A new salicylaldehyde-based azo dye and its two lanthanide() complexes displaying slow magnetic relaxation

A new salicylaldehyde-based azo dye 5-azotriazolyl-3-methoxysalicylaldehyde (H 2 TMSA) and its two Ln 3+ complexes {[Ln(HTMSA) 3 (H 2 O) 2 ][Ln(HTMSA) 3 (DMF)(H 2 O)]}·15H 2 O (Ln = Dy( 1 ) and Tb( 2 )) have been synthesized and characterized by IR, Raman, 1 H NMR and single-crystal X-ray diffractio...

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Published in:Dalton transactions : an international journal of inorganic chemistry 2018-10, Vol.47 (42), p.14975-14984
Main Authors: He, Jian-Qiang, Xie, Shang-Fang, Lai, Bi-Lin, Yang, Meng, Chen, Wen-Bin, Zhang, Yi-Quan, Dong, Wen
Format: Article
Language:English
Subjects:
Angles (geometry)
Azo dyes
Crystallography
Crystals
Density functional theory
Hydrazones
Magnetic anisotropy
Magnetic induction
Magnetic relaxation
Mathematical analysis
NMR
Nuclear magnetic resonance
Oxygen atoms
Single crystals
Time dependence
X-ray diffraction
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Summary:A new salicylaldehyde-based azo dye 5-azotriazolyl-3-methoxysalicylaldehyde (H 2 TMSA) and its two Ln 3+ complexes {[Ln(HTMSA) 3 (H 2 O) 2 ][Ln(HTMSA) 3 (DMF)(H 2 O)]}·15H 2 O (Ln = Dy( 1 ) and Tb( 2 )) have been synthesized and characterized by IR, Raman, 1 H NMR and single-crystal X-ray diffraction techniques. H 2 TMSA shows an azo form in acidic (pH < 5.05) and strong basic (pH > 12.41) conditions, and a pH-dependent azo-hydrazone tautomerism in the range of pH 5.05 to 12.41, which is demonstrated by the time-dependent density functional theory (TD-DFT) calculations. Single-crystal X-ray diffraction reveals that 1 and 2 are isostructural complexes in which the Ln 3+ ions are surrounded by six oxygen atoms from three dichelate HTMSA − ligands and two oxygen atoms from two solvent molecules forming a distorted square-antiprismatic geometry. Complex 1 shows distinct slow magnetic relaxation under a zero dc field, while 2 displays field-induced slow magnetic relaxation. Ab initio calculations were performed on the two complexes to understand their magnetic anisotropy and their different magnetic dynamics. A new salicylaldehyde-based azo dye 5-azotriazolyl-3-methoxysalicylaldehyde (H 2 TMSA) displaying pH-dependent azo-hydrazone tautomerism and its two Ln 3+ complexes displaying slow magnetic relaxation were reported.
ISSN:1477-9226
1477-9234
DOI:10.1039/c8dt02951b