Lanthanide metal-organic frameworks based on a thiophenedicarboxylate linker: Characterization and luminescence

Three topologically-related lanthanide thiophenedicarboxylate (TDC) metal-organic frameworks were synthesized using an identical metal:linker:solvet ratio. Nd(TDC)(3)(EtOH)(3)(H2O)center dot H2O (1; space group Cc, a = 24.035(2) angstrom, b = 10.063(1) angstrom, c = 18.998(1) angstrom, beta = 132.41(1)degrees) contains the same metal-TDC coordination modes as two other compounds which have the isostructural formula Ln(TDC)(3)(EtOH)(3)(H2O)H2O; Ln = Tb (2; space group (P) over bar 1, a = 12.807(9) angstrom, b = 14.557(1) angstrom, c = 19.128(1) angstrom, alpha = 106.66(2)degrees, beta = 105.62(2)degrees, gamma = 93.691(2)degrees), Dy (3; space group (P) over bar 1, a = 12.793(8) angstrom, b = 14.682(1) angstrom, c = 19.077(1) angstrom, alpha = 107.12(1)degrees, beta = 105.54(1)degrees, gamma = 93.518(2)degrees). An equimolar solvent mixture of water and ethanol causes both types of solvent molecules coordinating to metal centers. The fluorescence spectra of compounds 2 and 3 show characteristic bands related to their respective metal ions, but Dy-based 3 is very weak compared to Tb-based 2, indicating coordinating solvent molecules may be quenching Dy fluorescence. (C) 2012 Elsevier Masson SAS. All rights reserved.