Structural phase diagram for ZnS nanocrystalline thin films under swift heavy ion irradiation

The synthesis of nanocrystalline ZnS thin films by pulsed laser deposition and their modification by swift heavy ions are presented. The irradiations with 150 MeV Ni ions at fluences of 1×10¹¹, 1×10¹² and 1×10¹³ ions/cm² have been used for these studies. Irradiation results in structural phase transformation and bandgap modification of these films are investigated by using X-ray diffraction and UV-visible absorption measurements, respectively. Since stoichiometry changes induced by irradiation can contribute to the modification of these properties, elastic recoil detection analysis has been performed on pristine and 150 MeV Ni ions irradiated ZnS thin films using a 120 MeV Ag ion beam. The stoichiometry of the films has been found to be similar for pristine and ion irradiated samples. A structural phase diagram based on thermal and pressure spikes has been constructed to explain the structural phase transformation.     

Cloud Point Studies of Tween and Glycol in the Presence of Salts

This article deals with the cloud point studies of ethoxylated sorbitan ester, Tween in the presence of glycols, and salts. Cloud point temperature of Tween 20 (5 mol dm^?3) and Tween 80 (1 mol dm^?3) has been determined in the presence of various salts in addition to glycols. The glycols chosen for these studies were triethylene glycol (TEG), and ethylene glycol mono butylether (EGMBE). At concentration below 0.02 M these salts have no significant effect on cloud point temperature in all cases. The cloud point temperature of Tween+TEG and Tween+EGMBE found to decrease in the presence of sodium chloride (NaCl) and potassium chloride (KCl). The cloud point temperature of Tween 20 + TEG and Tween 20 + EGMBE found to increase in the presence of urea and nicotinamide. The change in cloud point was found to be more in case of nicotinamide as compare to urea. The influence of an additive on the cloud point depends on how it affects the intermicellar interactions. An effort has been made to understand the interaction between solvent and additives leading to a change in solubility of Tween.     

Polymeric stabilization of hybrid nanocomposites: a comparison between in situ and ex situ-grown CuInS2 in poly(3-hexylthiophene) polymer

CuInS₂ (CIS) particles were directly synthesized in P3HT matrix with different concentrations ratio of P3HT and CIS (1:2, 1:4, and 1:8) by decomposition of copper indium xanthate (CIX). Here, copper indium xanthate and P3HT were mixed homogeneously in o-dichlorobenzene (DCB), which induced the formation of the CIS nanoparticles by the thermal decomposition of the precursor compound in situ at temperatures as low as 110 °C. The effects of the precursor concentration on the size of the CIS nanoparticles was studied by microstructure investigations (TEM, AFM, XRD) and UV–vis measurements show that these CIS composites possess a direct bandgap energy higher than 1.45 eV depending on the concentration of P3HT. PL quenching of P3HT polymer (i.e., higher accessible fraction of fluorophores) was found to be more for in situ rather than ex situ conditions for comparable CIX concentrations or particle size. This can be attributed to the fact that in in situ synthesis, P3HT act as surface directing template for CIS nanoparticles which is not so in the case of ex situ synthesis. Due to this, the polymeric stabilization of the CIS nanocomposites is better realized for in situ synthesis as compared to ex situ synthesis.     

