Photochromism of a spiroperimidine compound in polymer matrices

Abstract

The photochromic behavior of a spiroperimidine compound, 2,3-dihydro-2-spiro-7′-(8′-imino-7′,8′-dihydronaphthalen-1′-amine)perimidine (PNI), doped in various polymers has been studied. Upon irradiation with 405 nm light, PNI exhibits photochromism, and a color change (light yellow to brown) is observed. The initial (closed) and colored (open) forms exhibit absorption maxima (λ_max) around 400 and 500 nm, respectively. The open form possesses a wide absorption band, extending to ∼750 nm. Little effect of the polymer matrix on the λ_max of either the closed or open forms was observed, and these values were also similar to those in solution. The lifetime of the open form depends mainly on the glass transition temperature (T_g) of the polymer, and ranges from, for example, 11 min to 5.4 d. This indicates that the lifetime of the open form can be readily tuned by simply choosing a suitable polymer matrix. Photochromism in different polymer substrates are demonstrated herein.