Synthesis And Characterisation Of Novel Hybrid Ion Exchange Materials Useful In Environmental Analysis

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Preparation of Selective Ion Exchange Material for Chemical Analysis by Sol-Gel Method

The sol-gel process provides a versatile method to prepare size, shape and charge selective materials for analysis. We report the synthesis and characterization of a new sulphosalicylate doped tetraethoxysilane composite material by sol-gel method. The synthetic conditions such as reactant concentrations and precipitating agents were varied to optimize the ion exchange properties of this material. The material has an ion exchange capacity of 0.64meq/g(dry) for sodium ions, 0.60meq/g(dry) for potassium ions, 1.84meq/g(dry) for magnesium ions, 1.08meq/g(dry) for calcium ions and 1.36meq/g(dry) for strontium ions. Its X-ray diffraction studies suggest that it is crystalline in nature. The material has been characterized by SEM, IR, TGA and DTG so as to identify the various functional groups and ion exchange sites present in this material. Further, various ion exchange studies such as determination of ion exchange capacity, elution behaviour, pH titration, distribution behaviour towards ion exchange and adsorption behaviour towards certain important dyes have been performed on this material. This material shows selectivity for Mg (II) among alkaline earth metal ions and Ni (II) among the transition metal ions in aqueous solutions. This material, therefore, has potential application for removal of these metal ions from aqueous systems. The material shows remarkable adsorption behaviour towards environmentally important representative dyes like malachite green and methylene blue

Conformational analysis and vibrational circular dichroism of Tris(ethylenediamine)ruthenium(II) complex: a theoretical study

The conformational preferences and vibrational circular dichroism of tris(ethylenediamine)ruthenium complex in two main configurations (Λ) and (Δ), have been performed using density functional theory. We find that for the free [Ru(en)3]2+ ion in the Δ-configuration, the conformational stability order is Δ)(δδδ) > Δ)(λδδ) > Δ)(λλδ) > Λ(λλλ) and that for the Λ-configuration it is Λ(δδδ) < Λ(δδδ) < Λ(λλδ) < Λ(λλλ). The energy differences between the four conformers for both the configurations Δ and Λ are relatively small, but the activation barriers for ring inversion from one conformation to another are significant, as compared to other such systems. We trace the origin of these results to the lower oxidation state of Ru and relatively larger Ru-N bond length. We have also studied the effect of counterions on the conformational stability for Ru(en)3Cl2. Our results indicate a reverse stability order for the associated complex, Ru(en)3 Cl2 and higher activation barriers for ring inversion as compared to the free complex ion Ru(en)32+. It is because of larger hydrogen bonding interactions between the three N-H bonds and the chloride ion in these two conformers as compared to other conformations, which is also evident from the VCD spectra of N-H stretching modes. We also investigate IR spectra for all conformations in Δ- and Λ-configurations and together with energetics and VCD spectra elucidate the spectroscopic characteristics of Ru(en)32+ complexes with and without the associated counterions

Plot of geometrical change (dihedral angle) with the Hammett Parameter, for the series of studied DMB derivates.

<p>Plot of geometrical change (dihedral angle) with the Hammett Parameter, for the series of studied DMB derivates.</p

Electron Transport and Nonlinear Optical Properties of Substituted Aryldimesityl Boranes: A DFT Study

<div><p>A comprehensive theoretical study was carried out on a series of aryldimesityl borane (DMB) derivatives using Density Functional theory. Optimized geometries and electronic parameters like electron affinity, reorganization energy, frontiers molecular contours, polarizability and hyperpolarizability have been calculated by employing B3PW91/6-311++G (d, p) level of theory. Our results show that the Hammett function and geometrical parameters correlates well with the reorganization energies and hyperpolarizability for the series of DMB derivatives studied in this work. The orbital energy study reveals that the electron releasing substituents increase the LUMO energies and electron withdrawing substituents decrease the LUMO energies, reflecting the electron transport character of aryldimesityl borane derivatives. From frontier molecular orbitals diagram it is evident that mesityl rings act as the donor, while the phenylene and Boron atom appear as acceptors in these systems. The calculated hyperpolarizability of secondary amine derivative of DMB is 40 times higher than DMB (<b>1</b>). The electronic excitation contributions to the hyperpolarizability studied by using TDDFT calculation shows that hyperpolarizability correlates well with dipole moment in ground and excited state and excitation energy in terms of the two-level model. Thus the results of these calculations can be helpful in designing the DMB derivatives for efficient electron transport and nonlinear optical material by appropriate substitution with electron releasing or withdrawing substituents on phenyl ring of DMB system.</p></div

Plot of Hammett Parameter with (a) electron affinity (eV) and (b) ionization potential (eV).

<p>Plot of Hammett Parameter with (a) electron affinity (eV) and (b) ionization potential (eV).</p

Schematic diagram of a two-layered OLED device.

<p>Schematic diagram of a two-layered OLED device.</p

Results of TDDFT calculations at B3PW91/6-311++G (d, p) level of theory for the electron transitions of DMB systems.

<p>Results of TDDFT calculations at B3PW91/6-311++G (d, p) level of theory for the electron transitions of DMB systems.</p

Sketch of aryldimesityl borane (DMB) derivatives study using DFT at B3PW91/6-311++G (d,p)level of theory.

<p>Sketch of aryldimesityl borane (DMB) derivatives study using DFT at B3PW91/6-311++G (d,p)level of theory.</p