Determination of Adsorbate Structures from 1,4-Phenylene Diisocyanide on Gold

Kestell, John; Abuflaha, Rasha; Boscoboinik, J. Anibal; Garvey, Michael; Bennett, Dennis W.

doi:10.1021/jz501761u

Cited by 20 publications

(48 citation statements)

References 33 publications

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“…While these assignments will be discussed in greater detail below, the ~2153 cm -1 peak is assigned to a stretching mode of a goldcoordinated isocyanide and confirms the adsorption of molecular 1,3-PDI on the surface. 28 As the exposure increases, the peak intensities of all of these features decrease, but the peaks also broaden significantly. Heating the sample to ~373 K, a temperature at which any second-layer 1,3-PDI has completely desorbed ( Figure 1(b)), has essentially no effect on the spectrum thereby confirming that the spectra shown in Figure 2 are for 1,3-PDI strongly bound to the surface.…”

Section: Resultsmentioning

confidence: 98%

“…3 This indicates that the self-assembly chemistry of 1,3-PDI on Au(111) is similar to that found for 1,4-PDI, [1][2][3] which forms one-dimensional oligomer chains on the surface comprising repeat -(Au-PDI)units, by extracting gold atoms from lowcoordination sites on the Au(111) substrate. 28 In order to investigate the structural motifs that result in oligomer formation, and to explore the most-stable adsorption sites, the formation of stable species following 1,3-PDI adsorption is investigated using DFT calculations. Note that the calculations did not include van der Waals interactions which have been shown to influence the geometry of 1,4-PDI.…”

Section: Discussionmentioning

confidence: 99%

“…11 In order to establish the nature of the structural unit that assembles to form extended surface structures, calculations were first performed for 1,3-PDI adsorbed directly on Au(111) (without a gold adatom), giving a binding energy of ~54 kJ/mol for the most stable structure, where binding energies are calculated from the energy difference between the most stable adsorbate structure and the sum of the energies of a clean Au(111) surface and gas-phase 1,3-PDI. Next, based on the geometry found for 1,4-PDI on Au(111), [10][11]28 a structure was generated with gold adatoms on the Au(111) surface, with the gold adatom located at a three-fold hollow site. The initial structures were constructed with the plane of 1,3-PDI fixed at various angles (0, 30, 60 and 90°) with respect to the surface and the geometries allowed to relax.…”

Section: Discussionmentioning

confidence: 99%

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Adsorption and Oligomerization of 1,3-Phenylene Diisocyanide on Au(111)

et al. 2016

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The adsorption and self-assembly of 1,3-phenylene diisocyanide (1,3-PDI) is studied on Au(111) using reflection-adsorption infrared spectroscopy (RAIRS), scanning tunneling microscopy (STM) and temperature-programmed desorption (TPD) supplemented by density functional theory (DFT) calculations and the results compared with the structures formed from 1,4-PDI where it assembled to form-(Au-PDI)oligomer chains that incorporate gold adatoms. The infrared spectra display a single isocyanide feature consistent with the isocyanide binding to gold adatoms while DFT calculations confirm that isocyanide binding to gold adatoms is more energetically favorable than binding to the surface. STM images show that 1,3-PDI forms zigzag chains containing hairpin bends that cause the chains to double back on each other, consistent with the 120º angle between the isocyanide groups. Hexagonal structural motifs are also observed that are proposed to be due to the self-assembly of three isocyanides as well as small structures that are assigned to 1,3-PDI dimers. The results suggest that the formation of gold-containing oligomers from isocyanide-containing molecules is a general phenomenon.

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Section: Resultsmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Adsorption and Oligomerization of 1,3-Phenylene Diisocyanide on Au(111)

et al. 2016

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“…3 The oligomer structure has been confirmed by comparing the results of density functional theory (DFT) calculations with the measured infrared spectra and scanning tunneling microscopy (STM) images collected as a function of tip bias. 24 It is found that the aryl ring of the PDI lies parallel to the surface, but that the molecule is strained such that the isocyanide group is bent by ~12° away from the planar, gas-phase structure. Chain propagation occurs through a mobile, vertical Au-PDI adatom complex that inserts into the terminus of an isocyanide group of PDI bound to a step edge or a surface defect.…”

