Influence of reaction temperature and stoichiometry on the coordination mode of a multidentate pyridylpyrazole ligand in Co() complexes: from a 0D mononuclear structure to 3D frameworks

One-pot solvothermal reactions of CoCl 2 ·6H 2 O with the semi-rigid ligand 3-(pyridin-4-yl)-1 H -pyrazole-5-carboxylic acid under different reaction temperatures and stoichiometry conditions gave rise to three new complexes: [Co(Hppza) 2 (H 2 O) 2 ] ( 1 ), [Co(Hppza) 2 ] n ( 2 ) and [Co(Hppza)(H 2...

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Published in:CrystEngComm 2022-08, Vol.24 (3), p.541-542
Main Authors: Zhang, Ling-Mei, Feng, Chao, Yang, Yu-Meng, Huang, Huan-Huan, Zhang, Guo-Ning, Wang, Yu-Cheng, Zhao, Hong
Format: Article
Language:English
Subjects:
Antiferromagnetism
Carboxylic acids
Chemical analysis
Chemiluminescence
Comparative studies
Ferromagnetism
Infrared spectroscopy
Ligands
Magnetic measurement
Pyrazole
Spectroscopic analysis
Stoichiometry
Thermogravimetric analysis
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Summary:One-pot solvothermal reactions of CoCl 2 ·6H 2 O with the semi-rigid ligand 3-(pyridin-4-yl)-1 H -pyrazole-5-carboxylic acid under different reaction temperatures and stoichiometry conditions gave rise to three new complexes: [Co(Hppza) 2 (H 2 O) 2 ] ( 1 ), [Co(Hppza) 2 ] n ( 2 ) and [Co(Hppza)(H 2 O)Cl] n ( 3 ), which were characterized by elemental analysis, FT-IR spectroscopy, UV-vis absorption spectroscopy, thermogravimetric analysis (TGA) and X-ray diffraction methods. A comparative study revealed the marked sensitivity of the structural chemistry of the above-mentioned ligand to the synthesis conditions. Complex 1 , which exhibited a zero-dimensional (0D) structure of mononuclear cobalt( ii ), was formed at 120 °C with a metal-to-ligand molar ratio of 2 : 1. A further increase in the reaction temperature to 130 °C resulted in the two-dimensional (2D) structure of 2 . Moreover, the three-dimensional (3D) structure of 3 was formed when the metal-to-ligand molar ratio was changed to 1 : 1 at 130 °C. The magnetic measurements of 3 showed weak ferromagnetic coupling with the decrease in temperature from 8 to 30 K and antiferromagnetic interaction among the Co II ions. In addition, the luminescence and electrogenerated chemiluminescence (ECL) behavior of 1-3 were also studied. Three Co( ii ) coordination polymers with different dimensionality have been successfully constructed under controlled conditions by changing the reaction temperature and stoichiometry.
ISSN:1466-8033
1466-8033
DOI:10.1039/d2ce00468b