Pro Libris: Lubuskie Pismo Literacko-Kulturalne, nr 4 (2008)

172 s. : il

Influence of temperature on the crystallization of Cu^II complex with tetradentate Schiff base

<p>The complex of copper(II) with N₂O₂ Schiff base, 2,2′-[1,3-propanediyl)bis(nitriloeth-1-yl-1-ylidene)]diphenol (<b>H</b>_<b>2</b><b>L</b>), has been synthesized from methanol. Crystallization of the complex was conducted at room temperature (20 °C) and at 4 °C. Carrying out the crystallization process at various temperatures leads to the formation of two different complexes CuL·MeOH (<b>1</b>) and [{Cu₂L₂}{CuL}₂]·2MeOH (<b>2</b>). The Schiff base and its complexes were characterized by elemental analysis, X-ray crystallographic techniques, spectroscopic (UV–Vis, IR), and thermal (TG\DSC) methods. Complex <b>1</b> crystallizes in the monoclinic space group <i>P2</i>_<i>1</i><i>/c</i>. The N₂O₂ core forms a tetrahedrally distorted square-planar geometry around the metal center. Crystallization of <b>2</b> took place in the centrosymmetric triclinic space group (<i>P</i>). In the structure of <b>2</b> there are two crystallographically different Cu^II ions, one is four-coordinate in a square planar geometry, whereas the second has a five-coordinate square pyramidal geometry. The complexes are stable at ambient temperature. After heating at first they lose methanol molecules, then the organic part undergoes gradual fragmentation and combustion.</p

Thermal Investigations of Annelated Triazinones—Potential Analgesic and Anticancer Agents

In this article, for the first time, TG-DSC and TG-FTIR investigations of potential pharmaceutics, i.e., analgesic and anticancer active annelated triazinones (1–9) have been presented. The thermal behaviour of these molecules was established in oxidative and inert conditions. The solid–liquid phase transition for each compound (1–9) was documented by one sharp DSC peak confirming the high purity of each sample studied. All the molecules were characterised in terms of calorimetric changes and mass changes during their heating. They revealed high thermal stability in oxidative and inert conditions. The observed tendency in thermal stability changes in relation to a substituent present at the phenyl moiety was found to be similar in air and nitrogen. It was confirmed that annelated triazinones 1–9 were stable up to a temperature range of 241–296 °C in air, and their decomposition process proceeded in two stages under oxidative conditions. In addition, it was established that their thermal stability in air decreased in the following order of R at the phenyl moiety: 4-Cl > 3,4-Cl2 > H > 3-Cl > 4-CH3 > 2-CH3 > 3-CH3 > 2-Cl > 2-OCH3. The volatile decomposition products of the investigated molecules were proposed by comparing the FTIR spectra collected during their thermogravimetric analysis in nitrogen with the spectra from the database of reference compounds. None of annelated triazinones 1–9 underwent any polymorphic transformation during thermal studies. All the compounds proved to be safe for erythrocytes. In turn, molecules 3, 6, and 9 protected red blood cells from oxidative damage, and therefore may be helpful in the prevention of free radical-mediated diseases

Lanthanide metal–organic frameworks: Structural, thermal and sorption properties

Two coordination polymers of erbium(III) and neodymium(III) ions with 1,3,5-benzenetricarboxylic acid were synthesized under the solvothermal conditions from the dimethylformamide solution. They were characterized by the attenuated total reflectance Fourier transform spectroscopy (ATR-FTIR), thermogravimetry and differential scanning calorimetry (TG-DSC), thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TG-FTIR) and X-ray diffractions methods. The single-crystal X-ray analysis confirmed formation of three-dimensional framework of Er(III) 1,3,5-benzenetricarboxylate with the channels occupied by dimethylformamide and water molecules. Porosity of crystalline complexes was investigated by the nitrogen sorption experiments. The Nd and Er compounds exhibit real porosity with the BET surface area of 259 and 225 m 2 /g, respectively. The Horvath–Kawazoe analysis of pore-size distributions for the obtained complexes points out to their microporous character

Structural and Thermal Investigations of Co(II) and Ni(II) Coordination Polymers Based on biphenyl-4,4′-dioxydiacetate Linker

Two coordination polymers, [Co(µ4-L)(H2O)2]n (1) and [Ni(µ-L)(H2O)4]n (2), were solvothermally assembled from the corresponding metal(II) chlorides and biphenyl-4,4-dioxydiacetic acid (H2L) as a flexible dicarboxylate linker. The cobalt(II) compound 1 featured a layer-pillared 3D metal-organic network with a cds topology, while the nickel(II) derivative 2 represented a linear chain 1D coordination polymer with a 2C1 topology. The µ4− and µ-L2− linkers exhibited different denticity and coordination modes in the synthesized compounds, thus contributing to their structural diversity. The dimensionality of 1 and 2 had an influence on their thermal stability and decomposition processes, which were investigated in detail by TG-DSC and TG-FTIR methods. Thermal decomposition products of coordination polymers were also analyzed by PXRD, confirming the formation of Co3O4/CoO and NiO as final materials. The obtained compounds broaden a family of coordination polymers assembled from flexible dicarboxylate linkers

A Top-Down Approach and Thermal Characterization of Luminescent Hybrid BPA.DA-MMA@Ln₂L₃ Materials Based on Lanthanide(III) 1H-Pyrazole-3,5-Dicarboxylates

In this study, novel hybrid materials exhibiting luminescent properties were prepared and characterized. A top-down approach obtained a series of polymeric materials with incorporated different amounts (0.1; 0.2; 0.5; 1, and 2 wt.%) of dopants, i.e., europium(III) and terbium(III) 1H-pyrazole-3,5-dicarboxylates, as luminescent sources. Methyl methacrylate and bisphenol A diacrylate monomers were applied for matrix formation. The resulting materials were characterized using Fourier transform infrared spectroscopy (FTIR) and thermal analysis methods (TG-DTG-DSC, TG-FTIR) in air and nitrogen atmosphere, as well as by luminescence spectroscopy. The homogeneity of the resulting materials was investigated by means of optical microscopy. All obtained materials exhibited good thermal stability in both oxidizing and inert atmospheres. The addition of lanthanide(III) complexes slightly changed the thermal decomposition pathways. The main volatile products of materials pyrolysis are carbon oxides, water, methyl methacrylic acid and its derivatives, bisphenol A, 4-propylphenol, and methane. The luminescence properties of the lanthanide complexes and the prepared hybrid materials were investigated in detail