Cadmium(II) and calcium(II) complexes with N,O-bidentate ligands derived from pyrazinecarboxylic acid

Abstract

The synthesis and characterization of cadmium(II) and calcium(II) complexes with N,O-bidentate ligands derived from pyrazinecarboxylic acid (3-hydroxy-2-quinoxalinecarboxylic acid HL 1 , pyrazine-2-carboxylic acidwere studied by elemental analyses, IR, Raman spectroscopy and thermogravimetric methods (TG, DTG, DSC). In addition, the molecular structure of complex 1 has been determined by X-ray single crystal diffraction. Thermal analysis reveals a decomposition process of 1, 3 complexes in multiple stages. The data obtained from TG and DSC curves for 1, 3 confirm not only the presence but also the nature of water (crystallization and coordination) and the stoichiometry of the studied metal complexes. The results of thermal studies are in good agreement with their crystal structures. Thermal behavior of complex 2 indicates a single complete decomposition process of the sample. In addition, complex 2 as a coordination polymer is the most stable all of them and the thermal stability of the obtained complexes can be ordered in the following sequence: 1 \ 3 ( 2.

Supramolecular Gelation of Cadmium Oleate in the Synthesis of Nanocrystals for Applications in Photonics and Optoelectronics

“…In addition, the alkene C–H stretch at 3006 cm –1 is maintained (see Figure S9b), which supports gelation through supramolecular assembly rather than a covalent oligomerization mechanism through the oleate double bond. The oleate ligand coordination motif was also confirmed via FT-IR, in particular, through examining the difference (Δ) between the asymmetric (v a ) and symmetric (v s ) COO – vibration modes of Cd oleate. − The v a mode appears as a broad peak at 1570–1532 cm –1 , and the v s mode appears at 1422 cm –1 , yielding a Δ of 113–148 cm –1 (Figure S9c). This range is associated with an asymmetric chelated bidentate binding mode and confirms the absence of oleate acting as a bridging ligand (Δ > 200 cm –1 ). , The Cd 2+ ion chelated with two oleate ligands (see Figure b) assembles with neighboring Cd oleate complexes due to noncovalent interactions (e.g., London dispersion forces) between the long-chain oleate ligands, creating a supramolecular network similar to that reported for other oleate-based complexes. ,, …”

Magnetic Solid-Phase Extraction using Ionic Liquid-Modified Magnetic Nanoparticles for The Simultaneous Extraction of Cadmium and Lead in Milk Samples; Evaluation of Measurement Uncertainty

“…Hence, we attempted to assess the impacts of other co-existence possible metal ions on the extraction efficiency and evaluation of method selectivity in relation to the co-existence metal ions complex with PCA. Since PCA has been used as a ligand for metal ions such as Ca 2+ , Ni 2+ , Cu 2+ , and Zn 2+ , these ions may form complexes with PCA if being present in the solution [46][47][48]. Therefore, to assess the potential interaction due to the complex formation of the mentioned metal ions with PCA and its effect on the two analyses' extraction efficiency, various quantities of metal ions were added into 50 millilitres of the sample solution contacting 20 µgL -1 of the target analytes.…”

Hydrogen and Halogen Bond Mediated Coordination Polymers of Chloro-Substituted Pyrazin-2-Amine Copper(I) Bromide Complexes

“…In this regard, aminopyrazine carboxylic acids (L), of the forms L, and L + , for the construction of hydrogen-bonded organic co-crystals [26][27][28][29][30][31], and L − functioning as a polydentate ligand in the preparation of coordination compounds [32][33][34][35][36][37][38][39] are reported in the literature. The presence of aromatic N-atoms and carboxylic acid/carboxylate groups within the same ligand may enhance the N-M bond strengths, often assisted by the polydentate bonding nature of O-atoms [26].…”