LnIII/MnII-LnIII complexes derived from a salicylic azo dye ligand: synthesis, structures, magnetic and fluorescence properties

Two Ln(III) complexes Ln(HTMSA)(3)(H2O)(2)5.5H(2)O (Ln = Dy (1) and Tb (2), H(2)TMSA = 5-azotriazolyl-3-methoxysalicylaldehyde) and two Mn-II-Ln(III) clusters [Mn(H2O)(6)][MnLn(2)(TTMSA)(4)(HTTMSA)(2)(H2O)(6)]4H(2)O (Ln = Dy (3) and Tb (4), H(2)TTMSA = 5-azotetrazolyl-3-methoxysalicylaldehyde) have been synthesized and structurally characterized. Single-crystal X-ray diffraction reveals that 1 and 2 are isostructural complexes in which the Ln(III) ions are surrounded by six oxygen atoms from three chelate HTMSA ligands and two oxygen atoms from two coordinated water molecules forming a distorted square-anti-prismatic geometry. In complexes 3 and 4, the Mn-II ions adjust two Ln(III) mononuclear anion clusters into tri-nuclear Ln(III)-Mn-II-Ln(III) anion clusters, with an additional [Mn(H2O)(6)](2+) as a counter ion to maintain the electroneutrality of the compound. Magnetic studies reveal that all the complexes 1-4 show nonzero out-of-phase signals, indicating single-molecule magnet behavior. The photoluminescence spectra of all the complexes were investigated and are discussed in detail.

Automated summary

Two Ln(III) complexes and two Mn-II-Ln(III) clusters were synthesized and characterized. The Ln(III) complexes have a distorted geometric structure surrounded by HTMSA ligands. The Mn-II ions assemble the Ln(III) mononuclear complexes into trinuclear anion clusters. Magnetic studies reveal single-molecule magnet behavior in all the complexes. The photoluminescence spectra were also investigated and discussed in detail.