Tetrafluoroterephthalic Acid Research Articles

Synthesis and Crystal Structure of Coordination Polymer [Sc2(HOCH2CH2OH)4(tFBDC)3] · 2HOCH2CH2OH

The heating of a mixture of as-precipitated scandium hydroxide and tetrafluoroterephthalic acid in ethylene glycol leads to the formation of the complex [Sc2(HOCH2CH2OH)4(tFBDC)3]·2HOCH2CH2OH (tFBDC2− = tetrafluoroterephthalate) (1). According to the X-ray data, compound 1 is a chain coordination polymer. Sc(III) cations and tFBDC2− anions form double chains (ribbons). The coordination number of Sc(III) is completed to seven by ethylene glycol molecules acting as chelate ligands. There is a complex system of hydrogen bonding interactions induced by oxygen atoms of carboxylic groups of perfluorinated ligands and coordinated and lattice ethylene glycol.

Tuning the Topology from fcu to pcu: Synthesis and Magnetocaloric Effect of Metal–Organic Frameworks Based on a Hexanuclear Gd(III)-Hydroxy Cluster

Two polynuclear, cluster-based metal–organic frameworks (MOFs), formulated as {H2[Gd6(OH)8(H2O)6(p-BDC-F4)6]·3(2,2′-bpy)·6H2O} (1) and {H2[Gd6(OH)8(H2O)6(m-BDC-F4)6]·3(4,4′-bpy)·6H2O} (2) (p-BDC-F4 = tetrafluoroterephthalic acid, m-BDC-F4 = tetrafluoroisophthalic acid), are synthesized by hydrothermal reactions of GdIII ions with perfluorinated benzenedicarboxylate. Structure analysis illustrates that both 1 and 2 are constructed by the hexanuclear GdIII-hydroxy cluster molecular building block {Gd6(OH)8(COO)12(H2O)6}, generating a 12-connected fcu-MOF and a 6-connected pcu-MOF, respectively. Compounds 1 and 2 are stable in some refluxing organic solvents, boiling water, and aqueous solutions in the pH range of 2–11. Notably, magnetic investigation indicates that 1 and 2 display a significant magnetocaloric effect.

Water-Based Synthesis and Enhanced CO2 Capture Performance of Perfluorinated Cerium-Based Metal–Organic Frameworks with UiO-66 and MIL-140 Topology

Reaction of cerium ammonium nitrate and tetrafluoroterephthalic acid in water afforded two new metal–organic frameworks with UiO-66 [F4_UiO-66(Ce)] and MIL-140 [F4_MIL-140A(Ce)] topologies. The two...

Tuning Light-Driven Motion and Bending in Macroscale-Flexible Molecular Crystals Based on a Cocrystal Approach.

Flexible molecular crystals with stimuli-responsive properties are highly desirable; however, uncovering them is still a challenging goal. Herein, we report a cocrystal approach to obtain elastic molecular crystals that exhibit light-induced fluorescence changes and dynamic mechanical responses at the macroscale level. Cocrystals of naphthylvinylpyridine and tetrafluoroterephthalic acid were fabricated in different stoichiometry ratios (2:1 and 1:1), which present different shapes [two-dimensional (2D) and one-dimensional (1D) morphologies], photoemission, and mechanical properties (rigidity and flexibility). Moreover, obviously different photomechanical energy conversions (light-driven cracking/popping and bending/motion) occur for the 2D and 1D cocrystals, respectively. Nuclear magnetic resonance (NMR) spectra show the occurrence of photoinduced [2 + 2] cycloaddition in both cocrystals, which is the primary mechanism for their photoactuating behaviors. Crystal structure analysis and theoretical calculation further reveal that protonation and the hydrogen-bonding network play important roles in light-stimulus-bendable 1D cocrystal. Thus, the transformation from rigidity to flexibility based on cocrystallization with different stoichiometry may offer an effective means to tune the dynamic light-driven responses for smart crystalline materials.

