Tautomerism in Oxoporphyrinogens and Pyrazinacenes

Jonathan P. Hill, Jan Labuta, Shinsuke Ishihara, GaryJ. Richards, Yongshu Xie, Francis D Souza, and Katsuhiko Ariga 

Protic tautomerism [1], which involves reversible intramolecular transfer of protons, usually between electronegative atoms, is an important feature not only of biologically relevant heterocycles [2] but also of a variety of potentially useful synthetic systems [3]. For instance, several current research themes involve the study of tautomeric processes as memory elements or as molecular switches with a view to developing future molecule-scale devices [4, 5]. 

Tautomerism Concepts and Applications in Science and Technology, First Edition. 

Pyrazinacenes are nitrogen-substituted analogs of the acenes [16], for example, pentacene [22], which is a well-studied p-type semiconductor used in organic electronic devices. Pyrazinacenes, on the other hand, may be complementary to pentacene in that they can offer n-type semiconductor behavior by a very similar 

NMR signals through an achiral host. (Reproduced from Xie et al. [13]. Copyright (2008), with permission of American Chemicai Society.) 

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