Crystal Structure and Reversible Photochromism of Pb(II)‐N,N‐Dimethylformamide Modified Keggin‐Type Polyoxometalates

Abstract

AbstractTwo Pb(II)‐DMF complex modified Keggin‐type polyoxometalate compounds, [Pb(DMF)7]2[SiW12O40] 2DMF (1) and [Pb(DMF)4(H2O)2][Pb2(μ2‐DMF)2(DMF)8][PW12O40]2 (2) (DMF = N,N‐dimethylformamide), have been demonstrated in this work. Both 1 and 2 are characterized by X‐ray single crystal diffraction, Fourier transform infrared (FTIR), and UV–vis spectra, and elemental analyses. The crystal structure analysis indicates that compound 1 is composed of Pb(II)‐DMF complex and Keggin‐type [SiW12O40]4− polyoxoanion, in which the Pb2+ coordinates to the polyoxoanion by different Pb−O bonds, while compound 2 is composed of [Pb(DMF)4(H2O)2]2+, dimeric [Pb2(μ2‐DMF)2(DMF)8]4+ cations, and two kinds of Keggin‐type [PW12O40]2− polyoxoanions. By ultraviolet irradiation, both 1 and 2 display the reversible color change from white (for 1) or light yellow (for 2) to blue, which can be applied as new crystalline photochromic materials. Upon heating, the blue color of the two compounds can be recovered within 5 min. The successful syntheses of compounds 1 and 2 provide a new route for the design and synthesis of reversible photochromic crystalline materials.