Synthesis of Organic Thiosulfates Tailored for the Electrochemical Deposition of ‘Self-Assembled Monolayers’ at Gold Surfaces

Abstract

The synthesis of organic thiosulfates, up to 10 nm in length, which were tailored for generating artificial monomembranes on gold surfaces by electrochemically initiated deposition, was accomplished. (E)-3-(4-Hydroxyphenyl)acrylic acid (4-hydroxy cinnamic acid) was employed as aromatic head group and (C 10 H 20 -O-) n (n = 1, 3, 5, 7) building blocks were attached. The synthetic procedure comprises a series of nucleophilic substitutions under carefully defined conditions. Extended purification is crucial for eliminating non-reacted starting materials.

Characterization of Nanostructured Surfaces Generated by Reconstitution of the Porin MspA from Mycobacterium smegmatis

“…To mimic the mycobacterial OM, the lengths of the hydrophobic surfactants should vary between 3 and 10 nm, because MspA features a hydrophobic docking unit approximately 4 nm in length 18. A phenyl group was introduced in close proximity to the polar head group to enable the formation of densely packed SAMs 27. The deposition of the surfactant onto the gold electrode should be precisely controlled.…”

“…Such an experimental strategy is mandatory for the reconstitution of bio‐nanostructures within an artificial monomembrane. The synthesis of the tailored surfactants is described in a separate publication 27…”

Nanoarray‐Surfaces by Reconstitution of the Porin MspA into Stabilized Long‐Chain‐Lipid‐Monolayers at a Gold‐Surface

“…According to these considerations, 3-(4-hydroxy-phenyl)-acrylic acid has been chosen as the preferential head group of our tailor-made surfactants. Note that the surfactants headgroup, derived from (E)-3-(4-hydroxyphenyl)acrylic acid, leads to a tilt of approximately 1188 AE 28 with respect to the oligo-decylether chains linked to the gold surface [18].…”

“…The synthesis and characterization of the long-chain surfactant employed here: A 3 : (2E)-3-[4-({10-[(10-{[10-(sodiumsulfothio)decyl]oxy}decyl)oxy]decyl}oxy)-phenyl] acrylic acid; was described in detail in a separate publication [18]. Fig.…”

“…Furthermore, the artificial monomembrane lipid monolayer should have a low fluidity in order to mimic the dense packing of the mycolic acids within the "inner-leaflet" of the outer mycobacterial membrane [17]. The recently published synthesis of tailored long-chain organic surfactants bearing a terminal thiosulfate group (Bunte salts) [18] provides us with the right tools to achieve these goals. In this publication, we report the results obtained when using (2E)- Table 1).…”