No abstract

In recent times, SnSe has attracted considerable attention as an environmentally friendly alternative to cadmium-and lead-based photovoltaic materials. Herein, we report a rapid, facile, reproducible, and purely green method for the synthesis of SnSe nanosheets (NS) in an aqueous solution of bovine serum albumin (BSA). Interestingly, BSA itself acted as a reducing agent, stabilizing agent and shape directing template. Time dependent TEM imaging showed the self-assembly of the nanoparticles (NPs) into single crystalline NS. A probable mechanism has been proposed on the basis of the alteration of the intrinsic a-helix structure of BSA into b-pleated sheets at the pH ($3.0) of the reaction mixture. This directs the self-assembly of small SnSe NPs into the NS like structure. It was further evident that the -NH and the -S-S-linkages in the protein are involved in the functionalization of the NPs. As grown SnSe nanomaterial was found to display room temperature photoluminescence (PL), which has been rarely reported. The PL spectra appeared to be the convolution of two bands at 425 and 470 nm, which were attributed to the band-gap and trap/surface state emission, respectively. Moreover, the reduction potential values obtained from the cyclic voltammetry indicate better thermodynamic feasibility for the reduction of SnSe, while the cytotoxicity studies revealed no toxic effects up to a concentration of 100 mM. This signifies the potential application of these nanomaterials in photovoltaics and biomedical contexts.

The present study aims at the generation of a triblock copolymer vs sodium sulfate aqueous biphasic system (ABS), its application toward extraction of molybdenum species, and finally purification and regeneration of the block copolymer. The ABS was characterized for its biphasic region by constructing the phase diagram using turbidometric titration methods. Extractions were monitored using the spectrophotometric method directly in the block copolymer medium. Complete extraction of molybdenum species was observed in this method. Interference from other closely related metal ions in the extraction process was found to be negligible excepting oxo and polyoxometallates of vanadium and tungsten. Regeneration of the polymer was done using a thermoseparation technique followed by successive treatment with ion exchange resins. ∼87% of the pure triblock copolymer could be regenerated as a result of such treatment.

A pulse radiolysis study on pyrrolidinium cation based ionic liquids is presented herein. Time-resolved absorption spectra for 1-methyl-1-propylpyrrolidinium dicyanamide (DCA) at 500 ns after the electron pulse show broad absorption bands at wavelengths below 440 nm and at 640 nm. In pyrrolidinium bis(trifluoromethylsulfonyl)imide (NTf) and tris(perfluoroethyl)trifluorophosphate (FAP) ILs, the transient absorption below 440 nm is much weaker. The absorption at 500 ns, which increases with wavelength from 500 nm to beyond 800 nm, was assigned to the tail of the solvated electron NIR absorption spectrum, since it disappears in the presence of NO. In the DCA IL, the presence of a reducing species was confirmed by the formation of pyrene radical anion. The difference in the transient species in the case of the DCA IL compared to other two ILs should be due to the anion, with cations being similar. In pseudohalide ILs such as DCA, radicals are formed by direct hole trapping by the anion (X + h → X), followed by addition to the parent anion. Prediction of the UV/vis absorption spectra of the dimer radical anion by computational calculation supports the experimental results. The oxidizing efficiency of (DCA) and its reduction potential ( E) have been determined.

Non-toxic and photoluminescent (PL) tin oxide nanoparticle synthesis in Deep Eutectic Solvent (DES) is being reported herein. Both radiation (electron beam and γ radiation) as well as solvothermal methods were...

In view of potential biomedical application of the noble metal nanoparticles, we report a size controlled yet simple and green synthesis of resveratrol stabilized silver and gold nanoparticles having low polydispersity of size. Here, resveratrol plays two simultaneous roles, reducing the metal ions and providing efficient capping of the small nanoparticles. This gives rise to specific size of silver and gold nanoparticles at specific ratios of metal to resveratrol. The particles have been characterized by XRD and transmission electron microscopy. The nanoparticle sols are stable for months. The UV Visible absorption spectra of the silver sol show the plasmon peak of spherical nanoparticles, presence of which is further reflected in the TEM images. Size of the silver particles obtained is in between 11 to 21 nm depending on the ratio of resveratrol to metal ion used. Resveratrol capped silver nanoparticles exhibit high antibacterial activity against Gram negative wild type E coli BW (25113). The minimum inhibitory concentration (MIC) of nano-silver against the bacterium has been estimated to be 6.48 μg/ml, which is significantly lower than that reported in some earlier as well as recent publications. Reaction of gold ions with resveratrol, on the other hand, produces gold nanoparticles of sizes varying from 7 to 29 nm at different ratios of resveratrol to the metal ions. Particles with higher size and aspect ratio are formed at lower concentration of the capping agent whereas particles with very small size and pseudo-spherical morphology are formed at higher capping concentration. Difference in the formation kinetics of silver and gold nanoparticles has been attributed to the different growth mechanisms in the two cases. Possible modes of anchorage of resveratrol to silver nanoparticles have been investigated using surface enhanced resonance Raman spectroscopy (SERS) which shows that the silver nanoparticles are capped by resveratrol molecule primarily through O-Ag linkages of the p-OH aromatic ring. This, in turn, demonstrates the feasibility of using these nanoparticles as SERS templates.

No abstract

Porous SnSe nanoparticles have been synthesized in imidazolium based RTIL via electron beam irradiation. RTIL provides a stabilizing environment as well as an in situ source of reducing radicals for the reduction of precursors.