Solvothermal Synthesis, Crystal Structure, and Luminescent Properties of Three Heterometallic Lanthanide-Transition-Metal Frameworks Constructed from Three Types of CuBr Motifs

摘要

Three three-dimensional (3D) heterometallic lanthanide-transition-metal (hetero-Ln-TM) compounds with the formula [Ln(6)(Cu4Br3)(Cu2Br2)(2)(Cu2Br)(IN)(20)(H2O)(12)]2H(2)O [Ln = Gd (1), Ln = Sm (2), Ln = Eu (3)] based on the linkages of one-dimensional Ln organic chain and CumBrn units were synthesized by mixing Ln(2)O(3) with isonicotinic acid (HIN = pyridine-4-carboxylic acid) under hydrothermal condition. During the synthesis, two ligands were used: the isonicotinate (IN-) stabilizes the cluster and links the one-dimensional Ln organic chains and CumBrn motif, whereas Br- anions play a very important role in the formation of the distinct CumBrn units. It is interesting that there are three different Cu-Br motifs: a closed four-membered ring [Cu2Br2] subunit, a linear [Cu2Br] subunit, an S-sharp [Cu4Br3] subunit. Strong fluorescence of compounds 2 and 3 suggests an efficient energy transfer from the ligand to Eu3+ ions. The luminescent investigation indicates that 2 and 3 are excellent candidates for fluorescent materials.