Tetrafluoroterephthalic Acid Research Articles

Relaxometric properties and biocompatibility of a novel nanostructured fluorinated gadolinium metal-organic framework.

A novel Gd-MOF based on tetrafluoro-terephthalic acid has been synthesized and its structure has been solved using X-ray single crystal diffraction data. The compound, with the formula [Gd2(F4BDC)3·H2O]·DMF, is isostructural with other Ln-MOFs based on the same ligand and has been recently reported. Its crystals were also reduced to nanometer size by employing acetic acid or cetyltrimethylammonium bromide (CTAB) as a modulator. The relaxometric properties of the nanoparticles were evaluated in solution by measuring 1H T1 and T2 as a function of the applied magnetic field and temperature. The biocompatibility of Gd-MOFs was evaluated on murine microglial BV-2 and human glioblastoma U251 cell lines. In both cell lines, Gd-MOFs do not modify the cell cycle profile or the activation levels of ERK1/2 and Akt, which are protein-serine/threonine kinases that participate in many signal transduction pathways. These pathways are fundamental in the regulation of a large variety of processes such as cell migration, cell cycle progression, differentiation, cell survival, metabolism, transcription, tumour progression and others. These data indicate that Gd-MOF nanoparticles exhibit high biocompatibility, making them potentially valuable for diagnostic and biomedical applications.

Evaluation of Ce-MOFs as Photoanode Materials for the Water Oxidation Reaction: The Effect of Doping with [Ru(bpy)(dcbpy)(H2O)2]2+ Catalyst.

Artificial photosynthesis stands out as a highly effective method for harnessing sunlight to produce clean and renewable energy. The light-absorbing properties, chemical stability, and high redox activity of Ce-based metal-organic frameworks (MOFs) make them attractive materials for visible-light-driven water splitting. Currently, Ce-based MOFs remain a relatively underexplored system for photocatalytic water oxidation in acidic media. In this study, we synthesized a Ce-MOF with different linkers (1,4-benzenedicarboxylic acid, tetrafluoroterephthalic acid, 2-nitroterephthalic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, and 4,4'-biphenyldicarboxylic acid), which exhibit light-absorbing capability. Ce-based MOFs doped with [Ru(bpy)(dcbpy)(H2O)2]2+ (MOF-1 and MOF-2) water oxidation catalyst showed an enhanced photoelectrocatalytic current of ∼10-4 A·cm-2 at pH = 1, which is comparable with the [Ru(bpy)(dcbpy)(H2O)2]2+-doped MIL-126 Fe-based MOF. We also demonstrated the long-term durability of Ru-doped Ce-MOFs for photoelectrocatalytic water oxidation under acidic conditions. The as-synthesized MOFs were analyzed with powder X-ray diffraction (PXRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-visible diffuse reflectance spectroscopy, scanning electron microscopy (SEM), and electric conductivity measurements. This study contributes to the development of cost-effective materials for sustainable photocatalytic water splitting processes.

Fluorine-doped carbon dots (F-CDs) adsorbing DNA via hydrophobic interaction play dual-role of quenching carrier and signal reference for ratiometric fluorescence strategy to detect microRNA

