Molecular Complexes of Cyclophanes. XIV. Charge‐transfer complexes of polynuclear[2.2] paracyclophanes with π‐acceptors

Abstract

The charge‐transfer (CT) spectra of the π‐complexes formed by several π‐acceptors with some polynuclear[2.2]paracyclophanes have been measured. Comparison of these CT complexes with those of model compounds supports the existence of the transannular electronic interactions in the paracyclophane nucleus. The infrared spectra of a number of CT complexes reveal the increase of the electron density on the π‐acceptor molecule in the CT complexes. Some crystalline CT complexes were prepared and analysed.

Hierarchic Supramolecular Interactions within Assemblies in Solution and in the Crystal of 2,3,6,7‐Tetrasubstituted 5,5′‐(Anthracene‐9,10‐diyl)bis[pyrimidin‐2‐amines]

“…Anthracenes substituted at C(9) are known to form CT complexes with TCNE [21 -23]. In the case of the 9,10-[2.2]-para-anthracenophane, while in CH 2 Cl 2 solution a l max value of 865 nm was reported for the CT band [23], in the crystal which is of green color, the TCNE molecules lie in an unparallel orientation to the anthracene planes, at an angle of 1448 [21], bridging anthracenophanes along the stacking axis. This is quite untypical for other arene · TCNE complexes where the overlap between the HOMO of the arene and the LUMO of TCNE is maximized in a parallel orientation.…”

New Access to the Chemistry of Piperonylidinyl‐4‐[2.2]‐Paracyclophanylamine and Some Electron π‐Deficients

“…9 [2.2]Paracyclophanes serve as excellent donating systems in charge-transfer complexation comparable with classical aromatic compounds; this is mainly due to the presence of the transannular electronic interactions between the two benzene rings in the cyclophane molecule. [10][11][12][13][14][15][16][17][18] Furthermore, an anomalous behavior of 4-amino[2.2]paracyclophane and its N-methyl derivative towards TCNE and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) was reported. 19 Interesting reaction products obtained were 2-…”