Systematic Control of the Packing Density of Self-Assembled Monolayers Using Bidentate and Tridentate Chelating Alkanethiols

Park, Joon-Seo; Vo, Andy Nguyen; Barriet, David; Shon, Y.; Lee, T. Randall

doi:10.1021/la0475573

Cited by 125 publications

(277 citation statements)

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“…All other low-density monolayer synthesis approaches are tailored to one or two possible functional groups. [14][15][16][17]23 Despite advantages in stability and adaptability, our previous approach fails to achieve the synthetic simplicity of alternative LD-SAM methods. In particular, the electrostatic methods developed by the Frechette group are staggeringly simple.…”

Section: Introductionmentioning

confidence: 93%

“…While similar phenomena 3 are expected in other protein/SAM interactions, there are few stable, low-density monolayer systems available for these studies. [14][15][16] We recently developed a unique synthetic approach towards low-density monolayers (LDSAMs) on gold using the solution-phase synthesis of a y-shaped adsorbate by a two to one thiol to yne addition reaction (Figure 1b). 7 When millimolar solutions of these adsorbates are contacted with gold substrates, a self-assembled monolayer forms with a layered structure.…”

Section: Introductionmentioning

confidence: 99%

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Photopatterning of Stable, Low-Density, Self-Assembled Monolayers on Gold

Safazadeh

Berron

2015

Langmuir

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Photoinitiated thiol-yne chemistry is utilized as a click reaction for grafting of acid-terminated alkynes to thiol-terminated monolayers on a gold substrate to create stable, low-density monolayers. The resulting monolayers are compared with a well-packed 11-mercaptoundecanoic acid monolayer and the analogous low-density monolayers prepared through a solution phase synthetic approach. The overall structuring of the monolayer prepared by solid-phase grafting is characterized by contact angle goniometry and Fourier transform infrared spectroscopy. The results show that the product monolayer has an intermediate surface energy and a more disordered chemical structuring compared to a traditional well-packed self-assembled monolayer, showing a low-packing density of the chains at the monolayer surface. The monolayer's structure and electrochemical stability were studied by reductive desorption of the thiolates. The prepared low-density monolayers have a higher electrochemical stability than traditional well-packed monolayers, which results from the crystalline structure at the gold interface. This technique allows for simple, fast preparation of low-density monolayers of higher stability than well-packed monolayers. The use of a photomask to restrict light access to the substrate yielded these low-density monolayers in patterned regions defined by light exposure. This general thiol-yne approach is adaptable to a variety of analogous low-density monolayers with diverse chemical functionalities.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Photopatterning of Stable, Low-Density, Self-Assembled Monolayers on Gold

Safazadeh

Berron

2015

Langmuir

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“…Tridentate ligands such as terpyridine derivatives are good choices in term of geometry, but many of these metal complexes are not or only weakly luminescent with such ligands. Various rigid moieties containing thiol or amino functionality, substituted on different N-N chelating ligands, have been employed by different groups [34][35][36]. From these results it is evident that multiple anchoring groups would lead to a better stability of the formed monolayers.…”

Section: Introductionmentioning

confidence: 99%

Luminescent acetylthiol derivative tripodal osmium(II) and iridium(III) complexes: Spectroscopy in solution and on surfaces

Ramachandra

Polo

Edafe

et al. 2011

Pure and Applied Chemistry

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Luminescent Os(II) and Ir(III) complexes containing a tripodal-type structure terminalized with three thiol derivatives are described. The tripod is introduced through derivatization, with a rigid spacer, of a phenanthroline ligand coordinated to the metal ion, and the entire structure possesses axial geometry. The geometry of the complexes combined with the three anchoring sites, the thiol groups, allows the complexes to adopt an almost perpendicular arrangement to the surfaces and the formation of a well-packed monolayer on Au substrates. The photophysical and electrochemical behavior of the complexes is studied in solution and on surfaces. Furthermore, a self-assembled monolayer (SAM) of Os(II) complexes on an ultraflat Au surface is used to fabricate a metal–molecule–metal junction with Au and In Ga eutectic as electrodes. The Os(II) SAM in the tunneling junction exhibits rectification behavior which is opposite in direction to that which we have previously shown for Ru(II) SAMs.

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“…To circumvent these issues, efforts to create SAMs with added conformational freedom has led to the design of low-density SAMs (LD-SAMs) whereby the surface packing density is carefully controlled by increasing the steric hindrance between chains during the deposition step. Modification of the thiol headgroup using asymmetric dialkyl sulfides [16,17] or chelating thiols [18] has been one approach employed to reduce packing density. Alternatively, low-density monolayers have also been obtained via a two-step process that involves modification of the terminal group.…”

Section: Introductionmentioning

confidence: 99%