Abstract
Here, we show that association of stilbene molecules is facilitated by water on silica gel because of hydrophobic interaction and photodimerization becomes the main photochemical process. Irradiation of trans-stilbene (t-1) on silica gel gives cis-stilbene (c-1), phenanthrene (2), benzaldehyde (3), and dimers r-ctt-4 and r-tct-4. The yields of the dimers increase and those of 2 and 3 decrease with an increase in the amount of t-1 loaded on silica gel. Atmospheric oxygen is responsible for the formation of 2 and 3. The yields of the dimers also increase with an increase in the water on a silica-gel surface and change drastically at the point where the percentage of water to silica gel is around 25 wt%. All active sites on a silica-gel surface would be covered completely with 25 wt% of water.
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Financial support from The Shinsei Foundation is gratefully acknowledged.
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Hasegawa, T., Usuba, K., Kondo, S. et al. Enhancement of association of organic molecules on silica gel by surface water: surface photoreaction of stilbene. Environ Chem Lett 6, 107–111 (2008). https://doi.org/10.1007/s10311-007-0116-z
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DOI: https://doi.org/10.1007/s10311-007-0116-z