whose properties can be fine-tuned by either electrochemical or photochemical means. In the course of this process. we noted that organic nanotubes formed by the non-tubular subunits of electrochemically and photochemically active calix[4]hydroquinone (CHQ) possess infinitely long one-dimensional hydrogen-bond arrays. Based on simple electro/photochemistry uniform and ultrathin silver nanowires can be self-synthesized inside these organic CHQ nanotubes. These subnanowires, which are extremely long and have widths corresponding to the fee lattice constant of the bulk silver metal (0.4 nm), are stable for long periods Of time under ambient conditions, Based on both experimental and theoretical analysis of these ultra-thin silver subnanowires, we believe that they could serve as model systems for investigating wide-ranging and exciting one-dimensional physical phenomena (as a quantum wire) and also be employed as possible nanoconnectors in potential nanoelectronic devices. (C) 2002 Elsevier Science B.V. All rights reserved.