The synthesis of the novel organic donor 1,4-benzothiazino[2,3-b]phenothiazine (3) via a double Cadogan-type ring closure is reported. The target molecule is characterized by a H-1-NOE spectrum and by X-ray analysis, thus confirming the ''migration'' of the lateral alkyl groups involved in this rearrangement. Surprisingly, the solid-state structure of neutral 3 shows that one phenothiazine subunit exists in a nearly planar conformation, a feature hitherto only known from crystalline radical ion salts of phenothiazine and from phenothiazines with strong electron-withdrawing substituents. 3 undergoes electrochemical oxidation at an extremely low potential as shown by cyclic voltammetry. EPR and ENDOR spectroscopic investigations of the radical cation of 3 demonstrate the delocalization of the unpaired electron over the whole pentacene perimeter, whereas in the neutral monoradical the spin is localized on one phenothiazine subunit.
The synthesis of the novel organic donor 1,4-benzothiazino[2,3-b]phenothiazine (3) via a double Cadogan-type ring closure is reported. The target molecule is characterized by a H-1-NOE spectrum and by X-ray analysis, thus confirming the ''migration'' of the lateral alkyl groups involved in this rearrangement. Surprisingly, the solid-state structure of neutral 3 shows that one phenothiazine subunit exists in a nearly planar conformation, a feature hitherto only known from crystalline radical ion salts of phenothiazine and from phenothiazines with strong electron-withdrawing substituents. 3 undergoes electrochemical oxidation at an extremely low potential as shown by cyclic voltammetry. EPR and ENDOR spectroscopic investigations of the radical cation of 3 demonstrate the delocalization of the unpaired electron over the whole pentacene perimeter, whereas in the neutral monoradical the spin is localized on one phenothiazine subunit.
The synthesis of the novel organic donor 1,4-benzothiazino[2,3-b]phenothiazine (3) via a double Cadogan-type ring closure is reported. The target molecule is characterized by a H-1-NOE spectrum and by X-ray analysis, thus confirming the ''migration'' of the lateral alkyl groups involved in this rearrangement. Surprisingly, the solid-state structure of neutral 3 shows that one phenothiazine subunit exists in a nearly planar conformation, a feature hitherto only known from crystalline radical ion salts of phenothiazine and from phenothiazines with strong electron-withdrawing substituents. 3 undergoes electrochemical oxidation at an extremely low potential as shown by cyclic voltammetry. EPR and ENDOR spectroscopic investigations of the radical cation of 3 demonstrate the delocalization of the unpaired electron over the whole pentacene perimeter, whereas in the neutral monoradical the spin is localized on one phenothiazine subunit.