Organic–inorganic interactions revealed by Raman spectroscopy during reversible phase transitions in semiconducting [(C2H5)4N]FeCl4

The alkylammonium halogenoferrate families are subjected to diverse studies according to their wide field application. However, these compounds show various transitions depending on the preparation process. In this paper, the [(C₂H₅)₄N]FeCl₄ compound was successfully synthesized using a slow evaporation solution growth method at room temperature. An optical absorption measurement confirms the semiconductor nature with a band gap around 2.95 eV. The X-ray powder diffraction (XRPD) data confirmed the formation of a single-phase with hexagonal-type structure. The differential scanning calorimetry (DSC) indicated that the [(C₂H₅)₄N]FeCl₄ compound undergoes eight reversible phase transitions between 193 and 443 K. At high temperature (T > 423 K) the plastic nature of the crystals was confirmed. Temperature-controlled X-ray diffraction reveals that the thermal expansion of the crystal structure is non homothetic in the (a,b) plane and along the c axis. The temperature dependence of the Raman spectra up to 443 K revealed specific reorientations and molecular displacements of the organic and inorganic components associated with the phase transitions. We aim to thermally stabilize the [(C₂H₅)₄N]FeCl₄ compound which has a band gap suitable for photocatalytic processes.

The alkylammonium halogenoferrate families are subjected to diverse studies according to their wide field application.     

Electrical conductivity and vibrational studies induced phase transitions in [(C2H5)4N]FeCl4

The compound, tetraethylammonium tetrachloroferrate [(C₂H₅)₄N]FeCl₄, was prepared by slow evaporation at room temperature. It was characterized by X-ray powder diffraction, thermal analysis, and impedance and vibrational spectroscopy. X-ray diffraction data confirmed formation of a single phase material which crystallized at room temperature in the hexagonal system (P6₃mc space group). DSC showed the existence of two phase transitions at 413 K and 430 K. Electrical conductivity was measured in the temperature and frequency ranges of 390 K to 440 K and 40 Hz to 110 MHz, respectively. Nyquist plots revealed the existence of grains and grain boundaries that were fitted to an equivalent circuit. AC conductivity plots were analyzed by Jonscher''s power law. Variations in the “s” values indicated that CBH models describe the conduction mechanism in regions I and II. Temperature dependence of Raman spectra showed that the most important changes were observed in the cationic parts ([(C₂H₅)₄N]⁺). The activation energy value obtained from the line width decreased which indicated an order–disorder model.

Complex impedance spectra of [(C₂H₅)₄N]FeCl₄ at different temperature.     

Synthesis,structural and electrical characterization of a new organic inorganic bromide: [(C3H7)4N]2CoBr4

A new organic inorganic hybrid [TPA]₂CoBr₄, where TPA = [(C₃H₇)₄N]⁺ (i.e., tetra-propyl-ammonium) compound has been synthesized by slow evaporation method at room temperature. Single crystal X-ray diffraction (SC-XRD), X-ray powder diffraction (XRPD), thermal analyses, vibrational and complex impedance spectroscopy have been used to characterize both structural, thermal, electrical properties. [TPA]₂CoBr₄ crystallizes in the monoclinic system (C2/c space group) with the following cell parameters: a = 33.145 (5) Å, b = 14.234 (3) Å, c = 15.081 (2) Å and β = 110.207 (5)°. In the crystal structure, the organic TPA cations which form layers stacked along the a-axis, are separated from each other by inorganic tetrahedral [CoBr₄]²⁻ anions. The XRPD pattern confirms both the high purity of the sample and the crystalline nature of the powder. The differential scanning calorimetry (DSC) analysis shows an endothermic peak at 394 K upon heating which is ascribed to a structural phase transition since no decomposition of the titled compound is evidenced by thermogravimetric analysis. The ac conductivity and the dielectric properties confirm the presence of the phase transition. At the structural phase transition around 394 K, a change from a quantum mechanical tunneling to a correlated barrier hopping conduction models is determined from the temperature dependence of the exponent s of the Jonscher''s power law. The analysis of complex impedance spectra shows that the electrical properties of the material are heavily dependent on frequency and temperature, indicating a relaxation phenomenon and semiconductor-type behavior. One single semicircle is detectable in the Nyquist plots of the complex impedance spectra which can be satisfactorily fitted with a combination R//CPE elements assigned to the bulk response. This behavior suggests that the sample is electrically homogeneous. Capacitance analysis proves the high effective permittivity at radio frequencies in the sample.