Synthesis and crystal structure of p-acylated calix[4]arene ethers

C-acylation of calix[n]arenes is an important reaction which has been primarily utilized for their further functionalization to provide conformers with varying shapes, cavity dimensions and molecular receptor characteristics that can bind ionic and neutral species in a selective and specific manner. The length of the alkyl chain at the upper or the lower rim of calixarenes can be adjusted as required to give derivatives which can span the channels and membranes and majorly influence transport phenomenon. As a part of our program to obtain calixarene based derivatives that can span and scan artificial membranes, C-acylation of calix[4]arene has been examined to yield peracylated and partially acylated calixarene ethers. 5,11,17,23-Tetraacetyl-25,26,27,28-tetramethoxycalix[4]arene has been obtained in 80 % yield by treatment of tetramethoxycalix[4]arene with acetyl chloride in the presence of aluminum chloride using dichloromethane as the solvent. The structure was established by the conversion to corresponding phenyl hydrazones and oximes. The tetraacetyltetramethoxycalix[4]arene 2a crystallized in a monoclinic lattice, space group P2₁/C with a = 10.320(2) Å, b = 18.928(4) Å, c = 18.421(4) Å, β = 95.44(3)^o, Z = 4. The corresponding methyl substituted O7 directs inwards towards the cavities of calix[4]arene to give an inward flattened partial cone conformation. Molecular packing shows the presence of intermolecular C–H···O, H-bonding interactions between methyl and methylene hydrogens and oxygens of the acetyl groups.     

Use of radiofrequency power to enable glow discharge optical emission spectroscopy ultrafast elemental mapping of combinatorial libraries with nonconductive components: nitrogen-based materials

Combinatorial chemistry and high-throughput techniques are an efficient way of exploring optimal values of elemental composition. Optimal composition can result in high performance in a sequence of material synthesis and characterization. Materials combinatorial libraries are typically encountered in the form of a thin film composition gradient which is produced by simultaneous material deposition on a substrate from two or more sources that are spatially separated and chemically different. Fast spatially resolved techniques are needed to characterize structure, composition, and relevant properties of these combinatorial screening samples. In this work, the capability of a glow discharge optical emission spectroscopy (GD-OES) elemental mapping system is extended to nitrogen-based combinatorial libraries with nonconductive components through the use of pulsed radiofrequency power. The effects of operating parameters of the glow discharge and detection system on the achievable spatial resolution were investigated as it is the first time that an rf source is coupled to a setup featuring a push-broom hyperspectral imaging system and a restrictive anode tube GD source. Spatial-resolution optimized conditions were then used to characterize an aluminum nitride/chromium nitride thin-film composition spread. Qualitative elemental maps could be obtained within 16.8 s, orders of magnitude faster than typical techniques. The use of certified reference materials allowed quantitative elemental analysis maps to be extracted from the emission intensity images. Moreover, the quantitative procedure allowed correcting for the inherent emission intensity inhomogeneity in GD-OES. The results are compared to quantitative depth profiles obtained with a commercial GD-OES instrument.     

Preferential recognition of zinc ions through a new anthraquinonoidal calix[4]arene

A novel anthraquinonoidal calix[4]arene derivative was designed and synthesized for the preferential recognition of biologically important zinc in preference to prominently similar cadmium ions and other metal ions via quenching of fluorescence intensity. The stoichiometry of host guest complexation has been determined to be 1:1. The fluorescence changes associated with the recognition event may be attributed to the interaction of zinc ions with the nitrogenous functionality attached at the lower rim of calix[4]arene cavity which allows spatial disposition of the anthraquinonoid segments.     

Simultaneous quantitative estimation of oxybenzone and 2-ethylhexyl-4-methoxycinnamate in sunscreen formulations by second order derivative spectrophotometry

Simultaneous determination of 2-ethylhexyl-4-methoxycinnamate (OMC) and oxybenzone (OB) in commercial sunscreen formulations has been achieved by using second order derivative spectrophotometry. The analytical methodology described does not require elaborate pretreatment of samples. The results obtained could be validated by reverse phase HPLC assay by using isocratic methanol: water (88: 12) solvent system. The sensitivity of the developed derivative spectrophotometry method was determined to be 9.0 × 10⁻³ L/mg for OB and 9.56 × 10⁻³ L/mg for OMC. The limit of instrumental detection (LOD) was determined to be 0.6 mg/L for OB and 1.38 mg/L for OMC with relative standard deviation of 0.001 and 0.004 for OB and OMC respectively. The method developed can be used for quick assay of commercial sunscreens. The article is published in the original.