Di(9-alkylcarbazol-3-yl)arylamines as Electroactive Amorphous Materials for Optoelectronics

Star-shaped molecules of di(9-alkylcarbazol-3-yl)arylamines were synthesized and found to constitute new glass-forming materials with glass transition temperatures ranging from 40 to 147°C. The electron photoemission spectra of the molecular glasses were recorded and ionisation potentials of 4.9–5.0 eV were established. Room temperature time of flight hole drift mobilities of the di(9-alkylcarbazol-3-yl)phenylamines molecularly dispersed in polycarbonate-Z approached 5 · 10⁻⁶ cm²/Vs at high electric fields. Some of the compounds were converted to cross-linkable derivatives, which are potential components for insoluble charge transport layers.     

Di(9-alkylcarbazol-3-yl)arylamines as Electroactive Amorphous Materials for Optoelectronics

Summary. Star-shaped molecules of di(9-alkylcarbazol-3-yl)arylamines were synthesized and found to constitute new glass-forming materials with glass transition temperatures ranging from 40 to 147°C. The electron photoemission spectra of the molecular glasses were recorded and ionisation potentials of 4.9–5.0 eV were established. Room temperature time of flight hole drift mobilities of the di(9-alkylcarbazol-3-yl)phenylamines molecularly dispersed in polycarbonate-Z approached 5 · 10⁻⁶ cm²/Vs at high electric fields. Some of the compounds were converted to cross-linkable derivatives, which are potential components for insoluble charge transport layers.     

Thiophene-based glass-forming hole-transporting hydrazones

The synthesis, optical, thermal, and photoelectrical properties of new thiophene-based hydrazones are reported. The ionization potentials of the films of thiophene-based hydrazones, measured by the electron photoemission technique, range from 4.99 to 5.58 eV. Hole-drift mobilities in the solid solutions in bisphenol-Z polycarbonate (PC-Z) of the synthesized hydrazones were studied by time of flight technique. Room temperature charge mobilities in the solid solution of 5,2″-diformyl-2,2′:5′,5″-terthiophene di(N,N-diphenylhydrazone) in PC-Z exceeded 10⁻⁵ cm²/Vs at high applied electric fields. Correspondence: Juozas Vidas Grazulevicius, Department of Organic Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas, Lithuania.     

Intensification of Biocatalytical Processes by Synergistic Substrate Conversion. Fungal Peroxidase Catalyzed <Emphasis Type="Italic">N</Emphasis>-Hydroxy Derivative Oxidation in Presence of 10-Propyl Sulfonic Acid Phenoxazine

Many industrial pollutants, xenobiotics, and industry-important compounds are known to be oxidized by peroxidases. It has been shown that highly efficient peroxidase substrates are able to enhance the oxidation of low reactive substrate by acting as mediators. To explore this effect, the oxidation of two N-hydroxy derivatives, i.e., N-hydroxy-N-phenyl-acetamide (HPA) and N-hydroxy-N-phenyl-carbamic acid methyl ester (HPCM) catalyzed by recombinant Coprinus cinereus (rCiP) peroxidase has been studied in presence of efficient substrate 3-(4a,10a-dihydro- phenoxazin-10-yl)-propane-1-sulfonic acid (PPSA) at pH 8.5. The bimolecular constant of PPSA cation radical reaction with HPA was estimated to be (2.5 ± 0.2)·10⁷ M⁻¹ s⁻¹ and for HPCM was even higher. The kinetic measurements show that rCiP-catalyzed oxidation of HPA and HPCM can increase up to 33,000 times and 5,500 times in the presence of equivalent concentration of high reactive substrate PPSA. The mathematical model of synergistic rCiP-catalyzed HPA–PPSA and HPCM–PPSA oxidation was proposed. Experimentally obtained rate constants were in good agreement with those calculated from the model confirming the synergistic scheme of the substrate oxidation. In order to explain the different reactivity of substrates, the docking of substrates in the active site of the enzyme was calculated. Molecular dynamic calculations show that the enzyme–substrate complexes are structurally stable. The high reactive PPSA exhibited higher affinity to enzyme active site than HPA and HPCM. Furthermore, the orientation of HPA and HPCM was not favorable for proton transfer to the distal histidine, and different substrate reactivity was explained by these diversities.     

