A new family of Er(III) complexes: from chains to nanotubes

The reaction, in a gel medium, of Er(III) chloride with the trisodium salt of benzene-1,3,5-tricarboxylic acid (H(3)TMA) yielded three different kind of crystals. All three have been structurally characterized. ErTMA(H2O)(5). 3.5H(2)O (1) crystallizes in C2/c with a = 14.7396(15), b = 16.9874(15), c = 14.4591(14) Angstrom, beta = 118.754(9)degrees and Z = 8. Its crystal st ructure has been reported elsewhere already. It consists of juxtaposed cris s-cross chains. ErTMA(H2O)(3). 1.5H(2)O (2) has been found to be isostructu ral to the Gd(III) complex reported already. It crystallizes in C2/c with a = 20.452(2), b = 9.973(1), c = 15.251(1) Angstrom, beta = 125.68 degrees a nd Z = 8. Its structure consists of parallel double-sheet networks based on honeycomb-like motifs. Er(3)TMA(3)(H2O)(8). 4H(2)O (3) crystallizes in P ( 1) over bar with a = 9.988(2), b = 15.656(3), c = 19.698(3) Angstrom, alpha = 110.77(2), beta = 100.63(2), gamma = 100.58(2)degrees and Z = 2. Its str ucture consists of parallel tube like layers based on the honeycomb-like mo lecular motifs already observed in 2. The crystal structure is reported her ein. A predominant phase diagram has been established versus the concentrat ions of the gel medium and of the solutions. Heating one of them progressiv ely liberates water molecules, which finally leads to ErTMA (4), which can reversibly bind water reforming 1. (C) 2000 Elsevier Science S.A. All right s reserved.