A new organic inorganic hybrid [TPA]₂CoBr₄, where TPA = [(C₃H₇)₄N]⁺ (i.e., tetra-propyl-ammonium) compound has been synthesized by slow evaporation method at room temperature.     

Bupropion inhibits nicotine-evoked [(3)H]overflow from rat striatal slices preloaded with [(3)H]dopamine and from rat hippocampal slices preloaded with [(3)H]norepinephrine

Bupropion, an efficacious antidepressant and smoking cessation agent, inhibits dopamine and norepinephrine transporters (DAT and NET, respectively). Recently, bupropion has been reported to noncompetitively inhibit alpha3beta2, alpha3beta4, and alpha4beta2 nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus oocytes or established cell lines. The present study evaluated bupropion-induced inhibition of native alpha3beta2* and alpha3beta4* nAChRs using functional neurotransmitter release assays, nicotine-evoked [(3)H]overflow from superfused rat striatal slices preloaded with [(3)H]dopamine ([(3)H]DA), and nicotine-evoked [(3)H]overflow from hippocampal slices preloaded with [(3)H]norepinephrine ([(3)H]NE). The mechanism of inhibition was evaluated using Schild analysis. To eliminate the interaction of bupropion with DAT or NET, nomifensine or desipramine, respectively, was included in the superfusion buffer. A high bupropion concentration (100 microM) elicited intrinsic activity in the [(3)H]DA release assay. However, none of the concentrations (1 nM-100 microM) examined evoked [(3)H]NE overflow and, thus, were without intrinsic activity in this assay. Moreover, bupropion inhibited both nicotine-evoked [(3)H]DA overflow (IC(50) = 1.27 microM) and nicotine-evoked [(3)H]NE overflow (IC(50) = 323 nM) at bupropion concentrations well below those eliciting intrinsic activity. Results from Schild analyses suggest that bupropion competitively inhibits nicotine-evoked [(3)H]DA overflow, whereas evidence for receptor reserve was obtained upon assessment of bupropion inhibition of nicotine-evoked [(3)H]NE overflow. Thus, bupropion acts as an antagonist at alpha3beta2* and alpha3beta4* nAChRs in rat striatum and hippocampus, respectively, across the same concentration range that inhibits DAT and NET function. The combination of nAChR and transporter inhibition produced by bupropion may contribute to its clinical efficacy as a smoking cessation agent.     

First-principles study on the mechanical and electronic properties of energetic molecular perovskites AM(ClO4)3 (A = C6H14N22+, C4H12N22+, C6H14N2O2+; M = Na+, K+)

Density functional theory (DFT) simulations were conducted to study the crystal structures, and mechanical and electronic properties of a series of new energetic molecular perovskites, including (C₆H₁₄N₂)[Na(ClO₄)₃], (C₆H₁₄N₂)[K(ClO₄)₃], (C₄H₁₂N₂)[Na(ClO₄)₃] and (C₆H₁₄N₂O)[K(ClO₄)₃], abbreviated as DAP-1, DAP-2, PAP-1, and DAP-O2, respectively. By calculating the elastic constants, moduli (Young''s modulus E, bulk modulus B, and shear modulus G), Poisson ratio ν and Pugh''s ratio B/G, we found that the four energetic molecular perovskites not only possessed good mechanical stability but excellent mechanical flexibility and ductility. In addition, DFT calculations were used to investigate the electronic properties of all of the perovskite compounds. The band gaps of DAP-1 and DAP-2 were comparable, and the band gap of PAP-1 was the smallest and that of DAP-O2 was the largest. A comprehensive analysis of the density of states and the M–O bonding characteristics provided a good explanation for the band gap characteristics. Besides, we found that the modulus properties of these molecular perovskite energetic compounds are also tightly bound to the strength of M–O bonding.

Using the pCOHP method it was revealed the band gap, and the modulus properties are related to the type and strength of the M–O bonds in a series of molecular perovskite high-energetic compounds AM(ClO₄)₃ (A = C₆H₁₄N₂₂⁺, C₄H₁₂N₂₂⁺, C₆H₁₄N₂O₂⁺; M = Na⁺, K⁺).     

