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A novel rhodamine-tryptamine conjugate-based fluorescent and chromogenic chemosensor (RTS) for detection of Hg2+ present in water was reported. After gradual addition of Hg2+ in aqueous methanol solution of RTS, a strong orange fluorescence and deep-pink coloration were observed. The probe showed high selectivity towards Hg2+ compared to other competitive metal ions. The 1:1 binding stoichiometry between RTS and Hg2+ was established by Job's plot analysis and mass spectroscopy. Initial studies showed that the synthesized probe RTS possessed fair non-toxicity and effectively passed through cell walls of model cell systems, viz., human neuroblastoma (SHSY5Y) cells and cervical cells (HeLa) to detect intercellular Hg2+ ions, signifying its utility in biological system. The limit of detection (LOD) was found to be 2.1 nM or 0.42 ppb by fluorescence titration. Additionally, the potential relevance of synthesized chemosensor for detecting Hg2+ ions in environmental water samples has been demonstrated.ᅟ [ABSTRACT FROM AUTHOR]

A novel pyrrole fused coumarin based simple and practicable molecular probe has been synthesized under metal free green conditions which can recognize copper (II) in acetonitrile solvent. The synthesized probe displayed fluorescence quenching through selective binding with Cu 2+ over other competitive metal ions. Job’s plot, 1 H NMR titration and Mass spectral study revealed that the most abundant species formed when metal to ligand ratio was 1:1. The limit of detection (LOD) for Cu 2+ was found to be 11.3 nM or 2 ppb which is significantly lower than the maximum contaminant level (1.3 ppm of Cu), according to United State Environmental Protection Agency (USEPA). The fluorescent sensor was highly cell permeable and illustrated fluorescence ‘Turn-Off’ in presence of Cu 2+ ions in fluorescent imaging of human cervical cancer (HeLa) cell. [ABSTRACT FROM AUTHOR]

Abstract: An efficient and environmentally benign synthetic method has been developed for the library synthesis of biologically important multi‐functionalized isoindolo[2, 1‐a]quinazolines by two component domino condensation of 2‐carboxybenzaldehyde and 2‐aminobenzohydrazides/2‐aminobenzamides using graphene oxide (GO) as catalyst under solvent free conditions. The solvent‐free strategy exploiting inexpensive and eco‐compatible GO as mild carbocatalyst with large surface area is the major significant advantage of the present protocol. Furthermore, low catalyst loading, good to excellent yield of the products and easy recovery and recyclability of GO attribute considerable supremacy to the present protocol. [ABSTRACT FROM AUTHOR]

Herein, we are reporting a facile route to synthesize magnetically separable Cu nanoparticle loaded CoFe 2 O 4 @SBA15 catalysts, which exhibits high catalytic activity towards (i) reduction of various synthetic dyes, trifluralin, (ii) synthesis of DHPMs via Biginelli reaction pathway in solventless condition and (iii) 1,2,3-triazole derivatives by ‘Click reaction’ in aqueous medium. To the best of our knowledge, this is the first time one single catalyst is reported which shows its high activity for these three important reactions. [ABSTRACT FROM AUTHOR]

In this paper, we report a simple aqueous solution based chemical method for preparation of Cu nanoparticle loaded mesoporous silica SBA-15 (Cu@SBA-15) catalysts. Synthesized catalysts were characterized by powder X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscope (HRTEM), N 2 adsorption–desorption surface area and pore size analyzer, and particle size analyzer. Catalytic activity of Cu nanoparticle loaded SBA-15 towards reduction of various dyes, such as 4-nitrophenol, Methyl Orange, Congo Red, Rhodamine B, Methylene Blue and mixture of dyes were investigated in the presence of excess NaBH 4 . Catalysis reactions were monitored by employing UV–vis spectroscopy. Catalysis reactions followed pseudo-first order rate equation. These catalysts exhibited excellent catalytic activity and convenient recycling. The high catalytic activity, cost effectiveness and simple preparation methodology make 12.5Cu@SBA-15 an attractive catalyst for decolorization of organic dyes. [ABSTRACT FROM AUTHOR]

In this paper, we report a simple but novel aqueous solution based ‘one-pot’ method for preparation of (Ni 0.65 Zn 0.35 Fe 2 O 4 ) x –(BaFe 12 O 19 ) 1 − x nanocomposites consisting of hard ferrite–soft ferrite phases. Nanocomposites, having same compositions, have also been prepared by employing a physical mixing method. X-ray diffraction analysis showed the presence of nanocrystalline Ni 0.65 Zn 0.35 Fe 2 O 4 and BaFe 12 O 19 phases in the composites, prepared by both methods. However, transmission electron microscopic and scanning electron microscopic analysis revealed that, nanocomposites, prepared by one-pot method, possessed better homogeneous intimacy of Ni 0.65 Zn 0.35 Fe 2 O 4 and BaFe 12 O 19 phases than that of the nanocomposites, prepared by physical mixing method. Nanocomposites, prepared by one-pot method, have shown magnetically single phase behaviour with good spring exchange coupling interaction between hard and soft ferrite phases. These composites possessed enhanced magnetic properties with high saturation magnetization as well as high coercivity. These nanocomposites also exhibited very good microwave absorption properties in the X-band region. Composite having composition (Ni 0.65 Zn 0.35 Fe 2 O 4 ) 0.85 –(BaFe 12 O 19 ) 0.15 showed the minimum reflection loss of ~− 21 dB (> 99% absorption) at 9.86 GHz for absorber thickness of 3.05 mm. Magnetic and microwave absorption properties of the nanocomposites, prepared by one-pot method, were found be superior to those of the nanocomposites prepared by physical mixing method as well as pure Ni 0.65 Zn 0.35 Fe 2 O 4 and BaFe 12 O 19 nanoparticles. [ABSTRACT FROM AUTHOR]

