Unprecedented Selenium and Lanthanide Simultaneously Bridging Selenotungstate Aggregates Stabilized by Four Tetra‐vacant Dawson‐like {Se 2 W 14 } Units

In the presence of the larger [H 2 N(CH 3 ) 2 ] + and K + counter cations as structure‐stabilizing agents, a class of unprecedented selenium and lanthanide (Ln) simultaneously bridging tetra‐vacant Dawson‐like selenotungstate aggregates [H 2 N(CH 3 ) 2 ] 2 Na 9 K 2 H 19 {[Ln 4 W 4 Se 4 O 22 (H 2 O) 5 ](Se 2 W 14 O 52 ) 2 } 2 ⋅ 60 H 2 O [Ln=Tb III ( 1 ), Dy III ( 2 ), Ho III ( 3 ), Er III ( 4 ), Tm III ( 5 ), Yb III ( 6 )] have been obtained by the one‐pot assembly reaction of Na 2 WO 4 ⋅ 2 H 2 O, Ln(NO 3 ) 3 ⋅ 6 H 2 O, and Na 2 SeO 3 under moderately acidic aqueous conditions and the complexes were structurally characterized by elemental analyses, IR spectra, single‐crystal X‐ray diffraction, powder X‐ray diffraction (PXRD), and thermogravimetric (TG) analyses. It should be noted that the appropriate molar ratio of Se/W is extremely important in the formation of 1 – 6 and can effectively ameliorate the yield of 1 – 6 . Moreover, dimethylamine hydrochloride is also indispensable and plays a considerably important role in improving the solubility of Ln ions and stabilizing the structures of 1 – 6 . The main polyoxoanion skeletons of 1 – 6 are constructed from two sandwich‐type tetra‐vacant Dawson‐like {[Ln 4 W 4 Se 4 O 22 (H 2 O) 5 ](Se 2 W 14 O 52 ) 2 } 16− half‐units linked through two W‐O‐Ln bridges. The sandwich‐type half‐unit comprises two tetra‐vacant Dawson‐like [Se 2 W 14 O 52 ] 12− fragments encapsulating a unique dodecanuclear Se‐Ln‐W [Ln 4 W 4 Se 4 O 22 (H 2 O) 5 ] 8+ oxo cluster. Their solid‐state visible and NIR fluorescent properties and lifetime decay behaviors were measured and their solid‐state luminescent spectra mainly demonstrate the characteristic emission bands of Ln 3+ ions. Moreover, the dominant wavelengths, the color purity, and correlated color temperatures of 1 – 5 have been also calculated. In addition, the luminous flux values of 1 – 5 are 2031, 6992, 3071, 921, and 477 lumen, respectively.