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

Abstract

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 [SiW 12 O 40 ] 4− polyoxoanion, in which the Pb 2+ coordinates to the polyoxoanion by different Pb−O bonds, while compound 2 is composed of [Pb(DMF) 4 (H 2 O) 2 ] 2+ , dimeric [Pb 2 ( 2 -DMF) 2 (DMF) 8 ] 4+ cations, and two kinds of Keggin-type [PW 12 O 40 ] 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.

Properties of Mortar with Recycled Aggregates, and Polyacrylonitrile Microfibers Synthesized by Electrospinning

“…These results confirm that the structure of the microfibers is PAN. You could also observe some bands at approximately 1368, 1256 and 1088 cm −1 , which are characteristic of DMF, a solvent used in the synthesis of PAN microfibers [54,55]. On the other hand, the thermogravimetric analysis is shown in Figure 2b.…”