Synthesis of a Black Dye with Absorption Capabilities Across the Visible-to-Near-Infrared Region: A MO-Mixing Approach via Heterometal Coordination of Expanded Porphyrinoid

An expanded metalloporphyrin-based “black dye” Au–Pd oxohexaphyrin (AuPd-1) with absorption capabilities across the visible-to-near-infrared (NIR) range was synthesized. This black dye, AuPd-1, possessed efficient light-harvesting and photostable capabilities, which were indicative of superior photothermal (PT) conversion abilities. Encapsulation of AuPd-1 with a micellar nanocapsule resulted in a compound that demonstrated intense photoacoustic (PA) properties in the NIR region in water. This finding indicated how metal (d)–ligand (π) molecular orbital interactions in metalloporphyrins could aid in the design of visible-to-NIR light-harvesting black dyes for PT and PA applications.

本研究合成了一种基于扩环金属卟啉（metalloporphyrin）的"黑色染料"金-钯氧代六卟啉（AuPd-1），该化合物具备可见光至近红外（near-infrared, NIR）全波段的光吸收能力。该黑色染料AuPd-1兼具高效光捕获性能与优异光稳定性，表明其拥有出色的光热（photothermal, PT）转换能力。通过胶束纳米胶囊对AuPd-1进行包封后，所得复合物在水溶液的近红外区域展现出极强的光声（photoacoustic, PA）信号响应性能。该研究成果揭示了金属卟啉中金属(d轨道)-配体(π轨道)分子轨道相互作用的调控机制，可为面向光热与光声应用的可见光-近红外光捕获型黑色染料的设计与开发提供理论指导。