Structure and Growth of Hexyl Azobenzene Thiol SAMs on Au(111)

Tamada, Kaoru; Nagasawa, Jun’ichi; Nakanishi, Fusae; Abe, Koji; Ishida, Takao; Hara, Masahiko; Knoll, Wolfgang

doi:10.1021/la971348j

Cited by 99 publications

(109 citation statements)

References 49 publications

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“…[84][85][86] Importantly, the rectangular lattices of alkylthiols with azobenzene headgroups have been found to resemble the unit cells of SAMs of arenethiols on Au(111) suggesting that the packing is mainly governed by p-p interactions between the aromatic moieties. However, it is still a matter of debate, whether the SAM packing leads to a commensurate molecular lattice, [87][88][89] or whether the strong interchain interaction among the adjacent molecules dominates leading to the formation of incommensurate lattices. [40,90,91] …”

Section: Discussionmentioning

confidence: 99%

Single Component Self‐Assembled Monolayers of Aromatic Azo‐Biphenyl: Influence of the Packing Tightness on the SAM Structure and Light‐Induced Molecular Movements

Elbing

Błaszczyk

Hänisch³

et al. 2008

Adv Funct Materials

106

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Aiming at modulating the packing density within functional self‐assembled monolayers (SAMs), two azo‐biphenyl derivatives AZO1 and AZO2 comprising a terminal sulfur anchor group have been designed and synthesized. While AZO1 allows for a coplanar arrangement of both biphenyl subunits, additional steric repulsion due to two methyl side groups attached to the footing biphenyl of AZO2 results in an increased intermolecular distance within the SAM, providing additional free volume. SAMs of both derivatives on gold and platinum substrates have been formed and thoroughly investigated by photoelectron (XPS) and near‐edge absorption fine structure (NEXAFS) spectroscopy as well as cyclic voltammetry and scanning tunneling microscopy. These measurements confirmed the formation of tightly packed SAMs for AZO1, while AZO2 formed SAMs consisting of less organized and more loosely packed molecules. Optical investigations of both azo derivatives in solution as well as their SAMs displayed efficient photoisomerization in solution and in SAMs. Comparable maximal cis/trans ratios of ca. 0.9 have been observed in all cases upon irradiation at λ = 370 and 360 nm for AZO1 and AZO2, respectively. The thermally induced cis → trans back reaction on AZO1 was found to be slower by a factor of 3 in SAMs as compared to solution, while AZO2 displayed comparable rates of the back reaction in both environments. This behavior can be explained by the different nature of molecular isomerization in the two SAM systems: whereas the isomerization in AZO1 SAMs takes place in a highly coordinated, collective way and involves many adjacent molecules, AZO2 species behave rather individually even packed in SAMs, such that their isomerization process is similar in SAMs and in solutions.

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Section: Discussionmentioning

confidence: 99%

Single Component Self‐Assembled Monolayers of Aromatic Azo‐Biphenyl: Influence of the Packing Tightness on the SAM Structure and Light‐Induced Molecular Movements

Elbing

Błaszczyk

Hänisch³

et al. 2008

Adv Funct Materials

106

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“…Thiolate ligands adsorbed onto Au(111) are therefore model systems for investigating how surface properties such as wetting [8,9], friction [4,10], and conduction [11] can be tuned via SAMs. A variety of experimental techniques have been employed to characterise the structure and properties SAMs including ellipsometry [9,12], atomic force microscopy [7,13], scanning tunneling microscopy [14], x-ray diffraction [15], contact angle [9,12], and Fourier transform infra-red spectroscopy [16].…”

Section: Introductionmentioning

confidence: 99%

The effect of surface symmetry on the adsorption energetics of SCH3 on gold surfaces studied using Density Functional Theory

2005

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Adsorption of methanethiol onto the three, high symmetry gold surfaces has been studied at the density functional level using a linear combination of atomic orbitals approach. In all three cases the bond energy between the thiolate radical and surface is typical of a covalent bond, and is of the order of 40 kcal.mol -1 . For the (111) the fcc hollow site is slightly more stable than the bridge site. For the (100) surfaces the four-fold hollow is clearly the most stable, and for the reconstructed (110) surface the bridge/edge sites either side of the first layer atoms are preferred. The calculated differences in binding energy between the three surfaces indicate that the thiolate will preferentially bind to the Au (110) or (100) before (111) surface, by about 10 kcal.mol -1. The (110) surface is slightly more favourable than the (100), although the energy difference is only 3 kcal.mol -1. The results suggest the possibility of selectively functionalising the different facets offered by a gold nanoparticle.

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“…After UV exposure, the substrate was rinsed with ethanol and milliQ water, and the removal of SAM in the area exposed was investigated by Fourier transform infrared-reflection absorption spectroscopy (FTIR-RAS, Bio-Rad 175C) 7,8) . Then, the -PEG-Biotin terminated SAM was prepared from 4 mM thiol solution into array spots exposed.…”

Section: Formation Of a Patterned Sam By Uv Lithographymentioning

confidence: 99%

The Detection of Antigen-Antibody Recognition on an Array Chip by Surface Plasmon Field-Enhanced Fluorescence Imaging (SPFI)

Nishizawa

Tomimori

Tawa

et al. 2009

Trans. Mat. Res. Soc. Japan

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Multi-array analysis method recently attracts attention as a useful technique to detect antigen-antibody interactions in a small amount of reagents. Surface plasmon resonance (SPR) has been used as one of the highly sensitive techniques which can detect antigen-antibody interaction in the multi-array coated by a thin metal film. We proposed the surface plasmon field-enhanced fluorescence Imaging (SPFI) with higher sensitivity than SPR detection. The fluorescence from fluorescence molecules near the substrate (within 40 nm) is quenched by a thin metal film as found from previous studies. Therefore the change of distance due to the interaction of the protein (antigen) in cell with antibody immobilized at the substrate surface was monitored by the change of the fluorescence intensity using SPFI. Further we fabricated array spots on the substrate using a self assembled monolayer (SAM) possible to suppress the non-specific adsorption out of the spot exposed to UV light, and the antibody was prepared into the spots. Two kinds of antibodies modified with fluorescent-dyes were immobilized to the different array spots. Our SPFS system can recognize binding of cells based on the specific antigen-antibody interaction in the multi-array system.

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Structure and Growth of Hexyl Azobenzene Thiol SAMs on Au(111)

Cited by 99 publications

References 49 publications

Single Component Self‐Assembled Monolayers of Aromatic Azo‐Biphenyl: Influence of the Packing Tightness on the SAM Structure and Light‐Induced Molecular Movements

Single Component Self‐Assembled Monolayers of Aromatic Azo‐Biphenyl: Influence of the Packing Tightness on the SAM Structure and Light‐Induced Molecular Movements

The effect of surface symmetry on the adsorption energetics of SCH3 on gold surfaces studied using Density Functional Theory

The Detection of Antigen-Antibody Recognition on an Array Chip by Surface Plasmon Field-Enhanced Fluorescence Imaging (SPFI)

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