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Quantitative detection of external stimuli, such as light, heat, and force, is an important challenge for sensing materials. Near-infrared (NIR) light is used in a variety of fields, such as biological, physical, medical, and engineering applications. Visualization and quantitative detection of invisible NIR are significant for its safe use. Here we fabricate a paper-based device coated with polypyrrole (PPy) and layered polydiacetylene (PDA). As PPy induces evolution of heat with irradiation of NIR, the effective conjugation length of the layered PDA is changed by the dynamic structure changed through the heat conduction. The visible color change from blue to red proceeds on the paper device. The red-color intensity has a relationship with the irradiation power of NIR. These facts suggest that the irradiation time and power of NIR are quantified by the color. Moreover, the results indicate that layered PDA can be applied to the quantification of external stimuli through conversion from the desired stimulus to the detectable one. [ABSTRACT FROM AUTHOR]

Intercalation chemistry has been developed mainly in inorganic layered compounds. Organic layered materials, such as layered polydiacetylene (PDA), exhibit the intercalation nature and dynamic properties. The intercalation of guest ions or molecules has the potential to control the dynamic properties through changes in the structural stability of the organic layered materials. Here we found that the partial intercalation states of the guest ions induced the changes in the layered structures and dynamic properties of PDA. The concentration of the intercalated metal ions, such as zinc ions (Zn2+), was controlled in the layered PDA. Although the layered PDA without the intercalation of the guest showed irreversible color transition from blue to red at a certain temperature, the temperature-responsive and reversible color-change properties emerged from the Zn2+-intercalated layered PDA even at the partial intercalation states. The results indicate that the structures and dynamic properties of organic layered materials can be controlled by the partial intercalation state. [ABSTRACT FROM AUTHOR]