Tuning the Dimensionality of Polyoxometalate-Based Materials by Using a Mixture of Ligands

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• 作者：Guillaume Rousseau ; Luisa Marleny Rodriguez-Albelo ; William Salomon ; Pierre Mialane ; J茅r么me Marrot ; Floriant Doungmene ; Isra毛l-Martyr Mbomekall茅 ; Pedro de Oliveira ; Anne Dolbecq
• 刊名：Crystal Growth & Design
• 出版年：2015
• 出版时间：January 7, 2015
• 年：2015
• 卷：15
• 期：1
• 页码：449-456
• 全文大小：471K
• ISSN：1528-7505

文摘

Five molecular one-, two-, or three-dimensional (1D, 2D, or 3D) organic鈥搃norganic hybrid polyoxometalates (POMs) based on the {蔚-PMo^V₈Mo^VI₄O₄₀Zn₄} (蔚Zn) Keggin unit have been synthesized under hydrothermal conditions using a mixture of O- and N-donor ligands. (TBA)₆[PMo^V₈Mo^VI₄O₃₇(OH)₃Zn₄]₂(C₁₄H₈O₄)₃路6H₂O (蔚₂(biphen)₃) is a 3D material with two interpenetrated networks built from dimeric (蔚Zn)₂ POMs linked by 4,4鈥?biphenyldicarboxylate (biphen) ligands. (TBA)₂[PMo^V₈Mo^VI₄O₃₈(OH)₂Zn₄](C₇H₆N₂)₃(C₁₄H₈O₄)_1/2路H₂O (蔚(bim)₃(biphen)_1/2), (TBA)₃[PMo^V₈Mo^VI₄O₃₈(OH)₂Zn₄](C₇H₆N₂)₂(C₈H₄O₄)路6H₂O (蔚(bim)₂(isop)), (TBA)_7/3[PMo^V₈Mo^VI₄O₃₈(OH)₂Zn₄](C₇H₆N₂)_8/3(C₈H₄O₄)_2/3 (蔚(bim)_8/3(bdc)_2/3), and (TBA)₃[PMo^V₈Mo^VI₄O₃₈(OH)₂Zn₄](C₇H₆N₂)₂(C₉H₃O₆)_2/3路6H₂O (蔚(bim)₂(trim)_2/3) all consist of monomeric 蔚Zn units bound to two types of organic ligands: benzimidazole (bim) and one of the following carboxylate ligands: biphen, 1,3-benzenedicarboxylate (isop), 1,4-benzenedicarboxylate (bdc), or 1,3,5-benzenetricarboxylate (trim) ligands. While 蔚(bim)₃(biphen)_1/2 is a molecular complex, 蔚(bim)₂(isop) and 蔚(bim)_8/3(bdc)_2/3 adopt a chain arrangement, and 蔚(bim)₂(trim)_2/3 is a 2D compound. In these materials, the limitation of the dimensionality is a direct consequence of the protonation of the nitrogen atom of the bim ligands. The electrocatalytic activity for the hydrogen evolution reaction (HER) of these five new POM-based coordination polymers has been studied, showing that their performance depends mainly on the presence of the 蔚Zn Keggin units but also on their structure. Modified electrodes fabricated with 蔚(bim)₂(trim)_2/3 entrapped in a carbon paste revealed that this hybrid is the most efficient electrocatalyst of the series, being stable and catalyzing the HER in the pH 1鈥? range.