Raman, FT‐IR, and DFT studies of 3,5‐pyrazoledicarboxylic acid and its Ce(III) and Nd(III) complexes

Abstract

3,5-Pyrazoledicarboxylic acid was used as a ligand for the synthesis of its Ce(III) and Nd(III) complexes. The complexes of Ce(III) and Nd(III) with 3,5-pyrazoledicarboxylic acid were synthesized and their compositions were determined by elemental analysis. Vibrational study in the solid state of 3,5-pyrazoledicarboxylic acid and its new Ce(III) and Nd(III) complexes was performed by IR and Raman spectroscopy. The changes observed between the IR and Raman spectra of the ligand and of the complexes allowed us to establish the coordination mode of the metal in both complexes. The comparative vibrational analysis of the free ligand and its lanthanide(III) complexes gave evidence that 3,5-pyrazoledicarboxylic acid binds Ln(III) through the deprotonated carboxylic oxygens. The density functional theory (DFT) calculated geometries, harmonic vibrational modes and Raman scattering activities of the ligand were in good agreement with the experimental data, and a complete vibrational assignment is being proposed. The experimental IR and Raman bands of the ligand were assigned to normal modes on the basis of DFT calculations. The effect of the intramolecular hydrogen bonds in the ligand on vibrational mode positions is also discussed. The characteristic IR and Raman bands of 3,5-pyrazoledicarboxylic acid and its lanthanide complexes were specified and discussed.

Reversible Breaking and Forming of Metal–Ligand Coordination Bonds: Temperature‐Triggered Single‐Crystal to Single‐Crystal Transformation in a Metal–Organic Framework

“…Notably, the last two bands are found in the Ln-O stretching zone. [39,40] This result supports the hypothesis that a Ln À O À OH species is formed during the first reaction cycle and behaves as the real active intermediate in the catalytic reaction. This would explain the increase in activity observed after the first reaction cycle.…”

In situ formation of high performance Ni-phytate on Ni-foam for efficient electrochemical water oxidation

“…The successful chelation of phytate anions was confirmed by the peaks corresponding to C 1s [21] and P 2p [11] in the XPS spectrum. Figure 2e shows Raman peaks at about 815 and 1520 cm -1 which correspond to P-O-C rock stretching [22] and ring C-H bending [22][23][24], respectively. The peaks at 972, 983 and 1679 cm -1 are attributed to the -C-H out-of-plane deformation [25], C-C-H bending, O-P-O stretching [16] and asymmetrical stretching modes [24].…”

“…Figure 2e shows Raman peaks at about 815 and 1520 cm -1 which correspond to P-O-C rock stretching [22] and ring C-H bending [22][23][24], respectively. The peaks at 972, 983 and 1679 cm -1 are attributed to the -C-H out-of-plane deformation [25], C-C-H bending, O-P-O stretching [16] and asymmetrical stretching modes [24]. Compared with the original sodium phytate [26,16], the ATR-IR (Fig.…”

Polarized raman spectroscopy for determining the orientation of di‐d‐phenylalanine molecules in a nanotube

“…Raman spectroscopy is a powerful nondestructive technique used for studying the structure and conformation of molecular species. It has been applied to study many types of materials, including inorganic and organic compounds, polymers, proteins, and peptides . Raman spectroscopy has the ability to probe a protein's secondary and tertiary structure, determine the conformation of side chains, and determine the local environment of aromatic amino acid residues .…”