Metallization of a Thiol-Terminated Organic Surface Using Chemical Vapor Deposition

Abstract

The deposition and the subsequent decomposition of an organometallic precursor, (eta (3)-allyl)(eta (5)-cyclopentadienyl)palladium [Cp(allyl)Pd], on an organic surface exposed by self-assembled monolayers (SAM) was studied using X-ray photoelectron spectroscopy (XPS) and infrared reflection absorption spectroscopy (IRRAS). The interfacial chemical reactions of the vapor-deposited metal precursor with the pendant thiol group of the SAMs made from oligophenyldithiols, which are either prepared directly (terphenyldimethyldithiol, TPDMT) or by a deprotection route from SAMs formed by a monoacylated derivative of biphenyldimethyldithiol (dep. BPDMAc-1) have been studied in detail. When the TPDMT-SAMs were exposed to Cp(allyl)Pd vapor, a Pd (2+)/allyl-terminated SAM surface was obtained (to a lower extent this was also the case for dep. BPDMAc-1 SAMs), which was stable against exposure to H 2 gas. Reduction to Pd (0) by H 2 was only observed when small amounts of Pd (0) were already present, for example, after prolonged exposure to the precursor. The catalytic activity of the small Pd (0) particles also caused a decomposition of the SAMs upon exposure to air.

1,n-Alkanedithiol (n = 2, 4, 6, 8, 10) Self-Assembled Monolayers on Au(111): Electrochemical and Theoretical Approach

“…Dithiol SAMs have been utilized to make nanodevices, measurements of electricity transport and multilayer formation. [3][4][5][6][7][14][15][16][17][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] But most of those studies only focus on the electronic properties of dithiol SAMs. Compared to the well studied monothiolate SAMs, there are relatively less reports focused on the structure and growth of dithiol SAMs.…”

“…[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]41,[45][46][47][48][49][50][51][52][53][54][55] In this upright molecular structure, the unbound thiol group is pendent with respect to the Au substrate and serves as the platform for the applications, such as the preparation of copper (I)-dithiol or CdS nanoparticle-dithiol multilayer thin films, the formation of multilayer through disulfide linkage spontaneously or electrochemically, the measurement of electron transfer through single molecule or the construction of metalmolecule-metal sandwich structure. 3,[22][23][24][25][26][27][30][31][32][33][34][35][36][37][38] However, the quality of those thiol terminated surface has been debated. Loose pack, ill-defined dithiol adlayers, which were prepared by simple immersion of gold substrate into a solution of dithiol, were rep...…”

“…Among them, thiol-terminated surface, with their high affinity to metals, can serve as templates for the formation of metal film or metal wires at SAM-ambient interface by preventing the diffusion of metal into SAMs and formation of a short circuit. [3][4][5][6][7][14][15][16][17][22][23][24][25] It can also be used as building blocks for constructing multilayers. [27][28][29][30][31][32][33][34][35] The most suitable constituent for the formation of thiol terminated SAMs is dithiol.…”

“…52,53 In order to obtain compact thiol-terminated dithiol SAMs, different formation methods were proposed including protection of one thiol-group as thiolacetate and the following regeneration of SH on top of the formed dithiol SAMs and using organodithiols with more rigid backbonds. 25,52,53 The control of formation condition such as using different solvent, removal of oxygen from SAMs formation solution were also suggested. [22][23][24][25]30,31,41,[47][48][49][50][51][54][55][56][57] Formation of disulfide bond through the terminated free thiols on top of dithiol SAMs were reported as well.…”

1,6-Hexanedithiol Self-Assembled Monolayers on Au(111) Investigated by Electrochemical, Spectroscopic, and Molecular Mechanics Methods

“…Among them, thiol-terminated surfaces, with their high affinity to metals, can serve as templates for the formation of metal film or metal wires at the SAM-ambient interface by preventing the diffusion of metal into SAMs and the formation of a short circuit. [4][5][6][7][14][15][16][17]22,23,[27][28][29] The most suitable constituent for the formation of a thiol-terminated SAM is dithiol. Dithiol SAMs have been utilized to make nanodevices, for measurements of electricity transport, and for multilayer formation.…”