Extraction, Purification and Electrical Characterization of Gross Galactomannan and Purified Galactomannan Obtained from Adenanthera pavonina L. Seeds.

Aiming of self-sustainable production, the search for biodegradable and biocompatible materials has brought with it the need to know the physicochemical and dielectric characteristics of polysaccharide-based composite structures, which can be used as important and promising raw materials for biotechnology and electronic industries. Galactomannans are polysaccharides, extracted from seeds and microbiological sources, consisting of mannose and galactose. In this context, this work aimed to extract, purify and characterize by XRD, FTIR and impedance spectroscopy galactomannan obtained from seeds of Adenanthera pavonina L. The purification process was made with ethyl alcohol at concentrations of 70, 80 and 90 %. Polymeric films were prepared by solvent slow evaporation at low temperatures. XRD measurements revealed that Galactomannan from Adenanthera pavonina L., after purification, has a semi-crystalline structure due to the identification of two peaks the first between 5.849° and 6.118° and the second between 20.011° and 20.247°. FTIR spectra showed the functional groups associated with monosaccharides of the galactomannan from Adenanthera pavonina L. seeds, as well as the typical polysaccharide bands and peaks, confirmed by literature data. The impedance results give an increment on the state-of-the-art of this biomaterial by showing the existence of dielectric relaxations, independent of the degree of purification, using the dielectric modulus formalism. The permittivity analysis reveals the presence of water in the structure of the film, whose dipoles contribute to the relatively high value of the dielectric constant. From the results obtained, it can be concluded that purified galactomannan has the potential for possible applications in the electronics industry as a green and eco-friendly dielectric material.

Phase changes of tris(glycinato)chromium(III) monohydrate crystal systematically studied by thermal analyses, XRPD, FTIR, and Raman combined with ab initio calculations.

Tris(glycinato)chromium(III) monohydrate [Cr(C2H4NO2)3·H2O] crystals were grown through the slow solvent evaporation method. The crystals were studied by Fourier transform infrared (FTIR) and Raman spectroscopy at room temperature. The assignments of vibration modes were performed using the Density Functional Theory (DFT). Thermal analyses (TGA, DTA, and DSC), X-ray diffraction (XRD), and Raman were used to study the phase changes on the crystals under high- and low-temperature conditions. Temperature-dependent XRPD measurements were carried out in the interval of 473-12 K. Several changes were observed in the patterns, like the appearance of new peaks and the disappearance of peaks occurring within 373-393 K due to water loss. In addition, the Raman measurements were performed in the 423-10 K interval. Several changes on the inter and intramolecular vibration bands during the cooling, such as decreasing bands' intensities, the appearance of vibration modes, and discontinuities on the modes' behavior, were observed. These spectral modifications occurred at about 370 K and within 120-220 K, thus, confirming that the crystals undergo two phase changes, one being structural and the other one conformational, respectively, at high- temperature and low-temperature conditions. Finally, thermal investigations corroborated the structural and vibrational results under high temperatures.

Structural, thermal, electronic, vibrational, magnetic, and cytotoxic properties of chloro(glycinato-N,O)(1,10-phenanthroline-N,N')­copper(II) trihydrate coordination complex.

Chloro(glycinato-N,O)(1,10-phenanthroline-N,N')­copper(II) trihydrate complex was synthesized through the slow evaporation method. The crystal's structural, thermal, magnetic, and vibrational properties were obtained by X-ray powder diffraction (XRPD), thermal analyses, magnetization, Raman, and Fourier-transform infrared (FT-IR) spectroscopy. XRPD results showed that the crystalline complex belongs to a monoclinic system (P21/n). Thermal analyses revealed that around 333 K, the material undergoes a thermodynamically irreversible process. Magnetic data showed a paramagnetic behavior with weak ferromagnetic interactions. Moreover, all the Raman- and infrared-active bands were assigned from computational calculations based on the density functional theory (DFT) to analyze intra-molecular vibrational modes. In addition, the cytotoxic assay on colorectal cancer cells was performed to evaluate the antitumor activity of this ternary compound. Therefore, the antineoplastic activity of [Cu(1,10-phenanthroline)(glycine)Cl]•3H2O complex in HCT-116 cells was confirmed, showing a potent cytotoxic effect.