Organic semiconductor materials are interesting due to their application in various organic electronics devices. [1]benzothieno[3,2-b][1]benzothiophene (BTBT) is a widely used building block for the creation of such materials. In this work, three novel solution-processable regioisomeric derivatives of BTBT—2,7-bis(3-octylthiophene-2-yl)BTBT (1), 2,7-bis(4-octylthiophene-2-yl)BTBT (2), and 2,7-bis(5-octylthiophene-2-yl)BTBT (3)—were synthesized and investigated. Their optoelectronic properties were characterized experimentally by ultraviolet–visible and fluorescence spectroscopy, time-resolved fluorimetry, and cyclic voltammetry and studied theoretically by Time-Dependent Density Functional Theory calculations. Their thermal properties were investigated by a thermogravimetric analysis, differential scanning calorimetry, polarizing optical microscopy, and in situ small-/wide-angle X-ray scattering measurements. It was shown that the introduction of alkyl substituents at different positions (3, 4, or 5) of thiophene moieties attached to a BTBT fragment significantly influences the optoelectronic properties, thermal stability, and phase behavior of the materials. Thin films of each compound were obtained by drop-casting, spin-coating and doctor blade techniques and used as active layers for organic field-effect transistors. All the OFETs exhibited p-channel characteristics under ambient conditions, while compound 3 showed the best electrical performance with a charge carrier mobility up to 1.1 cm2·V−1s−1 and current on/off ratio above 107.

Electrolyte-gated organic field-effect transistors are electronic devices that are being actively developing as a platform for ultra-sensitive biosensors. The organic semiconductor shelf-life stability is important for the practical application of EGOFETs. Therefore, we aimed to develop the organic semiconductor that combines high electrical performance with stability of thin film morphology and electrical characteristics. Two OSC materials were investigated: commercially available C8-BTBT and siloxane dimer BTBT, D2-Und-BTBT-Hex, both characterized by high transconductance and ON/OFF ratio after EGOFET fabrication. Shelf-life was evaluated by keeping the devices under ambient conditions and periodical measuring transfer characteristics in water. C8-BTBT devices demonstrated a sharp decline of ON/OFF ratio within three weeks, which was associated with the thin film reorganization from metastable surface induced 2D crystals to thermodynamically stable 3D crystals leading to appearance of defects in the thin film and subsequent separation into individual crystals. D2-Und-BTBT-Hex had much more stable morphology due to intrinsic properties of the dimer molecules: the presence of a bulky but flexible disiloxane group linking two BTBT moieties together, which leads to a higher molar weight and less crystallization enthalpy. Both these factors stabilize the surface phase thus increasing stability of the thin films of the dimer. It was shown that the devices using D2-Und-BTBT-Hex as a semiconductor layer can be stored at shelf without any additional precautions for at least 4 months.

Electrolyte-gated organic field-effect transistors (EGOFETs) is a popular platform for numerous sensing and biosensing applications in aqueous media. In this work, the variation of electrical characteristics of EGOFETs based on small-molecule organic semiconductor C8-BTBT and polystyrene blend in water solutions at different pH values was investigated. A positive shift of the threshold voltage with near-Nernstian pH sensitivity was demonstrated in the pH range from 4.9 to 2.8, while no measurable pH dependence in the range from 4.9 to 8.6 pH was registered. These results indicate chemical doping of the molecules of organic semiconductors by protons from the electrolyte in the acidic region. In order to check the applicability of the EGOFETs in a flow mode, a flow chamber was designed and assembled. The preliminary results obtained in the flow mode measurements showed a fast response to pH variation.

Requirements of speed and simplicity in testing stimulate the development of modern biosensors. Electrolyte-gated organic field-effect transistors (EGOFETs) are a promising platform for ultrasensitive, fast, and reliable detection of biological molecules for low-cost, point-of-care bioelectronic sensing. Biosensitivity of the EGOFET devices can be achieved by modification with receptors of one of the electronic active interfaces of the transistor gate or organic semiconductor surface. Functionalization of the latter gives the advantage in the creation of a planar architecture and compact devices for lab-on-chip design. Herein, we propose a universal, fast, and simple technique based on doctor blading and Langmuir-Schaefer methods for functionalization of the semiconducting surface of C8-BTBT-C8, allowing the fabrication of a large-scale biorecognition layer based on the novel functional derivative of BTBT-containing biotin fragments as a foundation for further biomodification. The fabricated devices are very efficient and operate stably in phosphate-buffered saline solution with high reproducibility of electrical properties in the EGOFET regime. The development of biorecognition properties of the proposed biolayer is based on the streptavidin-biotin interactions between the consecutive layers and can be used for a wide variety of receptors. As a proof-of-concept, we demonstrate the specific response of the BTBT-based biorecognition layer in EGOFETs to influenza A virus (H7N1 strain). The elaborated approach to biorecognition layer formation is appropriate but not limited to aptamer-based receptor molecules and can be further applied for fabricating several biosensors for various analytes on one substrate and paves the way for "electronic tongue" creation.

