Assembly of an Electronically Switchable Rotaxane on the Surface of a Titanium Dioxide Nanoparticle

Long, Brenda; Nikitin, Kirill; Fitzmaurice, Donald

doi:10.1021/ja037592g

Cited by 87 publications

(82 citation statements)

References 22 publications

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“…Molecular machines (13)(14)(15)(16)(17) are attractive systems for deployment in the development of nanovalves on account of their abilities to be customized and optimized for a range of functions at the nanoscale. The attachment of supramolecular and molecular machines to nanoparticles has been achieved in a number (18)(19)(20)(21) of different classes of systems. In our most recent research, described in this report, the movable control element that has been used to control the flow of molecules in a nanovalve is a bistable, redox-controllable [2]rotaxane R 4ϩ , shown in Fig.…”

mentioning

confidence: 99%

A reversible molecular valve

Nguyen

Tseng

Celestre

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

459

262

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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.controlled release ͉ nanomachine ͉ nanovalve P rogress in designing and synthesizing nanovalves that control access to and from the pores in inorganic materials is proceeding apace. Our previous work (1), involving the fabrication of pseudorotaxane-derivatized, nanostructured thin films, demonstrated a reusable but irreversible nanovalve that acts like a cork in a bottle, opening the orifices of a two-dimensional hexagonal array of cylindrical pores and allowing the contents to spill out. Other examples, using more traditional control mechanisms, have been described in the literature. Based on photodriven motions involving cis-trans isomerizations of NAN double bonds, azobenzenes tethered to the walls of the nanoporous membranes function (2) as a regulatory mechanism for mass transport through the channels of nanoporous materials. Using the intermolecular dimerization of tethered coumarins, dimers act (3, 4) as a net to control the access to and from the pores of derivatized MCM-41 upon photoactivation and subsequent dedimerization. Chemically linked CdS nanoparticles on derivatized mesoporous silica nanospheres function (5) as caps to control the release of chemicals from the pores. Although, in the latter two examples, covalent bonds are broken to control the release of the pore's contents, the first instance is one in which a change in a molecule's configuration, and hence shape, does the trick. Based on pH-sensitive intermolecular hydrogen bonds between poly-(ethyloxazoline) and poly(methacrylic acid), a polymer gel can be eroded electrically, leading to the release of a trapped insulin load (6). A heat-responsive polymer, poly(N-isopropylacrylamide) (PNIPAAm), has also been used (7) as the source of hindrance at the pores' orifices to modulate the transport of solute, albeit in an irreversible fashion. By using monolithic copolymers to define pores with tunable sizes ranging from tens to thousands of nanometers, PNIPAAm has been shown (8) to behave as a reversible valve in microfluidic chips. The electrochemical corrosio...

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mentioning

confidence: 99%

A reversible molecular valve

Nguyen

Tseng

Celestre

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

459

262

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“…4 The deposition of rotaxane molecules on solid surfaces 5,6 is a promising approach toward this purpose. Although the functionalization of the surface of solid materials, such as gold nanoparticles, 7 silica, 8 ITO electrodes, 9 and TiO 2 , 10 has been reported the effective introduction of interlocked molecules on the surface remains a challenge. In our previous research work, we reported synthesis of [2]rotaxanes composed of dibenzo [24]crown-8-ether and dialkylammonium with ferrocenyl and trisiloxysilyl or silsesquioxane terminal groups as well as their electrochemical properties.…”

Section: Rotaxanesmentioning

confidence: 99%

Silica Nanospheres Functionalized by Ferrocene-containing [2]Rotaxane

Yu¹,

Suzaki²,

Maekawa³

et al. 2014

Chemistry Letters

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“…[19] The integration of such systems with surfaces in order to read out the logic operation remains, however, a scientific challenge. [20] A further interesting application includes the use of electrodriven molecular machines for the electrical contacting of redox enzymes. Redox enzymes lack direct electrical communication between their redox centers and electrode surfaces.…”

Section: Feature Articlementioning

confidence: 99%

From Molecular Machines to Microscale Motility of Objects: Application as “Smart Materials”, Sensors, and Nanodevices

Willner

Basnar

Willner

2007

Adv Funct Materials

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Machinelike operations are common functions in biological systems, and substantial recent research efforts are directed to mimic such processes at the molecular or nanoscale dimensions. The present Feature Article presents three complementary approaches to design machinelike operations: by the signal‐triggered mechanical shuttling of molecular components; by the signal‐triggering of chemical processes on surfaces, resulting in mechanical motion of micro/nanoscale objects; and by the fuel‐triggered motility of biomolecule–metal nanowire hybrid systems. The shuttling of molecular components on molecular wires assembled on surfaces in semirotaxane configurations using electrical or optical triggering signals is described. The control of the hydrophilic/hydrophobic surface properties through molecular shuttling or by molecular bending/stretching processes is presented. Stress generated on microelements, such as cantilevers, results in the mechanical deflection of the cantilever. The deposition of a redox‐active polyaniline film on a cantilever allows the reversible electrochemically induced deflection and retraction of the cantilever by the electrochemical oxidation or reduction of the polymer film, respectively. A micro‐robot consisting of the polypyrrole (PPy) polymer deposited on a multi‐addressable configuration of electrodes is described. Au magnetic core/shell nanoparticles are incorporated into a polyaniline film, and the conductivity of the composite polymer is controlled by an external magnet. Finally, the synthesis of a hybrid nanostructure consisting of two actin filaments tethered to the two ends of a Au nanowire is described. The adenosine triphosphate (ATP)‐fueled motility of the hybrid nanostructure on a myosin monolayer associated with a solid support is demonstrated.

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Assembly of an Electronically Switchable Rotaxane on the Surface of a Titanium Dioxide Nanoparticle

Cited by 87 publications

References 22 publications

A reversible molecular valve

A reversible molecular valve

Silica Nanospheres Functionalized by Ferrocene-containing [2]Rotaxane

From Molecular Machines to Microscale Motility of Objects: Application as “Smart Materials”, Sensors, and Nanodevices

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