Synthesis and Characterization of Liquid‐Crystalline Tetraoxapentacene Derivatives Exhibiting Aggregation‐Induced Emission

Abstract

A series of new tetrakis(dialkoxyphenyl) dicyanotetraoxapentacene derivatives (1 a–c) were prepared by reaction of the appropriate terphenyl diols with tetrafluoroterephthalonitrile in good yields. Compounds 1 b and 1 c, which bear hexyloxy and decyloxy side chains, exhibited columnar hexagonal mesophases, as shown by polarized optical microscopy, variable‐temperature powder X‐ray diffraction, and differential scanning calorimetry. Single‐crystal X‐ray diffraction of methoxy‐substituted 1 a revealed that the dicyanotetraoxapentacene core is highly planar, consistent with the notion that these molecules are able to stack in columnar mesophases. A detailed photophysical characterization showed that these compounds exhibit aggregation‐induced emission in solution, emission in nonpolar solvents, weak emission in polar solvents, and strong emission in the solid state both as powder and in thin films. These observations are consistent with a weakly emissive charge‐transfer state in polar solvents and a more highly emissive locally excited state in nonpolar solvents.

Synthesis of Emissive Heteroacene Derivatives via Nucleophilic Aromatic Substitution

“…This motif has been used for the preparation of rigid, macromolecular networks such as polymers with intrinsic microporosity, − covalent organic frameworks, , as well as cyclodextrin-based polymers for wastewater treatment. , In these examples, the DCTOP moiety serves primarily as a rigid linker. Recently, we showed that dialkoxyphenyl DCTOP derivatives exhibit columnar mesophases and have aggregation-induced emission . Given the interesting properties of these materials, their similarity to heteroacenes, and their potential as luminescent dyes, there is an interest in exploring this synthetic approach for the preparation of other heteroacene analogues.…”

“…Recently, we showed that dialkoxyphenyl DCTOP derivatives exhibit columnar mesophases and have aggregationinduced emission. 18 Given the interesting properties of these materials, their similarity to heteroacenes, and their potential as luminescent dyes, there is an interest in exploring this synthetic approach for the preparation of other heteroacene analogues.…”

Crystal Packing of a Series of 1,2,3,4-Substituted Phenoxazine and Dibenzodioxin Heterocycles

“…Our previous studies focused on nucleophilic substitution reactions of bidentate nucleophiles with tetrafluoroterephthalonitrile to furnish a series of heteropentacene analogues, where the solid state structures and crystal packing of these compounds were described. , Using this methodology, compounds 1 – 6 were conveniently accessed via nucleophilic aromatic substitution of a fluorinated arene with either catechol or a 2-aminophenol derivative.…”

Columnar Mesomorphism of Board‐Shaped Perylene, Diketopyrrolopyrrole, Isoindigo, Indigo, and Quinoxalino‐Phenanthrophenazine Dyes

“…This often leads to better defined intermolecular interactions and allows for the adjustment of optoelectronic properties, such as fluorescence and charge transport. [36,45,46] Several unusual columnar mesophase structures have been reported for some of these board-shaped dyes and it is our intention to specifically highlight rare supramolecular structures and their underlying molecular structures. Concepts such as shape-anisotropy (aspect ratios), nanosegregation, and relative packing volumes were applied qualitatively to reason the formation of different types of columnar mesophase based on molecular design.…”