Characterization of a tropane radioligand, [(3)H]2beta-propanoyl-3beta-(4-tolyl) tropane ([(3)H]PTT), for dopamine transport sites in rat brain

PTT (2beta-propanoyl-3beta-[4-tolyl] tropane) is a tropane analog relatively selective for dopamine transporters in binding and uptake assays in vitro, with long-acting psychostimulant properties in vivo. To explore its utility in binding to dopamine transporters, [(3)H]PTT was synthesized and assayed for binding in rat striatal membranes and by in vitro autoradiography. In membranes, binding of [(3)H]PTT was saturable to a single class of binding sites with a K(D) value of 3 nM. The pharmacology of [(3)H]PTT binding in striatal membranes was consistent with that of a ligand selective for dopamine transporters, with dopamine-selective compounds being significantly more potent in displacing [(3)H]PTT binding than those for 5-HT or norepinephrine transporters. Although the ability of various transporter inhibitors to displace both [(125)I]RTI-55 and [(3)H]PTT binding correlated significantly with each other, there was a better correlation of inhibitor potencies versus [(3)H]PTT binding and dopamine uptake than versus [(125)I]RTI-55 binding and dopamine uptake. The differences in correlations were most noticeable for compounds relatively selective at the 5-hydroxytryptamine (serotonin) transporter. The autoradiographic distribution of [(3)H]PTT binding in coronal sections was consistent with the known distribution of the dopamine transporter, with high levels of binding evident in caudate nucleus, nucleus accumbens, and olfactory tubercle. Moderate densities of [(3)H]PTT binding were also observed in substantia nigra pars compacta, and ventral tegmental area, as well as in the anterior cingulate cortex and portions of the hypothalamus. In addition, nonspecific binding was less than 5% of total binding. Thus, [(3)H]PTT provides an accurate and convenient marker for the dopamine transporter.     

Pharmacological properties of ABT-239 [4-(2-{2-[(2R)-2-Methylpyrrolidinyl]ethyl}-benzofuran-5-yl)benzonitrile]: I. Potent and selective histamine H3 receptor antagonist with drug-like properties

Histamine H3 receptor antagonists are being developed to treat a variety of neurological and cognitive disorders that may be ameliorated by enhancement of central neurotransmitter release. Here, we present the in vitro pharmacological and in vivo pharmacokinetic profiles for the nonimidazole, benzofuran ligand ABT-239 [4-(2-{2-[(2R)-2-methylpyrrolidinyl]ethyl}-benzofuran-5-yl)benzonitrile] and compare it with several previously described imidazole and nonimidazole H3 receptor antagonists. ABT-239 binds to recombinant human and rat H3 receptors with high affinity, with pK(i) values of 9.4 and 8.9, respectively, and is over 1000-fold selective versus human H1, H2, and H4 histamine receptors. ABT-239 is a potent H3 receptor antagonist at recombinant human and rat receptors, reversing agonist-induced changes in cAMP formation (pK(b) = 7.9 and 7.6, respectively), guanosine 5'-O-(3-[35S]thio) triphosphate ([35S]GTPgammaS) binding (pK(b) = 9.0 and 8.3, respectively), and calcium mobilization (human pK(b) = 7.9). ABT-239 also competitively reversed histamine-mediated inhibition of [3H]histamine release from rat brain cortical synaptosomes (pK(b) = 7.7) and agonist-induced inhibition of contractile responses in electric field stimulated guinea pig ileal segments (pA2 = 8.7). Additionally, ABT-239 is a potent inverse agonist, inhibiting constitutive [35S]GTPgammaS binding at both rat and human H3 receptors with respective pEC50 values of 8.9 and 8.2. ABT-239 demonstrates good pharmacokinetic characteristics in rat, dog, and monkey with t1/2 values ranging from 4 to 29 h, corresponding with clearance values and metabolic turnover in liver microsomes from these species, and good oral bioavailability ranging from 52 to 89%. Thus, ABT-239 is a selective, nonimidazole H3 receptor antagonist/inverse agonist with similar high potency in both human and rat and favorable drug-like properties.     

