Starting from N-hexylphenothiazine, a versatile construction kit of brominated and borylated phenothiazines can be easily prepared by a sequence of bromination, bromo-lithium exchange/borylation, and Suzuki coupling. Subsequent Suzuki arylation of the building blocks gives soluble, monodisperse, and structurally well defined oligophenothiazines in good yields. The molecular weights at the peak maximum (Mp), obtained by GPC (gel permeation chromatography), and the actual molecular weights of the oligomer series, obtained by mass spectrometry, show excellent correlation. A QM/MM conformational analysis for the complete series reveals that the obvious butterfly-shaped phenothiazine structure multiplies and significantly reduces the hydrodynamic volume of the oligomers. The electronic properties (absorption and emission spectroscopy and cyclic voltammetry) give reasonable correlations with the chain length. With regard to the emission maxima, the effective conjugation length is already reached with the hexamer. Oligophenothiazines are highly fluorescent, with high fluorescence quantum yields, and are simultaneously highly electroactive, with low oxidation potentials.

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Phenothiazine is coupled under Buchwald-Hartwig conditions with bromo anthracenes and perylene as substrates to give phenothiazine-anthracene and phenothiazine-perylene dyads and triads. Investigation of the electronic properties of these sterically demanding N-aryl phenothiazines by absorption and emission spectroscopy, cyclic voltammetry, and DFT calculations revealed that the individual chromophores are decoupled in the electronic ground state but show unique electronic communication in the excited state. For the anthracenyl-bridged diphenothiazine an intense electronic coupling of the phenothiazinyl units is detected upon oxidation. Besides, attempts to synthesize phenothiazine compounds with even more sterically demanding aryl substituents in the 10-position under N-arylation conditions gave rise to the formation of quite unexpected products of arylation and/or oxidative coupling. The folding angle of the phenothiazine in a consanguineous series correlates well with the first oxidation potential.

Triethoxysilyl functionalized phenothiazinyl carbamates were synthesized and covalently grafted onto mesoporous MCM-41. XRD and N2 adsorption measurements indicated the presence of a highly ordered two-dimensional hexagonal structure of functional materials, while the incorporation of organic compounds in the solid materials was proven by means of 13C and 29Si solid-state NMR spectroscopy as well as by FT-IR spectroscopy. Upon oxidation with (NO)BF4, stable phenothiazine radical cations were generated in the pores of the materials, which can be detected by means of UV−vis and EPR spectroscopy.