Structural Diversity in Neodymium Bipyrimidine Compounds with Near Infrared Luminescence: from Mono- and Binuclear Complexes to Metal-Organic Frameworks
Résumé
Treatment of Nd(NO3)3 with 2,2′-bipyrimidine (bpm) afforded the mononuclear adduct [Nd(NO3)3(bpm)(MeOH)2] (1) after recrystallization from MeOH, while reactions of hydrated NdCl3 and various -diketonates in the presence of bpm gave the binuclear compounds [{Nd(dbm)3(THF)}2(μ-bpm)] (2) and [{Nd(bta)3(MeOH)}2(μ-bpm)] * bpm (3 * bpm) (Hdbm ) dibenzoylmethane, Hbta ) 4,4,4-trifluoro-1-phenyl-1,3-butanedione) and the one-dimensional coordination polymer [Nd(tta)3(μ-bpm) * MeOH]∞ (4 * MeOH) (Htta ) 2-thenoyltrifluoroacetone). The crystal structures of 2-4 demonstrate that the bpm molecule can act as a planar bridging ligand between two lanthanide ions as large as Nd3+. Luminescence measurements revealed that near-IR emission from neodymium can be obtained after excitation of either the bpm or the -diketonate ligand, and that an energy transfer occurs from the -diketonate group to the bpm molecule.