The syntheses and crystal structures of the monopotassium salts of difluorinated and tri/perfluorinated trimesic acid (1,3,5-benzenetricarboxylic acid ≡ H 3 BTC) are presented, namely, K(H 2 dF-BTC) (Fdd2, Z = 16) and K(H 2 pF-BTC) (Cc, Z = 4). For the first time, together with already known K(H 2 mF-BTC), all fluorination degrees of trimesic acid are accessible and can be used for a systematic study of the influence of fluorination on the stability of the resulting coordination polymers and metal−organic frameworks (MOFs). The monopotassium salts show a decreasing (chemical) stability in water upon heating, as well as a decreasing thermal stability, as evidenced by differential scanning calorimetry/ thermogravimetric analysis (DSC/TGA). A similar decreasing thermal stability is found for two series of isostructural coordination polymers (UHM-33 topology:• 1 / 2 H 2 O with L 2− = HBTC 2-, HmF-BTC 2− and HdF-BTC 2− ). Remarkably, while the decomposition temperatures decrease with increasing fluorination of the linker, the releasing temperatures for embedded solvent molecules (DMA and H 2 O, respectively) increase. To identify possible candidates for the synthesis of isostructural coordination polymers and MOFs with BTC 3− ligands with different degrees of fluorination, a database-adapted approach was developed, which utilizes the increased torsion angle between the carboxylate groups and the phenyl rings in these materials as a structure-determining parameter.

Five new complexes containing 2, 4, 6‐trifluorobenzoateas ligand have been synthesized and structurally characterized, namely Li(C6F3H2COO)(H2O) (P21, Z = 2, 1),Cs(C6F3H2COO)(C6F3H2COOH) (P21/c, Z = 4, 2),Cu(C6F3H2COO)2(H2O)2 (P$\bar{1}$, Z = 1, 3), Cu(C6F3H2COO)2(MeOH) (P21/c. Z = 4, 4) and Ag(C6F3H2COO)(H2O) (C2/c, Z = 8, 5). 1–3 and 5 are coordination polymers forming strands (1, 3, 5) or corrugated layers (2). In 1 and 2 the benzoate ligand acts as a bridging ligand, whereas in 3 and 5 the benzoate ligand is not bridging and the molecular units are interconnected by bridging water molecules. In 4 and 5, dimeric Cu2 and Ag2 units, respectively, are formed with short M···M contacts. The dimeric units in 4 resemble the well‐known paddlewheel structural motif. In 5 these dimeric units are further connected by bridging water molecules, whereas in 4 only very weak F···H interactions connect the dimeric units. DTA/TG experiments on 1, 3 and 4 reveal that in a first step solvent molecules (H2O, MeOH) are unquestionably released. In 1–5 the torsion angles of the carboxylate group with respect to the aromatic ring deviate significantly from zero. These results are in very good agreement with the results of quantum chemical calculations of free 2, 4, 6‐trifluorobenzoic acid and its dimer at the DFT and RI‐MP2 level of theory.

Abstract. 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.

Starting from the potassium salt of monofluorinated trimesic acid, K[H2mfBTC], and the respective lanthanide nitrates, Ln(NO3)3 · xH2O, 14 new coordination polymers were obtained and characterized by X‐ray single crystal structure analyses. Depending on the size of the Ln3+ cations three different structure types were observed with chain‐like (Ln = La‐Gd and Er‐Lu) or layer‐like (Ln = Tb‐Ho) polymeric units. The Eu3+ and Tb3+ compounds show an intense red and green luminescence. Details are discussed in the article by Uwe Ruschewitz et al. on page http://onlinelibrary.wiley.com/doi/10.1002/zaac.201700108/abstract.

Reaction of Sc(NO3)3·5H2O with K(H2 pF-BTC) – the monopotassium salt of perfluorinated trimesic acid – led to the formation of single crystals of [ Sc ( p F − BTC ) ( H 2 O ) 3 ] ∞ 1 ⋅ 4 H 2 O ${}_{\infty }{}^{1}[\text{Sc}(pF-\text{BTC}){({\text{H}}_{2}\text{O})}_{3}]\cdot 4{\text{H}}_{2}\text{O}$ ( P 1 ‾ $P‾{1}$ , Z = 2). DTA/TGA measurements revealed that all water molecules were released below 200 °C. Using powder synchrotron radiation diffraction data, the crystal structure of the residue of the dehydration was elucidated and the results confirmed the formula [ Sc ( p F − BTC ) ] ∞ 3 ${}_{\infty }{}^{3}[\text{Sc}(pF-\text{BTC})]$ (Fddd, Z = 16). The compound is similar, but not isostructural to the recently published UoC-4 (I41/amd, Z = 8; UoC: University of Cologne) with a difluorinated trimesate (dF-BTC3–) as connecting linker. Both compounds can be classified as metal-organic frameworks (MOFs) consisting of a 3D network of Sc3+ nodes connected by the fluorinated trimesate ligands. They contain small pores, but their opening windows are too small for any guest molecules to pass. Remarkably, UoC-4 with a lower symmetric ligand (dF-BTC3–) crystallizes in a higher symmetry space group (I41/amd) than UoC-6 (Fddd). This can be rationalized by increasing torsion angles of the carboxylate moieties in the pF-BTC3– ligand.