Fluorine-Doped Cationic Carbon Dots for Efficient Gene Delivery

Carbon dots (CDs) focus great attention in a broad range of adhibitions because of their excellent optical properties and high biocompatibility and property adjustability. However, the developed CDs have rarely been used as effective gene vectors until now. In this work, we devised and synthesized novel fluorine-doped cationic CDs (FCDs) using tetrafluoroterephthalic acid as a fluorine source and using branched polyethylenimine to furnish positive charge sites. The FCDs achieve dramatic positive EGFP and luciferase gene transfection efficiency as well as low cytotoxicity in commonly used cell lines at a low weight ratio, even in primary and stem cells. It is worth pointing out that the FCDs possess superior efficiency and biocompatibility, compared to some widely used commercial reagents such as 25 kDa polyethylenimine and Lipofectamine 2000. In addition, the FCDs show excellent efficient transfection even at high serum concentration and low DNA dose, indicating potential practical applications.

Crystal Structure of Tris- (2,3,5,6-Tetrafluorobenzoato)Scandium [Sc(C6F4HCO2)3

The heating of a mixture of as-precipitated scandium hydroxide and tetrafluoroterephthalic acid in methanol is accompanied by acid decarboxylation and the formation of a tris-(2,3,5,6- tetrafluorobenzoato)scandium complex compound. According to the data of the single crystal X-ray diffraction analysis, the compound has a chain structure due to the carboxylate anion functioning as a μ2-bridging ligand. The polymer chains are linked together by π–π interactions between the phenyl rings.

A reversible acid-base fluorescent switch based on molecular cocrystal of 4-[2-4-quinolinyl)vinyl]phenol and tetrafluoroterephthalic acid

Photoactive cocrystal materials have received growing research interest in construction of photofunctional systems owing to the crucial roles in modifying the photo-related properties of molecular solids, based on the non-bonding interactions between self-assembly units. Herein, we report tunable luminescence and acid-base stimuli-responsive properties of a cocrystal assembled by 4-[2-(4-quinolinyl)vinyl]phenol ( qv ) and tetrafluoroterephthalic acid ( a ). The luminescent properties (such as wavelength, quantum yield and fluorescence lifetime) of qv.a changed obviously relative to the pristine qv , due to the proton transfer and the alternation of molecular arrangement within two-component crystalline material. The photoemission intensity of qv.a underwent from weak to strong upon HCl gas fuming, and the corresponding wavelength changed from 517 nm to 597 nm, which can be reversibly transferred after exposed in NH 3 . Such luminescent switching behavior may provide an effective way to develop new types of photoactive stimuli-responsive materials and optical sensors.

Cu(II) coordination polymers constructed by tetrafluoroterephthalic acid and varied imidazole-containing ligands: Syntheses, structures and properties

Six new copper(II) coordination polymers combining 2,3,5,6-tetrafluoroterephthalatic acid (H2tfBDC) and diverse imidazole-containing ligands, {[Cu(tfBDC)(1,2-bix)2]·2(H2O)}n (1), {Cu(tfBDC)(Im)2}n (2), {[Cu(1,4-bmimb)2(H2O)]·(tfBDC)·2(H2O)}n (3), {Cu(1,4-bimb)2(H2O)2·(tfBDC)}n (4), {[Cu(1,3-bix)2(H2O)2]·(tfBDC)·6(H2O)}n (5) and {[Cu(1,4-bix)2(H2O)2]·(tfBDC)·(1,4-bix)·4(H2O)}n (6) (1,2-bix = 1,2-bis(imidazole-1-ylmethyl)-benzene, Im = imidazole, 1,4-bmimb = 1,4-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene, 1,4-bimb = 1,4-bis(imidazol-1-yl)-butane, 1,3-bix = 1,3-bis(imidazole-1-ylmethyl)-benzene, 1,4-bix = 1,4-bis(imidazole-1-ylmethyl)-benzene), have been obtained and structurally verified by single-crystal X-ray diffraction analyses and further characterized by powder X-ray diffraction (PXRD), elemental analyses and infrared spectroscopy (IR). Single crystal X-ray diffraction analysis revealed that 1 is 2D 4-connected sql topology (point symbol: {44·62}) based on a single metal ion node. Compound 2 is characterized as an infinite 1D chain structure, which is further extended into a 2D layer through N-H···O hydrogen bonds and then a 3D supramolecular architecture via π···π stacking interactions. Note that 2 was prepared through an in situ ligand reaction in which N,N’-carbonyldiimidazole (cdi) broke up into imidazole ligand. Compound 3 possesses a 3D 4-fold interpenetrated architecture with 4-connected dia topology (Schläfli symbol: {66}) in which tfBDC2- is stabilized in the channel by hydrogen bonds. Compounds 4–6 are all linear 1D coordination polymers. In 4, the free tfBDC2- ligand acts as a μ4-bridge to link four coordinated water molecules from the chain to construct a 2D structure via hydrogen bonds. While in 5 and 6, the uncoordinated tfBDC2- ligands and multimeric water clusters is responsible for the conversion of these 1D coordination polymers into 3D supramolecular assemblies through O–H⋯O hydrogen bonding interactions. Moreover, the UV–vis spectra and thermal stability of 1–6 are discussed in detail.

