Heinz A. Staab

Transannular interactions in [2.2] phanes as studied by magnetic resonance and optical spectra

The interaction of π-electrons in [2,2] phanes was studied both experimentally and theoretically. The fluorescence and phosphorescence spectra were measured at liquid helium temperature; in addition, the zero field splitting parameters D and E were determined by ODMR in zero field and by ordinary ESR at X-band. The results for the phanes with two identical aromatic units can be summarized as follows: The rather small reduction of the D and E values of the order of 10% with respect to the monomers indicates, in agreement with the theoretical treatment given in part II, that the two unpaired electrons of the excited triplet state have a high probability to be at a given time in the same half of the molecule. While the fluorescence spectra show the typical behaviour of emission spectra of dimers or excimers, the phosphorescence spectra exhibit some remaining structure. This behaviour which indicates a somewhat weaker coupling among the triplet orbitals as compared to the singlet orbitals can also be understood on the basis of theoretical considerations. For a phane with two different aromatic units the behaviour is found to be more similar to the corresponding aromatic monomer with the lower excited states with some perturbation by the other part of the phase also in agreement with theoretical expectation.

Syntheses, Structures and Basicities of 1,2,4,5-Tetrakis(dimethylamino)benzene and 2,3,6,7-Tetrakis(dimethylamino)naphthalene

1,2,4,5-Tetrakis(dimethylamino)benzene (4) and 2,3,6,7-tetrakis(dimethylamino)naphthalene (5) were prepared and structurally determined. Electron-donor functions, protonation, and the geometry of intramolecular hydrogen bonds are discussed. By oxidation of 4 to its dication the benzenoid aromaticity is cancelled in favour of two independent cyanine-type units as determined by X-ray structure analysis.

Transannular interactions in [2.2] phanes as studied by luminescence and optical detection of magnetic resonance

Emission spectra of different types of [2.2] naphthalenophanes were measured at 1.25 K in glasses as well as in small single crystals. In addition, the D and E values of the excited triplet states were studied by optical detection of magnetic resonance in zero field and the results compared with the corresponding monomeres.

Transanular interaction in [2.2]phanes: [2.2](2,7)pyrenophane

Abstract The emission spectra of [2.2] (2,7) pyrenophane and the zero field splitting parameters D und E of its excited triplet state were measured in glasses and in small single crystals at 1.3 K. The results are being compared with monomer pyrene and 2,7-dimethylpyrene in liquid and solid solutions as well as in single crystals.