Lanthanide hexacyanidoruthenate frameworks for multicolor to white-light emission realized by the combination of d-d, d-f, and f-f electronic transitions

[Image: see text] We report an effective strategy toward tunable room-temperature multicolor to white-light emission realized by mixing three different lanthanide ions (Sm(3+), Tb(3+), and Ce(3+)) in three-dimensional (3D) coordination frameworks based on hexacyanidoruthenate(II) metalloligands. Mono-lanthanide compounds, K{Ln(III)(H(2)O)(n)[Ru(II)(CN)(6)]}·mH(2)O (1, Ln = La, n = 3, m = 1.2; 2, Ln = Ce, n = 3, m = 1.3; 3, Ln = Sm, n = 2, m = 2.4; 4, Ln = Tb, n = 2, m = 2.4) are 3D cyanido-bridged networks based on the Ln–NC–Ru linkages, with cavities occupied by K(+) ions and water molecules. They crystallize differently for larger (1, 2) and smaller (3, 4) lanthanides, in the hexagonal P6(3)/m or the orthorhombic Cmcm space groups, respectively. All exhibit luminescence under the UV excitation, including weak blue emission in 1 due to the d-d (3)T(1g) → (1)A(1g) electronic transition of Ru(II), as well as much stronger blue emission in 2 related to the d-f (2)D(3/2) → (2)F(5/2,7/2) transitions of Ce(III), red emission in 3 due to the f-f (4)G(5/2) → (6)H(5/2,7/2,9/2,11/2) transitions of Sm(III), and green emission in 4 related to the f-f (5)D(4) → (7)F(6,5,4,3) transitions of Tb(III). The lanthanide emissions, especially those of Sm(III), take advantage of the Ru(II)-to-Ln(III) energy transfer. The Ce(III) and Tb(III) emissions are also supported by the excitation of the d-f electronic states. Exploring emission features of the Ln(III)–Ru(II) networks, two series of heterobi-lanthanide systems, K{Sm(x)Ce(1–x)(H(2)O)(n)[Ru(CN)(6)]}·mH(2)O (x = 0.47, 0.88, 0.88, 0.99, 0.998; 5–9) and K{Tb(x)Ce(1–x)(H(2)O)(n)[Ru(CN)(6)]}·mH(2)O (x = 0.56, 0.65, 0.93, 0.99, 0.997; 10–14) were prepared. They exhibit the composition- and excitation-dependent tuning of emission from blue to red and blue to green, respectively. Finally, the heterotri-lanthanide system of the K{Sm(0.4)Tb(0.599)Ce(0.001)(H(2)O)(2)[Ru(CN)(6)]}·2.5H(2)O (15) composition shows the rich emission spectrum consisting of the peaks related to Ce(III), Tb(III), and Sm(III) centers, which gives the emission color tuning from blue to orange and white-light emission of the CIE 1931 xy parameters of 0.325, 0.333

Field-induced slow magnetic relaxation in Mn9W6Mn_9W_6 cluster-based compound

Magnetic measurements of a three-dimensional (3D) molecular magnet built of Mn₉[W(CN)₈]₆ clusters have been carried out to study its static and dynamic properties. Measurements of ac susceptibility in the presence of static magnetic field revealed slow magnetic relaxations. It was found that for the 120 Hz wave frequency the optimal static field which maximizes the imaginary component of the ac susceptibility is about 500 Oe