2017/06/07 by John Krautwurst, Rainer Lamann, Uwe Ruschewitz
paper · doi:10.1002/zaac.201700108
The synthesis of monofluorinated trimesic acid (H 3 mfBTC = 2‐fluoro‐1,3,5‐benzene‐tricarboxylic acid) described in the literature leads in fact to its monopotassium salt K(H 2 mfBTC) ( 1 ), which was identified by a single crystal structure analysis ( Pc, Z = 2). It is obtained as a single‐phase product and shows good solubility in water so that from aqueous solutions fourteen new coordination polymers with Ln III cations were synthesized and structurally characterized. Depending on the size of the cations three different structure types with different water contents were observed. For Ln III = La 3+ – Nd 3+ and Sm 3+ – Gd 3+ the composition 1 ∞ [ Ln III (mfBTC) 3/3 (H 2 O) 6 ] was found and confirmed by a structural analysis ( Cc, Z = 4; CN = 9). For Ln III = Tb 3+ – Ho 3+ the composition 2 ∞ [ Ln III (mfBTC) 3/3 (H 2 O) 3 ] · H 2 O was obtained and confirmed by X‐ray single crystal structure analysis ( C 2/ c, Z = 8; CN = 9). Finally, for Ln III = Er 3+ – Lu 3+ the composition 1 ∞ [ Ln III (mfBTC) 2/2 (H 2 O) 5 ] · 2H 2 O was found and again confirmed by X‐ray single crystal structure analysis ( P 1 , Z = 2; CN = 8). Subtle changes of the cationic radii lead to different coordination spheres and thus to different compositions. The thermal stability of selected compounds representing all three structure types was investigated by DTA/TGA measurements. All compounds are stable up to at least 100 °C, before the release of water molecules starts. The Eu III and Tb III compounds show the expected intense red and green luminescence.