Self-assembly of two Keggin-based 3D and 2D complexes with cobalt (II)-bis(triazole) motifs: Influenced by the spacer length of the ligands

Two Keggin-based inorganic–organic hybrid complexes, [Co2(H2O)2(btb)4(HPMoVI10MoV2O40)] (1) and [Co2(btx)5(HPMoVI10MoV2O40)] (2) (btb = 1,4-bis(1,2,4-triazol-1-yl)butane, btx = 1,6-bis(1,2,4-triazol-1-yl)hexane), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, and thermogravimetric analyses (TGA). Complex 1 exhibits 2D ladder-like metal–organic layers, which are further linked by the Keggin anions to construct a 3D twofold interpenetrating framework. Complex 2 shows a 2D metal–organic network containing two kinds of pores, in which the Keggin anions acting as bidentate inorganic linkages reside alternately. The flexible bis(triazole) ligands btb and btx with different spacer lengths play an important role in the formation of the final structures. In addition, the electrochemical and photocatalytic properties of 1 and 2 have been reported.

Graphical abstractTwo Keggin-based inorganic–organic hybrid CoII complexes have been synthesized by changing the spacer length of bis(triazole)-based ligands. Complex 1 exhibits a 3D twofold interpenetrating framework. Complex 2 shows a 2D POM-based network.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The flexible bis(triazole) ligands show merits to construct POM-based complexes. ► By tuning the spacer length of ligands, two 3D and 2D complexes were obtained. ► The title complexes show good electrocatalytic and photocatalytic properties.