Structural Transformation of Azonia[5]helicene Photoproduct via Reaction Field Function of Layered Inorganic Material

In an attempt to generalize "on surface synthesis", which has unique potential in the area of organic synthesis, the focus was placed on layered silicates having a highly flat surface. The photoreaction of (+/-)-13-bromo-6a-azonia[5]helicene (AHHBr) and (+/-)-2-bromo-13-methyl-6a-azonia[5]helicene (AHBrMe) in solution and within the layers was examined. In the case of AHBrMe, the photoproduct was different from that in solution. H-1 nuclear magnetic resonance (NMR), Fourier transform-infrared spectroscopy (FT-IR), and electrospray ionization-mass spectrometry (ESI-MS) measurements revealed that the photoproduct obtained within the layers was a benzo-perylene molecule with a completely flat lactone structure (AL). This study is the first example of the successful conversion of a chemical reaction path due to the steric effect of the flat surface of layered silicate.