The color purple has long been used as a symbol of royalty and power in art, fashion, and architecture. This correlation with aristocracy can be traced back to the use of molluscan purple, a rich purple dye that is still presently more expensive than gold, by royalty as early as the 18th century BCE. While the molluscan purple dye is composed of a mixture of various proteins, its color is derived from indigotin, indirubin and their brominated derivatives, including the molecule, 6,6′-dibromoindigotin, an analogue of the indigotin dye which is also widely used in various modern industries. Both dyes can exhibit high stability, in particular against photodamage from UV and Visible radiation. In this study, we present the gas phase absorption spectrum and excited-state lifetimes of 6,6′-dibromoindigotin combined with static calculations of the excited and ground-state potential energy surfaces. The lifetime measurements reveal that molluscan purple has nearly the same relaxation rate as indigotin providing new insights in the possible relaxation mechanisms of the indigotin family of dye molecules.

中文翻译：

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探索软体动物紫色如何在各个时代得以延续：6,6'-二溴靛蓝的激发态动力学

紫色长期以来一直被用作艺术、时尚和建筑领域皇室和权力的象征。这种与贵族的联系可以追溯到公元前 18 世纪皇室对软体动物紫的使用，这是一种浓郁的紫色染料，目前仍然比黄金更贵。虽然软体动物紫色染料由多种蛋白质的混合物组成，但其颜色源自靛蓝、靛玉红及其溴化衍生物，包括分子 6,6'-二溴靛蓝，它是靛蓝染料的类似物，也广泛用于各种现代工业。两种染料均表现出高稳定性，特别是针对紫外线和可见辐射造成的光损伤。在这项研究中，我们结合激发态和基态势能面的静态计算，展示了 6,6'-二溴靛蓝的气相吸收光谱和激发态寿命。寿命测量表明，软体动物紫色具有与靛蓝几乎相同的弛豫率，这为靛蓝染料分子家族可能的弛豫机制提供了新的见解。