ω-Thiolation of Phenolic Surfactants Enables Controlled Conversion between Extended, Bolaform, and Multilayer Conformations.

The self-assembly of ω-thiolated surfactants onto gold is a well-studied phenomenon; however, control over the final organization within the thin films is either limited or requires extensive pre- and post-deposition chemical modifications. On the other hand, Langmuir-Blodgett deposition from the air-water interfaces affords a high degree of control over lateral organization within the film, yet it is generally employed to create physisorbed, soft matter films. Despite this, relatively little is known about the impact of the ω-thiolation on either the air-water of deposited film organization. Here, we show that the introduction of a terminal hydrophilic thiol on a phenolic surfactant does not necessarily disrupt a highly organized film nor does it necessarily induce a bolaform conformation at the interface. We show that the relative proportions of different conformations can be controlled using pH, relaxation time, surface pressure, and combinations thereof. Moreover, at high pH, the system undergoes a monolayer-to-multilayer transition wherein well-defined multilayer structures and morphologies are generated. These multilayers appear to comprise a single bolaform conformation atop an extended-chain condensed phase. We demonstrate that these structures can be transferred using Langmuir-Blodgett deposition demonstrating that combining these two approaches has the potential to achieve greater control over the functional properties of robust, chemisorbed films.