Nickel metal-organic framework nanoparticles as electrode materials for Li-ion batteries and supercapacitors

Nickel-based metal-organic framework ([Ni(4,4′-bpy)(tfbdc)(H2O)2], Ni-MOF) nanoparticles with the size of 45–250 nm were synthesized by a facile hydrothermal route in combination with a grinding treatment (4,4′-bpy = 4,4′-bipyridine, H2tfbdc = tetrafluoroterephthalic acid). The materials were characterized by elemental analysis, IR spectrum, thermogravimetric analysis, powder X-ray diffraction, X-ray photoelectron spectrum (XPS), transmission electron microscope (TEM), scanning electron microscope (SEM), and the Brunauer–Emmett–Teller (BET) surface. As electrode materials for supercapacitors, the Ni-MOF nanoparticles delivered a high specific capacitance of 2548 F g−1 in 1 M KOH solution at a current density of 1 A g−1. When applied as anode materials of Li-ion batteries, the Ni-MOF nanoparticles displayed a higher reversible capacity, a better cyclic stability, and a higher rate performance, which still maintained 406 mAh g−1 after 50 cycles at a current density of 50 mA g−1. The better electrochemical performances may be attributed to the unique structure feature, and short route for electrolyte/Li-ions diffusion in nanosized Ni-MOF.

Extending the series of p-substituted tetrafluorobenzoic acids: synthesis, properties and structure

The synthesis of the derivatives of p-aminotetrafluorobenzoic acid, p-H2NC6F4CO2H (2b), by hydrolysis, acylation or interaction with aldehydes was developed giving H2NC6F4CO2K (2a), C6F5C(O)N(H)C6F4CO2Et (3) and (E)-ArCHNC6F4CO2Et (4–11). The chemical derivatization of tetrafluoroterephthalic acid, p-HO2CC6F4CO2H (12), by hydrolysis, etherification and reduction was performed giving a number of symmetrical X(O)CC6F4C(O)X (13–15; X=Cl, NEt2, OMe) or unsymmetrical YC6F4CO2Me (15a–b, 16, 18–21; Y=CO2K, CO2H, CH2OH, C(O)Cl, C(O)C6H3(i-Pr)2, CO2CH2C6F4CO2Me, CO2C6H4Bu-t), HOCH2C6F4CO2H (17), [MeO2CC6F4]2Y (22, 23; Y=OCH2CH2O, N(H)C6H4N(H)) compounds. All substances were thoroughly investigated by spectroscopic methods (multinuclear NMR and IR spectroscopy, mass-spectrometry). The molecular structures of p-H2NC6F4CO2Et (2) and p-HO2CC6F4CO2Me (15b) have been determined by X-ray diffraction analysis.

Nanoscale zinc-based metal-organic framework with high capacity for lithium-ion batteries

Layered zinc-based metal-organic framework ([Zn(4,4′-bpy)(tfbdc)(H2O)2], Zn-LMOF) nanosheets were synthesized by a facile hydrothermal method (4,4′-bpy = 4,4′-bipyridine, H2tfbdc = tetrafluoroterephthalic acid). The materials were characterized by IR spectrum, elemental analysis, thermogravimetric analysis, powder X-ray diffraction, transmission electron microscope (TEM), scanning electron microscope (SEM), and the Brunauer–Emmett–Teller (BET) surface. When the Zn-LMOF nanosheets with the thickness of about 24 ± 8 nm were used as an anode material of lithium-ion batteries, not only the Zn-LMOF electrode shows a high reversible capacity, retaining 623 mAh g−1 after 100 cycles at a current density of 50 mA g−1 but also exhibits an excellent cyclic stability and a higher rate performance.