The expression levels of microRNAs (miRNA) can provide insights into the occurrence, progression, and treatment efficacy in tumors, highlighting the need for precise and easily controllable detection methodologies. The reasonable design of carbon dots enables the precise manipulation of luminescence and surface characteristics. Herein, fluorine doped carbon dots (F-CDs) were designed and prepared to establish a reasonable control of the interaction force between DNA and F-CDs. F-CDs were synthesized through a hydrothermal reaction involving tetrafluoroterephthalic acid and tetraethylene pentaamine, resulting in noteworthy optical and amphiphilic properties. F-CDs proficiently interact with single-stranded DNA (ssDNA) through hydrophobic interaction, leading to the quenching of dye labeled ssDNA, while maintaining self-fluorescence stability. The quenching mechanism was elucidated. The complementary DNA sequence induced nearly 100% desorption of ssDNA from F-CDs. Assisted by the target cycling signal amplification from duplex specific nuclease (DSN) and the self-fluorescence of F-CDs, an effective ratiometric strategy utilizing the adsorption system of F-CDs and probe DNA for let-7a was established for detecting let-7a, a critical miRNA in the assessment of tumor development. Under the optimized conditions, this method demonstrated high sensitivity and reproducibility in detecting let-7a with the linear range from 1.0 fM to 10.0 nM and a low limit of detection (LOD) of 3.0 fM. The recovery of let-7a in plasma and the evaluation of let-7a levels in seven cell types underscored the method's potential for efficient applications in monitoring of miRNA levels in real samples.

Rational construction of edge-grafted g-C3N4 via cross-linking aromatic compounds with C[sbnd]F bonds for efficient photocatalytic H2 evolution

Chemical modification of g-C3N4 (CN) for electron directional transport to separate charge carriers is important for its photocatalytic application, but remains a challenge. In this research, Tetrafluoroterephthalic acid (TFBDC) was utilized to modify CN by the crossing-linking reaction of carboxyl groups in TFBDC and terminal NH2 groups in CN. The introduction of fluorine into the CN framework through benzene-ring linkage to CF bonds achieves the dual regulation of electron hybridization structure and electron directional transport from the center to the edge of CN, which can greatly promote the separation of charge carriers in plane, as supported by density functional theory (DFT) calculations and femtosecond transient absorption spectrum (fs-TAS). The decay dynamics analysis from fs-TAS results indicates the slower exciton annihilation and longer shallow electron trapping in TFBDC-50/CN (τ1: 1.3 ps, τ2: 136.4 ps) compared to CN (τ1: 3.3 ps, τ2: 149.4 ps), both of which can be attributed to the graft of benzene rings with CF bonds. This grafting strategy not only promotes the participation of more electrons in the photocatalytic water splitting process, resulting in the hydrogen evolution rate of TFBDC-50/CN being increased to 5.4 times that of CN, but also exhibits remarkable recycle stability, enhancing the overall performance of the photocatalytic system. The results obtained in this work can provide beneficial references for research aimed at exploring chemical modification of CN for the enhancement of photocatalytic performance.

Remarkable improvement of MOF-based triboelectric nanogenerators with strong electron-withdrawing groups

A metal-organic framework (MOF) with extraordinary designability and functionality has been reported as a promising material for triboelectric nanogenerators (TENGs) to harvest energy from the ambient environment. However, the limited performance of current MOF-TENGs severely restricts their further development. Herein, we tackle this challenge by introducing strong electron-withdrawing groups. We designed and synthesized UiO-66–4F with Zr6O4(OH)4 and tetrafluoroterephthalic acid (TFA) ligands. The four F atoms in a TFA ligand with strong electron negativity accounts for a huge improvement of the MOF-based TENGs, as demonstrated by experiments on different contrasting materials, and further examined with density functional theory calculations to reveal the underlying mechanism. Thanks to the enhanced surface property and strong electron-withdrawing capability enabled by introducing the UiO-66–4F, the UiO-66–4F@PDMS TENG generates a power density that is 77.5 times higher than that of a PDMS TENG, and the voltage output reaches a record high at 937 V in MOFs-based TENGs. The UiO-66–4F@PDMS TENG also exhibits high flexibility and good transparency, and is revealed to charge commercial capacitors and power 354 commercial LEDs. Our work provides a strategy to explore the fabrication and application of high-performance MOF-based TENGs.

