Environmental Chemistry Letters

, Volume 6, Issue 2, pp 107–111 | Cite as

Enhancement of association of organic molecules on silica gel by surface water: surface photoreaction of stilbene

  • Tadashi Hasegawa
  • Kakeru Usuba
  • Soichiro Kondo
  • Yutaka Maeda
Original Paper


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.


Inorganic particulate Photocycloaddition Cyclobutane Dimer Hydrophobic interaction 



Financial support from The Shinsei Foundation is gratefully acknowledged.


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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Tadashi Hasegawa
    • 1
  • Kakeru Usuba
    • 1
  • Soichiro Kondo
    • 1
  • Yutaka Maeda
    • 1
  1. 1.Department of ChemistryTokyo Gakugei UniversityTokyoJapan

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