The one-pot assembly reaction of Na2WO4 center dot 2H(2)O, RE(NO3)(3)center dot 6H(2)O, and NaAsO2 in the participation of dimethylamine hydrochloride as an: organic solubilizing agent in the acidic aqueous solution led to a class of trigonal pyramidal {AsO2(OH)} bridging rare-earth substituted arsenotungstate (AT) aggregates [H2N(CH3)(2)](8)Na-8{[W3RE2 (H2O)(8)ASO(8) (OH)][B-alpha-AsW(9)Q(33)](2)}(2)center dot 65H(2)O [RE = Eu-III (1), Gd-III (2), Tb-III (3), Dy-III (4), Ho-III (5), Y-III (6)], which were structurally characterized by elemental analyses, IR spectra, single-crystal X-ray diffraction, and thermogravimetrit (TG) analyses. The common structural feature of 1-6 is that their polyoxoanions consist of a novel tetrameric unit [(W3RE2(H2O)(8)-AsO8(OH))(B-alpha-AsW9O33)(2)(16-) constituted by four trivacant Keggin [alpha-AsW9O33](9-) fragments linked through an unseen elliptical [W6RE4(H2O)(16)As2O16(OH)(2)](20+) moiety. Their polyoxoaniOnic infrastructures can also be described as a fusiOn of two =equivalent dimeric subunits [(W3RE2(H2O8O7)(B-alpha-AsW9O33)(2)](8-) bridged via two mu(2)-{AsO2(OH)} linkers. To the best of our knowledge, such a linking mode with trigonal pyramidal {As02(OH)} groups as linkers connecting adjacent RE containing polyoxometalate moieties together is very rare. The thermal stability of 1-6 was also investigated on the crystalline samples, and the thermal decomposition processes of 1, 4,. and 6 were comparatively deeply studied. The fluorescent properties and decay times of 1, 3, and 4 were measured, and they exhibit the characteristic emissions of RE centers. The lifetimes of I and 3 mainly originate from the contribution Of RE ions whereas the overall lifetime of 4 is contributed by the synergistic interactions of AT fragments and Dy3+ ions.