An experimental and theoretical study of the electronic spectra of tetraethylammonium [tris(1,3-dithiole-2-thione-4,5-dithiolato)M] and tetraethylammonium [tris(1,3-dithiole-2-one-4,5-dithiolato)M], for M = Sn(IV) and Sb(V)
JOURNAL OF MOLECULAR STRUCTURE
Authors: da Silva, Victor Hugo M.; Junior, Henrique C. S.; Hollauer, Eduardo; Comerlato, Nadia M.; Ferreira, Glaucio B.
Abstract
Metal-dmit complexes and related compounds have been studied extensively over the last few decades. Experimental reports of its UV-Vis spectra present the main spectroscopic features, although many details of the electronic structure still have to be investigated. This work presents a detailed analysis of the UV-vis spectra of the [NEt4](x)[M(L)(3)] (L = dmit and dmio), for M,x = Sn,2 and Sb,1. The experimental spectrum was deconvoluted and analyzed with B3LYP and CAM-B3LYP DFT methodologies. The results lead to an assignment of several bands involving LMCT, besides confirming the presence of a metal orbital in the HOMO-LUMO boundary, with additional observation performed through the analysis of the dmio complex in order to enhance the results. Several methods such as EDA, NBO, and QTAIM were applied to determine the covalent character of the metal-ligand interaction. Furthermore, the solvent effect was evaluated using the CPCM model to observe the changes in the overall properties. (C) 2020 Elsevier B.V. All rights reserved.
Production and physicochemical characterization of a new amine derivative of gellan gum and rheological study of derived hydrogels
CARBOHYDRATE POLYMERS
Authors: Fiorica, Calogero; Pitarresi, Giovanna; Palumbo, Fabio Salvatore; Mauro, Nicolo; Federico, Salvatore; Giammona, Gaetano
Abstract
The production of an amine derivative of gellan gum, named GG-EDA, was here obtained by functionalizing the polysaccharide backbone with pendant ethylenediamine moieties. The obtained derivative was characterized by spectroscopic, colorimetric, chromatographic and rheological analyses to study the effect of the free amino groups on the physicochemical properties of the macromolecule. A titration experiment was conducted to study the acid-base dissociation constants in aqueous media for the carboxylic and amino groups in the GG-EDA and to shed light on the possibility that the derivative shows a polyampholyte structure under physiological conditions. The rheological analysis conducted on both physical and chemical hydrogels based on GG-EDA revealed that the presence of amino groups plays a fundamental role in influencing the viscoelastic properties and stability of the produced samples.
COA
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