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

Dalton Trans

Guangzhou Key Laboratory for Environmentally Functional Materials and Technology, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China.

Published: October 2018

A new salicylaldehyde-based azo dye 5-azotriazolyl-3-methoxysalicylaldehyde (H2TMSA) and its two Ln3+ complexes {[Ln(HTMSA)3(H2O)2][Ln(HTMSA)3(DMF)(H2O)]}·15H2O (Ln = Dy(1) and Tb(2)) have been synthesized and characterized by IR, Raman, 1H NMR and single-crystal X-ray diffraction techniques. H2TMSA 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 Ln3+ 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.

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http://dx.doi.org/10.1039/c8dt02951bDOI Listing

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