General Strategy to Access N‑Aryl Heptamethine Indocyanines for Optical Tuning

We herein report a three-step methodology for the facile construction of N-aryl heptamethine indocyanine (Cy7) dyes. A comparative screening was first conducted to identify the optimal synthetic strategy for N-aryl indoleninium as the key precursor. The subsequent process refinement enabled efficient preparation of N-aryl Cy7 derivatives. Integrated NMR spectroscopy, theoretical calculations, and photophysical characterization revealed how N-arylation modulates the physiochemical properties of the Cy7 scaffold, spanning molecular conformation, electronic configuration, and photophysical characteristics.