Two photochromic compounds, trans-3,3′-dipentyl-3,3′-dihydroxy-2,2′-bi-1H-indene-1,1′-dione (I), and cis-3,3′-di (2-methylally)-3,3′-dihydroxy-2,2′-bi-1H-indene-1,1′-dione (II), were synthesised and their crystal structures were determined by X-ray crystallography. The photoinduced properties of the compound were studied. The results showed that compound I exhibited reversible photochromism, and at the same time a stable organic radical was generated, while compound II did not show photochemical properties.