Fluorinated polybenzimidazole as binders for high-temperature proton exchange membrane fuel cells

The performance of high-temperature proton exchange membrane fuel cells (HT-PEMFCs) is highly affected by the binders in the catalyst layer. However, the currently commonly used binders such as acidophilic polybenzimidazoles (PBIs) and hydrophobic fluorinated polymers (e.g. PTFE) could not conduct protons or facilitate rapid gas transport simultaneously. Herein, two fluorinated PBIs (F6PBI and F4PBI) are designed and synthesized as binder materials from the easily obtained monomers of hexafluoroglutaric acid (HFGA) and tetrafluoroterephthalic acid (TFPA). Combined with the good proton conductivity of PBI and high fuel permeability of PTFE, the H2/O2 single cell based on PA/mPBI membrane using F6PBI binder in catalyst layer exhibits a larger electrochemical surface area (ECSA) of 67 cm2/mgPt corresponding to a Pt-mass specific power density of 1.41 W/mgPt. Therefore, the MEA achieved the highest peak power density of 705 mW/cm2 at 160 °C with F6PBI binder of 5 wt% and catalyst of 0.50 mgPt/cm2, which is over 100 mW/cm2 higher than MEAs using mPBI and PTFE as binder materials. And the H2/O2 cell using F6PBI binder exhibits good stability of more than 800 h at a current of 0.3 A/cm2 at 160 °C.

Synthesis of Hierarchical-Porous Fluorinated Metal-Organic Frameworks with Superior Toluene Adsorption Properties.

Constructing metal-organic frameworks (MOFs) with high volatile organic compounds (VOCs) adsorption capacity and excellent water resistance remain challenging. Herein, a monocarboxylic acid-assisted mixed ligands strategy was designed to synthesize a novel fluorinated MOFs, MIL-53 (Al). The monocarboxylic acid promoted crystallization and produced abundant crystal defects, which increased pore volume. Moreover, the competitive coordination between tetrafluoroterephthalic acid and 1,4-dicarboxybenzene was moderated by monocarboxylic modulators, significantly improving the hydrophobicity. The toluene uptake of the optimal sample reached 254.85 mg g-1 under humid conditions, increased by 33.56 % of MIL-53(Al), and the QWet /QDry (the ratio of adsorption quality under wet to adsorption quality under dry) was 0.92, remarkably surpassing that of origin MIL-53 (0.72). The recycle experiment showed superior reusability with no performance degradation after 10 recycle under RH=50 % (relative humidity). The adsorptive kinetic and thermodynamic analysis proves that the adsorption process is controlled by surface mono-layer adsorption and pore diffusion. The fluorine group affects the internal diffusion, which weakens the transfer rate. This strategy opens a new prospect of obtaining hierarchical functional MOFs for meeting the VOCs uptake under the practical application.

In Situ X-ray Diffraction Investigation of the Crystallisation of Perfluorinated CeIV -Based Metal-Organic Frameworks with UiO-66 and MIL-140 Architectures*.

We report on the results of an in situ synchrotron powder X-ray diffraction study of the crystallisation in aqueous medium of two recently discovered perfluorinated CeIV -based metal-organic frameworks (MOFs), analogues of the already well investigated ZrIV -based UiO-66 and MIL-140A, namely, F4_UiO-66(Ce) and F4_MIL-140A(Ce). The two MOFs were originally obtained in pure form in similar conditions, using ammonium cerium nitrate and tetrafluoroterephthalic acid as reagents, and small variations of the reaction parameters were found to yield mixed phases. Here, we investigate the crystallisation of these compounds, varying parameters such as temperature, amount of the protonation modulator nitric acid and amount of the coordination modulator acetic acid. When only HNO3 is present in the reaction environment, only F4_MIL-140A(Ce) is obtained. Heating preferentially accelerates nucleation, which becomes rate determining below 57 °C. Upon addition of AcOH to the system, alongside HNO3 , mixed-phased products are obtained. F4_UiO-66(Ce) is always formed faster, and no interconversion between the two phases occurs. In the case of F4_UiO-66(Ce), crystal growth is always the rate-determining step. A higher amount of HNO3 favours the formation of F4_MIL-140A(Ce), whereas increasing the amount of AcOH favours the formation of F4_UiO-66(Ce). Based on the in situ results, a new optimised route to achieving a pure, high-quality F4_MIL-140A(Ce) phase in mild conditions (60 °C, 1 h) is also identified.

