A reversible molecular valve

Thoi D. Nguyen; Hsian-Rong Tseng; Paul C. Celestre; Amar H. Flood; Yi Liu; J. Fraser Stoddart; Jeffrey I. Zink

doi:10.1073/pnas.0504109102

New Research In

Communicated by M. Frederick Hawthorne, University of California, Los Angeles, CA, May 25, 2005 (received for review January 27, 2005)

Abstract

In everyday life, a macroscopic valve is a device with a movable control element that regulates the flow of gases or liquids by blocking and opening passageways. Construction of such a device on the nanoscale level requires (i) suitably proportioned movable control elements, (ii) a method for operating them on demand, and (iii) appropriately sized passageways. These three conditions can be fulfilled by attaching organic, mechanically interlocked, linear motor molecules that can be operated under chemical, electrical, or optical stimuli to stable inorganic porous frameworks (i.e., by self-assembling organic machinery on top of an inorganic chassis). In this article, we demonstrate a reversibly operating nanovalve that can be turned on and off by redox chemistry. It traps and releases molecules from a maze of nanoscopic passageways in silica by controlling the operation of redox-activated bistable [2]rotaxane molecules tethered to the openings of nanopores leading out of a nanoscale reservoir.

Footnotes

↵ * To whom correspondence may be addressed. E-mail: stoddart{at}chem.ucla.edu or zink{at}chem.ucla.edu.
Author contributions: T.D.N., J.F.S., and J.I.Z. designed research; T.D.N., H.-R.T., and P.C.C. performed research; H.-R.T. contributed new reagents/analytic tools; T.D.N., A.H.F., Y.L., and J.I.Z. analyzed data; and T.D.N., A.H.F., J.F.S., and J.I.Z. wrote the paper.
Abbreviations: CBPQT⁴⁺, cyclobis(paraquat-p-phenylene); TTF, tetrathiafulvalene; DNP, dioxynaphthalene; ICPES, isocyanatopropyltriethoxysilane; Ir(ppy)₃, Tris(2,2′-phenylpyridyl)iridium(III).
Freely available online through the PNAS open access option.
Copyright © 2005, The National Academy of Sciences