Spectral engineering and tunable thermoelectric behavior in a quasiperiodic ladder network

Double-stranded quasiperiodic copper mean arrangement has been studied in respect of its electronic property and thermoelectric signature. The two-arm network is demonstrated by a tight-binding Hamiltonian. The eigenspectrum of such aperiodic mesh that does not convey translational invariance, is significantly dependent on the parameters of the Hamiltonian. It is observed that specific correlation between the parameters obtained from the commutation relation between the on-site energy and overlap integral matrices can eventually modify the spectral nature and generate absolutely continuous energy spectrum. This part is populated by atypical extended states that has a large localization length substantiated by the flow of the hopping integral under successive real space renormalization group method steps. This sounds delocalization of single particle energy states in such non-translationally invariant networks. Further this can be engineered at will by selective choice of the relative strengths of the parameters. This precise correlation has a crucial impact on the thermoelectric behavior. Anomalous nature of thermoelectric coefficient may inspire the experimentalists to frame tunable thermo-devices. Specific correlations can help us to tune the continuous band and determine the band position at will.     

UV-vis-NIR and EPR characterisation of the redox series [MQ(3)](2+,+,0,-,2-), M = Ru or Os, and Q = o-quinone derivative

The neutral title compounds with Q = 3,5-di-tert-butyl-o-quinone or 4,6-di-tert-butyl-N-phenyl-o-iminobenzoquinone (Q(x)) were studied by UV-vis-NIR spectroelectrochemistry and by EPR spectroscopy in the case of the odd-electron monocation and monoanion intermediates. Supported by DFT and TD-DFT calculations, the results indicate stepwise electron removal from predominantly ligand-based delocalised MOs on oxidation whereas the stepwise electron uptake on reduction involves unoccupied MOs with considerably metal-ligand mixed character. In both cases, the strong near-infrared absorption of the neutral precursors diminishes. In comparison to the ruthenium series, the osmium analogues exhibit larger transition energies from enhanced MO splitting and a different EPR response due to the higher spin-orbit coupling. The main difference between the quinone (1(n), 2(n)) and corresponding monoiminoquinone systems (3(n), 4(n)) is the shift of about 0.6 V to lower potentials for the monoimino analogues. While the absorption features do not differ markedly, the EPR data reflect a higher degree of covalent bonding for the complexes with monoimino ligands.     

Processable heat-resistant polymers. XI. Synthesis and characterization of unsaturated polyamideimides

Polycondensation of the diacid chloride of 2-(3-carboxy vinyl)phenyl-1,3-dioxoisoindoline-5-carboxylic acid with m-phenylenediamine and the diacid chloride of 2-(4-carboxy phenyl)-1,3-dioxoisoindoline-5-carboxylic acid with 1,5-bis(3-aminophenyl)1,4-pentadien-3-one was carried out in polar solvents to produce new unsaturated polyamide–imides. The solution and the thermal, electrical, and a few other properties of the polymers were studies. The polymers were soluble in highly polar solvents. The solubility parameter of the polymers was calculated from the Small's group contribution. The polymers were fairly thermostable and underwent crosslinking creaction when heated, preferably in the presence of a suitable catalyst. The crosslinked polymers were in soluble even in highly polar solvents and possessed higher thermal stability. The swelling behavior of the polymers was studied and the molecular weight between two consecutive crosslinks was determined. X-ray diffraction and the dielectric properties of the polymers and their crosslinked products were also studied.     

Gravimetric determination of palladium with quinolinimide as a reagent

Summary Quinolinimide which is found to be a selective reagent for palladium forms a complex of the composition Pd(C₇H₃O₂N₂)₂. The reagent quantitatively precipitates palladium from solutions of p_H 0.5 to 2.5 in presence of common ions as well as platinium metals, except tin which, however, can be kept in solution by complexing with citric acid. The palladium complex being stable up to 307° C can be directly weighed.

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Zusammenfassung Chinolinimid wird als selektives Reagens für Palladium vorgeschlagen. Bei p_H-Werten zwischen 0,5 und 2,5 kann Palladium quantitativ in Form des Komplexes Pd(C₇H₃O₂N₂)₂ gefällt werden, wobei die meisten anderen Ionen, auch die der Platinmetalle, in Lösung bleiben. Zinn stört, kann aber mit Citronensäure maskiert werden. Der Palladiumkomplex ist bis 307° C stabil und kann direkt ausgewogen werden.

     

One pot low temperature synthesis of graphene coupled Gd-doped ZnFe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanocomposite for effective removal of antibiotic levofloxacin drug

Nanocomposites of reduced graphene oxide (rGO) coupled gadolinium doped ZnFe₂O₄ (GZFG) have been successfully one pot in-situ synthesized adopting low temperature solution process from zinc nitrate, iron nitrate, gadolinium acetate and graphene oxide with varying concentrations of gadolinium (upto 10% Gd with respect to Zn) in the precursor medium. X-ray diffraction and transmission electron microscopy studies confirm the presence of single phase cubic spinel structure of ZnFe₂O₄ that uniformly distributed over the rGO layers. With increasing Gd doping concentration in precursor medium, the average crystallite size of ZnFe₂O₄ diminishes gradually from ~11 to ~5.5?nm. Raman and X-ray photoelectron spectral analyses confirm an existence of interaction between rGO and ZnFe₂O₄ in GZFG samples. Using antibiotic levofloxacin in water, the drug removal capacity (DRC) of GZFG has been performed by optimization of parameters such as gadolinium doping concentration in precursor medium, solution pH, etc. However, the gadolinium doping leads to an improvement in DRC of the nanocomposite and the 5% Gd doped sample shows about 86% DRC at the optimized condition. This simple strategy can be utilized in the synthesis of rGO coupled Gd doped other metal oxide nanocomposites for DRC application.

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