The application of arylamines as redox auxiliaries, polar crystals, and organic semiconductors

Abstract

Arylamines and derivatives thereof have been developed for use in several applications. Among these include: the development of an arylamine moiety to act as a trigger and redox catalyst for an organic reaction, the use of a specific arylamine moiety as a synthon in the preparation of a series of polar organic crystalline materials, and a preliminary investigation of an arylamine salt as a potential organic semiconductor. The synthesis of novel norbornadiene (N) derivatives with appended redox-auxiliary (RA) units for use as switchable photoelectrochromic materials is reported. The photochemical and electrochemical properties are investigated by UV-vis spectroscopy, chemical actinometry, and cyclic voltammetry. The pendant RA functions as a stable redox unit capable of catalyzing the conversion of the N form to the quadricyclane (Q) form, releasing stored ring-strain energy as heat. Aside from demonstrating the principle of RA catalysis, the new N derivatives demonstrate possible utility as recyclable solar fuels or as photo-electrical switchable systems for informational or mechanical applications at the molecular level. A second project involving the preparation of a series of m-phenylenediamine derivatives which assemble (crystallize) preferentially with polar order is described. The crystal structures of these analogs have been elucidated by X-ray crystallography, and their crystalline properties explored by differential scanning calorimetry. Insight gained through this study has led to a greater understanding of the requirements for polar ordering of these molecules, allowing for the rational design of certain polar organic crystals derived from such structures. Finally, a preliminary study of the structure and properties of radical cation and dication salts of tetra(p-anisyl)-p-phenylenediamine (TAPD), which show promise for use as organic one-electron oxidants and as organic semiconductors, is presented. The preparation and characterization of TAPD salts is described. Their electrochemical properties have been explored by powder pellet I-V electrochemical measurements.