Supramolecular assemblies of tetrafluoroterephthalic acid and N-heterocycles via various strong hydrogen bonds and weak C[sbnd]H⋯F interactions: Synthons cooperation, robust motifs and structural diversity

A series of organic solid states including three salts, two co-crystals, and three hydrates based on tetrafluoroterephthalic acid (H2tfBDC) and N-bearing ligands (2,4-(1H,3H)-pyrimidine dione (PID), 2,4-dihydroxy-6-methyl pyrimidine (DHMPI), 2-amino-4,6-dimethyl pyrimidine (ADMPI), 2-amino-4,6-dimenthoxy pyrimidine (ADMOPI), 5,6-dimenthyl benzimidazole (DMBI), 2-aminobenzimidazole (ABI), 3,5-dimethyl pyrazole (DMP), and 3-cyanopyridine (3-CNpy)), namely, [(PID)2·(H2tfBDC)] (1), [(DHMPI)2·(H2tfBDC)] (2), [(H-ADMPI+)2·(tfBDC2−)·2(H2O)] (3), [(H-ADMOPI+)2·(tfBDC2−)·(H2O)] (4), [(H-DMBI+)2·(tfBDC2−)·2(H2O)] (5), [(H-ABI+)2·(tfBDC2−)] (6), [(H-DMP+)·(HtfBDC−)] (7), and [(H-3-CNpy+)·(HtfBDC−)] (8), were synthesized by solvent evaporation method. Crystal structures analyses show that the F atom of the H2tfBDC participates in multiple CH⋯F hydrogen bond formations, producing different supramolecular synthons. The weak hydrogen bonding CH⋯F and NH⋯F play an important part in constructing the diversity structures 2–8, except in crystal 1. In complexes 1–3, they present the same synthon R22(8) with different N-heterocyclic compounds, which may show the strategy in constructing the supramolecular. Meanwhile, the complex 3 exhibits a 2D layer, and the independent molecules of water exist in the adjacent layers. In complexes 4 and 5, the water molecules connect the neighboring layers to form 3D network by strong OH⋯O hydrogen bonding. These crystals 1–8 were fully characterized by single-crystal X-ray crystallography, elemental analysis, infrared spectroscopy (IR), and thermogravimetric analysis (TGA).

Removal of Pharmaceuticals from Water via π–π Stacking Interactions in Perfluorinated Metal–Organic Frameworks

As more prescription and over-the-counter drugs are consumed worldwide, more and more drugs and their metabolites are entering the water stream with a water purification infrastructure not designed for their removal. Eventually this problem in conjunction with increasing amounts of industrially related waste organic molecules (i.e., PAHs) could lead to largescale water contamination. Herein we report a new perfluorinated In-derived metal–organic framework entitled YCM-101 synthesized from InCl3 and tetrafluoroterephthalic acid. YCM-101 is capable of removing the antibiotic tetracycline from aqueous solution, putatively accomplished via π–π stacking interactions of the electron deficient MOF linker and the electron rich aromatic components of tetracycline. This hypothesis was supported by obtained crystal structures of both benzene and pyridine participating in π–π stacking with YCM-101.

