Trapping the δ Isomer of the Polyoxometalate-Based Keggin Cluster with a Tripodal Ligand.
We report the synthesis, structural, and electronic characterization of the theoretically predicted, but experimentally elusive δ-isomer of the Keggin polyoxometalate polyanion. A family of δ-Keggin polyoxoanions of the general formula, (TEA)Hp Naq [H2 M12 (XO4 )O33 (TEA)]⋅r H2 O where p, q, r=[2,3,8] for 1 and [4,1,4] for 2 were isolated by the reaction of tungstate(VI) and vanadium(V) with triethanolammonium ions (TEAH), acting as a tripodal ligand grafted to the surface of the cluster thereby stabilizing the polyanionic δ-Keggin archetype. The δ-Keggin species were characterized by single-crystal X-ray diffraction, FT-IR, UV/Vis, NMR, and ESI-MS spectrometry. Electronic structure and structure-stability correlations were evaluated by means of DFT calculations. The compounds exhibited multi-electron transfer and reversible photochromic properties by undergoing single-crystal-to-single-crystal (SC-SC) transformations accompanied with color changes under light.
WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland (UK) http://www.croninlab.com.
Harikleia
H
Sartzi
WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland (UK) http://www.croninlab.com.
Haralampos N
HN
Miras
WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland (UK) http://www.croninlab.com.
Laia
L
Vilà-Nadal
WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland (UK) http://www.croninlab.com.
De-Liang
DL
Long
WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland (UK) http://www.croninlab.com. lee.cronin@glasgow.ac.uk.
Leroy
L
Cronin
Keggin isomers; assembly; photochromism; polyoxometalates; supramolecular chemistry