Exchange Reactions between Alkanethiolates and Alkaneselenols on Au{111}

Abstract

When alkanethiolate self-assembled monolayers on Au{111} are exchanged with alkaneselenols from solution, replacement of thiolates by selenols is rapid and complete, and is well described by perimeter-dependent island growth kinetics. The monolayer structures change as selenolate coverage increases, from being epitaxial and consistent with the initial thiolate structure to being characteristic of selenolate monolayer structures. At room temperature and at positive sample bias in scanning tunneling microscopy, the selenolate–gold attachment is labile, and molecules exchange positions with neighboring thiolates. The scanning tunneling microscope probe can be used to induce these place-exchange reactions.

Gold surfaces and nanoparticles are protected by Au(0)–thiyl species and are destroyed when Au(I)–thiolates form

“…Once the nature of Au-SR bonds are understood, the relative properties of related systems such as Au-SeR and Ag-SR bonds are easy to interpret. Au-Se bonds are both stronger and more structurally diverse than Au-S bonds (76). Contributions from covalent bonding depicted by structure 1b decrease in going down the periodic table, whereas the dispersive contributions that dominate the binding pertinent to structure 2a increase and so the observed increased bond strength is only interpretable by the Au(0)-thiyl description.…”

“…Ligand exchange reactions on nanoparticles are known to proceed with thiol reactants and products (1). Many different mechanisms for this process have been found, including adsorption of the incoming species at defect sites followed by place exchange, as well as direct SN2-type ligand replacement (76,89,90). The SN2-type processes would be expected to involve a radical mechanism that includes hydrogen transfer between the incoming and outgoing thiol ligands and is the most obvious interpretation of the available data, whereas an Au(I)-thiolate description of the bonding would demand that proton loss and recapture occur independent of the SN2 reaction and is difficult to reconcile with the used experimental conditions (90).…”

Quantifying the Bonding Strength of Gold‐Chalcogen Bonds in Block Copolymer Systems

“…Our research group has been working on selenium‐ and tellurium‐containing polymers and has proven that they are promising biomaterials for controlled delivery and keeping the balance of reactive oxygen species (ROS) . Over the past several decades, compared to the study of Au−S bonds, the research on Au‐Se bonds has been relatively limited, and that on Au−Te bonds has been even rarer …”

“…Our research group has been working on selenium-a nd tellurium-containing polymers and has provent hat they are promising biomaterialsf or controlled delivery and keeping the bal-ance of reactive oxygen species (ROS). [11][12][13][14][15][16][17] Over the past several decades, compared to the study of AuÀSb onds, the researcho nA u-Se bonds has been relatively limited, [18][19][20][21][22] and that on AuÀTe bondsh as been even rarer. [23][24][25] Investigatingt he relative strength of gold-chalcogen interactions is of great significance for systems such as chalcogenprotected gold surfaces and nanoparticles.U nderstanding the natureo fg old-chalcogen interactions can provide am eans for regulating the structures and functionalities of these systems and developing their applications.…”

Triptycene-terminated thiolate and selenolate monolayers on Au(111)

“…The strength of the chalcogenate–gold bond represents an upper limit to the MOF deposition temperature. Thus, replacing thiolate by selenolate with its stronger bond to gold [7,22–25] might open an opportunity to increase the temperature range for liquid epitaxy of MOFs. The insertion of a methylene spacer group between the anchor group and aromatic moieties has been reported to improve the structural quality of, e.g., anthracene-based SAMs [26–27].…”