Fromt the UCSB Current article, An Unexpected Finding: 

In the pursuit of a new class of photovoltaic materials, researchers at UC Santa Barbara happened upon an entirely different discovery that addresses a centuries-old mystery of chemistry: Why does an iodine solution turn blue-black when starch is added to the mix?

The exact structural-chemical mechanism that causes the intense deflection of blue light during this transformation has been a subject of active speculation until this point. Shedding light on this mechanism, UCSB researchers in the labs of materials professors Fred Wudl and Ram Seshadri report first observation of crystalline infinite iodide polymers, discovered as part of a pyrroloperylene-iodine complex, an organic semiconductor that contains iodine. Their paper, Infinite Polyiodide Chains in the Pyrroloperylene-Iodine Complex, was recently published in Angewandte Chemie.

Please read the entire article at the UCSB Current.