A noble bimetal oxysulfide CuVOS catalyst for highly efficient catalytic reduction of 4-nitrophenol and organic dyes

A novel copper–vanadium bimetallic oxysulfide (CuVOS) nanoparticle catalyst was successfully synthesized by a facile method. The samples were characterized by X-ray photoelectron spectrometry (XPS), X-ray diffractometry (XRD), field-emission scanning electron microscopy (FE-SEM), UV-Vis diffuse spectroscopy (DRS), Fourier transform infrared spectroscopy (FTIR), and N₂ adsorption–desorption isotherms. In order to check the catalytic efficiencies toward reduction reaction, 4-nitrophenol (4-NP) and other organic dyes such as rhodamine-B (RhB), methylene blue (MB), and methyl orange (MO) were used. The results showed that the CuVOS prepared in the presence of a suitable amount of N₂H₄ during the synthesis of the nanoparticles exhibited the fastest reduction capabilities by using NaBH₄ as a reducing agent. It was demonstrated that a 100 mL 4-NP (20 ppm) solution was completely reduced by 5 mg CuVOS-3 within 2 min. Moreover, the complete reduction of 100 mL of MO, RhB, and MB solutions of 100 ppm was also achieved by 5 mg CuVOS-3 within 2 min, 6 min, and 5 min, respectively. Hence, the CuVOS is an efficient catalyst for reducing 4-NP and organic dyes and can have great potential for industrial application.

A novel CuVOS catalyst was successfully synthesized by a facile method. The CuVOS with optimum amount of N₂H₄ had higher catalytic activity.     

Formation of submicron-sized silica patterns on flexible polymer substrates based on vacuum ultraviolet photo-oxidation

Formation of precise and high-resolution silica micropatterns on polymer substrates is of importance in surface structuring for flexible device fabrication of optics, microelectronic, and biotechnology. To achieve that, substrates modified with affinity-patterns serve as a strategy for site-selective deposition. In the present paper, vacuum ultraviolet (VUV) treatment is utilized to achieve spatially-controlled surface functionalization on a cyclo-olefin polymer (COP) substrate. An organosilane, 2,4,6,8-tetramethylcyclotetrasiloxane (TMCTS), preferentially deposits on the functionalized regions. Well-defined patterns of TMCTS are formed with a minimum feature of ∼500 nm. The secondary VUV/(O)-treatment converts TMCTS into SiO_x, meanwhile etches the bare COP surface, forming patterned SiO_x/COP microstructures with an average height of ∼150 nm. The resulting SiO_x patterns retain a good copy of TMCTS patterns, which are also consistent with the patterns of photomask used in polymer affinity-patterning. The high quality SiO_x patterns are of interests in microdevice fabrication, and the hydrophilicity contrast and adjustable heights reveal their potential application as a “stamp” for microcontact printing (μCP) techniques.

Patterned surface treatment on a polymer substrate is carried out by 172 nm VUV through a photomask. TMCTS pattern formation is guided by the resulting affinity-pattern. The secondary VUV treatment converted TMCTS patterns into silica patterns.     

Critical role of the endogenous interferon ligand–receptors in type I and type II interferons response

Separate ligand–receptor paradigms are commonly used for each type of interferon (IFN). However, accumulating evidence suggests that type I and type II IFNs may not be restricted to independent pathways. Using different cell types deficient in IFNAR1, IFNAR2, IFNGR1, IFNGR2 and IFN‐γ, we evaluated the contribution of each element of the IFN system to the activity of type I and type II IFNs. We show that deficiency in IFNAR1 or IFNAR2 is associated with impairment of type II IFN activity. This impairment, presumably resulting from the disruption of the ligand–receptor complex, is obtained in all cell types tested. However, deficiency of IFNGR1, IFNGR2 or IFN‐γ was associated with an impairment of type I IFN activity in spleen cells only, correlating with the constitutive expression of type II IFN (IFN‐γ) observed on those cells. Therefore, in vitro the constitutive expression of both the receptors and the ligands of type I or type II IFN is critical for the enhancement of the IFN activity. Any IFN deficiency can totally or partially impair IFN activity, suggesting the importance of type I and type II IFN interactions. Taken together, our results suggest that type I and type II IFNs may regulate biological activities through distinct as well as common IFN receptor complexes.     

Mesoporous PbO nanoparticle-catalyzed synthesis of arylbenzodioxy xanthenedione scaffolds under solvent-free conditions in a ball mill

A protocol for the efficient synthesis of arylbenzodioxy xanthenedione scaffolds was developed via a one-pot multi-component reaction of aromatic aldehydes, 2-hydroxy-1,4-naphthoquinone, and 3,4-methylenedioxy phenol using mesoporous PbO nanoparticles (NPs) as a catalyst under ball milling conditions. The synthesis protocol offers outstanding advantages, including short reaction time (60 min), excellent yields of the products (92–97%), solvent-free conditions, use of mild and reusable PbO NPs as a catalyst, simple purification of the products by recrystallization, and finally, the use of a green process of dry ball milling.

