Tuning the oxidation states of copper ions ( + I/ + II) to construct different Keggin-based topology structures

摘要

Through tuning the oxidation states of Cu~(I/II), two Keggin-based compounds with different topologies, [Cu_5~1(btx)_4(PW]_(10)~(VI)O_(40))] (1) and [Cu_2~(II)(btx)_4(SiW_(12)O_(40))] (2) (btx= l,6-bis(l,2, 4-triazol-l-yl)hexane), were synthesized and structurally characterized. In 1, there exist decanuclear Cu~I circuits, which are linked through N1-containing btx ligands to construct a grid-like 2-D layer. Three sets of these layers interpenetrate to build a three-fold interpenetrating framework. The Keggin polyanions connect the adjacent three-fold interpenetrating frameworks to construct a 3-D structure. In 2, the Cu~(II)-btx moiety shows a (6~6) 3-D hexagonal channel-style framework. The Keggin polyanion offering four terminal oxygen atoms incorporates with this metal-organic framework imbedding the channels. The different oxidation states of copper ions (+I/+II) induces distinct coordination modes of btx and Keggin polyanions and affects the whole structural topologies. Tuning the oxidation states of copper ions is an effective strategy for obtaining POM-based topologies. In addition, the electrochemical properties of 1 and 2 bulk-modified carbon-paste electrodes are reported.