Adsorption Structures and Electronic Properties of 1,4-Phenylene Diisocyanide on the Au(111) Surface

Zhou, Jing; Acharya, Danda; Camillone, Nicholas; Sutter, Peter; White, Michael G.

doi:10.1021/jp205349e

Cited by 40 publications

(60 citation statements)

References 48 publications

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“…Zhou et al predicted by DFT calculations that vertically adsorbed PDI on Au has the HOMO and LUMO states at 0.7 and 3 eV above the Fermi level of the metal (E F ) that can be modified by changing the surface coverage. 51 This means that an induced charge-transfer effect from the metal to the adsorbate may occur by changing the excitation laser wavelength to fit the 3 eV transition energy between the PDI LUMO and the Fermi level. Furthermore, Li et al also predicted that the energetic gap between the LUMO and E F can change when varying the surface coverage.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Plasmonic Effects of Phenylenediisocyanides Linked at Interparticle Junctions of Metal Nanoparticles

et al. 2014

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Surface-enhanced Raman scattering (SERS) spectroscopy was employed in the present work to elucidate the adsorption of two diisocyanide molecules: 1,4-phenylenediisocyanide (PDI) and 1,4″-terphenylenediisocyanide (TPDI) on nanogaps of Ag and Au nanoparticles (NPs). The main goal of this work was the study of the adsorption of these molecules and more specifically the coordination mechanism and the orientation of these molecules on the metal surface as well as the study of the effect of the above adsorbates on the aggregation and formation of interparticle junctions. To get more insight into the above phenomena, we have investigated different experimental variables such as the numbers of phenylene rings (monophenylene vs terphenylene), the nature of the metal (Au and Ag), the excitation wavelength (532 and 785 nm), and the surface coverage provided by different adsorbate concentrations. The experiments carried out at these conditions revealed the existence concentration of critical values at 0.1 and 3 μM corresponding to changes in the coordination and a complete surface coverage of interparticle junctions. Finally, we have also deduced the great importance of charge-transfer processes occurring between the metal surface and diisocyanide molecules. This charge transfer exhibits a strong dependence on the surface coverage.

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Section: ■ Materials and Methodsmentioning

confidence: 99%

Plasmonic Effects of Phenylenediisocyanides Linked at Interparticle Junctions of Metal Nanoparticles

et al. 2014

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“…6 Spectroscopic studies of Au-PDI oligomers on Au(111) show that the HOMO of the oligomer lies B0.88 eV below the Fermi level, with a LUMO B3.32 eV above it, consistent with a HOMO tunnelling barrier. 17 More recent experiments found a barrier height of 0.19 AE 0.02 eV (ref. 36) where the difference from previous results was ascribed to different numbers of PDI molecules in the contact.…”

Section: à2mentioning

confidence: 98%

“…[15][16][17] The relatively short (B1.1 nm) repeat distance between gold atoms in the oligomer suggests the possibility of being able to chemically bond between gold nanoparticles with various separations by incorporating a number of repeat units until the gap is bridged. PDI has been previously proposed as a prototypical molecular electronic component, 4,6,[18][19][20][21] and theory suggests that PDI is a suitable candidate for device applications.…”

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confidence: 99%

Linking gold nanoparticles with conductive 1,4-phenylene diisocyanide–gold oligomers