An efficient one-pot multicomponent protocol was developed for the synthesis of arylbenzodioxy xanthenedione scaffolds using mesoporous PbO nanoparticles as reusable catalyst under solvent-free ball milling conditions.

Recently, the ball milling technique has received great attention as an environmentally benign strategy in the context of green organic synthesis.^1a The process of “ball milling” has been developed by adding mechanical grinding to the mixer or shaker mills. The ball milling generates a mechanochemical energy, which promotes the rupture and formation of the chemical bonds in organic transformations.^1b Subsequently, detailed literature^1c and books on this novel matter have been published.^2a,b Several typical examples include carbon–carbon and carbon–heteroatom bond formation,^2c organocatalytic reactions,^2d oxidation by using solid oxidants,^2e dehydrogenative coupling, asymmetric, and peptide or polymeric material synthesis, which have been reported under ball milling conditions.^2e Hence, the organic reactions using ball milling activation carried out under neat reaction environments, exhibit major advantages,^2f including short reaction time, lower energy consumption, quantitatively high yields and superior safety with the prospective for more improvement than the additional solvent-free conditions and clear-cut work-up.^3–5On the other hand, the organic transformations using metal and metal oxide nanoparticles⁶ are attracting enormous interest due to the unique and interesting properties of the NPs.^7,8,9a Particularly, PbO NPs^9b provide higher selectivity in some organic reactions^9c and find applications in various organic reactions, like Paal–Knorr reaction,¹⁰ synthesis of diethyl carbonate,¹¹ phthalazinediones,¹² disproportionation of methyl phenyl carbonate to synthesize diphenyl carbonate,¹³ the capping agent in organic synthesis, and selective conversion of methanol to propylene.¹⁴ In addition, the PbO NPs are also used in many industrial materials.^15,16However, till date, PbO NPs have not been explored in MCRs leading to biologically important scaffolds. Among others, the xanthene scaffolds¹⁷ are one of the important heterocyclic compounds¹⁸ and are extensively used as dyes, fluorescent ingredients for visual imaging of the bio-molecules, and in optical device technology because of their valuable chemical properties.¹⁹ The xanthene molecules have conjointly been expressed for their antibacterial activity,²⁰ photodynamic medical care, anti-inflammatory drug impact, and antiviral activity. Because of their various applications, the synthesis of these compounds has received a great deal of attention.²¹ Similarly, vitamin K nucleus^22,23 shows a broad spectrum of biological properties, like anti-inflammatory, antiviral, antiproliferative, antifungal, antibiotic, and antipyretic.^24a As a consequence, a variety of strategies^24b have been demonstrated in the literature for the synthesis of xanthenes and their keto derivatives, like rhodomyrtosone-B,^25a rhodomyrtosone-I,^25b and BF-6 ^25c as well as their connected bioactive moieties. Few biologically active xanthene scaffolds are shown in (Fig. 1).Open in a separate windowFig. 1Some biologically important xanthenes and their keto derivatives.Due to the significance of these compounds, the synthesis of xanthenes and their keto derivatives using green protocols is highly desirable. Reported studies reveal that these scaffolds are synthesized by three-component condensations using p-TSA²⁶ and scolecite²⁷ as catalysts. However, these methods suffer from the use of toxic acidic catalysts like p-TSA, long reaction times (3 h), harsh refluxing²⁶ or microwave reaction conditions,²⁷ and tedious work-up procedures. The previously reported methods for the synthesis of xanthenediones are shown in Scheme 1.Open in a separate windowScheme 1Previous protocol for the synthesis of xanthenedione derivatives.Herein, we report an economical and facile multicomponent protocol, using ball milling, for the synthesis of 7-aryl-6H-benzo[H][1,3]dioxolo[4,5-b]xanthene-5,6(7H)-dione using PbO NPs as a heterogeneous catalyst (Scheme 2). The PbO NPs are non-corrosive, inexpensive, and easily accessible.Open in a separate windowScheme 2General reaction scheme of PbO NP-catalyzed synthesis of the xanthenedione scaffolds under ball milling conditions.In our protocol,²⁸ the PbO NPs were initially prepared by mixing sodium dodecyl sulphate (2.5 mmol) and sodium hydroxide (10 mL, 0.1 N) with an aqueous methanolic solution of lead nitrate (2 mmol) under magnetic stirring at 30 °C by continuing the reaction for 2 h. Then, the obtained white polycrystalline product was filtered, washed with H₂O, and dried at 120 °C, followed by calcination at 650 °C for 2 h. During this step, the white PbO NPs turned pale yellow in colour. Eventually, the synthesized PbO was then characterized by spectroscopic and analytical techniques.The powder X-ray diffraction (XRD) pattern revealed the crystalline nature of the PbO NPs as the diffraction peaks corresponding to (131), (311), (222), (022), (210), (200), (002), and (111) crystal planes were identified (Fig. 2). The XRD outline of the synthesized PbO NPs was further established for the formation of space group Pca2₁ ²⁹ with a single orthorhombic structure (JCPDS card number 76-1796). The sharp diffraction peaks indicated good crystallinity, and the average particle size of the PbO NPs was estimated to be 69 nm, as calculated using the Debye–Scherer equation.Open in a separate windowFig. 2The powder XRD pattern of PbO NPs.The surface morphology of the PbO NPs was analyzed by scanning electron microscopy (SEM), and the SEM image revealed the discrete and spongy appearance of the PbO NPs (Fig. 3).Open in a separate windowFig. 3The SEM image of PbO NPs.Moreover, the elemental composition obtained from energy dispersive X-ray (EDX) analysis confirmed that the material contains Pb and O elements, and no other impurity was present (Fig. 4).Open in a separate windowFig. 4The EDAX spectrum of crystalline PbO NPs.The transmission electron microscopy (TEM) image shown in Fig. 5 indicated the formation of orthorhombic crystallites of PbO with several hexagon-shaped particles. The dark spot in the TEM micrograph further confirmed the synthesis of PbO NPs, as the selected area diffraction pattern associated with such spots reveals the occurrence of the PbO NPs in total agreement with the X-ray diffraction data (Fig. 6). The average size of the PbO nanocrystals by TEM was approximated to be around 20 nm.Open in a separate windowFig. 5The TEM image of nanocrystalline PbO NPs.Open in a separate windowFig. 6The SAED image of nanocrystalline PbO NPs.The Fourier transform infrared (FT-IR) spectrum (ESI, S6^†) of the PbO NPs displayed peaks at 575, 641, and 848 cm⁻¹, which corresponds to the Pb–O vibrations. Furthermore, the absorption band at ∼3315 cm⁻¹ was due to the presence of the hydroxyl group (–OH) in the NPs.The N₂ adsorption–desorption isotherms of the PbO nanoparticles shown in Fig. 7 was consistent with type IV adsorption–desorption isotherms with H1 hysteresis corresponding to the cylindrical mesoporous structure. Moreover, the surface area, pore-volume, and BJH pore diameter were found to be 32.0 m² g⁻¹, 0.023 cm³ g⁻¹, and 30.9 Å, respectively.Open in a separate windowFig. 7BET surface area and pore size of nanocrystalline PbO catalyst.The catalytic activity of the synthesized PbO NPs was tested in a one-pot multicomponent synthesis of arylbenzodioxoloyl xanthenedione derivative under ball milling condition according to the reaction scheme 2a, with 3,4-dimethoxybenzaldehyde (166.2 mg, 1.0 mmol), 3,4-methylenedioxyphenol (138.0 mg, 1.0 mmol), and 2-hydroxy-1,4-naphthoquinone (174.0 mg, 1.0 mmol) as reactants. The reaction conditions, the ball milling parameters (speed, time, and ball to solids ratio), and the PbO nanocatalyst amount were first optimized to produce the highest yield using experimental design as shown in

