Metal-thiolate bonds, formation

The kinetics of the deposition of In20i films have not been investigated by many groups, since most of them concentrate on the physical properties and possible applications. The published results are listed in Table 3-8. In addition, there are only two remarks about decomposition pathways. Maruyama andTabata [111] state that indium acetate needs no oxygen as reactant to form indium oxide, i.e., some of the metal-oxygen bonds are not broken during the deposition. Also, as proposed by Nomura and coworkers [122], the butylindium thiolate decomposes via formation of indium sulfides ... 

The original work of Nuzzo and Allara [4] on the use of the strong interaction between gold surfaces and organosulfur compounds for monolayer construction opened the field of SAMs prepared by molecular self-assembly on metal substrates via formation of metal-thiolate (or disulfide or dialkyl sulfide) bonds [15]. The introduction of functional SAMs on metal substrates was a natural development that followed [10, 11]. Owing to the similarity with highly specialized biological membranes, functional SAMs are sometimes called artificial membranes. 

A recent alternative approach is the use of diacetylene-containing alkylthiol monomer units that, when attached to metals via the thiolate bond, form planar arrays that are photopolymerized [20-22]. Sueh a strategy, shown in Fig. 1, eombines the advantages of SAM formation with the improvements of a more robust polymer end-product. Previous work with L-B films of diacetylenic amphiphiles has demonstrated in-plane requirements for topo-ehemie-ally controlled polymerization [23]. Templating of the diacetylene topochemistry via the thiol docking to metal surface lattice sites spaced according to the metal... 

The pKa value reflects the formation and dissociation constants of metal-carboxylate bonds. The dissociation is prevented by the presence of NH 0 hydrogen bonds of coordinating carboxylate because the NH O hydrogen bonds lower the pKa value of the corresponding carboxyUc acid [65-67]. The hydrogen bonds toward the coordinating oxygen or sulfur atom of pheno-late [63] or thiolate have a similar fimction with each other [43,68). 

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