Cyanines are organic dyes bearing two aza-heterocycles linked by a polymethine chain. Excited states, fluorescence, redox activity, and energy transfer are interesting properties of cyanines which have been used by chemists. Moreover, they are easily accessible and highly tunable. For all these reasons, cyanines are often selected for applications like fluorescent probes, phototherapy and photovoltaics. However, considering cyanines as photocatalysts is a new field of investigation and has been sparsely reported in the literature. This field of research has been launched on the basis of near-infrared light photocatalysis. With a deeper NIR light penetration, the irradiation is compatible with biological tissues. Due to the longer wavelengths that are involved, the safety of the operator can be guaranteed. In this perspective review, the photophysical/redox properties of cyanines are reported as well as their preparations and applications in modern synthetic approaches. Finally, recent examples of cyanine-based NIR-photocatalysis are discussed including photopolymerization and organic synthesis.

中文翻译：

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花青类近红外光催化：合成、应用和前景


花青是带有两个由聚次甲基链连接的氮杂杂环的有机染料。激发态、荧光、氧化还原活性和能量转移是花青的有趣特性，已被化学家使用。此外，它们易于访问且高度可调。由于所有这些原因，花青经常被选择用于荧光探针、光疗和光伏等应用。然而，将花青视为光催化剂是一个新的研究领域，文献中报道很少。这一研究领域是在近红外光光催化的基础上展开的。具有更深的近红外光穿透力，照射与生物组织相容。由于涉及的波长较长，可以保证操作人员的安全。在这篇综述中，报道了花青的光物理/氧化还原性质以及它们在现代合成方法中的制备和应用。最后，讨论了基于花青的近红外光催化的最新例子，包括光聚合和有机合成。