Are radio‐contrast agents commonly used in discography toxic to the intact intervertebral disc tissue cells?

In the literature, there have been no studies showing clear results on how radio‐contrast pharmaceuticals would affect intact disc tissue cells. In this context, it was aimed to evaluate the effects of iopromide and gadoxetic acid, frequently used in the discography, on intact lumbar disc tissue in pharmaco‐molecular and histopathological level. Primary cell cultures were prepared from the healthy disc tissue of the patients operated in the neurosurgery clinic. Except for the control group, the cultures were incubated with the indicated radio‐contrast agents. Cell viability, toxicity and proliferation indices were tested at specific time intervals. The cell viability was quantitatively analysed. It was also visually rechecked under a fluorescence microscope with acridine orange/propidium iodide staining. Simultaneously, cell surface morphology was analysed with an inverted light microscope, while haematoxylin and eosin (H&E) staining methodology was used in the histopathological evaluations. The obtained data were evaluated statistically. Unlike the literature, iopromide or gadoxetic acid did not have any adverse effects on the cell viability, proliferation and toxicity (P < 0.05). Although this study reveals that radio‐contrast pharmaceuticals used in the discography, often used in neurosurgical practice, can be safely used, it should be remembered that this study was performed in an in vitro environment.     

Synthesis and anti‐inflammatory activity of diversified heterocyclic systems

In continuation with our research program on the development of novel bioactive molecules, we report herein the design and synthesis of a series of diversified heterocycles ( 4 – 22 ). The synthesized compounds were evaluated for their anti‐inflammatory activity. The chemical structures of the newly synthesized compounds have been confirmed by NMR, FTIR, and microanalysis.