We present a simple and generalizable synthetic route toward phase-pure, monodisperse transition-metal-substituted ceria nanoparticles (M0.1Ce0.9O2–x, M = Mn, Fe, Co, Ni, Cu). The solution-based pyrolysis of a series of heterobimetallic Schiff base complexes ensures a rigorous control of the size, morphology and composition of 3 nm M0.1Ce0.9O2–x crystallites for CO oxidation catalysis and other applications. X-ray absorption spectroscopy confirms the dispersion of aliovalent (M3+ and M2+) transition metal ions into the ceria matrix without the formation of any bulk transition metal oxide phases, while steady-state CO oxidation catalysis reveals an order of magnitude increase in catalytic activity with copper substitution. Density functional calculations of model slabs of these compounds confirm the stabilization of M3+ and M2+ in the lattice of CeO2. These results highlight the role of the host CeO2 lattice in stabilizing high oxidation states of aliovalent transition metal dopants that ordinarily would be intractable, such as Cu3+, as well as demonstrating a rational approach to catalyst design. The current work demonstrates, for the first time, a generalizable approach for the preparation of transition-metal-substituted CeO2 for a broad range of transition metals with unparalleled synthetic control and illustrates that Cu3+ is implicated in the mechanism for CO oxidation on CuO-CeO2 catalysts.

The mononuclear complexes belonging to the [M(valXn)]0/+ family [H2valXn are bicompartmental ligands derived from o-vanillin and 1,2- or 1,3-diamines; M = Ni(II), Cu(II), Au(III)] can efficiently act as receptors towards various hydrogen bond donors. The co-crystallization processes between [Ni(valXn)] complexes and ammonium salts (NH4Z, Z− = ClO4−; PF6−; C6H5NH3ClO4) led to different supramolecular arrangements in the crystals depending on the host:guest molar ratio used in reactions. For a 2:1 stoichiometry, supramolecular dimers were obtained in the crystals: 2[Ni(valen)]·NH4Z (Z− = ClO4−, 1a; Z− = PF6−, 1b), 2[Ni(valphen)]·NH4ClO4·CH3OH 1c, 2[Ni(valmen)]·C6H5NH3ClO43, while for a 1:1 stoichiometry a supercomplex with a quadruple deck architecture resulted: 4[Ni(valen)]·3NH4ClO42. The co-crystallization of the Reinecke salt with mononuclear complexes from the [M(valXn)] family affords the following crystals: [Ni(valen)]2·NH4[Cr(NCS)4(NH3)2]·CH3OH 4, [Ni(valdmpn)]2·NH4[Cr(NCS)4(NH3)2]·2H2O 5, and [Cu(valpn)]·NH4[Cr(NCS)4(NH3)2]·CH3CN 6, in which the [M(valXn)] complexes interact with the ammonium ions and ammonia ligands, resulting in supramolecular chains. The composition and the topology of the supramolecular chain can be changed by replacing the ammonium ion from the Reinecke salt with a cationic receptor, [Au(valpn)]+:[Au(valpn)][Cr(NCS)4(NH3)2] 7.

A series of five N,N′-bis(2-hydroxy-3-methoxybenzylidene)-1,3-propanediamine (H2L) ytterbium complexes, namely, [Yb(H2L)2(CH3OH)](ClO4)3 (1), [Yb(H2L)(NO3)3]2·CH2Cl2 (2), [Yb(H2L)2(NO3)]2(PF6)4·4H2O·2CH2Cl2 (3), [Yb(H2L)(OAc)2]2(PF6)2·4CH2Cl2 (4) and [Yb3L′3(OH)2Cl(H2O)5]Cl3·4H2O (5) (HL′ = 2-hydroxy-3-methoxybenzaldehyde), have been synthesized by reactions of H2L with multifarious Yb(III) salts. X-ray diffraction analysis reveals that complex 1 shows a unique mononuclear structure constructed from two chelating H2L ligands in crossover mode. Complex 2 exhibits a dinuclear structure bridged by two H2L ligands. Complexes 3 and 4 possess two novel dinuclear structures linked by NO3− and OAc− anions, respectively. Complex 5 displays a trinuclear structure supported by three L′ and two OH− anions. Noticeable, complex 3 can be transformed from 2 by introducing (NH4)(PF6). The PF6− counterion plays an essential role in steering the structural transformation. The anions dominate the final structures of 1–5. All complexes 1–5 exhibit NIR luminescence, which can be rationalized on the basis of different structural effects. Preliminary catalytic studies reveal that all complexes 1–5 are able to catalyze effectively a typical Henry reaction with good yields.

