I had a few thoughts while reading the article "Reining in Ripening" (C&EN, Oct. 29, 2007, page 10).
The article mentions that: "A big player in ripening control is the ethylene receptor, which detects and transduces the signal that triggers its metamorphosis." The article goes on to say that "the receptor exists as a dimer held together by disulfide bonds. A single copper ion is shared between the monomer units, and it mediates ethylene binding to the dimer."
The article also states that "2,5-norbornadiene was found to compete with ethylene for a seat in the receptor. But the molecule isn't great at keeping ethylene out of the way, and it is far too stinky to be useful in commercial food applications."
I spent many years in the labs at Sunoco dimerizing 2,5-norbornadiene. I heartily agree that the monomer is a stinky molecule; however, the liquid dimers of 2,5-norbornadiene are pleasantly fragrant. In fact, a perfume company contacted Sunoco requesting 2,5-norbornadiene-dimer patent rights. May I suggest that one consider said dimers as competitors with ethylene for a seat in these ethylene receptors? 2,5-Norbornadiene dimers are still olefinic and their double size may help keep ethylene "out of the way."
Harry K. Myers Jr.