P-glycoprotein-independent apoptosis induction by a novel synthetic compound, MMPT [5-[(4-methylphenyl)methylene]-2-(phenylamino)-4(5H)-thiazolone

To develop new anticancer agents that are effective for treatment of chemoresistant tumors, we screened a chemical library for compounds that can effectively kill both paclitaxel-sensitive lung cancer cell H460 and P-glycoprotein-overexpressing paclitaxel-resistant cell H460/TaxR. A synthetic compound, MMPT (5-[(4-methylphenyl)methylene]-2-(phenylamino)-4(5H)-thiazolone), was identified to induce cytotoxic effects in both H460 and H460/TaxR cells but not in normal fibroblasts. MMPT effectively inhibited the growth of several human lung cancer cell lines in a dose-dependent manner, with 50% inhibitory concentrations ranging from 4.9 to 8.0 microM. The inhibitory effect on cancer cells is independent of the status of p53 and P-glycoprotein. Moreover, MMPT had no obvious toxic effects on normal human fibroblasts and mesenchymal stem cells at the 50% inhibitory concentration for lung cancer cell lines. Treating lung cancer cells with MMPT-induced apoptosis with caspase-3, -8, -9, and poly(ADP-ribose) polymerase cleavage and cytochrome c release from mitochondria. MMPT-induced apoptosis was abrogated when c-Jun N-terminal kinase (JNK) activation was blocked with a specific JNK inhibitor, SP600125. Furthermore, in vivo administration of MMPT suppressed human H460 xenograft tumor growth in nude mice. Our results suggest that MMPT may induce tumor-selective cell killing in both P-glycoprotein-negative and -positive cancer cells and could be a new anticancer agent for treatment of refractory tumors.     

Effect of Bi2O3 content on the microstructure and electrical properties of SrBi2Nb2O9 piezoelectric ceramics

Lead-free ceramics, SrBi₂Nb₂O₉–xBi₂O₃ (SBN–xBi), with different Bi contents of which the molar ratio, n(Sr) : n(Bi) : n(Nb), is 1 : 2(1 + x/2) : 2 (x = −0.05, 0.0, 0.05, 0.10), were prepared by conventional solid-state reaction method. The effect of excess bismuth on the crystal structure, microstructure and electrical properties of the ceramics were investigated. A layered perovskite structure without any detectable secondary phase and plate-like morphologies of the grains were clearly observed in all samples. The value of the activation energy suggested that the defects in samples could be related to oxygen vacancies. Excellent electrical properties (e.g., d₃₃ = 18 pC N⁻¹, 2P_r = 17.8 μC cm⁻², ρ_rd = 96.4% and T_c = 420 °C) were simultaneously obtained in the ceramic where x = 0.05. Thermal annealing studies indicated the SBN–xBi ceramics system possessed stable piezoelectric properties, demonstrating that the samples could be promising candidates for high-temperature applications.

Lead-free ceramics, SrBi₂Nb₂O₉–xBi₂O₃ (SBN–xBi), with different Bi contents of which the molar ratio, n(Sr) : n(Bi) : n(Nb), is 1 : 2(1 + x/2) : 2 (x = −0.05, 0.0, 0.05, 0.10), were prepared by conventional solid-state reaction method.     

Construction of 2D/2D layered g-C3N4/Bi12O17Cl2 hybrid material with matched energy band structure and its improved photocatalytic performance

A series of visible-light-induced 2D/2D layered g-C₃N₄/Bi₁₂O₁₇Cl₂ composite photocatalysts were successfully synthesized by a one step chemical precipitation method with g-C₃N₄, BiCl₃ and NaOH as the precursors at room temperature and characterized through XRD, FTIR, XPS, TEM, BET and UV-vis DRS measurements. The results of XRD, FTIR and XPS indicated that g-C₃N₄ has been introduced in the Bi₁₂O₁₇Cl₂ system. The TEM image demonstrated that there was strong surface-to-surface contact between 2D g-C₃N₄ layers and Bi₁₂O₁₇Cl₂ nanosheets, which contributed to a fast transfer of the interfacial electrons, leading to a high separation rate of photoinduced charge carriers in the g-C₃N₄/Bi₁₂O₁₇Cl₂ system. Rhodamine B was considered as the model pollutant to investigate the photocatalytic activity of the resultant samples. The g-C₃N₄/Bi₁₂O₁₇Cl₂ composite showed a clearly improved photocatalytic degradation capacity compared to bare g-C₃N₄ and Bi₁₂O₁₇Cl₂, which was ascribed to the interfacial contact between the 2D g-C₃N₄ layers and Bi₁₂O₁₇Cl₂ sheet with a matched energy band structure, promoting the photoinduced charges'' efficient separation. Finally, combined with the results of the trapping experiment, ESR measurements and the band energy analysis, a reasonable photocatalytic mechanism over the 2D/2D layered g-C₃N₄/Bi₁₂O₁₇Cl₂ composite was proposed.

