Formation of Metal-free J-aggregates in Merocyanine/Spiropyran Mixed Langmuir-Blodgett Film

Abstract

In order to fabricate metal-free J-aggregate, merocyanine(MD)/spiropyran(SP) mixed LB film was transferred on a glass plate from a pure aqueous solution. Upon UV-light illumination, SP molecules isomerized from SP-form to photomerocyanine (PMC)-form and PMC-form molecules formed J-aggregate with self-assembly. Subsequent vapor-treatment of dimethylamine (DMA) aqueous solution after UV-light illumination induced J-aggregate formation of MD molecules. Metal-free J-aggregate of MD dye was formed by the stepwise treatment of UV illumination and the DMA vapor treatment. The formation mechanism of J-aggregate was discussed.

Keywords:

• J-aggregates
• Langmuir-Blodgett films
• merocyanine dyes
• spiropyran

Acknowledgments

This work was partially supported by a Grant-in-Aid for Scientific Research (B) (No. 16360040) from the Japan Society for the Promotion of Science. This work was also supported by the Photonics Materials Laboratory Project of Department of Frontier Research and Technology, Headquarters for Innovative Cooperation and Development, Kobe University.