Anisotropic energy transfer in a clay-porphyrin layered system with environment-responsiveness

• Published in: Physical chemistry chemical physics : PCCP 2020-07, Vol.22 (25), p.14261-14267
• Main Authors: Nishina, Haruka, Hoshino, Shota, Ohtani, Yuta, Ishida, Tamao, Shimada, Tetsuya, Takagi, Shinsuke
• Format: Article
• Language: English
• Subjects: Absorption; Clay; Energy transfer; Fluorescence; Langmuir-Blodgett films; Monolayers; Orientation; Waveguides
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d0cp02263b

The adsorption orientation behavior of tetrakis(1-methylpyridinium-3-yl)porphyrin ( m -TMPyP) and tetrakis(1-methylpyridinium-4-yl)porphyrin ( p -TMPyP) on the clay monolayer prepared by the Langmuir Blodgett (LB) technique was investigated using the absorption and dichroic spectra obtained on a waveguide. It was revealed that the orientation of m -TMPyP and p -TMPyP on the clay monolayer, that is parallel and tilted with respect to the clay surface, depends on the surrounding environments such as water and N , N -dimethylformamide (DMF). The anisotropic photochemical energy transfer between m -TMPyP as a donor and p -TMPyP as an acceptor in the layered system was investigated in water and in DMF-water (9/1 (v/v)) by a fluorescence observation. As a result, while energy transfer efficiency ( η ET ) was 60% for the parallel-parallel orientation in water, that was 10% for the tilted-tilted orientation in DMF-water (9/1 (v/v)). The major factor for the change of η ET could be a change of the distance between m -TMPyP and p -TMPyP, and the J value that is a parameter for spectral overlap between energy donor's fluorescence and acceptor's absorption. The adsorption orientation behavior of tetrakis(1-methylpyridinium-3-yl)porphyrin ( m -TMPyP) and p -TMPyP on the clay monolayer prepared by the Langmuir Blodgett (LB) technique was investigated using the absorption and dichroic spectra obtained on a waveguide.