Infinite coordination polymers based on rare-earth ions and pyrazole-3,5-dicarboxylate: structural, morphological and luminescent properties

Abstract

Rare-Earth based Infinite Coordination Polymers (RE-ICPs) are multifunctional materials since they can have several properties such as permanent porosity and luminescence. In addition, these compounds usually exhibit homogeneous spherical nanocrystalline particles, with micro- or nanometric dimensions. For these reasons, this class of materials can have potential applications in different areas, mainly as luminescent sensors and in light-emitting devices. Regarding the use of lanthanide-based ICPs (Ln-ICPs) as chemical sensors, the luminescence intensity of these materials can be quenched (most of the times) or increased in the presence of the analytes. Generally, Ln-ICPs exhibit low detection limits and high selectivity. On the other hand, regarding the application as light-emitting devices, the main interest is to synthesize Ln-ICPs with high quantum efficiency and intense emission. Within this perspective, in this work, luminescent coordination polymers will be obtained and characterized, aiming at applications in luminescent sensing of several chemical species and in light-emitting devices. Previous results obtained by our research group describes a new series of Ln-ICPs (Ln = Eu, Gd, Tb, Dy) containing pyrazole-3,5-dicarboxylate ligand and malonate anion as a coordination modulator (Ln-M samples). These materials are organized in the form of spherical particles with high shape and size homogeneity (~ 1.5 - 2.0 ¼m). These compounds will be synthesized with different percentages of Ln3+ ions in order to obtain different emission colors (mainly white light emission). It is also intended to investigate the use of the Ln-ICPs the detection of chemical species such as Cu2+, Fe3+, Cr3 + and Cr2O72- in aqueous medium. Raciometric detection of biomarkers will also be done using bimetallic Ln-M compounds. The final part of the project will rely on the processing of coordination polymers in the form of composite films (in combination with organic polymers) and as precursors for metal oxides. (AU)