Discovered in 1937 by Robin Hill, Hill reagents allowed the discovery of electron transport chains during photosynthesis. These are dyes that act as artificial electron acceptors, changing color when they are reduced. An example of a Hill reagent is 2,6-dichlorophenolindophenol (DCPIP).

References

• David Alan Walker (2002). "'And whose bright presence' – an appreciation of Robert Hill and his reaction". Photosynthesis Research. 73 (1–3): 51–54. doi:10.1023/A:1020479620680. PMID 16245102.
• Govindjee and David Krogmann (2004). "Discoveries in Oxygenic Photosynthesis (1727–2003): A Perspective". Photosynthesis Research. 80 (1–3): 15–57. doi:10.1023/B:PRES.0000030443.63979.e6. PMID 16328809.