Section: Introductionmentioning

confidence: 99%

Structural Changes in Self-Catalyzed Adsorption of Carbon Monoxide on 1,4-Phenylene Diisocyanide Modified Au(111)

et al. 2015

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The self-accelerated adsorption of CO on 1,4-phenylene diisocyanide-(PDI) derived oligomers on Au(111) is explored by reflection-absorption infrared spectroscopy and scanning tunneling microscopy. PDI incorporates gold adatoms from the Au(111) surface to form one-dimensional-(Au-PDI) n-chains that can also connect between gold nanoparticles on mica to form a conductive pathway between them. CO adsorption occurs in two stages; it first adsorbs adjacent to the oligomers that move to optimize CO adsorption. Further CO exposure induces PDI decoordination to form Au-PDI adatom complexes thereby causing the conductivity of a PDI-linked gold nanoparticle array on mica to decrease to act as a chemically drive molecular switch. This simple system enables the adsorption process to be explored in detail. DFT calculations reveal that both the-(Au-PDI) n-oligomer chain and the Au-PDI adatom complex are stabilized by co-adsorbed CO. A kinetic "foot-in-the-door" model is proposed in which fluctuations in PDI coordination allow CO to diffuse into the gap between gold adatoms to prevent the PDI from reattaching, thereby allowing additional CO to adsorb, to provide kinetic model for allosteric CO adsorption on PDI-covered gold.

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“…The aryl ring is likely to be oriented close to parallel to the surface in the trans oligomer chains, while they may be slightly tilted in the cis elbows and in the hexagonal units (Figure 3), possibly accounting for the additional aryl ring modes detected in the infrared spectra obtained after dosing Au(111) with 1,4-BDT (Figure 2), that are not detected for PDI on Au (111). 59 Evidence for the participation of gold adatoms in the selfassembled structures comes from scanning at different bias voltages. Figure 4d shows chains with alternating intensities with a ∼0.65 nm repeat distance having a dimmer feature between them, while Figure 4c shows hexagons that are ∼0.45 nm across due to flat-lying aryl rings.…”

Section: ■ Resultsmentioning

confidence: 99%

Self-Assembled Oligomeric Structures from 1,4-Benzenedithiol on Au(111) and the Formation of Conductive Linkers between Gold Nanoparticles

2015

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The adsorption and self-assembly of 1,4-benzene dithiol (1,4-BDT) is studied on a Au(111) surface using a combination of reflection−absorption infrared spectroscopy (RAIRS) and scanning tunneling microscopy (STM). 1,4-BDT is proposed to self-assemble into Au-1,4-BDT oligomer chains based on previous observations that analogous 1,4-phenylene diisocyanide (PDI) forms oligomers in which each of the isocyanides bind to gold adatoms, and since benzene thiol also adsorbs to gold via adatoms extracted from the substrate. RAIRS reveals that 1.4-BDT adsorbed on Au(111) at ∼120 K and heated, initially forms η 1 -thiolate species, but adsorption at room temperature results in the formation of dithiolates with the aryl ring oriented close to parallel to the surface. STM images show the formation of zigzag structures rather than linear chains because of the hybridization of the sulfur atoms, as well as hexagonal structures at lower coverages that are assembled from 1,4-BDT trimers linked by gold adatoms. It has also been found that PDI can link between gold nanoparticles on an insulating mica substrate to form electrically conductive bridges between them. An analogous decrease in resistance is found when gold nanoparticle arrays on mica are dosed with 1,4-BDT. The sheet resistance R varies with temperature as ln(R) versus 1/√T, similar to the behavior found previously for PDI. The data are analyzed to yield an estimate of the tunneling barrier of 0.17 ± 0.3 eV.

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Determination of Adsorbate Structures from 1,4-Phenylene Diisocyanide on Gold

Cited by 20 publications

References 33 publications

Adsorption and Oligomerization of 1,3-Phenylene Diisocyanide on Au(111)

Adsorption and Oligomerization of 1,3-Phenylene Diisocyanide on Au(111)

Structural Changes in Self-Catalyzed Adsorption of Carbon Monoxide on 1,4-Phenylene Diisocyanide Modified Au(111)

Self-Assembled Oligomeric Structures from 1,4-Benzenedithiol on Au(111) and the Formation of Conductive Linkers between Gold Nanoparticles

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