Mechanochemical Synthesis, Characterization, and Structure Determination of New Alkaline Earth Metal-Tetrafluoroterephthalate Frameworks: Ca(pBDC-F4)·4H2O, Sr(pBDC-F4)·4H2O, and Ba(pBDC-F4)

New fluorinated alkaline earth metal–organic frameworks were successfully synthesized by milling of metal hydroxides M(OH)2 with tetrafluoroterephthalic acid H2pBDC-F4. Both calcium- and strontium-tetrafluoroterephthalates are tetrahydrated, while the barium tetrafluoroterephthalate is free of coordinating water molecules. The two isomorphic structures Ca(pBDC-F4)·4H2O and Sr(pBDC-F4)·4H2O were solved from the powder diffraction data by ab initio structure determination and subsequent Rietveld refinement. The products were thoroughly characterized by elemental analysis, thermal analysis, magic-angle spinning NMR, Fourier transform infrared spectroscopy, scanning electron microscopy imaging, and Brunauer–Emmett–Teller measurements. Our findings suggest that the mechanochemical synthesis route is a promising approach for the preparation of new fluorinated alkaline earth metal–organic frameworks.

A series of reaction-controlled coordination polymers constructed from bis(imidazole) and tetrafluoroterephthalic acid ligands: syntheses, structural diversities, properties

Seven new mixed–ligand coordination polymers, {[Co0.5(bib)0.5(tftpa)0.5]·0.5H2O}n (1), [Cd2(bib)(tftpa)2]n (2), [Ni0.5(bib)0.5(tftpa)0.5]n (3), {[Co0.5(tftpa)(H2O)]·0.5bib·EtOH}n (4), {[Cd0.5(tftpa)(H2O)]·0.5bib·EtOH}n (5), [Cd3(bib)3(tftpa)3(MeOH)3]n (6), and [Cd(bib)(tftpa)(MeOH)]n (7) (bib = 1,4-bis(2-methylimidazol-1-yl)butane, H2tftpa = tetrafluoroterephthalic acid) have been synthesized under different reaction conditions and characterized by elemental analysis, IR, PXRD, single crystal X-ray diffraction analysis and thermogravimetric analysis. Complex 1 exhibits an unusual [2 + 2] interpenetrating diamond framework belonging to class IIIa with the point symbol 66. Complex 2 reveals a (3,4)-connected 3D framework with a unique double-stranded helical chain based on Cd–O–Cd and Cd–(COO)–Cd. Complex 3 presents a 4-fold interpenetrating 3D diamond framework belonging to class Ia with the point symbol 66. Complexes 4 and 5 display a 3D supramolecular architecture built on 2D stacked layers through hydrogen bonding and π–π interactions. Complex 6 also shows a 3D 4-fold interpenetrating diamond framework belonging to class Ia with the point symbol 66. Complex 7 features a 2D + 2D → 2D parallel polycatenated framework with the point symbol 44·62. The structural diversity of complexes 1–7 illustrate that a subtle change can have a marked effect on the crystal architectures. Moreover, the magnetic properties of complexes 1, 3, and 4, and the solid-state photoluminescence results for complexes 2, and 5–7 were also studied.

Syntheses, structures and properties of three 4-fold interpenetration coordination polymers based on two different dia interpenetrating modes

Three new 4-fold interpenetrated coordination polymers based on two different dia interpenetrating modes have been prepared successfully, namely [Cu0.5(bib)0.5(tftpa)0.5]n (1), {[Zn0.5(bib)0.5(tftpa)0.5]·0.5H2O}n (2) and [Cd(bib)(tftpa)(EtOH)]n (3) (bib=1,4-bis(2-methyl-imidazol-1-yl)butane, H2tftpa=tetrafluoroterephthalic acid). Complexes 1 and 3, with the same octahedral metal center, are obtained as 4-fold interpenetrated dia coordination frameworks; however, complex 2, with a tetrahedral metal center, presents a 4-fold dia network with an uncommon [2+2] mode of interpenetration. All of the polymers contain right- and left-handed helices that are constructed alternatively and each helix is built up from [M2(tftpa)(bib)]n. Additionally, thermogravimetric curves and luminescent emissions of 2 and 3 have been studied.

