Interfacial Characterization of Ruthenium-Based Amphiphilic Photosensitizers

Abstract

Nonreactive surfactant molecules have long been used and characterized for a wide range of applications in industries, life science, and everyday life. Recently, new types of functional amphiphilic molecules have emerged that bear another function, for example, a light-absorbing action, or catalytic properties. However, the surfactant properties of these molecules remain to date essentially unknown. In this context, we investigated here the interfacial activity of photocatalytic surfactants based on a ruthenium(II) tris-bipyridine core, functionalized with two alkyl tails. We realized a systematic characterization of the surfactant properties of these molecules at a water–air interface and studied the effect of the alkyl chain length and of the counterions (hexafluorophosphate or chloride) on these properties. Our data demonstrate that ruthenium surfactants with chloride counteranions form a denser layer at the interface, but their surfactant properties can dramatically deteriorate when the chain length of the alkyl tail increases, leading to simple hydrophobic molecules with poor surfactant properties for the longest chains (C17). These findings pave the way for a better use and understanding of photocatalytic soft interfaces.

A novel concept of photosynthetic soft membranes: a numerical study

“…It is worth to remark that, in general, soap films are stabilized using base surfactants; however, in this case the PS (see the chemical structure of the considered ruthenium-based PS in Supplementary file 1: Fig. S1) is assumed to also play the role of a base surfactant [18]. In the photochemical reaction, the photosensitizer is responsible for light harvesting and electron transfer from or to the neighboring catalysts, which drives one of the two half reactions.…”

“…Subsequently, the mesoscopic model was used to investigate the behavior of different mixtures of catalysts and photosensitizers. A +2 charged photosensitizer [18,21] and a neutral catalyst both for the CO 2 reduction side [22] and for the water oxidation side [21] were adopted. However, it is worth to note that other catalysts and photosensitizer may also be employed for other reactions of interest [42,50].…”

“…Here, the aim is to employ the photocatalytic properties of engineered surfactants in soft (soap film based) compartments for oxygen-fuel (i.e., carbon monoxide, CO) generation and separation. Soap films are composed of a water core stabilized by the presence of surfactant molecules that self-assemble at the gas-liquid interfaces [17,18]. Ideally, a soap film membrane where molecular catalysts are self-assembled on water may avoid problems of photocatalytic-surface deactivation due to microbubble formation, keeping the produced oxygen and the fuel separated for a sufficiently long time.…”

Resonance-Induced Reduction of Interfacial Tension of Water–Methane and Improvement of Methane Solubility in Water

“…With the increase of temperature or pressure, water–methane IFT gradually reduces and finally tends to be stable, − which is attributed to the influence of temperature and pressure on the solubility of methane in water . Surfactants can reduce water–gas IFT owing to the decrease in the interface free energy. − However, although the surfactants can reduce the water–methane IFT, they do not increase the solubility of methane in water . Recently, the influence of a direct current electric field on a water–methane–graphene system has been investigated using molecular dynamics (MD) simulations and reveals that the electric field can improve the solubility of methane in water .…”

Efeito Do Querosene Nas Propriedades Interfaciais E Na Estabilidade Da Emulsão De Um Óleo Pesado Brasileiro

“…Figura 3 Esquema da tensão interfacial dinâmica na interface água e óleo pelo método da gota. Adaptado de(TIMOUNAY et al, 2022) …”