Dynamics in Self-assembled Organic Monolayers at the Liquid/Solid Interface Revealed by Scanning Tunneling Microscopy

Feyter, Steven De; Xu, Hong; Mali, Kunal S.

doi:10.2533/chimia.2012.38

Cited by 14 publications

(19 citation statements)

References 56 publications

(61 reference statements)

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“…20 The IR spectra display only a sharp peak at 3407 cm À1 (see Section 3 in SI), representative of ÀNÀH groups exclusively interacting with dichloromethane. 47,48 This confirms that the monomeric extended foldamers do not form intramolecular hydrogen bonds in dichloromethane. Because 1-octanol is more strongly competing for hydrogen bonds than dichloromethane, we conclude that extended foldamers in their monomeric state do not form intramolecular hydrogen bonds and remain unfolded in 1-octanol as well.…”

Section: Resultssupporting

confidence: 58%

Preprogrammed 2D Folding of Conformationally Flexible Oligoamides: Foldamers with Multiple Turn Elements

Gobbo

Mali

et al. 2012

ACS Nano

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Controlling the molecular conformation of oligomers on surfaces through noncovalent interactions symbolizes an important approach in the bottom-up patterning of surfaces with nanoscale precision. Here we report on the design, synthesis, and scanning tunneling microscopy (STM) investigation of linear oligoamides adsorbed at the liquid-solid interface. A new class of extended foldamers comprising as many as four turn elements based on a structural design "rule" adapted from a mimic foldamer was successfully synthesized. The self-assembly of these progressively complex oligomeric structures was scrutinized at the liquid-solid interface by employing STM. Submolecularly resolved STM images of foldamers reveal characteristic in-plane folding and self-assembly behavior of these conformationally flexible molecules. The complexity of the supramolecular architectures increases with increasing number of turn elements. The dissimilarity in the adsorption behavior of different foldamers is discussed qualitatively in light of enthalpic and entropic factors. The modular construction of these oligomeric foldamers with integrated functionalities provides a simple, efficient, and versatile approach to surface patterning with molecular precision.

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Section: Resultssupporting

confidence: 58%

Preprogrammed 2D Folding of Conformationally Flexible Oligoamides: Foldamers with Multiple Turn Elements

Gobbo

Mali

et al. 2012

ACS Nano

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“…In this context, STM not only provides structural information of the host-guest complexes, but if appropriate conditions are met, it also allows to follow dynamic aspects of such systems, thus capturing molecular recognition events in real time. 5 STM has evolved as a versatile surface science technique for studying host-guest interactions over the past two decades and it can function in diverse type of environments ranging from the solution-solid interface 6 to ultrahigh vacuum (UHV) conditions. 7 A surface-confined host network is often obtained via selfassembly of an organic molecule onto a solid surface.…”

Section: Introductionmentioning

confidence: 99%

Host–guest chemistry in two-dimensional supramolecular networks

2016

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Nanoporous supramolecular networks physisorbed on solid surfaces have been extensively used to immobilize a variety of guest molecules. Host-guest chemistry in such two-dimensional (2D) porous networks is a rapidly expanding field due to potential applications in separation technology, catalysis and nanoscale patterning. Diverse structural topologies with high crystallinity have been obtained to capture molecular guests of different sizes and shapes. A range of non-covalent forces such as hydrogen bonds, van der Waals interactions, coordinate bonds have been employed to assemble the host networks. Recent years have witnessed a surge in the activity in this field with the implementation of rational design strategies for realizing controlled and selective guest capture. In this feature article, we review the development in the field of surface-supported host-guest chemistry as studied by scanning tunneling microscopy (STM). Typical host-guest architectures studied on solid surfaces, both under ambient conditions at the solution-solid interface as well as those formed at the ultrahigh vacuum (UHV)-solid interface, are described. We focus on isoreticular host networks, hosts functionalized pores and dynamic host-guest systems that respond to external stimuli.

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“…Increasing the temperature appears to affect the behaviour of the hydration water at the surface of mica, but not the respective ions’ dynamics. These timescales, remarkably slow for individual monovalent ions, have important implications for many interfacial processes, for example in electrochemical and electrokinetic systems 20 33 34 , in self-assembly processes 35 36 , and at biointerfaces where ions modulate charge transport 6 7 8 9 10 , mechanical properties 37 38 39 40 , and function 6 .…”

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confidence: 99%

Direct observation of the dynamics of single metal ions at the interface with solids in aqueous solutions

Ricci

Trewby

Cafolla

et al. 2017

Sci Rep

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The dynamics of ions adsorbed at the surface of immersed charged solids plays a central role in countless natural and industrial processes such as crystal growth, heterogeneous catalysis, electrochemistry, or biological function. Electrokinetic measurements typically distinguish between a so-called Stern layer of ions and water molecules directly adsorbed on to the solid's surface, and a diffuse layer of ions further away from the surface. Dynamics within the Stern layer remain poorly understood, largely owing to a lack of in-situ atomic-level insights. Here we follow the dynamics of single Rb + and H 3 O + ions at the surface of mica in water using high-resolution atomic force microscopy with 25 ms resolution. Our results suggest that single hydrated Rb + ions reside τ 1 = 104 ± 5 ms at a given location, but this is dependent on the hydration state of the surface which evolves on a slower timescale of τ 2 = 610 ± 30 ms depending on H 3 O + adsorption. Increasing the liquid's temperature from 5 °C to 65 °C predictably decreases the apparent glassiness of the interfacial water, but no clear effect on the ions' dynamics was observed, indicating a diffusion-dominated process. These timescales are remarkably slow for individual monovalent ions and could have important implications for interfacial processes in electrolytes.Most solids are charged in aqueous solutions. The ions dissolved in the liquid tend to accumulate near the solid's surface to ensure charge neutrality, forming a so-called electrical double layer. Countless natural and industrial processes rely on the organization and dynamics of ions in this layer, from crystal growth 1-3 , to heterogeneous catalysis 4 , electrochemistry 5 , or biological function [6][7][8][9][10] . Ionic distribution within the electrical double layer is typically described by the Gouy-Chapman-Stern model 11 that comprises a Stern layer of largely static ions and water molecules adsorbed to the solid's surface, and a diffuse layer of ions further away from the surface in the liquid. The diffuse layer region is generally well understood, but the Stern layer is more difficult to model, partly because continuous assumptions have to be made about an intrinsically discrete object where the size and nature of the adsorbed ions play an important role. Significantly, existing models assume a homogenous charge distribution within the Stern layer, which is unlikely to hold at the nanoscale. Recently, a handful of studies [12][13][14][15][16] have shown that it is possible to observe in-situ single ions within the Stern layer using atomic force microscopy (AFM). However these investigations were conducted at equilibrium and no information about the ion's dynamics could be derived. The motion of single ions at interfaces remains a central question in interfacial processes with significant implications in nanotechnology, for example in the development of novel power-generating devices 17,18 . Existing theories require corrections to explain experimental observations [19][20][21] . The 'dynami...

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Dynamics in Self-assembled Organic Monolayers at the Liquid/Solid Interface Revealed by Scanning Tunneling Microscopy

Cited by 14 publications

References 56 publications

Preprogrammed 2D Folding of Conformationally Flexible Oligoamides: Foldamers with Multiple Turn Elements

Preprogrammed 2D Folding of Conformationally Flexible Oligoamides: Foldamers with Multiple Turn Elements

Host–guest chemistry in two-dimensional supramolecular networks

Direct observation of the dynamics of single metal ions at the interface with solids in aqueous solutions

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