Expanded, Contracted, and Isomeric Porphyrins: Theoretical Aspects

• Published in: Chemical reviews Vol. 117; no. 4; pp. 3444 - 3478
• Main Author: Mack, John
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 22.02.2017
• Subjects: Chemistry; Circularity; Comparative analysis; Dichroism; Electronic structure; Magnetic properties; Mathematical models; Optical properties; Porphyrins; Spectrum analysis; Trends
• ISSN: 0009-2665; 1520-6890
• DOI: 10.1021/acs.chemrev.6b00568

The use of cyclic polyene perimeter-model approaches, such as Gouterman’s four-orbital model and Michl’s perimeter model, to analyze trends in the electronic structures and optical properties of expanded, contracted, and isomeric porphyrins is described with an emphasis on the use of magnetic circular dichroism (MCD) spectroscopy to validate the results of TD-DFT calculations. Trends in the electronic structures and optical properties of isomeric porphyrins are examined by comparing the properties of porphycenes, corrphycenes, hemiporphycenes, isoporphycenes, N-confused and neoconfused porphyrins, and norroles, whereas those of ring-contracted porphyrins are examined by comparing the properties of subporphyrins, triphyrins, and vacataporphyrins. The ring-expanded compounds that are examined include cyclo­[n]­pyrroles, [22]­pentaphyrins­(1.1.1.1.1), sapphyrins, smaragdyrins, isosmaragdyrins, orangarins, ozaphyrins, [26]­hexaphyrins(1.1.1.1.1.1), rubyrins, rosarins, amethyrins, isoamethyrins, bronzaphyrins, and doubly N-confused hexaphyrins.