Room-Temperature Phosphorescent Organic-Doped Inorganic Frameworks Showing Wide-Range and Multicolor Long-Persistent Luminescence.

Long-persistent luminescence based on purely inorganic and/or organic compounds has recently attracted much attention in a wide variety of fields including illumination, biological imaging, and information safety. However, simultaneously tuning the static and dynamic afterglow performance still presents a challenge. In this work, we put forward a new route of organic-doped inorganic framework to achieve wide-range and multicolor ultralong room-temperature phosphorescence (RTP). Through a facile hydrothermal method, phosphor (tetrafluoroterephthalic acid (TFTPA)) into the CdCO3 (or Zn2(OH)2CO3) host matrix exhibits an excitation-dependent colorful RTP due to the formation of diverse molecular aggregations with multicentral luminescence. The RTP lifetime of the doped organic/inorganic hybrids is greatly enhanced (313 times) compared to the pristine TFTPA. The high RTP quantum yield (43.9%) and good stability guarantee their easy visualization in both ambient and extreme conditions (such as acidic/basic solutions and an oxygen environment). Further codoped inorganic ions (Mn2+ and Pb2+) afford the hybrid materials with a novel time-resolved tunable afterglow emission, and the excitation-dependent RTP color is highly adjustable from dark blue to red, covering nearly the whole visible spectrum and outperforming the current state-of-the-art RTP materials. Therefore, this work not only describes a combined codoping and multicentral strategy to obtain statically and dynamically tunable long-persistent luminescence but also provides great opportunity for the use of organic-inorganic hybrid materials in multilevel anticounterfeiting and multicolor display applications.

A protonated salt constructed by tetrafluoroterephthalic acid and 5, 6-dimethyl benzimidazole: Design, synthesis, proton transfer and luminescent property

A steady self-assembled protonated salt, constructed by Tetrafluoroterephthalic acid (Tera) and 5, 6-dimethyl benzimidazole (DBZ), was designed and prepared in methanol/water solution. The structure and properties were characterized by experimental tests and analyzed by theoretical calculations on molecular level. Excellent symmetry of Tera, proton transfer bridged by water molecule, intermolecular hydrogen bonding play important roles in the self-assemble process. Proton migration analysis confirms the keying action of H2O molecules on co-crystallization. AIM analyses indicate hydrogen bonds are dominant to stabilize crystal packing. In addition, vibrational analysis and luminescent property of the protonated salt were also explored in details.

Manganese oxide/Metal-Organic Frameworks-Based Nanocomposites for Tumr Micro-environment Sensitive 1H/19F Dual-mode Magnetic Resonance Imaging in Vivo

A pH- and GSH-responsive 1H/19F dual-mode magnetic resonance imaging contrast agent (MRI CA) was constructed by incorporating MnOx into Zr-based MOF nanoparticles (MnOx/UiO-66-F/PPEG NPs) with an organic ligand of tetrafluoro-terephthalic acid (F4PTA). Under a weak acidic tumor micro-environment, MnOx/UiO-66-F/PPEG NPs would collapse to release MnOx and free F4PTA. Due to the released free F4PTA, 19F MRI signal was enhanced. Meanwhile, GSH, which is overexpressed in a tumor micro-environment, reduced MnOx to divalent manganese ions and improved the T1-weighted MR imaging capability. As a proof of concept, MnOx/UiO-66-F/PPEG NPs was favorable for dual 1H/19F MRI with a high signal-to-noise ratio in vivo.

