Synthesis and properties of phenothiazylene vinylene-based polymers: New organic semiconductors for field-effect transistors and solar cells

Synthesis, characterization, photophysical properties, and computational studies on N-hexylphenothiazine/cyanopyridine based π-conjugated copolymers

In this paper, π-conjugated copolymers, namely N-hexylphenothiazine/cyanopyridine/phenyl/benzothiadiazole, N-hexylphenothiazine/cyanopyridine/phenyl/9,9-dihexylfluorene, and N-hexylphenothiazine/cyanopyridine/phenyl/9,9-diethylhexylfluorene were readily synthesized via Pd-catalyzed Suzuki cross-coupling reaction. The polymer structures and their photophysical properties were characterized by elemental analysis, 1H NMR, GPC, TGA, XRD, UV-vis absorption and PL spectroscopy measurements. The coupling agent effect on photophysical properties of copolymers was investigated to rationally design polymers with particular physical properties to be employed in optoelectronic devices. The UV-vis absorption spectroscopy of copolymers showed λmax at a range of ∼334–474 nm and red-shifted in their films to a range of ∼342–381 nm. These copolymers displayed highly intense fluorescence in their solutions and films. The PL spectra of copolymers indicated red and near-infrared light, rendering them a prospect for being red and near-infrared light-emitting materials for PLEDs. XRD analysis demonstrated a d-spacing range of ∼3.79–4.32 Å, reflecting π-π stacking and some degree of crystallinity in some polymers, and only P1 and P2 showed peaks in the small-angle region, indicating lamellar structures. To understand the relationship between molecular structures of target materials and their photophysical and photovoltaic properties, density functional theory (DFT) and its time-dependent form (TD-DFT) were employed.

Synthesis and characterization of thermally stable polyimides with a pendent phenothiazine unit based on new diamine 10-(3,5-diaminobenzoyl)phenothiazine

A novel diamine 10-(3,5-diaminobenzoyl)phenothiazine (DBPT) with a side chain containing phenothiazine unit was synthesized. A new family of polyimides (PIs) containing phenothiazine unit in the side chains has been successfully synthesized by direct polycondensation of DBPT with pyromellitic dianhydride, 3,3′,4,4′-benzophenone tertacarboxylic dianhydride, and 4,4′-oxydiphthalic anhydride (ODA) via a conventional two-step chemical imidization process. The yield of polymers was good enough, which were soluble in most organic solvents. The molecular orbital energy gaps, thermal stability, and crystallinity of PIs were investigated by molecular modeling, thermogravimetric analysis, and wide-angle X-ray scattering, respectively. Thermal properties of polymers were good enough to permit the use of these PIs in various applications; only 49% weight loss is detected at 900°C in nitrogen atmosphere. X-Ray diffraction clearly reveals the amorphous nature of PIs. A quantum modeling study (density functional theory) has shown the influence of dianhydride structure on the energy difference of highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels.

Optical and electrochemical properties of ethynylaniline derivatives of phenothiazine, phenothiazine-5-oxide and phenothiazine-5,5-dioxide

Modifications in the sulfur oxidation state of phenothiazine results in dramatic changes to the excited-state geometry with little effect on the HOMO energy.

Redox active polymer brushes with phenothiazine moieties

We have investigated two different concepts to synthesize redox active polymer brushes using surface initiated atomic transfer radical polymerization (SI-ATRP). This polymerization technique allows the synthesis of well-defined grafted polymer brushes. In the initial step the surface was functionalized with a self-assembling monolayer of the SI-ATRP starter. Then, polymer brushes carrying phenothiazine moieties were grafted from the surface via SI-ATRP. The first concept consists of polymerizing monomers with phenothiazine pendant moieties to directly incorporate the redox functionality as side group in the growing polymer brush. The second concept consists of using grafted activated ester brushes which are functionalized with phenothiazine redox moieties in a successive reaction step. The electrochemical properties of the grafted redox active brushes were examined by cyclic voltammetry. Furthermore, the surface morphology and the chemical composition of the polymer brushes were characterized using scanning force microscopy (SFM), X-ray techniques, and UV/vis spectroscopy. Apart from their redox behavior, the synthesized brushes revealed increased mechanical stability on the nanoscale.