Cross-Step Place-Exchange of Oligo(phenylene−ethynylene) Molecules

Moore, Anthony N.; Mantooth, Brent A.; Donhauser, Zachary J.; Maya, Francisco; Price, David W.; Yao, Yuxing; Tour, James M.; Weiss, Paul S.

doi:10.1021/nl051717t

Cited by 38 publications

(73 citation statements)

References 36 publications

(113 reference statements)

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“…31 have limited abilities to distinguish single functional molecules from bundles, 40 the specific defect type typically determines whether one versus several molecules have been inserted at a particular site. 31,39,40 Assembly conditions can be selected to favor one or the other, and data can be analyzed to record essentially exclusively single functional molecules, 39 pairs, 48 or larger bundles. 3 …”

Section: Self-assembly and Measurementsmentioning

confidence: 99%

Molecular, Supramolecular, and Macromolecular Motors and Artificial Muscles

Li¹,

Paxton²,

Baughman³

et al. 2009

MRS Bull.

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Recent developments in chemical synthesis, nanoscale assembly, and molecularscale measurements enable the extension of the concept of macroscopic machines to the molecular and supramolecular levels. Molecular machines are capable of performing mechanical movements in response to external stimuli. They offer the potential to couple electrical or other forms of energy to mechanical action at the nano-and molecular scales. Working hierarchically and in concert, they can form actuators referred to as artificial muscles, in analogy to biological systems. We describe the principles behind driven motion and assembly at the molecular scale and recent advances in the field of molecular-level electromechanical machines, molecular motors, and artificial muscles. We discuss the challenges and successes in making these assemblies work cooperatively to function at larger scales.

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Section: Self-assembly and Measurementsmentioning

confidence: 99%

Molecular, Supramolecular, and Macromolecular Motors and Artificial Muscles

Li¹,

Paxton²,

Baughman³

et al. 2009

MRS Bull.

Self Cite

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“…The use of insertion self-assembly to position individual tether molecules in a dilute, non-phase separated manner is particularly advantageous in that it will allow the use of a range of tethers, including those with terminal functional groups that typically lead to phase separation. [10,30,31] Experimental Functional Surface Assembly: The Au substrates were prepared on Si{100} wafers by electron gun evaporation of 100-Å Cr and 1000-Å Au. The Au surfaces were immersed in an ethanol (reagent grade, denatured with methanol and 2-propanol) solution of oligo(ethylene glycol)-terrinated alkanethiol, 1 mM 1-(9-mercaptononyl)-3,6,9-trioxaundecan-11-ol (1) (Toronto Research Chemicals; Toronto, ON) for 24 h. The resulting SAMs were washed with ethanol and dried under nitrogen.…”

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confidence: 99%

Biospecific Recognition of Tethered Small Molecules Diluted in Self‐Assembled Monolayers

et al. 2007

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A model system for the capture of large biomolecule targets by small-molecule probes has been developed using a combination of insertion self-assembly and chemical functionalization. Key to selective molecular recognition of small molecules is the ability to tether these such that they are readily accessible for binding. This is particularly challenging because the tether alters a significant fraction of the probe molecule. It is also critical to space small-molecule probes so that they are dilute and exposed, rather than clustered via phase separation on capture surfaces, particularly when trying to bind large-molecule targets (e.g., proteins, nucleic acids). [1][2][3][4][5] Optimal dilution avoids the effects of steric hindrance [6][7][8] and multivalent non-specific interactions. Dilute surface coverage is also important to enable strategies to prevent nonspecific binding. We have developed a general method for addressing these problems [5,[9][10][11][12] and apply these to surfaces functionalized with the small-molecule neurotransmitter serotonin (5-hydroxytryptamine; Fig. 1). Serotonin is covalently bound to tethers inserted at dilute coverage into pre-existing self-assembled monolayers (SAMs) bearing a molecular surface of oligo(ethylene glycol). We chose serotonin as our initial probe both because of its important roles as a neurotransmitter involved in anxiety and mood disorders [13] and as a prototypical small molecule for which many high-affinity binding proteins have been identified [14] but for which many more remain unknown. We demonstrate access to and specific recognition of serotonin by comparing the capture from solution of antibodies directed against serotonin versus those specific for another neurotransmitter, dopamine, or the enzyme tyrosine hydroxylase. We also show that these surfaces resist nonspecific protein adsorption of bovine serum albumin (BSA). Previous attempts by us using analogous preparations on alkylamine-functionalized sepharose beads failed because they were fraught with nonspecific binding. The assembly/synthetic strategy described produces a smallmolecule-derivatized surface capable of biospecific recognition. This approach is readily translatable to most neurotransmitters, as well as to many other small molecules. In addition to identifying selective molecular recognition elements for future biosensor applications, these serotonin-functionalized surfaces will be used in combination with mass spectrometry to identify and to characterize expression patterns of brain proteins, such as membrane-associated receptors, that selectively bind to serotonin in experiments designed to investigate the etiologies of psychiatric disorders and their treatments. [15][16][17] Serotonin-derivatized surfaces were prepared using a fourstep process. Monolayers of oligo(ethylene-glycol)-terminated alkanethiol (1) were self-assembled on Au substrates. These SAMs have been prepared previously [7,8,[18][19][20][21][22] and resist nonspecific binding of proteins (extra care is taken to minimize film ...

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“…[2,3] but with a slightly different method for calculating molecular apparent heights, have reported motions of the inserted molecules across substrate step edges. [7] These motions were reported to be independent of the stochastic conductance switching reported by the same group. [2,3] Molecules at step edges and at Au vacancy islands often showed three different apparent heights, with the difference between the higher two values equal to that of the Au monatomic step, 2.4 , which was interpreted as motion of the molecule over the step edge.…”

Section: Introductionmentioning

confidence: 69%

Dynamics or Stochastic Conductance Switching of Phenylene–Ethynylene Oligomers?

2007

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Scanning tunneling microscopy (STM) studies of phenylene-ethynylene oligomers inserted in alkanethiolate self assembled monolayers (SAMs) are presented. Spontaneous changes in appearance of bundles of inserted molecules during imaging are observed. The results indicate that the appearance changes are caused by fluctuations of the number of molecules in the bundles, by diffusion and exchange of molecules, in contrast to previous reports which attribute the changes to stochastic conductance switching. The packing density of the SAM around the bundles of inserted molecules influence the fluctuations, as the fluctuations observed at 77 K all take place in bundles inserted at locally less-densely packed SAM areas. At room temperature fluctuations of bundles inserted in well-ordered areas are also observed.

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Cross-Step Place-Exchange of Oligo(phenylene−ethynylene) Molecules

Cited by 38 publications

References 36 publications

Molecular, Supramolecular, and Macromolecular Motors and Artificial Muscles

Molecular, Supramolecular, and Macromolecular Motors and Artificial Muscles

Biospecific Recognition of Tethered Small Molecules Diluted in Self‐Assembled Monolayers

Dynamics or Stochastic Conductance Switching of Phenylene–Ethynylene Oligomers?

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