Photoluminescence, FTIR and X-ray diffraction studies on undoped and Al-doped ZnO thin films grown on polycrystalline α-alumina substrates by ultrasonic spray pyrolysis

Undoped and aluminum-doped zinc oxide (ZnO) thin films have been grown on polycrystalline α-alumina substrates by ultrasonic spray pyrolysis (USP) technique using zinc acetate dihydrate and aluminum chloride hexahydrate (Al source) dissolved in methanol, ethanol and deionized water. A number of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and photoluminescence (PL) were used to characterize the obtained ZnO thin films. It was seen that the orientation changed with increase in substrate temperature. During the ZnO deposition Zn source reacted with polycrystalline α-Al₂O₃ substrate to form an intermediate ZnAl₂O₄ spinel layer. It has been interestingly found that the intensity of green emission at 2.48 eV remarkably increased when the obtained ZnO:Al films were deposited at 380 °C. The FTIR absorbance intensity of spectroscopic band at 447±6 cm⁻¹ is very sensitive to oxygen sublattice disorder resulting from non-stoichiometry, which is consistent with the result of PL characterization.     

Skin‐worn Soft Microfluidic Potentiometric Detection System

A flexible skin‐mounted microfluidic potentiometric device for simultaneous electrochemical monitoring of sodium and potassium in sweat is presented. The wearable device allows efficient natural sweat pumping to the potentiometric detection chamber, containing solid‐contact ion‐selective Na⁺ and K⁺ electrodes, during exercise activity. The fabricated microchip electrolyte‐sensing device displays good analytical performance and addresses sweat mixing and carry‐over issues of early epidermal potentiometric sensors. Such soft skin‐worn microchip platform integrates potentiometric measurement, microfluidic technologies with flexible electronics for real‐time wireless data transmission to mobile devices. The new fully integrated microfluidic electrolyte‐detection device paves the way for practical fitness and health monitoring applications.     

Enantioselective Synthesis of Polycyclic Aromatic Hydrocarbon (PAH)-Based Planar Chiral Bent Cyclophanes by Rhodium-Catalyzed [2+2+2] Cycloaddition

The enantioselective synthesis of polycyclic aromatic hydrocarbon (PAH)-based planar chiral cyclophanes was achieved for the first time by the rhodium-catalyzed intramolecular regio- and enantioselective [2+2+2] cycloaddition of tethered diyne-benzofulvenes followed by stepwise oxidative transformations. The thus synthesized planar chiral bent cyclophanes, that possess bent p-terphenyl- and 9-fluorenone-cores, were converted to 9-fluorenol-based ones with excellent ee values of >99 % by diastereoselective 1,2-reduction. These 9-fluorenol-based cyclophanes exhibited high fluorescence quantum yields, which were significantly higher than that of an acyclic reference molecule (78–82 % vs. 48 %). The bending effect on the chiroptical property was also examined, which revealed that the anisotropy factors (g_abs values) for electronic circular dichroism (ECD) of these 9-fluorenol-based planar chiral bent cyclophanes increase as the tether length becomes shorter.     

Solvent-Free Synthesis of Nano Zirconium Phenylphosphonates with Molten Phenylphosphonic Acid

Nanosized α-zirconium phenylphosphonate particles were successfully prepared by the reaction between different zirconium sources and molten phenylphosphonic acid in the absence of solvent. The resultant nanoplates exhibit particle sizes in the range of 15 to 30 nm. The use of a topotactic anion exchange method starting from α-zirconium phosphate instead resulted in the generation of 15 to 180 nm plates, while also resulting in nanoparticles with a higher degree of crystallinity. The topotactic anion exchange of the phosphate groups by phenylphosphonate groups could be performed to completion when performed in molten phenylphosphonic acid. Characterization of both the final products as well as the individual steps in the anion exchange were performed by powder XRD, fast neutron activation analysis, TGA, FTIR spectroscopy, TEM, solid-state NMR and XPS.     

