THERMAL CHARACTERISTICS OF ZIRCONIUM PHOSPHATE NANOPARTICLES LOADED WITH DIRHENIUM(III) COMPLEXES

Abstract

Using the method of differential thermal analysis and the method of isothermal effects, we investigated the thermal transformations of the inter-calation products of representatives of dirhenium(III) complexes of all structural types into the interlayer space of zirconium phosphate. Each of the samples was heated in the temperature range from 40 to 500 C. On the obtained thermograms of the samples, two main endothermic effects were observed, the first of which corresponds to the separation of water of crystallization from zirconium phosphate, and the second to the thermal transformations of dirhe-nium(III) complexes. The first weight loss for all intercalation products was 8.87–9.80%, that is, the percentage of water in the post samples was the same. The weight loss corresponding to the thermal transformation of dirhenium(III) complexes in the obtained nanoparticles was 6.15–11.24 and 12.30–29.90 % for molar ratios of the substance / zirco-nium phosphate, respectively, 1:30 and 1:5, which fully consistent with the proposed mechanism for the thermal decomposition of nanoparticles. As a result of research, it was determined that rhenium is not released from nanoparticles to the fullest extent when heated to 500 °C, which indicates the formation of nonvolatile products, such as ReO2. In addition, for some products of intercalation, such as trichlorotri-μ-carboxylates dirhenium(III), the weight loss is small compared with other representa-tives of nanoparticles, which is due to the difficult conversion of the complex compound as a result of the polymer structure of the complex. Thermal de-composition of phosphate ligands also prevents the complete elimination of the rhenium(III) compound due to the hydration of phosphate groups, which are coordinated in the axial position of the complex compound with the formation of pyrophosphates. Thus, the features of the behavior of samples during thermal studies are due to the structure of the com-plex compound formed in the interlayer space of zir-conium phosphate during the intercalation process.