Surface-to-surface contact g-C₃N₄/Bi₁₂O₁₇Cl₂ hybrid material with a matched energy band structure could efficiently transfer photoinduced charges, improving the photocatalytic activity.     

Inhibitor binding to type 4 phosphodiesterase (PDE4) assessed using [3H]piclamilast and [3H]rolipram

Piclamilast is a type 4 phosphodiesterase (PDE4) inhibitor with equal affinity for the high-affinity rolipram binding site (HARBS) and low-affinity rolipram binding site (LARBS). The binding of [(3)H]piclamilast to preparations of rat brain and peripheral tissue was investigated and compared with that of [(3)H]rolipram. [(3)H]piclamilast binding was high-affinity, saturable, reversible, and partially Mg(2+)-dependent. Binding was detected both to membrane and soluble fractions, with K(d) values of 3.1 and 4.5 nM, respectively. The B(max) values for [(3)H]piclamilast were about 1.5-fold greater than that of [(3)H]rolipram binding, suggesting that [(3)H]piclamilast, but not [(3)H]rolipram, binds to LARBS as well as the HARBS. The HARBS was present in all the brain regions examined, but not in peripheral tissues. All PDE4 inhibitors tested were potent competitors for [(3)H]piclamilast binding; the competition curves for rolipram, desmethylpiclamilast, ICI 63,197, and Ro 20-1724 were better described by a two-site model, while the competition curves for piclamilast, cilomilast, roflumilast, and CDP 840 were adequately described by a one-site model. Inhibitors of other PDE families were much less potent. The inhibition of [(3)H]piclamilast was further tested in the presence of 1 microM rolipram to isolate the LARBS. Under this condition, the competition curves for all the inhibitors were adequately described by a one-site model, with K(i) values close to that for the LARBS. The results indicated that [(3)H]piclamilast is a useful tool to directly study inhibitor interaction with the HARBS and the LARBS in rat brain.     

Pd-catalyzed C–C and C–N cross-coupling reactions in 2-aminothieno[3,2-d]pyrimidin-4(3H)-one series for antiplasmodial pharmacomodulation

In 2015, we identified gamhepathiopine (M1), a 2-tert-butylaminothieno[3,2-d]pyrimidin-4(3H)-one antiplasmodial hit targeting all development stages of the human malarial parasite P. falciparum. However, this hit compound suffers from sensitivity to hepatic oxidative metabolism. Herein, we describe the synthesis of 33 new compounds in the 2-aminothieno[3,2-d]pyrimidin-4(3H)-one series modulated at position 6 of this scaffold. The modulations were performed using three palladium-catalyzed cross coupling reactions, namely Suzuki–Miyaura, Sonogashira, and Buchwald–Hartwig. For the latter, we developed the reaction conditions. Then, we evaluated the synthesized compounds for their antiplasmodial activity on the K₁P. falciparum strain and their cytotoxicity on the human HepG2 cell line. Although we did not obtain a compound better than M1 in terms of the antiplasmodial activity, we identified compound 1g bearing a piperidine at position 6 of the thieno[3,2-d]pyrimidin-4(3H)-one ring with an improved cytotoxicity and metabolic stability. 1g is an interesting new starting point for further pharmacomodulation studies. This study also provides valuable antiplasmodial SAR data regarding the nature of the ring at position 6, the possible substituent on this ring, and the introduction of a spacer between this ring and the thienopyrimidinone moiety.

Pharmacomodulation at position 6 of a thienopyrimidinone antiplasmodial hit using palladium-catalyzed cross-coupling reactions afforded 33 new compounds, among which a new hit was found with enhanced metabolic stability.     

