Visible to near-infrared emission from $Ln^{III}(Bis-oxazoline)-[Mo^{V}(CN)_{8}]$ (Ln=Ce-Yb) magnetic coordination polymers showing unusual lanthanide-dependent sliding of cyanido-bridged layers

Complexes of lanthanides(III) (Ce–Yb) with 2,2′-bis(2-oxazoline) (Box) combined with octacyanidomolybdate(V) gave a series of magneto-luminescent coordination polymers, {[LnIII(Box)n(DMF)m][MoV(CN)8]}·x(solvent) (1–12). They are built of cyanido-bridged layers of a mixed 4- and 8-metal rings topology and show unique sliding of layers dependent on a 4f metal ion. For light lanthanides, dominant phase A, {[LnIII(Box)2(DMF)2][MoV(CN)8]}·1.5MeCN (Ln = Ce, 1; Pr, 2; Nd, 3), consists of ideally aligned, not shifted layers, giving large channels (13.7 × 14.0 Å). Intermediate lanthanides reveal phase B, {[LnIII(Box)2(DMF)2] [MoV(CN)8]}·H2O (Ln = Sm, 4; Eu, 5; Gd, 6; Tb, 7; Dy, 8), of smaller pores (8.4 × 10.6 Å) due to layer-H2O hydrogen bonding, which induces sliding of CN–-bridged layers. Heavy lanthanides show phase C, {[LnIII(Box)(DMF)3][MoV(CN)8]}·MeCN (Ln = Ho, 9; Er, 10; Tm, 11; Yb, 12), with large channels (13.7 × 13.7 Å) of a similar size to light lanthanides. This effect comes from the changes in LnIII coordination sphere affecting solvent–layer interactions. Compounds 1–12 reveal diverse emission depending on the interaction between LnIII and Box luminophors. For 2–5, 9, and 12, the ligand-to-metal energy-transfer-induced visible f-centered emission ranging from green for HoIII-based 9, orange from SmIII-based 4, to red for PrIII- and EuIII-containing 2 and 5, respectively. Near-infrared emission was found for 2–4, 9, and 12. Red phosphorescence of Box was detected for GdIII-based 6, whereas the selective excitation of ligand or LnIII excited states resulting in the switchable red to green emission was found for TbIII-based 7. The materials revealed LnIII–MoV magnetic coupling leading to ferromagnetism below 2.0 and 2.2 K for 4 and 7, respectively. The onset of magnetic ordering at low temperatures was found for 6 and 8. Compounds 1–12 form a unique family of cyanido-bridged materials of a bifunctional magneto-luminescence character combined with dynamic structural features