The synthesis and photophysical investigation of three novel meta-conjugated molecules based on 3,1,2-benzothiadiazole and thiophene-2,5-diyl derivatives linked through 1,3,5-benzene branching units are described. Each of them is a symmetrical molecule with two branching units, four identical lateral thiophene-containing fragments, and one central benzothiadiazole-containing fragment. To study the effect of the chemical structure on their photophysical properties, the molecules with different linearly conjugated lateral and central fragments due to incorporation of additional thiophene rings were synthesized and compared. It was shown that absorption spectra of the meta-conjugated molecules can be represented as a sum of absorption bands of model compounds for their peripheral and central fragments containing a common benzene ring being branched at the 1,3,5-benzene unit in the meta-conjugated molecules. Therefore, they cannot be considered simply as isolated π-conjugated systems of their peripheral and central fragments. Instead, DFT calculations showed that several transitions between the orbitals located in different regions of the meta-conjugated molecule are responsible for the formation of their absorption spectra, and they strongly depend on the degree of their overlapping. Theoretical absorption spectra reconstructed from the DFT data demonstrated a good agreement with the experimental results: the transitions with larger oscillator strength correspond to the bands with higher molar extinction coefficients and vice versa. It was shown that luminescence spectral maxima of the meta-conjugated molecules monotonically shift to the lower energy from 489 to 540 and 613 nm with increasing the number of thiophene rings in the peripheral and central fragments, respectively. However, luminescence quantum yield of the meta-conjugated molecules critically depends on the length of linearly conjugated fragments in its structure decreasing from 24% to 1.3% with increasing the number of thiophene rings in the lateral fragments but increasing to 90% in the molecule with more thiophene rings in both types of the fragments. The results obtained are well correlated to the ratio of radiative and nonradiative deactivation rate constants of the meta-conjugated molecules that indicates a high rate of internal conversion between the excited states corresponding to different fragments of the molecule. The CV measurements allowed estimating the HOMO, LUMO, and bandgap values of the target and model compounds, which confirm the presence of meta-conjugation within the molecules investigated. Thus, connection of linearly conjugated fragments through meta-positions (meta-conjugation) of a benzene ring leads to an intermediate option between fully conjugated and nonconjugated molecules due to partial delocalization of electron density through the 1,3,5-substituted benzene branching center.

This study investigates the effects of the degree of ion exchange of sodium cations for cesium cations in FAU(Y) on its physicochemical properties. Using aqueous and solid-state ion exchange, a number of NaY samples with an exchange degree of sodium cations for cesium cations varying from 29 to 89% were prepared. The samples were examined by SEM, X-ray fluorescence, low-temperature nitrogen adsorption, XRD, NH3-TPD, IR spectroscopy of adsorbed chloroform, and 27Al MAS NMR. It was demonstrated that samples with exchange degrees up to 87% can be synthesized with their crystalline structure intact. The test of the catalytic properties of the synthesized samples in aniline alkylation with methanol showed a growth in the selectivity for N-alkylated products as the number and strength of basic sites were progressively increased. Impregnating the Cs-containing zeolites with CsOH was found to significantly enhance the operating stability of the samples and the yield of N-alkylated products, compared to CsNaY. The CsOH-modified catalysts with a Na+/Cs+ exchange degree of 54–77% proved to be the most active and stable in aniline alkylation with methanol: they provided aniline conversion of 81–88% and selectivity for N-alkylation products as high as 99.6–99.7 mol %.

This study investigates the effects of FAU(Y) crystal size (350, 450, and 850 nm) on the physicochemical properties and catalytic performance of CsNaY samples in the alkylation of aniline with methanol. The physicochemical properties of the samples were examined by SEM, X-ray fluorescence analysis, low-temperature nitrogen adsorption, XRD, NH3–TPD, IR spectroscopy of adsorbed chloroform, and 27Al MAS NMR. Reducing the zeolite crystal size was found to strengthen the CsNaY basic properties and enhance the selectivity towards N-alkylated products. The highest activity and stability in aniline methylation was achieved by the CsNaY sample consisting of 450-nm crystals that had a Na+ for Cs+ ion exchange degree of 64% and was modified with CsOH. This sample provided aniline conversion of 95% and the selectivity towards N-alkylated product of 99.8%.