Co-based MOF for efficient degradation of RB in aqueous solutions by peroxymonosulfate activation

Metal-organic frameworks (MOFs) are being positively researched as potential materials in chemical, photo and biomimetic catalytic areas. Herein, we report a transition metal Co-containing MOF, namely CUST-501 {[Co2(H2O)(tfBDC)2(Phen)2]}, (tfBDC = Tetrafluoroterephthalic acid, Phen = 1,10-Phenanthroline monohydrate), synthesized via solvothermal method. CUST-501 was characterized by IR spectroscopy, powder X-ray diffraction (PXRD), X-ray single-crystal structure analysis and thermogravimetric analysis (TG). Furthermore, it can act as chemical catalysts, which shows fast activation of PMS for the RB degradation about 30 min in aqueous solution. In addition, the recyclability measurement reveals that CUST-501 is a stable, continuous and efficient catalyst which was used to activate PMS for achieving the purpose of degrading pollutants in water. This study indicates that CUST-501 can be used as efficient catalysts to produce radicals, further treating organic dyes and offering more options for future water treatment solutions.

Tumor micro-environment sensitive 19F-magnetic resonance imaging in vivo

19F MRI has been paid great attention because of its higher signal-to-noise ratio and larger chemical shift than 1H MRI. However, the low 19F content and sensitivity of environment limit its development in clinic. Herein, considering the large surface area and abundant metal active sites of metal organic framework (MOF) nanoparticles, we fabricated Zr-based MOF nanoparticles (UiO-66-F NPs) with an organic ligand of tetrafluoro-terephthalic acid (F4PTA) as a pH-sensitive 19F MRI contrast agent, which remained stable in a neutral condition, but could release free F4PTA in an acidic condition to enhance 19F MRI signal. As a proof of concept, UiO-66-F NPs-based contrast agent could turn on the 19F MRI signal in an acidic tumor micro-environment. The results provide an alternative strategy for the design of tumor micro-environment responsive 19F MRI contrast agents.

Synthesis, co-crystal structure, and DFT calculations of a multicomponent co-crystal constructed from 1H-benzotriazole and tetrafluoroterephthalic acid

A co-crystal of 1H-benzotriazole (HB) and tetrafluoroterephthalic acid (TETA) has been successfully prepared based on N-H⋯O, O-H⋯N, and C-H⋯F hydrogen bonding interactions and characterized using single crystal X-ray diffraction. Density functional theory (DFT) calculations and vibrational spectroscopy were performed to predict the molecular structure and electronic, chemical, and vibrational properties associated with these hydrogen bonds. Quantitative electrostatic potential analysis (ESP) explained the active hydrogen bonding sites in HB and TETA, and predicted the hydrogen bonding modes in their co-crystal structure. Quantum theory of atoms in molecules (QTAIM) and reduced density gradient (RDG) analyses suggested that the hydrogen bonds present in the HB-TETA co-crystal were moderate in nature expect O-H⋯N (1.735 Å, −62.377 kJ mol−1). Meanwhile, the dnorm-mapped Hirshfeld surface of TETA can be used to understand the characteristics of the close contacts; the features were reflected in 2D fingerprint plots. Natural bond orbital (NBO) analysis of the second order perturbation theory indicated that the LP(N19)→σ∗(O5-H7) (26.76 kcal mol−1), LP(O9)→σ∗(N21-H22) (6.69 kcal mol−1), and LP(F1)→σ∗(C24-H25) (6.05 kcal mol−1) interactions were responsible for the weak interactions in the co-crystal. The structural vibrations accompanying these hydrogen bond interactions were characterized by studying the computational HB-TETA model and experimental FT-IR/FT-Raman spectra. The downward shifts observed for the CO, N-H, and O-H stretching modes after co-crystallization were attributed to the hydrogen bonds.

Multicomponent supramolecular assemblies of 1(2H)-Phthalazinone and Tetrafluoroterephthalic acid: Understanding the role of hydrogen bonding on the structure and properties using experimental and computational analyses.

