Preparation, spectroscopic properties of 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) lanthanide complexes and the supramolecular structure of [Nd2L2(NO3)6(H2O)2]·H2O

The reaction of lanthanide nitrate with 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) yields six novel Ln(III) complexes ([Ln2L2(NO3)6(H2O)2]·H2O) which are characterized by elemental analysis, thermogravimetric analysis (TGA), conductivity measurements, IR, electronic and 1H NMR spectroscopies. A new quinoxalinedione-based ligand is used as antenna ligand to sensitize the emission of lanthanide cations. The lowest triplet state energy level of the ligand in the nitrate complex matches better to the resonance level of Eu(III) and Sm(III) than Tb(III) and Dy(III) ion. The f–f fluorescence is induced in the Eu3+ and Sm3+ complexes by exciting into the π–π* absorptions of the ligand in the UV. Furthermore, the crystal structures of a novel binuclear complex [Nd2L2(NO3)6(H2O)2]·H2O has been determined by single-crystal X-ray diffraction. The binuclear [Nd2L2(NO3)6(H2O)2]·H2O complex units are linked by the intermolecular hydrogen bonds and π–π interactions to form a two-dimensional (2-D) layer supramolecule.