Hole-transporting hydrazones

This tutorial review covers recent contributions in the area of hole-transporting hydrazones, which are widely used in optoelectronic devices. It is addressed to students and researchers interested in the synthesis and properties of organic electroactive materials. The thermal, charge transport and other properties of electroactive hydrazones are compared and the relationships between the molecular structures and properties are emphasized. The first part discusses the low-molar-mass hydrazones and presents examples of their synthetic routes and chemical structures. In the second part, polymeric arylaldehyde hydrazones containing hydrazone moieties as the side substituents and in the main-chain are described.     

Microwave power absorbed by and scattered from a multilayered zero-index anisotropic metamaterial-semiconductor cylinder

We present here dependencies of scattered and absorbed powers of incident perpendicularly and parallel polarized microwaves by a multilayered cylinder. We consider here the normal (angle ??=90^°) and oblique (angles ??=60^°,30^°,5^°) incidence of microwave on the cylinder. The one consists of a glass core that is coated by the six anisotropic metamaterial and lossy n-Si semiconductor alternative layers. Characteristics of a cylinder with the semiconductor external layer are presented. The dispersion dependency of n-Si losses was taken into account. The metamaterial is a uniaxial anisotropic medium with the electric and magnetic plasma resonances in the frequency range from 1 until 4?GHz. The anisotropic metamaterial can include the constitutive parameters equal to zero. The multilayered cylinder has the external radius equal to 2?mm. The glass core has a radius equal to 0.5?mm. The thickness of all layers is the same. We have compared the scattered and absorbed power dependencies on the microwave polarization, the angle of microwave incidence (the normal and oblique directions of the incidence to the z-axis), and the n-Si specific resistivity. We discovered specific dependencies of scattered and absorbed powers on the parameters.     

Microwave scattering diagrams of three-layered SiC-metamaterial/gyrotropic ferrite-SiC cylinders

We present here for the first time the rigorous solution of the boundary diffraction problem of microwave scattering by a multilayered 2D cylinder. The cylinder layers may be made of isotropic, uniaxial anisotropic, electrically and (or) magnetically gyrotropic materials. The number and thickness of the layers may have arbitrary values in our solution. We calculated scattering diagrams (a radial component of real part of the Poynting vector) inside and outside of cylinder using the solution. Here we present scattering diagrams from a three-layered cylinder made of SiC and metamaterial or saturate magnetized ferrite. Diagrams were computed for wave incidence angles θ=π/2,π/3,π/6 inside of metamaterial/ferrite layer at a distance of 1 mm and outside of cylinder at a distance of 2.5 mm from the cylinder axis.     

Reversibly Switchable Phase-Dependent Emission of Quinoline and Phenothiazine Derivatives towards Applications in Optical Sensing and Information Multicoding

Three new quinoline and di-tert-butyl phenothiazine isomeric derivatives were synthesized and characterized towards applications for oxygen sensing and optical information multicoding. The compounds with phenylene linker showed outstanding phase-dependent reversibility between ON/OFF states (low and high emission intensity, drastic shifting of emission colors, short- and long-lived fluorescence) in systematic grinding/fuming cycles, as required for multichannel memory devices based on optical information multicoding. The conformational diversity of the phenothiazine unit resulted in dual emission of the doped films implemented by the different luminescence mechanisms with peaks located at 414/530, 416/540, and 440/582 nm. The presence of a phenylene linker and thus two rotational degrees of freedom resulted in quenching of the delayed fluorescence of quasi-equatorial conformers in the solid state. The compound containing no phenylene bridge was characterized by two different driving photoluminescence mechanisms of the doped films: short fluorescence of the quasi-axial conformer and thermally activated delayed fluorescence of the quasi-equatorial form. This compound showed oxygen sensitivity with a Stern–Volmer constant of 7.5×10⁻⁴ ppm⁻¹.