Interfacial Studies Using Organized Organic and Inorganic Films

Abstract

Interfaces play an important role in various fields, such as catalysis, charge transfer / electrochemical processes, chemical reactions, molecular electronics, wetting, and biology. Building functional structures with a perfect, uniform, and organized arrangement is one of the foremost requirements in understanding interfacial properties, particularly for molecular electronics, sensors, and other niche applications based on advanced materials. In addition, fundamental aspects of properties and reactions of molecules / materials confined within a limited-size space enhance the understanding of the effects of proximity. Assembling molecules at water-air interfaces in a Langmuir trough offers exquisite control over the molecular organization, packing, and orientation. The dynamic nature of applied surface pressure (ranges to a few dozen megapascals) is an additional merit of the Langmuir monolayer, which affects the orientation and the relative intermolecular distance (proximity between the molecules). In the present study, the effect of surface pressure on the organized assembly of anilinium ions at the air-water interface during the in-situ electro-polymerization in a Langmuir trough is studied. The applied surface pressure on the monolayer (EGO-anilinium complex) during the in-situ electro-polymerization leads to the preferential formation of the polaronic form of polyaniline. The absence of applied surface pressure on the monolayer during the electro-polymerization results in the twisted bipolaronic form. Different PANI forms are subsequently subjected to understanding their characteristics toward electrochemical actuation, hygro-actuation, and electrochemical hydrogen evolution reaction. In the second aspect of organic assembly, the proximity effect in a Langmuir monolayer is used to investigate the possibility of abiotic formation of an amide from an acid and an amine. As for inorganic systems, 2D chalcogenides (MoSSe, VPS3) are assembled at the air-water interface, and the aligned monolayers of molybdenum chalcogenides are used for surface-enhanced Raman scattering studies. In a separate section, the lithium-ion charge storage characteristics of a conjugated Schiff-base polymer based on a diazabutadiene unit are studied.