Insight into the Effect of Stabilizers on Anticancer and Antibacterial Activity of AgBiS2 Nanomaterial.

The near-infrared (NIR) light-absorbing AgBiS2 nanoparticles can be excited by single-wavelength light, which is the primary characteristic of a photo responsive platform. Chemical synthesis of nanomaterials inevitably requires long-chain organic surfactants or polymers to stabilize them in the nano regime. These stabilizing molecules barricade the interaction of nanomaterials with biological cells. We have produced stabilizer-free (sf-AgBiS2 ) and polymer-coated (PEG-AgBiS2 ) nanoparticles; and assessed their NIR mediated anticancer and antibacterial activity to evaluate the effect of stabilizers. sf-AgBiS2 showed better antibacterial activity against Gram-positive Staphylococcus aureus (S. aureus) and displayed excellent cytotoxicity against HeLa cells and live 3-D tumour spheroids compared to PEG-AgBiS2 both in presence and absence of NIR radiation. The photothermal therapy (PTT) results illustrated the tumour ablation ability of sf-AgBiS2 , which converted light into heat effectively up to 53.3 °C under NIR irradiation. This work demonstrates the importance of synthesizing stabilizer-free nanoparticles to produce safe and highly active PTT agents.

Template free-synthesis of cobalt-iron chalcogenides [Co0.8Fe0.2L2, L = S, Se] and their robust bifunctional electrocatalysis for the water splitting reaction and Cr(vi) reduction.

The ease of production of materials and showing multiple applications are appealing in this modern era of advanced technology. This paper reports the synthesis of a pair of novel cobalt-iron chalcogenides [Co0.8Fe0.2S2 and Co0.8Fe0.2Se2] with enhanced electro catalytic activities. These ternary metal chalcogenides were synthesized by a one-step template-free approach via a hexamethyldisilazane (HMDS)-assisted synthetic method. Transient photocurrent (TPC) studies and electrochemical impedance spectra (EIS) of these materials showed free electron mobility. Their bifunctional activities were verified in both the electrochemical oxygen evolution reaction (OER) and in the electrochemical reduction of toxic inorganic heavy metal ions [Cr(vi)] in polluted water. The materials showed robust catalytic ability in the oxygen evolution reaction with minimum possible over potential (345 and 350 mV @ η10) as determined by linear sweep voltammetry and the lower Tafel values (52.4 and 84.5 mV dec-1) for Co0.8Fe0.2Se2 and Co0.8Fe0.2S2 respectively. Surprisingly, both the materials also showed an excellent activity towards electrochemical Cr(vi) reduction to Cr(iii). Besides the maximum current achieved for Co0.8Fe0.2S2, a minimum value for the Limit of detection (LOD) was obtained for Co0.8Fe0.2S2 (0.159 µg L-1) compared to Co0.8Fe0.2Se2 (0.196 µg L-1). We tested the durability of catalysts, the critical factor for the prolonged use of catalysts, through the recyclability measurements of these materials as catalysts. Both the catalysts presented outstanding durability and balanced electro catalytic activities for up to 1500 CV cycles, and chronoamperometry studies also confirmed exceptional stability. The enhanced catalytic activities of these materials are ascribed to the free electron movement, evidenced by the increased TPC measured and EIS. Therefore, the template-free synthesis of these electro catalysts containing non-noble metal illustrates the practical approach to develop such types of catalysts for multiple functions.

Impact of bandgap tuning on ZnS for degradation of environmental pollutants and disinfection.

