Two polyoxovanadoborates with over 100 nuclei assembled from a {V₁₄Co₁₂B₇₂} cluster

Combining theoretical prediction and experimental exploration, the first sandwich-type polyoxovanadoborate (POVB) with an odd number of nuclei, [V₁₁B₂₆O₇₃(OH)₁₀]⁸⁻(1), was discovered under hydrothermal conditions. Density-functional theory (DFT) gives a rationalization for the existence of this structure and the structural feature is consistent with the {V_NB_2N+X} (X = 2, 4, 6, 8) general formula. Excitingly, when Co and 1,10-phenanthroline (phen) are introduced into the synthesis of vanadoborates system, a 100-nuclei [Co₆(phen)₁₀(H₂O)₈][V₁₄Co₁₂B₇₂O₁₄₄(OH)₂₀]·28H₂O (2) and a 102-nuclei [Co₆(phen)₁₄(H₂O)₄][V₁₄Co₁₂B₇₂O₁₄₄ (OH)₂₀]·23H₂O (3) with the same core structure of [V₁₄Co₁₂B₇₂]¹²⁻ are obtained. The vase-shaped [V₁₄Co₁₂B₇₂] polyanion is a multilayered sandwich-type structure containing seven distinct structural layers and is the largest known POVB. Furthermore, 2 demonstrates exceptional thermal and chemical stability and serves as an efficient and stable catalyst for the photoreduction of carbon dioxide.