Synthesis and photochromic behavior of mono-, and biphotochromic system linked by p-phenylene bridge

The synthesis of mono- and bis-1,3-diazabicyclo[3.1.0]hex-3-ene derivatives with indole ring and p-phenylene spacer, which behave as photochromic materials, is reported. The structure–photochromic behavior relationship (SPBR) of the synthesized compounds has been analyzed.