Torsional Dynamics of Thioflavin T in Room‐Temperature Ionic Liquids: An Effect of Heterogeneity of the Medium

The ultrafast excited‐state dynamics of a fibril binding dye, thioflavin T (ThT), has been studied in two room‐temperature ionic liquids (RTILs): 1‐Butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and methyltrioctylammonium bis(trifluoromethylsulfonyl)imide. Previously, in most studies, it was observed that the excited‐state dynamics of the ThT dye were dependent on the viscosity of the medium. In our study, by using RTILs, we have demonstrated that the excited‐state dynamics of ThT are not only viscosity dependent, but also dependent on the heterogeneous nature of the medium. The effect of structural heterogeneity present in neat RTILs on the excited‐state dynamics of ThT was observed. For both RTILs, excitation wavelength dependency on the emission properties of ThT was observed.     

Thiol‐Directed Synthesis of Highly Fluorescent Gold Clusters and Their Conversion into Stable Imaging Nanoprobes

Fluorescent gold clusters (FGCs) with tunable emission from blue to red and quantum yields in the range of 6–17 % have been synthesized by simple modification of the conditions used for the synthesis of gold nanoparticles, namely by replacing the stronger reducing agent with a controlled amount of thiol. Various functional FGCs with hydrodynamic diameters of 5–12 nm have been successfully synthesized and used as cell labels. The results of our investigations strongly indicate that FGCs composed of Au⁰ are more stable imaging probes than commonly reported red/NIR‐emitting FGCs with a composition of Au⁰/Au^I, as this combination rapidly transforms into nonfluorescent large clusters on exposure to light. The FGC‐based nanoprobes reported herein exhibit stable fluorescence upon continuous light exposure and can be used as imaging probes with low cytotoxicity.     

Binuclear oxovanadium(IV) complexes of phthalazine hydrazone ligands

Summary The oxovanadium(IV) complexes [(VOSO₄·H₂O)₂L] and [(VO)₂L¹(-SO₄)] (L = hydrazone ligands derived from 1,4-dihydrazinophthalazine and benzaldehyde, 4-chlorobenzaldehyde, 4-methoxybenzaldehyde or acetophenone; L ¹H₂ = hydrazone ligands derived from 1,4-dihydrazinophthalazine and salicylaldehyde, 2-hydroxyacetophenone or 2-hydroxynaphthaldehyde) have been prepared and characterized by elemental analyses, electrical conductance, magnetic moments and spectral data. Reduced magnetic moments are observed for all sulfato-bridged derivatives, indicating antiferromagnetically coupled vanadium(IV) centres. The vanadium(IV) centres appear to have five-coordinated stereochemistries in the systems which involve two metals bound to each ligand. The thermal behaviour of the complexes was investigated by t.g. and d.t.g. techniques. The antifungal and antiviral activities of the hydrazones and their corresponding complexes were also investigated. The screening results have been correlated with the structural features of the tested compounds.     

Optimal observable analysis for the decay $$b \rightarrow s$$ plus missing energy

The decay \(b\rightarrow s\nu {\bar{\nu }}\) has received comparatively less attention than the semileptonic decay \(b\rightarrow s\ell ^+\ell ^-\), because neutrinos pass undetected and hence the process offers lesser number of observables. We show how the decay \(b\rightarrow s~+\) invisible(s) can shed light, even with a limited number of observables, on possible new physics beyond the Standard Model and also show, quantitatively, the reach of future B factories like SuperBelle to uncover such new physics. Depending on the operator structure of new physics, different channels may act as the best possible probe. We show, using the optimal observable technique, how almost the entire parameter space allowed till now can successfully be probed at a high-luminosity B factory.     

Direct CO2 capture and conversion to fuels on magnesium nanoparticles under ambient conditions simply using water

Converting CO₂ directly from the air to fuel under ambient conditions is a huge challenge. Thus, there is an urgent need for CO₂ conversion protocols working at room temperature and atmospheric pressure, preferentially without any external energy input. Herein, we employ magnesium (nanoparticles and bulk), an inexpensive and the eighth-most abundant element, to convert CO₂ to methane, methanol and formic acid, using water as the sole hydrogen source. The conversion of CO₂ (pure, as well as directly from the air) took place within a few minutes at 300 K and 1 bar, and no external (thermal, photo, or electric) energy was required. Hydrogen was, however, the predominant product as the reaction of water with magnesium was favored over the reaction of CO₂ and water with magnesium. A unique cooperative action of Mg, basic magnesium carbonate, CO₂, and water enabled this CO₂ transformation. If any of the four components was missing, no CO₂ conversion took place. The reaction intermediates and the reaction pathway were identified by ¹³CO₂ isotopic labeling, powder X-ray diffraction (PXRD), nuclear magnetic resonance (NMR) and in situ attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and rationalized by density-functional theory (DFT) calculations. During CO₂ conversion, Mg was converted to magnesium hydroxide and carbonate, which may be regenerated. Our low-temperature experiments also indicate the future prospect of using this CO₂-to-fuel conversion process on the surface of Mars, where CO₂, water (ice), and magnesium are abundant. Thus, even though the overall process is non-catalytic, it could serve as a step towards a sustainable CO₂ utilization strategy as well as potentially being a first step towards a magnesium-driven civilization on Mars.

We demonstrated the use of magnesium nanoparticles (and bulk) to convert CO₂ (pure & also from the air) to methane, methanol, formic acid and green cement without external energy within a few minutes, using only water as the sole hydrogen source.     

Morphology and Electrical Conductivity of Poly(N‐vinylcarbazole)/Carbon Nanotubes Nanocomposite Synthesized by Solid State Polymerization

This communication describes the morphology and DC conductivity of poly(N‐vinylcarbazole) (PNVC)/multi‐walled carbon nanotubes (MWCNTs) nanocomposite. The nanocomposite has been synthesized by solid state in situ polymerization of N‐vinylcarbazole (NVC) monomer in the presence of MWCNTs at an elevated temperature. Fourier transform infrared (FT‐IR) spectroscopy studies reveal the ability of MWCNTs to promote the in situ polymerization of the NVC monomer. Field‐emission scanning electron microscopy (FE‐SEM) observations show the homogeneous wrapping of MWCNTs' outer surface by PNVC polymer. Transmission electron microscopy (TEM) images and Raman spectroscopy results support the SEM observations. Thermogravimetric analyses reveal a significant improvement of thermal stability of the nanocomposite sample in the higher temperature region. The resulting nanocomposite material exhibits a dramatic improvement of the DC conductivity inherent to the PNVC. For example, the DC conductivity increases from ≈5.9 × 10⁻¹³ S · cm⁻¹ for PNVC to ≈12 S · cm⁻¹ for the nanocomposite, an increase of about 10¹³ in the electrical conductivity.