Current Physical Chemistry - Volume 9, Issue 2, 2019

Aim: To synthesize biocompatible nanoparticles of FAp co-doped with Yb/Er and Nd/Yb for bioimaging applications. Methods: Yb/Er FAp and Nd/Yb FAp was synthesized using microwave assisted wet precipitation and hydrothermal method respectively. Trisodium citrate was used as an organic modifier for the synthesis and then subjected to heat treatment for optical activation. For optical studies, Yb/Er FAp system was excited at 980 nm and Nd/Yb FAp at 800 nm. Results: In the case of Nd/Yb FAp the host matrix absorption and emission was observed, hence Nd/Yb was synthesized without citrate. On heat treatment of this for optical activation studies, when the Yb3+ concentration was increased to 10 mol%, the YbPO4 secondary phase was found to appear. Although, the Yb/Er FAp system resulted in large grain growth, no such grain growth was observed in Nd/Yb FAp and the grains were within the nano size regime even after heat treatment. Conclusion: Both the systems showed successful energy transfer from sensitizer to activator with a quantum yield of 74% for Yb/Er FAp and energy transfer efficiency of 71% for Nd/Yb FAp system. Both the samples were found to be cytocompatible and has the potential for using as probes for bioimaging applications.

Background: Fluorescence based bioimaging is one of the widely used method for obtaining imperative information on life processes. Objective: Within the expansive spectrum of fluorescent agents being investigated, the trivalent Lanthanide (Ln) ion based nanoparticles have attracted attention due to their intrinsic luminescence property. Methods: Here we report a modified sol gel assisted synthesis of Europium (Eu) and Samarium (Sm) doped Hydroxyapatite nanoparticles (HAp NPs). Doping Ln ions in the selffluorescent hydroxyapatite lattice contributed towards an increased luminescence in the NPs. Results: The XRD patterns reveal that the Eu+3 and Sm+3 doped HAp NPs display the characteristic peaks of hydroxyapatite in a hexagonal lattice structure, and the FTIR data confirms presence of characteristic functional groups. The as-synthesized HAp NPs exhibit short rod-shaped morphology with average length less than 60 nm. Upon excitation at representative wavelengths, the doped HAp NPs demonstrated characteristic emission lines of Eu+3 and Sm+3. Conclusion: The as-synthesized NPs displayed no toxicity towards HeLa cells and are easily internalized, exhibiting their potential as promising live cell bioimaging agents.

Background: Recently, great importance has been devoted to borate glass systems doped with rare-earth ions because of their unique peculiar properties in the field of photonics for optical applications. Objective: The purpose of the present study is to investigate the effect of concentration of Sm3+ ions on the luminescence properties of lead fluoroborate glasses through the energy transfer mechanism. Materials and Methods: Samarium doped lead fluoroborate glasses with chemical composition 20PbF2 .10Li2O .5SrO .5ZnO. (60-x) B2O3. xSm2O3 (where x = 0.1, 0.5, 1.0, 1.5 and 2.0 mol %) were prepared by means of melt quenching method. The concentration dependent luminescence properties were investigated in detail from the optical absorption, photoluminescence and decay analysis. Judd-Ofelt (J-O) theory was applied to analyze the optical absorption spectra. The experimental oscillator strengths of absorption bands have been used to determine the J-O parameters. Using the J-O parameters Ωλ (λ = 2, 4 and 6) and luminescence data several radiative parameters were obtained. Results: From the luminescence spectra, it was noticed that luminescence quenching starts at higher concentrations of Sm3+ ions (x ≥ 0.5 mol %). The decay curves of 4G5/2 → 6H7/2 transition exhibit a single exponential at lower dopant concentrations (x = 0.1 and 0.5 mol %) and non-exponential at higher concentrations (x ≥ 1 mol %). The concentration quenching was attributed to the energy transfer through the cross-relaxation between Sm3+ ions. The non-exponential curves were well fitted to Inokuti-Hirayama model for S = 6, indicating that the energy transfer between Sm3+ - Sm3+ ions is of dipole-dipole type. The calculated color coordinates of the as-prepared glasses fall within the reddish-orange region of the CIE diagram. Conclusion: All the experimental results indicate that the 0.5 mol% Sm3+ ions doped LLSZFB glass can be a possible choice for solid state lighting and display applications.

