Heptamethine Cyanine Dyes with a Robust C−C Bond at the Central Position of the Chromophore

Novel, highly fluorescent, monofunctional, water-soluble heptamethine cyanine dyes containing a robust C−C bond at the central position of the near-infrared fluorophore system were prepared by the Suzuki−Miyaura method. The reaction proceeded efficiently to replace the meso-chlorine atom with a carboxy-functionalized aryl moiety and afforded the desired compounds in high yields. This methodology is particularly attractive due to its versatility and the utilization of environmentally friendly water as solvent. The new compounds possess excellent spectral properties and readily label bioactive molecules on solid support. The results demonstrate the potential of using the new compounds as fluorescent antennae for molecular imaging, spectroscopy, microscopy, and chemical or biological molecular recognition studies.