The materials showing multiple applications are appealing for their practical use and industrial production. To realize the suitable property for various applications, we have produced ZnS (sf-ZnS) and metal-doped ZnS nanoflakes (sf-m-ZnS; where m = Cu, Ni, Cd, Bi, or Mn) and correlated their activity with bandgap variation. We obtained all these materials via hexamethyldisilazane (HMDS)-assisted synthetic method without using any surfactants, polymers, or template molecules and characterized them thoroughly using various techniques. Photocatalytic, as well as antibacterial, activities of these materials showed their bifunctional utility. We have demonstrated the effect of doping and consequent extension of absorption band to the visible region and resultant improved photocatalytic activity under sunlight. Thus, the change in bandgap influenced their performance as photocatalysts. Among all materials produced, sf-Cd-ZnS provided superior results as a photocatalyst while degrading two organic pollutants-rhodamine B (RhB) and methylene blue (MB) in water. The antibacterial activity of sf-ZnS and sf-m-ZnS against Gram-positive bacteria, i.e., Staphylococcus aureus (S. aureus), was examined by the zone of inhibition method, wherein sf-Ni-ZnS showed maximum activity. The enhanced activity of these ZnS materials can be attributed to the free surface of nanoparticles without any capping by organic molecules, which provided an intimate interaction of inorganic semiconductor material with organic and biomolecules. Thus, we have demonstrated modification of properties both by bandgap tuning of materials and providing the opportunity for intimate interaction of materials with substrates. The photocatalytic activity and antibacterial action of metal-doped ZnS produced by our method exhibited their potential for environmental remediation, specifically water purification.

Importance of Clean Surfaces on the Catalyst: SnS2 Nanorings for Environmental Remediation.

The focus of the work is the synthesis of SnS2 nanomaterials with (peg-SnS2NF) and without (sf-SnS2NR) the involvement of the organic template and the comparative study of their catalytic activities. The synthesis of these materials was achieved in a single-step procedure aided by hexamethyldisilazane (HMDS). These nanoparticles were subjected to X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, and UV-vis spectroscopy analyses to investigate their structural, topographical, surface, and optical properties. The present work suggests that the surfactant-free SnS2 nanoring (sf-SnS2NR) catalyst has lower surface area compared to the poly(ethylene glycol)-stabilized SnS2 nanoflower (peg-SnS2NF) catalyst but shows high activity under visible light for the photoreduction of Cr(VI) and the photocatalytic degradation of organic dyes. The work exposed the importance of the clean surfaces on the catalyst and is expected to have a high impact on the photocatalytic activity of the SnS2 nanomaterial. The study also endorses the utility of the HMDS-assisted synthetic method for the production of multifunctional semiconductor tin disulfide nanomaterials with multiple potential applications.

Syntheses, characterization and energetic properties of closo-(B12H12)2- salts of imidazolium derivatives.

The diimidazolium derivative of acetylene and its salt 3,3'-(but-2-yne-1,4-diyl)bis(1-methyl-1H-imidazol-3-ium)chloride (1) was synthesized by a solvent free sonochemical method and then the counter chloride ions were replaced by closo-dodecaborate [(B12H12)(2-)] and perchlorate (ClO4(-)) anions respectively. Along with these two ionic salts, a series of salts with closo-dodecaborate and alkyl imidazolium cations were also synthesized. All the compounds were characterized by NMR and MASS spectral data, elemental analyses and thermogravimetric analyses. In addition to that enthalpy of combustion, enthalpy of formation and heat of explosion of all the compounds were experimentally determined. Based on the properties of these compounds, they can be used as insensitive energetic materials in various fields in propellant research and technology such as solid rocket propellants and burn rate accelerators.

Single-pot synthesis of zinc nanoparticles, borane (BH3) and closo-dodecaborate (B12H12)(2-) using LiBH4 under mild conditions.

Reduction of ZnCl2 using LiBH4 in mesitylene yielded zinc nanoparticles (Zn-NPs), borane (BH3) and closo-dodecaborate (B12H12)(2-). The BH3 evolved gas was trapped as Ph3P:BH3 adduct while closo-(B12H12)(2-) was extracted by methanol and characterized from spectral data.

Tetraanionic nitrogen-rich tetrazole-based energetic salts.

