Indigo, an emblematic violet dye used for thousands of years to colour fabric, is resistant to fading on exposure to sunlight. Prior work has indicated that indigo is reactive towards both hydroperoxyl radicals and superoxide anions in solution. In order to promote photobleaching of indigo, we have utilised a BOPHY-based (BOPHY = aryl fused symmetrical pyrrole-BF₂ complex) chromophore known to form both superoxide ions and a stable alkyl hydroperoxide under illumination in aerated solution. Selective irradiation of the photocatalyst causes relatively fast fading of indigo, with the rate increasing gently with increasing concentration of indigo. Molecular oxygen and light are essential for effective bleaching. One molecule of photocatalyst can bleach more than 40 molecules of indigo. An active component of the photocatalyst is a butylated hydroxytoluene (BHT) residue which itself quenches the triplet excited state of indigo. This provides an ancillary mechanism for effecting photofading of indigo but, because the triplet is formed in very low yield, this route is less practical.

中文翻译：

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通过原位生成有机氢过氧化物对溶液中的靛蓝进行光催化脱色。

靛蓝是一种标志性的紫色染料，已经使用了数千年，用于对织物上色。先前的工作表明，靛蓝对溶液中的氢过氧自由基和超氧阴离子均具有反应性。为了促进靛蓝的光致漂白，我们使用了基于BOPHY的（BOPHY =芳基稠合的对称吡咯-BF ₂络合物）生色团，在充气溶液中照射下会形成超氧离子和稳定的氢过氧化物烷基。光催化剂的选择性照射导致靛蓝的褪色相对较快，并且随着靛蓝浓度的增加速率缓慢增加。分子氧和光对于有效漂白是必不可少的。一分子光催化剂可漂白40多个靛蓝分子。光催化剂的活性成分是丁基化羟基甲苯（BHT）残基，其本身可以淬灭靛蓝的三重激发态。这提供了用于进行靛蓝光褪色的辅助机制，但是由于三重态的产率非常低，因此该途径不太实用。