Tuning Emission Properties by Dye Encapsulation into Layered Silicates
This chapter describes the emission behavior of molecules on the surface of layered materials. Emission properties of molecules depend on their surrounding environment. Even in homogeneous environments, this emission behavior depends on solvent effects su
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Tuning Emission Properties by Dye Encapsulation into Layered Silicates Yohei Ishida and Shinsuke Takagi
Contents 1 2 3 4 5 6
Emission of Dyes Layered Silicates Photochemical Property and Layered Materials Complex of Dyes and Layered Silicates Photochemical Properties of Dyes in/on Layered Silicates Emission Enhancement of Dyes in/on Layered Silicates (Surface-Fixation Induced Emission (S-FIE)) 7 Color Tuning of Dyes in/on Layered Silicates 8 Reversible Environment-Responsiveness of Dyes in/on Layered Silicates 9 Summary References
Abstract This chapter describes the emission behavior of molecules on the surface of layered materials. Emission properties of molecules depend on their surrounding environment. Even in homogeneous environments, this emission behavior depends on solvent effects such as viscosity, permittivity, polarity, and so on. While the chemical reaction media provided by layered materials is the analog of solvent effects, the effect of layered materials induces important changes in the properties of the molecule. For example, the emission intensity could be enhanced 100 times by the complex formation with layered materials. Despite the drastic effect of layered materials on the photochemical properties of molecules, the use of layered materials is limited due to some factors. One of these factors is the complicated complex formation behavior of molecules on layered materials. This sometimes includes Y. Ishida Division of Material Science and Engineering, Faculty of Engineering, Hokkaido University, Hokkaido, Japan e-mail: [email protected] S. Takagi (*) Department of Applied Chemistry, Graduate Course of Urban Environmental, Sciences, Tokyo Metropolitan University, Tokyo, Japan e-mail: [email protected]
Y. Ishida and S. Takagi
segregation and aggregation that induce changes in photochemical properties. In recent decades, the intrinsic photochemical properties of molecules on layered materials were clarified by the progress in techniques to prepare complexes between molecules and layered materials. These examples will be described in this chapter. Keywords Chromism · Emission · Fluorescence · Layered materials · Synthetic clay · Transition probability
Abbreviations p-TMPyP AFM AIE CEC DMF SSA S-FIE TPAB XRD
Tetrakis(N-methylpyridinium-4-yl)porphyrin Atomic force microscopy Aggregation-induced emission Cation exchange capacity Dimethylformamide Saponite Surface-fixation induced emission 1,3,5-Tris[(N-pyridinium)aniline-4-yl]-benzene X-ray diffraction
1 Emission of Dyes This section briefly describes the main photophysical processes of chromophores. The energy diagram of a molecule is shown in Fig. 1. Before absorbing light, the molecule exists at an electronically ground state (S0). When the temperature is low enough, the vibrational state of the molecule is supposed to be ν ¼ 0. An electronically excited state (Sn (ν ¼ 0, 1, 2, . . .)) is produced when the molecule absorbs light. Absorption is governed by the transition probability rule [1, 2]. In the case that
kisc
S1 abs
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