Effect of Noble Metals on Luminescence and Single-Molecule Magnet Behavior in the Cyanido-Bridged Ln–Ag and Ln–Au (Ln = Dy, Yb, Er) Complexes

Abstract

Self-assembly of lanthanide­(III) complexes of 2,2′:6′,2″-terpyridine (terpy) with dicyanidoargentate­(I) and dicyanidoaurate­(I) anions in water results in the formation of six isostructural dinuclear systems [LnIII(terpy)­(H2O)­(NO3)2]­[MI(CN)2] (LnIII/MI = Dy/Ag, 1; Dy/Au, 2; Yb/Ag, 3; Yb/Au, 4; Er/Ag, 5; Er/Au, 6). They form three-dimensional supramolecular networks based on dinuclear molecules linked by hydrogen bonds, π–π interactions, and argentophilic (Ag···Ag) or aurophilic (Au···Au) interactions. All of the assemblies show complex solid-state strong UV and weak vis–NIR absorption due to overlapping contributions from 2,2′:6′,2″-terpyridine, dicyanidoargentate­(I), dicyanidoaurate­(I), and lanthanide­(III) ions. Moreover, they exhibit excitation-wavelength-dependent multicolor photoluminescence ranging from bright white to blue via yellow, green, and cyan colors due to variable contributions from the dicyanidometalate and ligand. Assemblies 3–6 show NIR emission originating from YbIII and ErIII metal centers. Furthermore, compounds 1–6 and their magnetically diluted samples are magnetic-field-induced single-molecule magnets with energy barriers of up to 35 K. The effect of noble metal substitution on the magnetic properties of particular lanthanide ions is described. The influence on the thermal anisotropic energy barrier, which relates to the strength of the magnetic anisotropy, depends on the type of lanthanide used. The Ag-to-Au substitution enhances the anisotropy of the prolate YbIII ion and decreases it for the oblate DyIII ion. It also modifies the strength of dipolar interactions affecting the slow magnetic relaxation processes.

Pseudo-Tetrahedral vs Pseudo-Octahedral ErIII Single Molecule Magnets and the 'Disruptive' Role of Coordinated TEMPO Radicals

“…Compared to the tetrahedral 1 and 3, the octahedral 4 performs worse as an SMM due to the much less favourable, higher-symmetry ligand scaffold as previously observed for several Er III complexes with coordination numbers exceeding 6. [48][49][50][51][52][53][54][55] Finally, our detailed magneto-structural and theoretical study of the pseudo-tetrahedral 1 and 3, clearly shows that in the presence of a small external magnetic field, the slow magnetic relaxation in these two SMMs is fully governed by the Raman relaxation process instead of Orbach in the whole investigated AC magnetic susceptibility temperature and frequency range. This observation again calls for a better understanding of this most basic relaxation process in the lanthanide-based SMMs.…”

Structural Disorder in High-Spin {CoII9WV6} (Core)-[Pyridine N-Oxides] (Shell) Architectures

“…The critical underlying prerequisite-axial magnetic anisotropy-has been shaped through cyanide-bridging of suitable d and f metal ion and dedicated coordination surrounding. For example, among the frequently exploited building blocks, one can indicate 6-coordinated fac-[M(L)(CN) 3 ] − (M-Fe III/II , Co III/II ; l-hydrotris(pyrazol-1-yl)borate, tetra(pyrazol-1-yl)borate) moieties with trigonal distortion [1][2][3][4], octahedral Co II with axial deformation [5,6], trans-[M(L)(CN) 2 ] (M-Fe, Cr; l-planar pentadentate ligands) heptagonal bipyramidal moieties [7,8] or intrinsically anisotropic 4d or 5d heavy metal precursors [9], and lanthanide complexes [10,11].…”

Ionic Complexes [Ph3PBu-n][Au(CN)2Cl2] and [Ph3PCH2OMe][Au(CN)2Cl2]: Synthesis and Structure

“…Интерес к данному семейству комплексов вызван обилием различных практически применимых свойств, которые им можно придавать и модифицировать путём внедрения дополнительных лигандов или координационных центров. Среди таких свойств магнетизм [1][2][3][4][5][6][7], люминесценция [7][8][9][10][11][12], вапохромизм [11][12][13][14][15][16] Полученные комплексы представляют собой кристаллические, устойчивые на воздухе вещества с четко определенной температурой плавления.…”