Electrolyte-gated organic field-effect transistors (EGOFETs) provide a versatile platform for ultrasensitive, fast, and reliable detection of biological molecules in liquid media using low-cost bioelectronic sensors. The key functional layers of the EGOFETs include the semiconductor and biorecognition layers based on conjugated organic molecules, which must meet high requirements for the operational stability in various electrolytes when detecting analytes. In this work, EGOFETs based on 2,6-dioctyltetrathienoacene as the semiconductor material were fabricated by the doctor blade method compatible with printing technologies. We also report on EGOFETs with the biorecognition layer based on a biotin-containing derivative of [1]benzothieno[3,2-b]benzothiophene, which was applied by the Langmuir-Schaeffer method. The possibility of stable operation of the fabricated EGOFETs in various electrolytes and their sensor responses to the electrolyte pH value and streptavidin are demonstrated.

This review summarizes and highlights the current state-of-the-art of research on chemical sensors and biosensors in liquid environment and neuromorphic devices based on electrolyte-gated organic transistors with the active semiconductor layer of organic π -conjugated materials (small molecules, oligomers and polymers). The architecture and principles of operation of electrolyte-gated organic transistors and the main advantages and drawbacks of these devices are considered in detail. The criteria for the selection of organic semiconductors for these devices are presented. The causes of degradation of semiconductor layers and ways of their elimination are discussed. Examples of the use of electrolyte-gated organic transistors as bio and chemical sensors, artificial synapses and computing devices are given. The bibliography includes 132 references.

Kinetic analysis of isobutylene synthesis from ethanol in the presence of a ZnO/ZrO2 catalyst synthesized by incipient wetness impregnation of zirconium hydroxide with zinc nitrate has been conducted. Analysis data have been used to determine primary, secondary, stable, and unstable products. The selectivity for the reaction products and the order of their formation have been determined. A general scheme of the reaction routes for ethanol conversion to isobutylene has been proposed.

Cs-containing FAU(Y)-type zeolite catalysts were prepared by conventional and novel ion exchange procedures followed by incipient wetness impregnation with CsOH. The novel ion exchange procedure involved hydrothermal treatment of NaY zeolite in aqueous solution of CsCl at 140–200 °C for 6–24 h. The samples were characterized by low-temperature nitrogen adsorption, X-ray fluorescence analysis, X-ray powder diffraction, scanning electron microscopy, 23 Na, 27 Al and 133 Cs magic angle spinning nuclear magnetic resonance, CO 2 and NH 3 -Temperature programmed desorption. The results show that hydrothermal treatment at 200 °C allows to obtain higher degrees of ion-exchange (up to 83%) with respect to conventional method giving maximum 66%–69%. Catalytic properties of Cs-containing FAU(Y) were studied in aniline methylation. The yield of N -methylaniline is shown to correlate with catalyst’s basicity. The best catalyst performance was achieved over the catalyst with the highest ion-exchange degree impregnated with CsOH. The selectivity to N -methylaniline over this catalyst reached 96.4%.

Synthesis of isobutylene from ethanol in the presence of ZnO/ZrO2 catalysts has been studied. The samples have been synthesized by incipient wetness impregnation of zirconium hydroxide derived from zirconyl chloride with zinc nitrate and subsequent calcination at 550°C. The synthesized samples have been studied by low-temperature nitrogen adsorption, SEM, XRD, IR spectroscopy of adsorbed CO, and TGA–DTA. Studies of the effect of the catalyst composition and the test conditions have revealed that, during the synthesis of isobutylene from ethanol, an optimum Zr : Zn molar ratio providing the production of isobutylene with a selectivity of 45–50% is 8–20 and optimum conditions for ethanol conversion to isobutylene are 500°C, a feed space velocity of 3 g/(g h), and a feedstock in the form of a 50% ethanol solution in water. According to thermogravimetric analysis, an increase in the zinc content in the samples leads to a decrease in the amount of coke deposits.

An approach is proposed to the determination of selenium and cadmium dopants in new nanocomposites based on zinc and indium oxides. The approach is based on a combination of highly efficient high resolution continuous source electrothermal atomic absorption spectrometry (ETAAS) for the analysis of suspensions and inductively coupled plasma mass spectrometry for the analysis of solutions. A procedure is developed for the determination of Se and Cd dopants and matrix components based on Zn and In in nanocomposite solutions by inductively coupled plasma mass spectrometry. Stabilizing agents for the preparation of suspensions are studied for the ETAAS analysis of powders without their decomposition. The results of determination of CdSe dopants by high resolution ETAAS are validated by inductively coupled plasma mass spectrometry.