Temperature-Induced Structural Transformations of Lanthanide Coordination Polymers Based on a Semirigid Tricarboxylic Acid Ligand: Crystal Structures and Luminescence Properties

Three new types of lanthanide coordination polymers.one-dimensional (1D) {[Ln(TCMA)(HTCMA)]center dot(DMF)center dot(H2O)(2)}(n) (1-2), three-dimensional (3D) {[Ln(TCMA)-(NO3)]}(n) (3-4), and zero-dimensional (0D) Ln(4)(TCMA)(4)-(OH)(4)(H2O)(8) (5-6) (Ln = Eu, Tb) have been hydrothermally synthesized by using the ligand N,N,N-tris{(2'-carboxy[1,1'-biphenyl]-4-yl)methyl}methylammonium chloride ([H(3)TCMA](+)-Cl). Interestingly, the 1D chain and 3D Ln-MOFs can be transformed to a more stable 0D cage structure by changing temperature-induced ligand's configuration transformation, which is attributed to the ligand's semirigid feature. Furthermore, the crystal structures of 1-6 were characterized and confirmed by X-ray single-crystal analysis, X-ray diffraction (XRD), thermogravimetric analysis (TGA), ultimate analysis, and infrared (IR) spectroscopy. The luminescence detection results show that the 3D Eu-MOFs have good sensitivity and selectivity to detect Fe3+ ions in methanol solutions. And, with careful adjustment of metal ratios (Eu/Tb) in the reaction mixtures, color tuning was easily achieved. Moreover, lifetime data and quantum yield are reported for these complexes (1-6) prepared in this study.

Automated summary

Three novel types of lanthanide coordination polymers were successfully synthesized via a hydrothermal method. The 1D chain and 3D Ln-MOFs can transform into a more stable 0D cage structure through temperature-induced ligand's configuration transformation. The materials were characterized using various analytical techniques, and it was found that the 3D Eu-MOFs exhibit good sensitivity and selectivity towards Fe3+ ions in methanol solutions.