Development of porous polymer monolith showing Visible-to-UV photon upconversion towards flow photochemical reactions Sakura Nakagawa 1 , Naoto Matsumoto 2 , Masanori Uji 2 , Kazuyoshi Kanamori 3,6 , Kazuki Nakanishi 4,5 , Nobuhiro Yanai 2,7 1 School. of Eng., Kyushu University, Japan, 2 Grad. School. of Eng., Kyushu University, Japan, 3 Grad. School. of Sci., Kyoto University, Japan, 4 IMaSS, Nagoya University, Japan, 5 iCeMS, Kyoto University, Japan, 6 PRESTO, JST, Japan, 7 FPREST, JST, Japan While ultraviolet (UV) light is useful in driving various photochemical reactions, it is impractical because of the limited UV sources and reaction vessels. Triplet-triplet annihilation-based photon upconversion (TTA-UC) is one of the methods to generate UV light from visible light. [1] However, photoreactions using UC from visible to UV light have only been reported in solution systems, and the development of solid materials has been desired for more practical use. In this work, we report on the development of porous polymer monolith that exhibits TTA-UC from visible to UV light for application to flow photochemical reactions (Fig. 1a). The monolith is a porous material with µm-scale co-continuous structures, enabling the use of flow systems. It was synthesized by polymerizing styrene dissolving CBDAC (donor) and TIPS-Nph (acceptor) [2] by using silica monolith as a template. [3] After template removal, the formation of co-continuous structures was observed. The UC emission with the peak top of 376 nm was obtained when a CW laser of 445 nm was irradiated to the chromophore-doped polystyrene monolith (Fig. 1b).
Fig.1 (a) Schematic diagram of porous polymer monolith for flow photochemical reactions. (b) Photoluminescence spectra of CBDAC and TIPS-Nph doped in polystyrene monolith at various excitation intensities (λ ex = 445 nm, 425 nm short-pass filter). References
1. M. Uji, et al., Ang. Chem. Int. Ed ., 2023 , 62, e202301506 2. M. Uji, et al., J. Mater. Chem. , C, 2022 ,10, 4558-4562 3. K. Nakanishi, et al., J. High Resol. Chromatogr. , 2000 , 23, 106-110
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