Wikipedia
Diiodobutadiyne
1,4-Diiodobuta-1,3-diyne is a small molecule related to diacetylene. It is used in the creation of the polymer poly(diiododiacetylene) (PIDA) by undergoing 1,4 polymerization. It is light sensitive and explosive if stored out of solution as a dry solid. It will undergo random 1,2 and 1,4 polymerization, as well as decomposition in solution if kept over an extended period of time, having a half life of just about two weeks.