Background: Of-late researches in colloid chemistry are becoming increasingly important in various branches of chemistry, industry, medicine and allied fields. Copper surfactants derived from various edible oils provide an interesting area of investigation pertaining to its fundamental information regarding their colloid-chemical behaviour. Copper (II) soaps and their urea complexes in polar and non-polar solvents have gained considerable popularity due to their immense use and widespread applications such as wood preservation, foaming, wetting, biocidal, pesticidal activities, fungicidal, detergency, emulsification, paints, lubrication etc. Objective: Present work has been initiated with a view to obtain a profile due to the nature and structure of copper soap and their urea complexes with long chain fatty acids in polar and non-polar solvent, which have great significance in explaining their characteristics under different conditions. The objective of the present work is study of micellar characterizations of copper soap and their urea complexes in polar (methanol) and non-polar (benzene) solvents of varying composition and subsequent determinations of CMC using physical properties such as, viscosity. This will provide fundamental information regarding their colloid chemical behavior. Methods: The density, molar volume, viscosity, specific viscosity, and fluidity of Cu (II) soap- urea complexes derived from various edible oils in a benzene-methanol solvent system have been determined at a constant temperature of 303.15 K. Results: The results were used to determine the critical micelle concentration (CMC), soap complex-solvent interactions and the effect of chain length of the surfactant molecules on various parameters. The values of the CMC in the higher volume percent of methanol are higher than those of the lower volume percent of methanol. The values of CMC for these complexes are following the order: CSoU>CSeU> CGU > CMU This shows that there is a decrease in the CMC values with an increase of the average molecular weight of the complex. The conclusions with regard to solute-solute and solutesolvent interactions have been discussed in terms of the well-known Moulik’s and Jones- Dole equations. The effect of surfactant concentration on the viscosity of the solution in the solvent mixtures has been discussed. The observations suggested that the solvent structure breaking effect by the solute on the solvent molecules is more prominent above the CMC as compared to below the CMC. Conclusion: The vital information about the micellar behavior of synthesized molecules as a solute and their interactions with different solvents will plays an important role in various industrial and biological applications.

Aims: In this investigation, we used accurate mass high-resolution gas chromatography mass spectrometry to study the gas phase carbocations rearrangements and fragmentation of toluene and halo-toluenes as well as their deuterium labeled compounds. Objective: Accurate mass of selected ions from ionization of toluene and related compounds revealed that the initially formed radical cation C7H8 +. does not rearrange to tropylium radical cation contradicting published literature. Methods: When the toluene radical cation was purely selected, it was found to lose a free radical (hydrogen atom) at collision energies greater than 5 eV and forming benzylium or tropylium cation C7H7 + (m/z = 91), with no other fragmentations. Results: The resulting cation at collision energy greater than 20 eV fragmented by losing acetylene or ethylene or allene molecule to form C5H5 + (m/z = 65), C5H3 + (m/z = 63) or C4H3 + (m/z = 51) respectively. Purely selected C5H5 + cation at collision energy greater than 30 eV lost acetylene molecule and formed C3H3 + (m/z =39). Conclusion: In this investigation toluene, halotoluene and their deuterated derivatives (structural isomers) were found to ionize in the gas phase with isomer retention. Historically, it has been suggested that the seven carbons and hydrogen atoms would become indistinguishable. However, this should be revised in the light of new technologies.

Background: The metal ions play a vital role in a large number of widely differing biological processes. Some of these processes are quite specific in their metal ion requirements. In that only certain metal ions, in specific oxidation states, can full fill the necessary catalytic or structural requirement, while other processes are much less specific. Objective: In this paper we report the binding of Mn (II), Ni (II) and Co (II) with albumin are reported employing spectrophotometric and pH metric method. In order to distinguish between ionic and colloidal linking, the binding of metal by using pH metric and viscometric methods and the result are discussed in terms of electrovalent and coordinate bonding. Methods: The binding of Ni+2, Co+2 and Mn+2 ions have been studied with egg protein at different pH values and temperatures by the spectrometric technique. Results: The binding data were found to be pH and temperature dependent. The intrinsic association constants (k) and the number of binding sites (n) were calculated from Scatchard plots and found to be at the maximum at lower pH and at lower temperatures. Therefore, a lower temperature and lower pH offered more sites in the protein molecule for interaction with these metal ions. Statistical effects seem to be more significant at lower Ni+2, Co+2 and Mn+2 ions concentrations, while at higher concentrations electrostatic effects and heterogeneity of sites are more significant. Conclusion: The pH metric as well as viscometric data provided sufficient evidence about the linking of cobalt, nickel and manganese ions with the nitrogen groups of albumin. From the nature and height of curves in the three cases it may be concluded that nickel ions bound strongly while the cobalt ions bound weakly.