Polyarene-based π-conjugated systems: synthesis, characterization, and mechanistic studies

Abstract

This thesis mainly deals with the synthesis and characterization of arenebased π-conjugated systems. The content can be divided into three major parts. In the first section, a series of tetraaryl-anthraquinodimethane derivatives (Ar₄-AQs) was synthesized via Suzuki coupling reactions, and these compounds were subjected to intramolecular cyclization reactions under chemical and photochemical conditions with the aim of making highly π-delocalized polycyclic aromatic hydrocarbons (PAHs). The Ar₄-AQs and their cyclized products were investigated by various spectroscopic analyses, including NMR, UV-Vis absorption spectroscopy, and X-ray crystallography to understand their structural, electronic, and photochemical properties. In the second part, microporous organic cross-linked polymer networks were successfully prepared from Schiff base condensation of a tetrabis(carboxaldehyde)-substituted Ar₄-AQ and para-phenylenediamine. Under optimized conditions, the resulting microporous organic materials showed good microporosity and crystallinity. In the third section, the detailed reaction mechanisms of intramolecular alkyne-dithiolium [3+2] cycloaddition reactions were investigated by a joint experimental and theoretical approach. A number of alkynyl-subsituted phenyldithiafulvenes was prepared as model compounds. Density functional theory (DFT) calculations were performed to reveal the effects of pH and degree of π- conjugation on reactivity.