p-HBDI showed weak fluorescence HO N△N-R N\N-CH3 N△N-CH N△N-CH3 CH3 1 R= CO2Et CH3 CH 2R= CH 3 5 Ethanol solutions of 2, 3, 4, and 5 showed only very weak fluorescence at room temperature, Satoshi Kojima, et al. Tetrahedron Letters 1998, 39, 5239Satoshi Kojima, et.al. Tetrahedron Letters 1998, 39, 5239 p-HBDI showed weak fluorescence