Achieving white light emission and increased magnetic anisotropy by transition metal substitution in functional materials based on dinuclear DyIII(4-pyridone)[MIII(CN)6]3- (M = Co, Rh) molecules

A building block approach has led to the construction of two unique bifunctional magneto-luminescent molecular materials, {[Dy-III(4-pyridone)(4)(H2O)(2)][M-III(CN)(6)]}center dot nH(2)O (M = Co, n = 2, 1; M = Rh, n = 4, 2), incorporating the cyanido-bridged dinuclear {(DyCoIII)-Co-III} (1) or {(DyRhIII)-Rh-III} (2) molecules, that crystallize within the supramolecular network in the attractive non-centrosymmetric Cmc2(1) space group. Both compounds reveal dual physical properties of colour-tunable photoluminescence and slow relaxation of magnetization. While 1 exhibits multi-coloured photoluminescence ranging from yellow to blue, tuned by the excitation wavelength, 2 additionally reveals nearly white light emission under 336 nm excitation at room temperature. 1 and 2 show 4f-metal-centered strong magnetic anisotropy presenting Single-Molecule Magnet (SMM) behaviour with the large anisotropic energy barriers of 187(6) K for 1, and 214(4) K for 2. We have shown and discussed that the replacement of [Co-III(CN)(6)](3-) by the heavier [Rh-III(CN)(6)](3-) analogue in {[Dy-III(4-pyridone)(4)(H2O)(2)][M-III(CN)(6)]}center dot 2H(2)O crystalline materials is an efficient route towards white light emissive solid state matrices composed of Single-Molecule Magnets with enhanced magnetic anisotropy. Such extraordinary photoluminescent molecule-based magnets can become good prerequisites for future application in bifunctional optical and magnetic devices.