Tissue distribution and functional correlation of [3H]leukotriene C4 and [3H]leukotriene D4 binding sites in guinea-pig uterus and lung preparations

To determine the distribution of leukotriene (LT) C4 and LTD4 receptors and functional significance of each receptor, we used [3H]LTC4 and [3H]LTD4 to measure the binding activity in various tissue homogenates and to correlate the relative ability of the LT agonists to inhibit binding with their contractile responses in guinea-pig uterine or lung parenchymal preparations. Guinea-pig brain contained the highest binding activity of 1 to 2 nM [3H] LTC4 followed by small intestine, heart, lung, kidney, uterus, etc., whereas guinea-pig lung had at least 2.7-fold greater [3H] LTD4 binding activity than any other tissues tested. In the brain and uterine homogenates, the rank order of potency for the compounds in competing with [3H]LTC4 for binding sites was LTC4 much greater than LTD4 greater than LTE4 greater than FPL-55712 = arachidonic acid. The in vitro functional study showed that the ability of the LT agonists to produce uterine contraction was in the order of LTC4 greater than LTD4 greater than LTE4, which is compatible with their relative effect for inhibition of uterine or brain [3H]LTC4 binding. In the lung homogenate, either LTC4, LTD4 or LTE4 inhibited effectively [3H]LTD4 binding and the potency order for the [3H]LTD4 competition study was LTD4 greater than LTE4 greater than LTC4 much greater than FPL-55712 greater than arachidonic acid. These LT agonists also produced lung contraction effectively and the difference among their contractile ability was not significant. We conclude that 1) there are distinct functional LTC4 and LTD4 receptors, 2) activation of the LTC4 receptor could account for the uterine contraction due to the LT agonists and 3) the lung contraction induced by LTC4, LTD4 and LTE4 is at least mediated partly by the LTD4 receptor.     

3H]Methoxymethyl-3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine binding to metabotropic glutamate receptor subtype 5 in rodent brain: in vitro and in vivo characterization

The binding of [3H]methoxymethyl-3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (methoxymethyl-MTEP), a potent and selective antagonist for metabotropic glutamate (mGlu)5 receptors, was characterized in rat brain both in vitro and in vivo. Nonspecific binding, as defined with 10 microM 2-methyl-6-(phenylethynyl)-pyridine (MPEP), was less than 10% of total binding in rat brain membranes. The binding of [3H]methoxymethyl-MTEP was of high affinity (K(d) = 20 +/- 2.7 nM), saturable (B(max) = 487 +/- 48 fmol/mg protein), and to a single site. The mGlu5 antagonists methoxymethyl-MTEP and MPEP displaced [3H]methoxymethyl-MTEP binding with IC50 values of 30 and 15 nM, respectively. In vivo administration of [3H]methoxymethyl-MTEP (50 microCi/kg i.v.) revealed 12-fold higher binding in hippocampus (an area enriched in mGlu5 receptors) relative to cerebellum (an area with few mGlu5 receptors) in rats. Similarly, administration of [3H]methoxymethyl-MTEP to mGlu5-deficient mice demonstrated binding at background levels in forebrain, whereas wild-type littermates exhibited 17-fold higher binding in forebrain relative to cerebellum. Systemic administration of unlabeled mGlu5 antagonists methoxymethyl-MTEP and MPEP to rats reduced the binding of [3H]methoxymethyl-MTEP with ID50 values of 0.8 and 2 mg/kg i.p., respectively, 1 h post-treatment. The mGlu5 agonist 2-chloro-5-hydroxyphenylglycine (CHPG) (0.3, 1, and 3 micromol) dose-dependently increased phosphoinositide (PI) hydrolysis in the hippocampus after i.c.v. administration in rats. CHPG-evoked increases in PI hydrolysis were blocked with MPEP at a dose (10 mg/kg i.p.) that markedly reduced [3H]methoxymethyl-MTEP binding in vivo. These results indicate that [3H]methoxymethyl-MTEP is a selective radioligand for labeling mGlu5 and is useful for studying the binding of mGlu5 receptors in rat brain in vitro and in vivo.     

