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In this paper, we report a facile method to produce large-area periodical bowl-like cobalt oxide (Co3O4) array films based on a self-assembled monolayer polystyrene sphere template and electrodeposition. After the template is removed, the resulting Co3O4 films consist of periodic, interconnected networks of monodisperse submicrometer pores with a diameter of 1 μm. Moreover, the individual bowl contains a large number of pores with a diameter of 50 ± 20 nm and the interstices between bowls are filled with Co3O4 nanoflakes. As a preliminary test, the electrochromic properties of the Co3O4 macrobowl arrays have been investigated and it is found that the film annealed at lower temperature exhibits better electrochromic performance. The Co3O4 array film annealed at 200 °C exhibits good electrochromism with color changes from dark gray to pale yellow and fast response times. The coloration efficiency is calculated to be 29 cm2 C−1 at 633 nm, with a variation of transmittance up to 33%.

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The Dawson anion P 2W 18O 62 (6-) has been used as a noncoordinating polyoxoanion template for the construction of two metal-organic frameworks, namely, [M 2(bpy) 3(H 2O) 2(ox)][P 2W 18O 62]2(H 2-bpy). nH 2O (M = Co(II), n = 3 ( 1); M = Ni(II), n = 2 ( 2)) (bpy = 4,4'-bipyridine; ox = C 2O 4 (2-)). Single-crystal X-ray analysis reveals that both of the structures exhibit 3D host frameworks constructed from the oxalate-bridged binuclear superoctahedron secondary building units (SBUs) and bpy linkers and the voids of which are occupied by Dawson anions, guest bpy, and water molecules. Magnetic studies reveal that there are antiferromagnetic exchange interactions among the transition-metal centers in compounds 1 and 2. Furthermore, a compound 1-modified carbon paste electrode ( 1-CPE) displays good electrocatalytic activity toward the reduction of nitrite.

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Reactions of 1:13 heteropoly anions [MV13O38](7-) (M = Mn, Ni) and lanthanide cations Ln3+ (Ln = La, Ce, or Pr) produce five isomorphic compounds, which are crystallized in the triclinic crystal system, space group P1, and formulated as [Ln6(H2O)25(MV12O38)(HMV13O38)].nH2O ((1) Ln = La, M = Mn, and n approximately 31; (2) Ln = Ce, M = Mn, and n approximately 29; (3) Ln = Pr, M = Mn, and n approximately 31; (4) Ln = La, M = Ni, and n approximately 28; (5) Ln = Pr, M = Ni, and n approximately 33). These compounds are two-dimensional polymeric structures constructed by hydrated lanthanide cations and two types of heteropoly anions, [MV13O38](7-) and [MV12O38](12-). In contrast to the previous reported 1:13 heteropoly anions, all with disordered structures, [MV13O38](7-) clusters in 1-5 are non-disordered with a distinct mode. The second kind of anionic cluster [MV12O38](12-) with O(h) symmetry, which consists of 13 entire edge-sharing MO(6) (M = V, Mn or Ni) octahedra, has not been reported hitherto. The emergence of the new cluster may be correlated to the six capping lanthanide cations surrounding it with a stabilization effect. In this paper, the syntheses and structures of the five polymeric lanthanide heteropolyvanadates of manganese(IV) and nickel(IV) have been presented.