Three novel 2D organic–inorganic hybrid CuII–LnIII heterometallic arsenotungstates

The hydrothermal reactions of Na8[A-α-HAsW9O34]·11H2O with CuCl2·2H2O, LnCl3 in the presence of ethylenediamine (en) lead to three novel 2D organic–inorganic hybrid CuII–LnIII heterometallic arsenotungstates Na3[Cu(en)2(H2O)][Cu(en)2]1.5[H3Ln(α-AsW11O39)2]·xH2O (Ln = DyIII, x = 5 (1); Ln = GdIII, x = 4 (2); Ln = LaIII, x = 5.5 (3)), which have been characterized by elemental analyses, IR spectra, optical diffuse reflectance spectra, thermogravimetric analyses and single-crystal X-ray diffraction. 1–3 are isomorphic and exhibit the unique 2D honeycomb (6,3)-network topology constructed from sandwich-type [H3Ln(α-AsW11O39)2]8− units through [Cu(en)2]2+ linkers. To the best of our knowledge, 1–3 represent rare 2D organic–inorganic hybrid CuII–LnIII heterometallic arsenotungstates. The photocatalytic measurements show that 1–3 can to some extent inhibit the photodegradation of rhodamine-B. Moreover, magnetic measurements demonstrate that there are the weak ferromagnetic behaviors in 1 and 2.