Two novel cocrystals were successfully constructed by 1(2H)-Phthalazinone (PHT) and Tetrafluoroterephthalic acid (TETA) based on O-H⋯O, N-H⋯O, C-H⋯O, C-H⋯F, N-H⋯N and C-H⋯N hydrogen bonding networks, and were well depicted by single crystal diffraction analysis. As predicted by electrostatic potential analysis, the stoichiometry of PHT to TETA is 2:1 and stabilized by O-H⋯O and N-H⋯O hydrogen bonds. The single crystal X-ray diffraction characterized that the two cocrystals were all made up by 2PHT-TETA motif in different ways. AIM analysis and Hirshfeld surfaces indicated the adjacent 2PHT-TETA units assemble through C-H⋯O, C-H⋯F and C-H⋯N hydrogen bonds, producing a 2D plane structure in cocrystal I. Meanwhile, the C-H⋯F, N-H⋯N and C-H⋯O hydrogen bonds between 2PHT-TETA units were the stabilizing factors in cocrystal II. Topological parameters such as ∇2ρ and H revealed the strength of hydrogen bonds were moderate in nature except O31⋯H32-O34 (1.704Å, -60.336kJmol-1) in compound I. The hydrogen bonding interactions, cocrystal stability and electron donor-acceptor interactions were investigated using natural bonding orbital analysis. It showed that electron transfer of n(O) σ*(O-H) and n(O) σ*(N-H) between PHT and TETA influence the packing characteristics significantly. Structural changes accompanying cocrystal process have been rationalized through the IR spectrum along with the quantum chemical calculations. The frequency downshifts of CO, N-H and O-H stretching after cocrystallization have been attributed to hydrogen bonding interactions.

Preparation of a fluorinated metal-organic framework and its application for the dispersive solid-phase extraction of perfluorooctanoic acid

A fluorinated metal-organic framework material (F-MOF) was successfully prepared using tetrafluoroterephthalic acid (H2tfbdc) as the ligand and Zn(II) as the central metal ion. The F-MOF exhibited excellent adsorption performance for perfluorooctanoic acid (PFOA), with a maximum adsorption capacity of 419.8 mg g−1. A sensitive dispersive solid-phase extraction using the F-MOF as an adsorbent, coupled with GC–MS analysis, was developed for detecting trace PFOA with a limit of detection as low as 2.6 ng L−1. This method was applied to detect PFOA in environmental water samples, yielding satisfactory results.

Strengthened Perovskite/Fullerene Interface Enhances Efficiency and Stability of Inverted Planar Perovskite Solar Cells via a Tetrafluoroterephthalic Acid Interlayer.

In this work, a novel back contact interface engineering is developed for inverted planar perovskite solar cells, in which a tetrafluoroterephthalic acid (TFTPA) interlayer is inserted between CH3NH3PbI3 and PC61BM to strengthen the interface contact. Benefiting from the strong Coulombic interactions between positive electron-poor tetrafluoroterephthalate moieties and negative electron-rich fullerene molecules, as well as the coordinate effect between -COOH groups of TFTPA and Pb2+ ions of perovskites surface, a tightly jointing and defect-passivated CH3NH3PbI3/PC61BM interface is formed. The strengthened CH3NH3PbI3/PC61BM back contact can significantly facilitate electron transport and simultaneously diminish the charge accumulation and recombination. Therefore, power conversion efficiency (PCE) of the TFTPA device is up to 19.39%, whereas the hysteresis effect is weak, and the PCE is improved by 20.4% compared with the control device which does not have a TFTPA interlayer. Particularly, the moisture stability of the TFTPA device is greatly improved as compared to the control device. Our findings illustrate that the back contact interface engineering is an important and promising approach for inverted planar perovskite solar cells.

A Novel Application of Fluorine Doped Carbon Dots Combining Vortex-Assisted Liquid-Liquid Microextraction for Determination of 4-Nitrophenol with Spectrofluorimetric Method.