Synthesis of Bi2O3/g-C3N4 for enhanced photocatalytic CO2 reduction with a Z-scheme mechanism

Bi₂O₃/g-C₃N₄ nanoscale composites with a Z-scheme mechanism were successfully synthesized by high temperature calcination combined with a hydrothermal method. These synthesized composites exhibited excellent photocatalytic performance, especially the 40 wt% Bi₂O₃/g-C₃N₄ composite, which produced about 1.8 times the CO yield of pure g-C₃N₄. The obtained products were characterized by X-ray diffraction (XRD) patterns, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and so on. Characterization results revealed that Bi ions had well covered the surface of g-C₃N₄, thus restraining the recombination of electron–hole pairs and resulting in a stronger visible-light response and higher CO yield. In addition, the electron transfer process through the Z-scheme mechanism also promoted the photocatalytic activity.

Bi₂O₃/g-C₃N₄ composites were synthesized and used in photocatalytic reduction of CO₂ with a Z-scheme mechanism.     

Pharmacology of (2S,4Z)-N-[(2S)-2-hydroxy-2-phenylethyl]-4-(methoxyimino) -1-[(2'-methyl[1,1'-biphenyl]-4-yl)carbonyl]-2-pyrrolidinecarboxamide,a new potent and selective nonpeptide antagonist of the oxytocin receptor

We have discovered a new, potent, selective, and orally active oxytocin receptor antagonist, (2S,4Z)-N-[(2S)-2-hydroxy-2-phenylethyl]-4-(methoxyimino)-1-[(2'-methyl[1,1'-biphenyl]-4-yl)carbonyl]-2-pyrrolidinecarboxamide (compound 1). We report the biochemical, pharmacological, and pharmacokinetic characterization in vitro and in vivo of this compound. Compound 1 competitively inhibits binding of [3H]oxytocin and the peptide antagonist 125I-ornithine vasotocin analog to human and rat oxytocin receptor expressed in human embryonic kidney 293-EBNA or Chinese hamster ovary cells with nanomolar potency. Selectivity against vasopressin receptor subtypes is >6-fold for V1a and >350-fold for V2 and V1b. Compound 1 inhibits oxytocin-evoked intracellular Ca2+ mobilization (IC50 = 8 nM). Compound 1 has no intrinsic agonist activity at the oxytocin receptor. Oxytocininduced contraction of isolated rat uterine strips is blocked by compound 1 (pA2 = 7.82). In anesthetized nonpregnant rats, single administration of compound 1 by i.v. or oral routes causes dose-dependent inhibition of contractions elicited by repeated injections of oxytocin with ED50 = 3.5 mg/kg i.v. and 89 mg/kg p.o., respectively. Compound 1 significantly inhibits spontaneous uterine contractions in pregnant rats near term when administered intravenously or orally. We conclude that compound 1 is a potent, selective, and orally active nonpeptide oxytocin receptor antagonist, which is a suitable candidate for evaluation as a potential tocolytic agent for the management of preterm labor.     

Detection of SARS-CoV-2 and its S and N proteins using surface enhanced Raman spectroscopy

The COVID-19 pandemic demonstrated the critical need for accurate and rapid testing for virus detection. This need has generated a high number of new testing methods aimed at replacing RT-PCR, which is the golden standard for testing. Most of the testing techniques are based on biochemistry methods and require chemicals that are often expensive and the supply might become scarce in a large crisis. In the present paper we suggest the use of methods based on physics that leverage novel nanomaterials. We demonstrate that using Surface Enhanced Raman Spectroscopy (SERS) of virion particles a very distinct spectroscopic signature of the SARS-CoV-2 virus can be obtained. We demonstrate that the spectra are mainly composed by signals from the spike (S) and nucleocapsid (N) proteins. It is believed that a clinical test using SERS can be developed. The test will be fast, inexpensive, and reliable. It is also clear that SERS can be used for analysis of structural changes on the S and N proteins. This will be an example of application of nanotechnology and properties of nanoparticles for health and social related matters.

The COVID-19 pandemic demonstrated the critical need for accurate and rapid testing for virus detection.     