Design and synthesis of certain substituted cycloalkanecarboxamides structurally related to safinamide with anticonvulsant potential

Research on Chemical Intermediates - A series of novel safinamide derivatives were synthesized and biologically evaluated for their anticonvulsant activity against maximal electroshock seizure...     

Elucidating structure and dynamics of crystalline α-zirconium phosphates intercalated with water and methanol by multinuclear solid-state MAS NMR: A comprehensive NMR approach

Solid-state NMR experiments on ²H, ³¹P, ¹³C, and ¹H nuclei, including ³¹P T₁, ¹H T₁, and ¹H T_1ρ measurements, as well as on the kinetics of proton-phosphorus cross-polarization have been performed to characterize the crystalline and amorphous α-zirconium phosphates, which were intercalated with D₂O and/or CD₃OD. The ¹³C{¹H} CP MAS NMR experiment performed for compound 1-CD ₃ OD (Zr (HPO₄)₂ ^. 0.2CD₃OD) with carbon cross-polarization via protons of phosphate groups has provided a prove that the methanol was intercalated into the interlayer spaces of this compound. The variable-temperature ²H solid-echo MAS NMR spectra of intercalated compounds demonstrated that the methanol molecules, in contrast to the mobile water, were immobile, keeping, however, free CD₃ rotations around the C₃-axis. It has been demonstrated that the intercalated species, D₂O and CD₃OD, do not affect the high-frequency motions of the phosphate groups. By utilizing local structural models that satisfy the constraints of the experimental data, it has been suggested that the immobile methanol molecules are located in the cavity between two neighboring layers of the zirconium phosphates. Thus, the present work illustrates the reliable criteria in a comprehensive NMR approach to structural and dynamic studies of such systems.     

Microwave irradiation： Novel and facile methods for the synthesis of new pyrimidinones

We describe here a rapid process for the preparation of new 9-chloromethyl-12-aryl-10,12-dihydrobenzo[5,6]chromeno[2,3-d]pyrimidin-11-ones 5a-d and 10-chloromethyl-7-aryl-7,9-dihydrobenzo[7,8]chromeno[2,3-d]pyrimidin-8-ones 6a-d by two different methods utilizing microwave irradiation. This methodology provides better yields(72%–80%) and high purity of the title compounds.     

Physicochemical Characterization of BADGE <Emphasis Type="Italic">n</Emphasis> = 0/Zinc Meso-tetra(4-pyridyl) Porphyrin Resin

In this work we introduce the zinc 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (ZnTPyP) macrocycle as a crosslinking agent of the epoxy resin BADGE n = 0. NMR, TEM and FTIR confirm that both homopolymerization and heteropolymerization (resulting in the formation of a pyridone) are taken place. DSC evidences two exothermic signals at 170 and 290°C, with enthalpy values of 262.3 and–20.7 J/g, respectively. Crystal powder diffraction supports that the second one corresponds to a physical process. The introduction of the ZnTPyP into the epoxy network improves the thermal stability of the material, which, although very weakly, shows ferromagnetic properties.     

Amphiphilic molecular design as a rational strategy for tailoring bicontinuous electron donor and acceptor arrays: photoconductive liquid crystalline oligothiophene--C60 dyads

For tailoring solution-processable optoelectronic thin films, a rational strategy with amphiphilic molecular design is proposed. A donor-acceptor dyad consisting of an oligothiophene and C60, when modified with a hydrophilic wedge on one side and a paraffinic wedge on the other (1Amphi), forms over a wide temperature range a photoconducting smectic A liquid crystal having bicontinuous arrays of densely packed donor and acceptor units. In contrast, when modified with only paraffinic wedges (1Lipo), the dyad forms a smectic A liquid crystalline mesophase, which however is poorly conductive. As indicated by an absorption spectral feature along with a synchrotron radiation small-angle X-ray scattering profile, 1Lipo in the lamellar structure does not adopt a uniform head/tail orientation. Such defective donor and acceptor arrays likely contain a large number of trapping sites, leading to short-lived charge carriers, as observed by a flash photolysis time-resolved microwave conductivity study.