An intrinsic shortcoming of self-organizing materials is their susceptibility to structural changes by mechanical forces and exposure to chemicals and radiation. Cross-linking of the molecules in the desired supramolecular structure is a generally applicable pathway to structurally more stable materials but is difficult to apply to self-organizing materials because the introduction of cross-linkable groups affects their self-organization and the process of cross-linking may alter the supramolecular structure of the 10 preceding phase. Reported here are the synthesis, thermal properties, and cross-linking of octaalkylthio substituted tetraazaporphyrins that contain either eight terminal azide groups or eight terminal acetylene groups. Synthesis of these compounds requires the preparation of the azide and alkyne containing sidechains and their reaction with 1,2-dicyanoethylene-1,2-dithiolate to the corresponding maleodinitrile intermediates. All maleodinitriles are successfully converted to tetraazaporphyrins by the established Mg 15 templated cyclotetramerization in typical yields of 60-70%. Thermal properties of the metal-free and copper(II) metallated tetraazaporphyrins were studied by thermal gravimetric analysis, polarized optical microscopy, differential scanning calorimetry, and variable temperature powder X-ray diffraction measurements. Azide substituted tetraazaporphyrins with trimethylene and hexamethylene spacers as well as acetylene derivatives with with trimethylene spacers unexpectedly display columnar mesophases over 20 ranges of temperature from 30 ºC to 110 ºC. A thermally activated cross-linking of a hexagonal columnar mesophase by cycloaddition at 65 ºC is demonstrated for a 1:1 mixture of azide and acetylene derivatives. At this temperatures the reaction progresses for up to 48 hours but renders the mesophase insoluble and stable to above 200 ºC. The structure of the mesophase is surprisingly little affected by the cross-coupling process that reaches a conversion of 60% of all azide and acetylene groups based on IR measurements. 25 Conversion of up to 80% of azide and acetylene groups is reached by copper catalysed cross-linking of a 1:1 mixture in solution to generate insoluble polymers. A similar degree of conversion is achieved by copper catalysed cross-linking of a 1:1 mixture as Langmuir film after 3 hours. However, transfer of intact cross-linked Langmuir films onto substrates was not successful.

We report the synthesis and properties of a series of novel triphenylenedicarboxyimides and thioimides (4−6) to probe the effect of thionation on the formation of columnar mesophases. These materials display broad columnar mesophases and high clearing points and self-associate in solution to form dimers. Overall, thionation improved the self-assembly in solution and led to a stabilization of the columnar mesophase. Furthermore, increasing the thionation of these materials led to a lowering of the lowest unoccupied molecular orbital (LUMO) energy level and a narrowing of the highest occupied molecular orbital−LUMO gap.

We report the synthesis of novel polycatenar dibenzo­pentacene­quinones 1 and 2 that are designed to form columnar liquid crystalline phases. The mesomorphic properties of these compounds were investigated by polarized optical microscopy, differential scanning calorimetry, and powder X-ray diffraction. While compound 1 exhibits two distinct columnar mesophases between 148 and 177 °C, fluorinated 2 exhibits a columnar mesophase from 121 to 336 °C. This dramatic stabilization of the columnar mesophase of 2 can be attributed to improved π-stacking as a result of arene–perfluoroarene interactions.

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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.