A magnetically separable core–shell CoFe2O4@SiO2‐SO3H nanocatalyst has been successfully exploited as a heterogeneous acid catalyst in the synthesis of diversely substituted biologically important spiro fused pyrrolo/indolo[1,2‐a]quinoxaline derivatives through the condensation of N‐(2‐aminophenyl)pyrroles/indoles and various cyclic conjugated 1,2‐diones in ethanol under ultrasonic irradiation. Room temperature synthesis, short reaction time, wide substrate scope, good to excellent yield of products and use of a magnetically separable and recyclable nanocatalyst make this method attractive and practicable. A magnetically separable CoFe2O4@SiO2‐SO3H nanocatalyst having core–shell morphology has been employed for the very first time in a benign strategy to synthesize a series of novel spiro fused quinoxaline derivatives under ultrasonic irradiation. Spiro fused quinoxaline derivatives derived from acenaphthoquinone, 9,10‐phenanthroquinone and [1,2]benzoquinone are reported. Room temperature synthesis, shorter reaction time, wide substrate scope, good to excellent yield and use of a magnetically separable and recyclable nanocatalyst make this synthetic protocol attractive. [ABSTRACT FROM AUTHOR]

Biogenic synthesis of gold nanoparticles have been accomplished using dried biomass of two high altitude lichen species, collected from the alpine region of Eastern Himalaya in Arunachal Pradesh state of North East India, without addition of any external reducing or stabilizing chemicals. The nanoparticles were characterised by UV–visible, FT-IR spectroscopy, powder X-ray diffraction (XRD), and transmission electron microscopy (TEM). The as-obtained gold nanoparticles showed surface plasmon resonance (SPR) band at ~535 nm. The XRD study furnished evidence for the formation of face-centered cubic structure of gold nanomaterials. The nanoparticles produced with Acroscyphus sp. consisted of multiply twinned quasi-spherical and prismatic shapes while those accessed with Sticta sp. are exclusively multiply twinned. The biomatrix loaded gold nanomaterial exhibited pronounced antioxidant activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Industrial scale adopted chemical method used for preparation of Sn doped CeO 2. • Sn-CeO 2 /GCE electrode demonstrated as an excellent electrocatalytic oxidation of nitrite (NO 2 –) • The remarkable sensitivities of nitrite found that 245.4 µA cm−2 mM−1 and 89.53 µA cm−2 mM−1. • The limit of detection (LOD) towards nitrite ion sensing was found to be 16 nM. Development of novel electrode materials for sensing water pollutant like nitrite, nitrate, paramedical pollutants and fertilizers is a more promising research area in electrochemical sensor field. Various pure as well as doped metal oxides were used as electrodes for sensing the water pollutants but, deficits in stability, reproducibility and real time analysis. In the present work, a promising Sn-doped CeO 2 based sensor was fabricated for sensing nitrite in water. A selective concentration of Sn (5%) doped CeO 2 nanoparticles were synthesized by facile chemical precipitation method. The structural, optical and morphological information were studied using various techniques. The morphological of the sample was revealed an agglomerated with spherical nanoparticles with size of 8.5 nm. The synergistic effect of Sn-CeO 2 /GCE improves the electrochemical behavior of nitrite on the modified surface. Sn-doped CeO 2 nanoparticles has a better surface property and provides a more fine-grained media to facilitate electron transfer during the reaction between analyte and electrode. The Sn-CeO 2 /GCE electrode possesses excellent electrocatalytic oxidation of nitrite (NO 2 –) which was investigated by cyclic voltammetry (CV) and amperometry techniques. The remarkable sensitivities of nitrite were found that 245.4 µA cm−2 mM−1 and 89.53 µA cm−2 mM−1 with R2 = 0.999 and RSD of ∼ 6%. Similarly, the limit of detection (LOD) towards nitrite ion sensing was found to be 16 nM. The real time application of Sn-CeO 2 /GCE sensor was demonstrated by the detection of nitrite present in environmental water samples with excellent recoveries. Hence, Sn-doped CeO 2 modified electrode also demonstrates good reproducibility, long time stability, and excellent selectivity properties. Thus, a developed electrochemical sensor possesses a novel promise for the construction of simple and sensitive nitrite analytical stage. [ABSTRACT FROM AUTHOR]