Hexadecadehydrodibenzo[20]-, tetracosadehydrotribenzo[30]-, and dotriacontadehydrotetrabenzo[40]annulenes: syntheses, characterizations, electronic properties, and self-associations.

Hexadecadehydrodibenzo[20]-, tetracosadehydrotribenzo[30]-, and dotriacontadehydrotetrabenzo[40]annulene derivatives ([20]-, [30]-, and [40]DBAs) possessing tetrayne linkages were synthesized. X-ray diffraction analysis demonstrated that the molecules of [30]DBA and p-xylene form a 2D sheetlike structure. Planar [20]- and [30]DBAs show significantly weak or almost no tropicity. The extension of the acetylenic linkages from a diyne to a tetrayne unit narrows HOMO-LUMO gaps. The self-association behavior of [30]DBA in solution resulting from effective pi-pi stacking interactions was observed.