Manganese(II), nickel(II), and cadmium(II) coordination polymers with tetrafluoroterephthalate: syntheses, crystal structures, and luminescence properties

Three new coordination polymers, [Mn(BDC-F4)(DMF)2(H2O)2]n (1), [Ni(BDC-F4)(DMF)(EtOH)]n (2), and [Cd(BDC-F4)(DMF)(EtOH)]n (3), have been synthesized by assembling transition metal salts with the rigid ligand tetrafluoroterephthalic acid (H2BDC-F4) in mixed EtOH/DMF solvent at pH ca. 2. For complex 1, the octahedral coordination geometry of the MnII center is provided by two oxygen atoms from two dianionic BDC-F4 ligands, two DMF ligands and two aqua ligands, giving a 1-D linear chain array. For complex 2, the NiII center is coordinated by two dianionic BDC-F4 ligands, two EtOH ligands and two DMF ligands, resulting in a 1-D chain structure. For complex 3, the CdII center is coordinated by four dianionic BDC-F4 ligands, one EtOH ligand and one DMF ligand, generating a 2-D layered structure. The results suggest that both the metal and the solution pH play an important role in the formation of the complexes. The spectroscopic, thermal, and luminescence properties of the complexes have been investigated.

Preparation of photoluminescent compounds of Eu(III), Sm(III), and Dy(III) containing anions of tetrafluoroterephthalic acid

The Ln2(H2O)4(L)3·2H2O and Ln2(phen)2(L)3·2H2O complexes [Ln = Eu(III), Sm(III), or Dy(III); H2L = C6F4(COOH)2, phen = 1,10-phenanthroline] have been prepared. Structures of the prepared compounds have been confirmed by X-ray diffraction and IR spectroscopy studies. The complexes of Eu(III) have exhibited red photoluminescence stronger than that of the complexes of Sm(III) and Dy(III).

Li2(tF‐BDC)(DMF)2]: A New Alkali Metal Salt of Tetra­fluoroterephthalic Acid (H2tF‐BDC)

AbstractThe DMF solvate of lithium tetrafluoroterephthalate [Li2(tF‐BDC)(DMF)2] (H2tF‐BDC = tetrafluoroterephthalic acid) was synthesized and structurally characterized from X‐ray single crystal data (Pbcn, Z = 8). Li+ (CN = 4) is coordinated tetrahedrally by four oxygen atoms of three different tF‐BDC2– linkers and one DMF molecule. The LiO4 tetrahedra are connected by common vertices to chains, which are bridged by tF‐BDC2– linkers to form a 2D polymeric unit. The DMF molecules are oriented perpendicular to these polymeric sheets, which are stacked along [100] in an AB fashion and held together by weak van der Waals interactions. Single crystals of [Li2(tF‐BDC)(DMF)2] were synthesized by precipitation from an ethanol/DMF solvent mixture, but single‐phase samples were only obtained by a mechanochemical approach starting from lithium acetate and H2tF‐BDC by adding DMF. The thermal stability of [Li2(tF‐BDC)(DMF)2] was investigated by DTA/TG measurements. The (endothermic) decomposition starts at 170 °C and is followed by a second exothermic decomposition at approx. 300 °C. The weight losses are in good agreement with a release of DMF and CO2. LiF is identified in the residue after heating at 500 °C.

Two Anhydrous Salts of Tetrafluoroterephthalic Acid (H2tF‐­BDC): K2tF‐BDC and Rb2tF‐BDC

AbstractTwo new anhydrous salts of tetrafluoroterephthalic acid (H2tF‐BDC), namely K2tF‐BDC (1) and Rb2tF‐BDC (2), were synthesized and structurally characterized. The crystal structure of 1 (I2/m, Z = 2) was solved and refined from X‐ray single crystal data. K+ (CN = 8) is coordinated by six oxygen atoms of five different tF‐BDC2– linkers and two fluorine atoms of two of these linkers, which connect the KO6F2 polyhedra to a 3D network. The crystal structure of 2 (P$\bar{1}$, Z = 1) was refined from X‐ray powder diffraction data. It crystallizes in a structure type already known from Tl2tF‐BDC. Rb+ (CN = 8) is also coordinated by six oxygen and two fluorine atoms. But six tF‐BDC2– linkers are involved in the coordination. Again, a 3D network is formed. Both compounds can be obtained as single‐phase samples. They are not porous and stable in air. The thermal stability was investigated by DTA/TG measurements. The decomposition starts at approx. 200 °C (1) and 230 °C (2). Their good solubility in water makes them interesting starting materials for the synthesis of new MOFs with the perfluorinated linker tF‐BDC2–.