The Composition-Tunable Polydiacetylenic Complex Films: Conformational Change upon Thermal Stimulation and Preferential Interaction with Specific Small Molecules

Polydiacetylenic complex films were prepared using 10,12-pentacosadiynoic acid (PCDA) and para-xylenediamine (pXDA) upon acid-base interactions. The thermochromatic reversibility of the complex films was modulated by changing the mixed molar ratio (3: 1, 2: 1, and 1: 1) of the two molecules. The corresponding conformational changes of the complex films were studied by ex situ FTIR analysis upon thermal stimulation for the first time. In addition, the binding specificities of , β-, and γ-cyclodextrins (CDs) with the films were studied, where the CDs can induce stronger red fluorescent emission of the films. These fundamental results may be useful for platforms that use these polydiacetylenic complex films as optoelectronic devices or chemical/biological sensors.