1,1,3,3-Tetra(1H-tetrazol-5-yl)propane-based energetic salts were synthesized in a simple and straightforward manner. The structures of these new salts were determined by (1)H and (13)C NMR spectroscopy, IR spectroscopy, MS, and elemental analysis. All of these compounds showed good thermal stabilities above 180 °C, as confirmed by thermogravimetric-differential thermal analysis (TG-DTA) measurements. Moreover, these salts also exhibited high positive enthalpies of formation, high nitrogen content, good thermal stabilities, and moderate detonation properties.

Zn(II), Cd(II) and Cu(II) complexes of 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrole: synthesis, structures and their high catalytic activity for efficient cyclic carbonate synthesis.

The syntheses of Zn(II), Cd(II) and Cu(II) complexes of 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrole (DIP(2)pyr)H 1 and their catalytic activities in CO(2) fixation are reported. The structures of these complexes were characterized by IR, (1)H, (13)C NMR and single crystal X-ray diffraction techniques. The catalytic activities of these complexes for the cycloaddition of CO(2) to an epoxide under one atmosphere of pressure and mild temperature conditions to yield cyclic carbonate have been studied. Among the four complexes synthesized, the Zn(II) and Cu(II) complexes were found to be versatile whereas the Cu(II) complex was more selective in the conversion. They were highly effective for the conversion of monosubstituted terminal epoxides, disubstituted terminal and internal epoxides to their corresponding cyclic carbonates with good to high yields.

Synthesis of amino, azido, nitro, and nitrogen-rich azole-substituted derivatives of 1H-benzotriazole for high-energy materials applications.

The amino, azido, nitro, and nitrogen-rich azole substituted derivatives of 1H-benzotriazole have been synthesized for energetic material applications. The synthesized compounds were fully characterized by (1)H and (13)C NMR spectroscopy, IR, MS, and elemental analysis. 5-Chloro-4-nitro-1H-benzo[1,2,3]triazole (2) and 5-azido-4,6-dinitro-1H-benzo[1,2,3]triazole (7) crystallize in the Pca2(1) (orthorhombic) and P2(1)/c (monoclinic) space group, respectively, as determined by single-crystal X-ray diffraction. Their densities are 1.71 and 1.77 g cm(-3), respectively. The calculated densities of the other compounds range between 1.61 and 1.98 g cm(-3). The detonation velocity (D) values calculated for these synthesized compounds range from 5.45 to 8.06 km s(-1), and the detonation pressure (P) ranges from 12.35 to 28 GPa.

Anatase-brookite mixed phase nano TiO2 catalyzed homolytic decomposition of ammonium nitrate.

Compared to the conventional ammonium perchlorate based solid rocket propellants, burning of ammonium nitrate (AN) based propellants produce environmentally innocuous combustion gases. Application of AN as propellant oxidizer is restricted due to low reactivity and low energetics besides its near room temperature polymorphic phase transition. In the present study, anatase-brookite mixed phase TiO(2) nanoparticles (~ 10 nm) are synthesized and used as catalyst to enhance the reactivity of the environmental friendly propellant oxidizer ammonium nitrate. The activation energy required for the decomposition reactions, computed by differential and non-linear integral isoconversional methods are used to establish the catalytic activity. Presumably, the removal of NH(3) and H(2)O, known inhibitors of ammonium nitrate decomposition reaction, due to the surface reactions on active surface of TiO(2) changes the decomposition pathway and thereby the reactivity.

Solution phase chemical synthesis of nano aluminium particles stabilized in poly(vinylpyrrolidone) and poly(methylmethacrylate) matrices.

The reduction of aluminium trichloride by lithium aluminium hydride in the presence of poly(vinylpyrrolidone) or poly(methylmethacrylate) in mesitylene yielded nano aluminium particles in the matrices of respective polymers. Solution phase synthesis methodology was used successfully to produce composites of various Al/polymer ratios. The composites were characterized by powder XRD patterns and 27Al-NMR with MAS spectroscopic study. The method was useful to produce up to 10 g of nano aluminium that were pure and stable.