The Design and Synthesis of New Materials using Nucleophilic Aromatic Substitution Reactions

Abstract

Abstract The overall objective of this research was to synthesize and study the structure-property relationships of novel polycyclic aromatic compounds capable of producing open crystalline networks based on π-stacking interactions in solid state. In this work, we describe a method of producing polycyclic aromatic compounds bearing electron-rich and electron-poor rings in order to promote cofacial π-stacking in the solid state. These compounds were synthesized from easily accessible molecules using nucleophilic aromatic substitution and copper-catalyzed aryl amination. The scope of phenoxazines bearing N-aryl substituents was explored for the synthesis of various polycyclic aromatic compounds. Interesting characteristics such as luminescence and predictable solid-state packing are displayed by electron-deficient phenoxazines. A focus was placed upon tuning the properties of the compounds by attaching phenoxazine units to different molecular architectures with the goal of producing open crystalline networks based on π-stacking interactions. The orange-colored solid compound 30 N-(4-bromophenyl) di-fluoro-di-cyano-phenoxazine was synthesized. Suzuki cross-coupling was used to attach an additional phenyl ring to compound 30 to produce compound 31. Similarly, compound 32 was synthesized by the reaction of 1, 4- benzenediboronic acid with two equivalents of compound 30. The crystal structure of compound 31revealed the presence of π-stacking interactions between the phenoxazine rings. The synthetic approach was extended to the preparation of heteropentacenes such as 52 and 58. Compound 52, which bears long alkyl chains, showed evidence of liquid crystallinity by polarized optical microscopy. However, the N-aryl heteropentacenes also showed limited stability