A new organic-inorganic hybrid dimeric polyoxometalate assembled by monovacant Dawson [α2-P2W17O61]10− and Eu(III) cations

Abstract

A novel organic-inorganic hybrid dimeric polyoxometalate was synthesized by the trivacancy precursor Na 12 [α-P 2 W 15 O 56 ]∙24H 2 O, which consists of dimer [{Eu(C 6 H 4 NO 2 )(H 2 O) 6 }{Eu(C 6 H 4 NO 2 ) 2 (H 2 O) 4 }{Eu(H 2 O) 3 } 2 (α 2 -P 2 W 17 O 61 ) 2 ] 11− ( 1a ), one Na + ion, eight protons and one [Eu(C 6 H 4 NO 2 )(H 2 O) 6 ] group for the charge balance, two C 6 H 5 NO 2 ligands. The decay time curve effectively demonstrates different potential energy transfer pathways triggered by different excitations, and also indicate POM components can sensitize the emission of Eu 3+ and lifetimes were prolonged. • A novel organic-inorganic hybrid dimeric POM NaH 8 [Eu(C 6 H 4 NO 2 )(H 2 O) 6 ][{Eu(C 6 H 4 NO 2 ) (H 2 O) 6 }{Eu(C 6 H 4 NO 2 ) 2 (H 2 O) 4 }{Eu(H 2 O) 3 } 2 (α 2 -P 2 W 17 O 61 ) 2 ]·(C 6 H 5 NO 2 ) 2 ·35H 2 O was prepared via the reaction of trivacancy Dawson Na 12 [α-P 2 W 15 O 56 ]∙24H 2 O and Eu 3+ cations in a acidic aqueous solution. • The UV/Vis spectrum of 1 shows four absorption band at 256, 340, 464 and 534 nm, which may originate from the pπ–dπ charge-transfer transitions of Dawson-type [α 2 -P 2 W 17 O 61 ] 10− polyoxoanions, the π−π* transition of C 6 H 5 NO 2 , and the 7F 0 –5D 2 and 7F 1 –5D 1 transitions of Eu 3+ cations, respectively. • The emission spectrum of the compound shows the characteristic emission peak of Eu 3+ at 580, 593, 614, 652, and 701 nm, which can be assigned to 5 D 0 → 7 F J (J = 0, 1, 2, 3, 4) transitions. • In addition, the decay time curve effectively demonstrates different potential energy transfer pathways triggered by different excitations, and also indicate POM components can sensitize the emission of Eu 3+ and lifetimes were prolonged. A new organic-inorganic hybrid dimeric polyoxometalate NaH 8 [Eu(C 6 H 4 NO 2 )(H 2 O) 6 ][Eu 4 (C 6 H 4 NO 2 ) 3 (H 2 O) 16 (α 2 -P 2 W 17 O 61 ) 2 ]·(C 6 H 5 NO 2 ) 2 ·35H 2 O ( 1 ) was prepared via the reaction of trivacant Dawson Na 12 [α-P 2 W 15 O 56 ]∙24H 2 O and Eu 3+ ion, which was further characterized by IR spectrum, thermogravimetric (TG) analysis, and X-ray single-crystal diffraction. Structural analysis revealed that 1 consists of an uncommon dimer [Eu 4 (C 6 H 4 NO 2 ) 3 (H 2 O) 16 (α 2 -P 2 W 17 O 61 ) 2 ] 11− ( 1a ), one [Eu(C 6 H 4 NO 2 )(H 2 O) 6 ] 2+ group, one Na + ion, eight protons for the charge balance, two C 6 H 5 NO 2 ligands and thirty-five lattice water molecules. The decay time curve effectively demonstrates different potential energy transfer pathways triggered by different excitations, and also indicate POM components can sensitize the emission of Eu 3+ and lifetimes were prolonged.