The structural modification of plant pigments allows the development of new functional dyes with tailored photophysical properties. Two-photon excitation fluorescence microscopy has emerged as an important technique, but requires the use of fluorophores having large two-photon absorption cross-sections in water. This feature is rarely found in natural or artificial dyes, but betalains, the main pigments of beetroots and some species of fluorescent flowers, can be modified to produce water-soluble two-photon fluorophores. Herein we describe the semisynthesis and photophysical characterization of two water-soluble artificial coumarinic betalains. The excitation of these compounds in the near-infrared results in yellow fluorescence with two-photon cross-sections in water of 323 GM and 179 GM.

植物色素的结构改性可以开发具有定制光物理性质的新型功能性染料。二光子激发荧光显微镜已经作为一种重要技术出现，但是需要使用在水中具有大的二光子吸收横截面的荧光团。这种特性在天然或人工染料中很少见，但是甜菜根的主要色素甜菜根和某些荧光花种的甜菜碱可以被修饰以产生水溶性的双光子荧光团。本文中，我们描述了两种水溶性人工香豆素甜菜碱的半合成和光物理特性。这些化合物在近红外光中的激发导致黄色荧光在323 GM和179 GM的水中具有两个光子截面。