Organoamine-Directed Assembly of 5p–4f Heterometallic Cluster Substituted Polyoxometalates: Luminescence and Proton Conduction Properties

The assembly of heterometallic cluster substituted polyoxometalates (POMs) remains a great challenge for inorganic synthetic chemistry up to now. Herein, a series of 5p–4f heterometallic cluster substituted POMs were successfully isolated by a facile one-step hydrothermal reaction method, namely H 17 (H 2 en) 3 [Sb III 9 Sb V Ln 3 O 14 (H 2 O) 3 ][(SbW 9 O 33 ) 3 (PW 9 O 34 )]·28H 2 O( 1-Ln, Ln = Ce, Sm, Eu, Gd, Tb, Dy) (en = ethylenediamine). Interestingly, by replacing en with imidazole, another series of 5p–4f heterometallic cluster substituted POMs H 13 (HIm) 4 K 2 Na 4 (H 2 O) 9 [Sb III 9 Sb V Ln 3 O 14 (H 2 O) 3 ][(SbW 9 O 33 ) 3 (PW 9 O 34 )]·26H 2 O ( 2-Ln, Ln = Sm, Eu, Gd, Tb, Dy, Im = imidazole) were obtained. Structural analyses indicate that both 1-Ln and 2-Ln are made up of an unprecedented 5p–4f heterometallic {Sb 10 Ln 3 O 14 (H 2 O) 3 } cluster stabilized simultaneously by mixed trilacunary heteropolyanions including {A-α-PW 9 O 34 } and {B-α-SbW 9 O 33 }. Impedance measurements indicate that both compounds exhibit different proton conduction properties, and the conductivity of 2 can reach up to 1.64 × 10 –2 S cm –1 at 85 °C under 98% relative humidity. Moreover, the fluorescence emission behaviors of both compounds have been studied.