Previous efforts in the field of sensing have focused on developing materials that can respond to a stimulus (e.g. light or chemical) with a measurable output signal in the solid phase. The limited solubility of these materials in water is one of their biggest disadvantages, since water is the medium for most environmental-sensing applications. One approach to address this issue is to incorporate the small molecules into a larger assembly, which can respond to stimuli at the interface between water and a solid film. In order to employ this strategy, the present research focuses on studying the assembly of anion-responsive azo-benzenes in liquid crystalline (LC) phases. As a proof of the concept, azo-benzenes with long alkyl chain ureas were synthesized. The compound 1 showed evidence of LC thermal transitions in a differential scanning calorimetry analysis. Additionally, organic solutions of 1 exhibited a variety of color changes when exposed to tetrabutylammonium halide salts. As part of a structure-property study of the assembly of azo-benzenes, the compound 2 was synthesized and characterized with spectroscopic and thermal analysis. Future efforts will focus on characterizing both compounds with polarized optical microscopy as part of a larger structure-property study of their assembly.

Anion-responsive liquid crystals

249th National Meeting (2015)

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