Dipodal Ferrocene‐Based Adsorbate Molecules for Self‐Assembled Monolayers on Gold

Abstract

1,1'-Difunctionalised ferrocene derivatives have been studied, which contain groups suitable for chemisorption on gold substrates, namely -NC, -PR(2) as well as a range of sulfur-containing units like -NCS, -SR, and thienyl. Thin films on gold have been fabricated from solution with most of these adsorbate species. Film thickness, composition and structure were investigated primarily by X-ray photoelectron and near-edge X-ray absorption fine-structure spectroscopy. The quality of self-assembled monolayers fabricated from 1,1'-diisocyanoferrocene (1) and 1,1'-diisothiocyanatoferrocene (2) turned out to be superior to that of films based on the other adsorbate species investigated. In addition to the surface coordination behaviour of 1 towards gold substrates, relevant aspects of the molecular coordination chemistry of 1 have also been addressed, including the synthesis and characterisation of [(mu-1){Cr(CO)(5)}(2)], [Ag(2)(mu-1)(2)](NO(3))(2) x H(2)O and [(mu-1)(AuCl)(2)]. The crystal structure of the gold complex is governed by aurophilic interactions and can be taken as a model for the arrangement of 1 in self-assembled monolayers on gold.

Synthesis, Electrochemical Behavior, and Self‐Assembly of Metallocene‐Functionalized Thiofluorenes

“…The spectrum clearly exhibits π* characteristic resonances of the 4e 1g and 3e 2u orbitals of the ferrocenyl moiety at both the L 2 -and L 3 -edges. [32,68,75] Our NEXAFS data for 4b/Au and 6b/Au agree well with the NEXAFS data recently reported [28,31] for 8b/Au and 9b/Au, respectively, which, together with the XPS data, suggest that 4b and 6b are suitable candidates for the fabrication of SAMs on the Au substrate. …”

“…As for 4b/Au, additional information is provided by the observation of the Fe 2p 3/2 XPS signal shown in Figure 5 (c), which is characteristic of Fe in the ferrocenyl moiety. [32,66] The XPS spectral features of C 1s, Ru 3d, and Fe 2p 3/2 observed in this study are quite similar to the XPS spectra of SAMs of 8b and 9b. [28,31,32] The S 2p spectra of both 4b/Au and 6b/Au in Figure 5 (b) exhibit a broad S 2p 3/2,1/2 doublet at 162.0 eV (S 2p 3/2 ), which can be assigned to the well-known thiolate species covalently bonded to metal substrates.…”

“…[32,66] The XPS spectral features of C 1s, Ru 3d, and Fe 2p 3/2 observed in this study are quite similar to the XPS spectra of SAMs of 8b and 9b. [28,31,32] The S 2p spectra of both 4b/Au and 6b/Au in Figure 5 (b) exhibit a broad S 2p 3/2,1/2 doublet at 162.0 eV (S 2p 3/2 ), which can be assigned to the well-known thiolate species covalently bonded to metal substrates. [67,68] On the basis of the intensity ratios of the C 1s and Au 4f XPS signals and the standard attenuation lengths of these emissions, [69] effective film thickness values for 4b/Au and 6b/Au were estimated to be 14.5 and 16.5 Å, respectively (accuracy Ϯ5 %).…”

“…284.4 eV, which is related to the biphenyl backbone and the cyclopentadienyl (µC p ) rings of Fc and Rc. [28,31,32] The C 1s peaks of the films of 4b and 6b are somewhat broader than that for the biphenyl thiol SAM. [28] Such an effect has also been observed recently for the SAMs of .…”

The Amide Group as Modulator of Crystalline and Liquid Crystalline Structures in Isocyano-Alkylanilide Silver(I) Complexes

“…6,7 These systems have been widely investigated for the rational design of functional solids on the basis of controlling intermolecular interactions and coordination bonds, 8,9 but not many examples are based on silver complexes with functionalized isocyanides. 10, 11 These include complexes [AgX(CNR)] (X = anionic ligand) with a wide structural diversity ranging from monomeric to polymeric structures and involving different coordination geometries of the silver atom, 10b,11,12, 13 and also a few cationic bisisocyanide complexes [Ag(CNR) 2 ]X. 10 We therefore decided to study the coordination ability of 4-isocyanoacetanilide towards Ag(I), and explore the possibility of modifying the formation of different supramolecular structures by modulating the intermolecular interactions, which can be achieved through the amide group.…”