et al. 2013

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A major challenge to fabricating molecular electronic circuits 1 is the difficulty of simultaneously chemically bonding molecular components to two metal electrodes. This can be accomplished by adjusting the electrode separation to match the molecular dimensions using break junctions 2-5 or by using a sharp tip to vary the electrode-surface spacing. 6 Such approaches provide detailed information on molecular conduction, but are not easily extended to planar systems required for a realistic circuit. 7Molecularly linked nanoparticles have been synthesized in solution and deposited onto surfaces 7,8 but the location of the nanoparticles in the circuit is dictated by the cross-linking structure. Ordered assemblies have been formed from functionalized nanoparticles but they are often not covalently connected. Finally, the length of the molecular linker can be matched to the nanoparticle spacing but requires the molecular size to be tailored to the separation of the nanoparticles. 10An alternative strategy is proposed based on recent observations that molecules that bind strongly to metals with low cohesive energies such as gold or copper can oligomerize by extracting metal atoms from the substrate.11-14 An example of this is the lateral self-assembly of 1,4-phenylene diisocyanide (PDI) on Au(111) that forms -(Au-PDI) n -oligomers comprising long, one-dimensional chains by extracting low-coordination gold atoms from surface defect sites. [15][16][17] The relatively short (B1.1 nm) repeat distance between gold atoms in the oligomer suggests the possibility of being able to chemically bond between gold nanoparticles with various separations by incorporating a number of repeat units until the gap is bridged. PDI has been previously proposed as a prototypical molecular electronic component, 4,6,[18][19][20][21] and theory suggests that PDI is a suitable candidate for device applications. 22This lateral self-assembly is explored by measuring the conductivity of a gold nanoparticle film on mica that has been exposed to PDI. Evaporating gold films on mica (and other insulating substrates)23-28 provides a simple method for growing isolated nanoparticles with different spacings merely by ensuring that the gold film thickness remains below a critical value, above which a continuous film is formed. The success of this approach relies on the oligomers being sufficiently mobile to bridge between nanoparticles. This mobility is illustrated in Fig. 1, which displays a typical series of 15 consecutive STM images (taken 53 seconds apart) of a saturated layer of Au-PDI chains on Au (111) showing the repeated lateral motion of an entire chain, where a line is drawn to highlight the chain motion, showing nine hopping events corresponding

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“…This is longer than that observed for PDI chains on Au(111), 11.7±0.2 Å, by approximately the length of an extra phenyl ring (see Figure 3). 17,18,24 The correlation between the monomer length and molecular dimensions supports an adsorption geometry in which BPDI molecules lie parallel (or nearly so) to the surface. Since abutting -NC terminal groups are not likely to be chemically linked, diisocyanide chain formation would require a common surface binding site for both terminal -NC groups.…”

Section: A Adsorption Structuresmentioning

confidence: 76%

“…[19][20][21][22][23] In a related study, Zhou et al examined the temperaturedependent surface morphology and electronic structure of PDI/Au(111) surfaces using a combination of variable-temperature STM and two-photon photoemission (2PPE) spectroscopy. 24 It was found that the PDI molecules vapor-deposited at low temperature formed disordered islands or very short chain segments at step edges. As the surface was heated to room temperature, the disordered islands disappeared and the PDI molecules self-organized into 1D molecular chains.…”

Section: Introductionmentioning

confidence: 99%

Characterization of one-dimensional molecular chains of 4,4′-biphenyl diisocyanide on Au(111) by scanning tunneling microscopy

Zhou

Zahl

et al. 2015

The Journal of Chemical Physics

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The morphology and electronic structure of vapor deposited 4,4'-biphenyldiisocyanide (BPDI) on a Au(111) surface were investigated using variable-temperature scanning tunneling microscopy. When deposited at room temperature, BPDI molecules form one-dimensional molecular chains similar to that recently observed for the structurally related 1,4-phenyl diisocyanide (PDI). Compared to PDI, the longer periodicity for the BPDI molecular chains is consistent with the addition of a second phenyl ring and supports a structural model in which the BPDI molecules lie parallel to the surface and interconnected by Au-adatoms. The molecular chains are mostly aligned along the 11̄0 direction of the Au(111) substrate, but exhibit frequent changes in angle that are consistent with directions between fcc and hcp three-fold hollow sites. Dispersion-corrected density functional theory calculations for one-dimensional chains of BPDI molecules bound end-to-end via their isocyanide groups to Au-adatoms reproduce the observed periodicity of the chains and show that this morphology is energetically favored over upright binding with one free -NC group. The spatially resolved conductance (dI/dV) map for BPDI on Au(111) exhibits a feature centered at -0.67 eV below the Fermi level which are delocalized along the chain with maxima at the Au-adatom and biphenyl positions. This occupied resonant feature is close to that previously observed for the PDI in both photoemission and conductance measurements and is attributed to an occupied interfacial state resulting from BPDI-Au interactions.

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Adsorption Structures and Electronic Properties of 1,4-Phenylene Diisocyanide on the Au(111) Surface

Cited by 40 publications

References 48 publications

Plasmonic Effects of Phenylenediisocyanides Linked at Interparticle Junctions of Metal Nanoparticles

Plasmonic Effects of Phenylenediisocyanides Linked at Interparticle Junctions of Metal Nanoparticles

Linking gold nanoparticles with conductive 1,4-phenylene diisocyanide–gold oligomers

Characterization of one-dimensional molecular chains of 4,4′-biphenyl diisocyanide on Au(111) by scanning tunneling microscopy

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