A simple and fast vortex-assisted liquid-liquid microextraction (VA-LLME) combining with fluorescent carbon dots have been developed for the determination 4-nitrophenol (4-NP). The high fluorescent quantum yield (58.9%) fluorine doped carbon dots (F-CDs) were synthesized using tetrafluoroterephthalic acid as a fluorine source and using citric acid as a fluorine source and using ethylenediamine as a nitrogen source via a one-step hydrothermal method. F-CDs fluorescence was effectively quenched by 4-NP due to inner filter effect (IFE) and the strong interactions between functional groups (-COOH,-OH, -NH2 and -F groups) of the F-CDs and 4-NP. In VALLME method, n-octanol was employed as extraction solvent, and vortex-mix was exploited as a gentle mix method to reduce emulsification time and improve the extraction efficiency. The detection limits, the quantification limit and relative standard deviation for the 4-NP were found as 15nM, 50nM and 3.5%, respectively. Moreover, the obtained F-CDs can be employed as fluorescent probe to detect 4-NP in real environmental water samples.

Potential-Induced High-Conductance Transport Pathways through Single-Molecule Junctions.

Employing single molecules as electronic circuit building blocks is one promising approach to electronic device miniaturization. We report single-molecule junction formation where the orientation of molecules can be controlled externally by the working electrode potential. The scanning tunneling microscopy break junction (STM-BJ) method is used to bridge tetrafluoroterephthalic acid (TFTPA) and terephthalic acid (TPA) molecules between the Au(111) electrode and the STM tip to measure the single-molecule conductance through the junction. When the Au(111) electrode is at negative potentials (with respect to the zero-charge potential), a highly ordered and flat-oriented superstructure forms, allowing for direct contact between the π system of the benzene ring of the molecules and the Au(111) electrode, leading to junction formation with no anchoring group involvement. Our first-principles nonequilibrium Green's function (NEGF) computation shows a flat configuration yields a conductance that is 3 orders of magnitude larger than for a molecule vertically connected to the electrodes via anchoring groups. Conductances of 0.24 ± 0.04 and 0.22 ± 0.02 G0 are experimentally measured with the flat configurations of TFTPA and TPA, respectively. These values are at least 2 orders of magnitude higher than the experimental values previously reported for the conductance of TPA bridged through carboxylic acid anchoring groups (3.8 × 10-4-3.2 × 10-3 G0). In contrast, a positively charged surface triggers an order-disorder transition eliminating the high-conductance states, most likely because the formation of the flat-oriented junction is prevented. The dependence of TFTPA conductance on the electrode potential (electrode Fermi level) suggests a LUMO mediated transport mechanism. Calculation confirms the lack of an effect of the addition of an electron-withdrawing group are investigated.

Two isostructural Co/Ni fluorine-containing metal-organic frameworks for dye adsorption and supercapacitor

Based on the mixed ligand system of tetrafluoroterephthalic acid (H2tfbdc) and 1,4-bis((1H-imidazol-1-yl)methyl)benzene (1,4-bimb), two isostructural metal-organic frameworks viz. [Co(tfbdc)(1,4-bimb)(H2O)2]n (1) and [Ni(tfbdc)(1,4-bimb)(H2O)2]n (2) have been synthesized by solvothermal method and characterized. Complexes 1–2 revealed three-dimensional (3D) 3-fold interpenetrating diamond frameworks. Due to the existence of fluorine-donor sites in the network, complexes 1–2 exhibited selective adsorption towards Congo red (CR) than methyl orange (MO), methyl blue (MB), rhodamine B (RhB) and methylene blue (MLB). Moreover, complexes 1–2 can be used as the electrode material for supercapacitor, and a high rate performance was observed for 1 (it retains 71.21% of its initial capacitance up to a high current density of 10 A g−1).