Synthesis, characterization, photochromism and crystal structure of a charge-transfer complex between an organic substrate and a polyoxometalate [C10H10N](4)GeMo12O40 center dot 6DMF (C10H10N=7-methyl-quinoline)

A charge-transfer complex, [C10H10N](4)GeMo12O40 . 6DMF, between the hetero polymolybdate anion, GeMo12O404- and the organic cation, protonated 7-methy l-quinoline has been synthesized and characterized. Light yellow crystals o f the title compound as a DMF solvate of formula [C10H10N](4)GeMo12O40. 6DM F were crystallized from DMF by diffusing acetone vapor into the solution. Spectroscopic data support the presence of a significant electronic interac tion between the electron-rich aromatic organic cations and the inorganic a nion in the solid state. The complex is strongly photosensitive under irrad iation with sunlight, resulting in charge-transfer by oxidation of the 7-me thyl-quinoline and reduction of the polyoxometalate. The variable temperatu re ESR spectra indicate thermal electron delocalization occurs among the Mo atoms in the title compound.