Synthesis and spectral properties of near-infrared aminophenyl-, hydroxyphenyl-, and phenyl-substituted heptamethine cyanines.

Diverse meso-aminophenyl-, hydroxyphenyl-, and phenyl-substituted heptamethine cyanine dyes were prepared by a modified Suzuki--Miyaura method in good yields. In addition, direct Suzuki coupling of Vilsmeier--Haack reagent extends the procedure to the synthesis of otherwise difficult cyanine dyes containing multiple heteroatoms in the indolium ring. The new compounds possess excellent spectral properties and can be used to label bioactive molecules and nanoparticles. The one-pot synthesis procedure eliminates the cumbersome steps of protecting/deprotecting amino or hydroxy groups.