Synthesis and Properties of Brominated 6,6′‐Dimethyl‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐diones

Abstract

Photochromic 6‐bromomethyl‐6′‐methyl‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione (2), 6,6′‐ bis(bromomethyl)‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione (3) and 6,6′‐bis(dibromomethyl)‐[2,2′‐ bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione (4) have been synthesized from 6,6′‐dimethyl‐[2,2′‐bi‐1H‐ indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione (1). The single crystal of 4 was obtained and its crystal structure was analyzed. The results indicate that in crystal 4, molecular arrangement is defective tightness compared with its precursor 1. Besides, UV‐Vis absorption spectra in CH2Cl2 solution, photochromic and photomagnetic properties in solid state of 2, 3 and 4 were also investigated. The results demonstrate that when the hydrogen atoms in the methyl group on the benzene rings of biindenylidenedione were substituted by bromines, its properties could be affected considerably.