Infinite Polyiodide Chains in the Pyrroloperylene-Iodine Complex: Insights into the Starch-Iodine and Perylene-Iodine Complexes

• Published in: Angewandte Chemie International Edition Vol. 55; no. 28; pp. 8032 - 8035
• Main Authors: Madhu, Sheri, Evans, Hayden A., Doan-Nguyen, Vicky V. T., Labram, John G., Wu, Guang, Chabinyc, Michael L., Seshadri, Ram, Wudl, Fred
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 04.07.2016; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Analogies; Chains (polymeric); conducting materials; Crystal structure; Crystallography; Iodine; perylenes; polyhalides; Raman spectra; Raman spectroscopy; solid-state structures; Starch; Wavelengths; X-ray diffraction; X-ray diffraction; conducting materials; polyhalides; perylenes; solid-state structures
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201601585

We report the preparation and X‐ray crystallographic characterization of the first crystalline homoatomic polymer chain, which is part of a semiconducting pyrroloperylene–iodine complex. The crystal structure contains infinite polyiodide I∞δ−. Interestingly, the structure of iodine within the insoluble, blue starch–iodine complex has long remained elusive, but has been speculated as having infinite chains of iodine. Close similarities in the low‐wavenumber Raman spectra of the title compound and starch–iodine point to such infinite polyiodide chains in the latter as well. The crystal structure of the pyrroloperylene–iodine complex (with a formula close to pyrroloperylene–I2.2) has been solved. The structure contains infinite polyiodide chains, the Raman spectrum of which resembles that of the famous starch–iodine complex, thus casting light on a historical puzzle (see picture). The complex displays nearly metallic conductivity and some signatures of a Peierls distortion of the chains at 150 K.