A series of five N,N′-bis(2-hydroxy-3-methoxybenzylidene)-1,3-propanediamine (H2L) ytterbium complexes, namely, [Yb(H2L)2(CH3OH)](ClO4)3 (1), [Yb(H2L)(NO3)3]2·CH2Cl2 (2), [Yb(H2L)2(NO3)]2(PF6)4·4H2O·2CH2Cl2 (3), [Yb(H2L)(OAc)2]2(PF6)2·4CH2Cl2 (4) and [Yb3L′3(OH)2Cl(H2O)5]Cl3·4H2O (5) (HL′ = 2-hydroxy-3-methoxybenzaldehyde), have been synthesized by reactions of H2L with multifarious Yb(III) salts. X-ray diffraction analysis reveals that complex 1 shows a unique mononuclear structure constructed from two chelating H2L ligands in crossover mode. Complex 2 exhibits a dinuclear structure bridged by two H2L ligands. Complexes 3 and 4 possess two novel dinuclear structures linked by NO3− and OAc− anions, respectively. Complex 5 displays a trinuclear structure supported by three L′ and two OH− anions. Noticeable, complex 3 can be transformed from 2 by introducing (NH4)(PF6). The PF6− counterion plays an essential role in steering the structural transformation. The anions dominate the final structures of 1–5. All complexes 1–5 exhibit NIR luminescence, which can be rationalized on the basis of different structural effects. Preliminary catalytic studies reveal that all complexes 1–5 are able to catalyze effectively a typical Henry reaction with good yields.

By connecting [LCuTb]3+ nodes with [Fe(CN)6]3− spacers a 1-D coordination polymer with slow relaxation of magnetization is obtained (L2− is the N,N′-propylene-bis(3-methoxysalicylideneiminato) anion).

By connecting [LCuTb]3+ nodes with [Fe(CN)6]3− spacers a 1-D coordination polymer with slow relaxation of magnetization is obtained (L2− is the N,N′-propylene-bis(3-methoxysalicylideneiminato) anion).

The mononuclear complexes belonging to the [M(valXn)]0/+ family [H2valXn are bicompartmental ligands derived from o-vanillin and 1,2- or 1,3-diamines; M = Ni(II), Cu(II), Au(III)] can efficiently act as receptors towards various hydrogen bond donors. The co-crystallization processes between [Ni(valXn)] complexes and ammonium salts (NH4Z, Z− = ClO4−; PF6−; C6H5NH3ClO4) led to different supramolecular arrangements in the crystals depending on the host:guest molar ratio used in reactions. For a 2:1 stoichiometry, supramolecular dimers were obtained in the crystals: 2[Ni(valen)]·NH4Z (Z− = ClO4−, 1a; Z− = PF6−, 1b), 2[Ni(valphen)]·NH4ClO4·CH3OH 1c, 2[Ni(valmen)]·C6H5NH3ClO43, while for a 1:1 stoichiometry a supercomplex with a quadruple deck architecture resulted: 4[Ni(valen)]·3NH4ClO42. The co-crystallization of the Reinecke salt with mononuclear complexes from the [M(valXn)] family affords the following crystals: [Ni(valen)]2·NH4[Cr(NCS)4(NH3)2]·CH3OH 4, [Ni(valdmpn)]2·NH4[Cr(NCS)4(NH3)2]·2H2O 5, and [Cu(valpn)]·NH4[Cr(NCS)4(NH3)2]·CH3CN 6, in which the [M(valXn)] complexes interact with the ammonium ions and ammonia ligands, resulting in supramolecular chains. The composition and the topology of the supramolecular chain can be changed by replacing the ammonium ion from the Reinecke salt with a cationic receptor, [Au(valpn)]+:[Au(valpn)][Cr(NCS)4(NH3)2] 7.

A new family of hetero-tri-metallic complexes [M(CuTb)]n (MIII = Co, Cr, Fe; n = 1, 2, ∞), composed of three series of three compounds (oligo- and poly-nuclear complexes based on [Cu–Tb] subunits), is presented and fully characterized. These nine compounds, viewed as different assemblies of single-molecule magnet (SMM) building blocks, connected to various hexacyanometalate centers, illustrate how the SMM behavior of the [CuTb] moiety can be modulated via the control of intermolecular interactions. Specifically, the combination of the “non-innocent” diamagnetic [CoIII(CN)6]3− center with a [Cu–Tb]3+ moiety enabled isolation of the magnetic entities, resulting in an improvement of the SMM behavior (ranging from Ueff = 5–7 cm−1 to 15–17 cm−1).

A new family of hetero-tri-metallic complexes [M(CuTb)]n (MIII = Co, Cr, Fe; n = 1, 2, ∞), composed of three series of three compounds (oligo- and poly-nuclear complexes based on [Cu–Tb] subunits), is presented and fully characterized. These nine compounds, viewed as different assemblies of single-molecule magnet (SMM) building blocks, connected to various hexacyanometalate centers, illustrate how the SMM behavior of the [CuTb] moiety can be modulated via the control of intermolecular interactions. Specifically, the combination of the “non-innocent” diamagnetic [CoIII(CN)6]3− center with a [Cu–Tb]3+ moiety enabled isolation of the magnetic entities, resulting in an improvement of the SMM behavior (ranging from Ueff = 5–7 cm−1 to 15–17 cm−1).