They don't want you to know. The structure may be in a patent or patent application assigned to InVitrogen or Molecular Probes, but it may not be obvious which one of the exemplified compounds is Alexa Fluor 680. You can try searching patents at uspto.gov. Then again, the application may not have published yet.

Thank you Adam B Shapiro . It´s really bad that the companies will not tell you what you are using, I guess I will try to avoid it in the future.

They will probably release the structure eventually, once the patent application publishes. Patent applications become public 18 months after they are filed (at least in the US).

Hi,

Might the molecule on p 1625 be the right structure?

Article Tracking Antibody Distribution with Near-Infrared Fluorescen...

Thanks Juha Kotimaa , that structure in Figure 1B looks correct, it´s a modified cyanine. so the NEM-AF680 would be:

(E)-2-((2E,4E)-5-(5-bromo-3,3-dimethyl-7-(3-sulfonatopropyl)-3H-pyrrolo[2,3-b]pyridin-7-ium-2-yl)penta-2,4-dien-1-ylidene)-3-(6-((2-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)ethyl)amino)-6-oxohexyl)-3-methyl-1-(3-sulfonatopropyl)indoline-5-sulfonate