Stimulus-dependent modulation of [(3)H]norepinephrine release from rat neocortical slices by gabapentin and pregabalin

Gabapentin (GBP; Neurontin) has proven efficacy in several neurological and psychiatric disorders yet its mechanism of action remains elusive. This drug, and the related compounds pregabalin [PGB; CI-1008, S-(+)-3-isobutylgaba] and its enantiomer R-(-)-3-isobutylgaba, were tested in an in vitro superfusion model of stimulation-evoked neurotransmitter release using rat neocortical slices prelabeled with [(3)H]norepinephrine ([(3)H]NE). The variables addressed were stimulus type (i.e., electrical, K(+), veratridine) and intensity, concentration dependence, onset and reversibility of action, and commonality of mechanism. Both GBP and PGB inhibited electrically and K(+)-evoked [(3)H]NE release, but not that induced by veratridine. Inhibition by these drugs was most pronounced with the K(+) stimulus, allowing determination of concentration-effect relationships (viz., 25 mM K(+) stimulus: GBP IC(50) = 8.9 microM, PGB IC(50) = 11.8 microM). R-(-)-3-Isobutylgaba was less effective than PGB to decrease stimulation-evoked [(3)H]NE release. Other experiments with GBP demonstrated the dependence of [(3)H]NE release inhibition on optimal stimulus intensity. The inhibitory effect of GBP increased with longer slice exposure time before stimulation, and reversed upon washout. Combination experiments with GBP and PGB indicated a similar mechanism of action to inhibit K(+)-evoked [(3)H]NE release. GBP and PGB are concluded to act in a comparable, if not identical, manner to preferentially attenuate [(3)H]NE release evoked by stimuli effecting mild and prolonged depolarizations. This type of modulation of neurotransmitter release may be integral to the clinical pharmacology of these drugs.     

A MnO2–[Ru(dpp)3]Cl2 system for colorimetric and fluorimetric dual-readout detection of H2O2

Two-dimensional (2D) MnO₂ nanosheets were synthesized by a template-free and one-step route, and the dye [Ru(dpp)₃]Cl₂ was linked onto the MnO₂ nanosheet surface via electrostatic interaction. The formed MnO₂–[Ru(dpp)₃]Cl₂ hybrid was used for a dual optical detection for H₂O₂, an important reactive oxygen species (ROS). Upon addition of H₂O₂, the reaction of MnO₂ with H₂O₂ results in the dissolution of MnO₂ nanosheets and simultaneous generation of O₂. The fading of the solution and simultaneous fluorescence change of [Ru(dpp)₃]Cl₂, sensitive to O₂, enables colorimetric and fluorimetric dual-mode detection of H₂O₂. The dual-output assay in a single probe provides a good sensitivity with a detection limit of 0.18 μM H₂O₂. The dual-signal strategy can efficiently overcome the shortcoming of the single detection mode, and improve the detection accuracy by an additional correction of output signals from each other. Moreover, the successful determination of H₂O₂ in the serum samples demonstrates the potential applicability of the MnO₂–[Ru(dpp)₃]Cl₂ based probe in biosensing and bioanalysis.

The MnO₂ nanosheets with anchored [Ru(dpp)₃]Cl₂ were prepared for colorimetric and fluorimetric dual-mode detection of H₂O₂.     

Thermal and structural properties,and molecular dynamics in organic–inorganic hybrid perovskite (C2H5NH3)2ZnCl4

The thermal and structural properties and molecular dynamics of layered perovskite-type (C₂H₅NH₃)₂ZnCl₄ are investigated by differential scanning calorimetry, thermogravimetric analysis, and magic angle spinning nuclear magnetic resonance spectroscopy. The thermal properties and phase transitions are studied. Additionally, the Bloembergen–Purcell–Pound (BPP) curves for the ¹H spin–lattice relaxation time T_1ρ in the C₂H₅NH₃ cation and for the ¹³C T_1ρ in C₂H₅ are shown to have minima as a function of inverse temperature. This observation implies that these curves represent the rotational motions of ¹H and ¹³C in the C₂H₅NH₃ cation. The activation energies for ¹H and ¹³C in the C₂H₅NH₃ cation are obtained; the molecular motion of ¹H is enhanced at the C-end and N-end of the organic cation, and that at the carbons of the main chain is not as free as that for protons at the C-end and N-end.

The thermal and structural properties and molecular dynamics of layered perovskite-type (C₂H₅NH₃)₂ZnCl₄ are investigated by DSC, TGA, and MAS NMR spectroscopy.