Indocyanine green

green to brown crystals or crystalline powder

A tricarbocyanine type of dye with infrared absorbing properties. Diagnostic aid (blood volume determination, cardiac output, hepatic function). Dyes and metabolites.

In infrared photography; in preparation of Wratten filters.

IC-Green (Akorn).

Poison by intravenous route. When heated to decomposition it emits very toxic fumes of SOx, Na2O, and NOx.

Indocyanine green (ICG) was prepared by a one-step condensation method with an overall yield of 92%[1]. The synthesis starts from three key intermediates:
(1) Compound 1: 1,1,2-trimethyl-1H-benzo[e]indole (2 mmol) was heated with 1,4-butane sultone (12 mmol) at 120 °C for 2 h; after cooling, removal of the solvent in vacuo, filtration and washing with acetone, compound 1 was obtained as a white powder (60% yield).
(2) Compound 2: 1-chloro-2,4-dinitrobenzene (4.9 mmol) and pyridine (4.95 mmol) were refluxed in acetone for 30 h; after cooling, removal of the solvent in vacuo, filtration and washing with hexane, compound 2 was obtained as a white powder (66.5% yield).
(3) Compound 3: a solution of aniline (3.47 mmol) in ethanol was added dropwise to compound 2 (1.74 mmol) in ethanol; the mixture was stirred at room temperature for 30 min, filtered in vacuo and washed twice with ethanol to afford compound 3 as a red powder (50.3% yield). In the final one-step condensation, a mixture of compound 1 (0.406 mmol), compound 3 (0.197 mmol), sodium acetate (0.368 mmol) and acetic anhydride (5 mL) was heated at 110 °C for 30 min; the solvent was removed by reduced-pressure distillation and the residue was filtered and washed with acetone to afford ICG as a green powder in 92% yield.

Store at -20°C

[1] Fang, X., Liu, W., Wu, X., Zhou, W., Chen, J., Liu, X., Xu, Z. (2021). One-step condensation synthesis and characterizations of indocyanine green. Results in Chemistry, 3, 100092. https://doi.org/10.1016/j.rechem.2020.100092

787/819 nm

0.09

232000