BTC Ligands Research Articles

Efficient, Color-Stable, Pure-Blue Light-Emitting Diodes Based on Aromatic Ligand-Engineered Perovskite Nanoplatelets.

Perovskite nanoplatelets (NPLs) show great potential for high-color-purity light-emitting diodes (LEDs) due to their narrow line width and high exciton binding energy. However, the performance of perovskite NPL LEDs lags far behind perovskite quantum dot-/film-based LEDs, owing to their material instability and poor carrier transport. Here, we achieved efficient and stable pure blue-emitting CsPbBr3 NPLs with outstanding optical and electrical properties by using an aromatic ligand, 4-bromothiophene-2-carboxaldehyde (BTC). The BTC ligands with thiophene groups can guide two-dimensional growth and inhibit out-of-plane ripening of CsPbBr3 NPLs, which, meanwhile, increases their structural stability via strongly interacting with PbBr64- octahedra. Moreover, aromatic structures with delocalized π-bonds facilitate charge transport, diminish band tail states, and suppress Auger processes in CsPbBr3 NPLs. Consequently, the LEDs demonstrate efficient and color-stable blue emissions at 465 nm with a narrow emission line width of 17 nm and a maximum external quantum efficiency (EQE) of 5.4%, representing the state-of-the-art CsPbBr3 NPL LEDs.

POM@TM-MOFs prism-structures as a superior bifunctional electrocatalyst for overall water splitting

In order to meet the application needs of electrochemical water splitting, it is extremely important but challenging to develop efficient, cost-effective, long-lasting bifunctional catalysts. Herein, three POM@TM-MOFs composites were synthesized to K6[P2W18O62] encapsulating into TM-BTC (TM = Fe, Co or Ni, BTC = 1,3,5-benzenetricarboxylic acid) by a well-established impregnation method. The TM-MOFs with internal diameters of 16.08 Å and 6.95 Å apertures are largely enclosed by BTC ligands that act as switches that open and close the channel to allow leaching and immersing of POM, which can solve the problem of POM agglomeration and poor stability and maintain the original porous structure of MOFs. POM@Ni-MOF showed excellent bifunctional electrocatalytic performance with overpotentials of 68 mV and Tafel slopes of 77.3 mV/dec for HER, overpotentials of 107.3 mV and Tafel slopes of 61 mV/dec for OER, respectively. More importantly, POM@Ni-MOF/CC∥POM@Ni-MOF/CC was obtained by POM@Ni-MOF for overall water splitting and required a low cell voltage of only 1.51 V at 10 mA cm−2, which is slightly lower than the Pt–C/CC//RuO2–C/CC system.

Ultra-Trace Electrochemical Determination of Glyphosate Using Bimetallic Metal–Organic Frameworks (MOFs) with Differential Pulse Voltammetry

Hierarchically bimetallic Zr-Cu metal–organic framework combined with 1,3,5-benzenetricarboxylic acid (Zr-CuBTC MOFs) was synthesized using hydrothermal reaction and used as modifier for investigation of non-electroactive glyphosate. These MOFs were dropcasted on a glassy carbon electrode (GCE) and non-electroactive glyphosate were tested by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). Glyphosate in water was recognized by the difference of currents in spiked and non-spiked glyphosate samples. At the same time, CuBTC and Fe-CuBTC were investigated for the best material for sensor development. The results showed the bimetallic Zr-CuBTC MOF is the most promising for the determination of glyphosate. Morphological and structural studies showed the coordination of Cu2+ with the presence of Zr4+ ions with BTC ligands provided a highly porous framework with active surface area up to 1337 m2 g−1. The pore diameter and pore volume increased to 1.75 nm and 0.687 cm3 g−1, respectively. Under optimal conditions, Zr-CuBTC modified on GCE (Zr-CuBTC/GCE) sensor is able to indirectly detect glyphosate in a water environment at a detection limit as low as 9 × 10−13 M. The developed sensor was employed to determine glyphosate in the surface water samples collected from the Red River, North Vietnam. The results showed good recoveries (94.6–107.1%) which were in agreement with liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) measurements. These results demonstrate the possibility of using this MOF material in sensor applications to determine trace pesticides in the contaminated water.

Construction of Bimetallic Co/Fe-Incorporated PTA/FDA Nanoclusters for Boosting Electrocatalytic Oxygen Evolution

Summary. Electrochemical water decomposition as a crucial approach for the gradual growth of renewable energy has attracted extensive attention. Metal-organic frameworks (MOFs) which benefit from ultra-high specific surface area, controllable nanostructures, and excellent porosity have been widely used as high activity catalyst for the decomposition of water by electrochemical means. Herein, the composition and morphology of metal–organic framework nanoclusters with bimetallic Co/Fe-incorporated PTA/FDA nanoclusters is designed for efficient and durable OER electrocatalysts, including CoFe-BTC/PTA, CoFe-BTC/FDA, and CoFe-PTA/FDA. The crystal structure of MOF materials is composed of alternating organic hydrocarbon BTC, PTA, or FDA and inorganic metal oxide layer. Co and Fe interact as central atoms, joining BTC, PTA, or FDA ligands to form a highly symmetric MOF structure. The electronic structures and active sites of various metals are different, and the insertion of iron atoms plays a certain role in the regulation of their electronic structures. CoFe-PTA/FDA shows significant OER overpotential η 10 = 295 mV (1.525 V vs. RHE) reached 10 mA cm-2, with 62.85 mV dec-1 for Tafel slope and pretty conspicuous stability (72 hours of continuous testing). The DFT calculation results show coordination unsaturated metal atom is the primary active center of these electrocatalytic reaction, and the coupling effect caused by adding Fe is the key to adjust the electrocatalytic activity.

A calixarene-based coordination cage as an efficient luminescent sensor for Fe3+, MnO4−, NB and 2,4-DNP in aqueous medium

A luminescent coordination cage formulated as {Mg24(TC4A)6(BTC)8(H2O)6} (SWU-2, H4TC4A = p-tert-butylthiacalix[4]arene, H3BTC = 1,3,5-benzenetricarboxylic acid) was successfully synthesized by the assembly of Mg4-TC4A units with BTC ligands.

Insights into Solid-To-Solid Transformation of MOF Amorphous Phases.

Metal-organic frameworks (MOFs) have been recently explored as crystalline solids for conversion into amorphous phases demonstrating non-specific mechanical, catalytic, and optical properties. The real-time control of such structural transformations and their outcomes still remain a challenge. Here, we use in situ high-resolution transmission electron microscopy with 0.01 s time resolution to explore non-thermal (electron induced) amorphization of a MOF single crystal, followed by transformation into an amorphous nanomaterial. By comparing a series of M-BTC (M: Fe3+, Co3+, Co2+, Ni2+, and Cu2+; BTC: 1,3,5-benzentricarboxylic acid), we demonstrate that the topology of a metal cluster of the parent MOFs determines the rate of formation and the chemistry of the resulting phases containing an intact ligand and metal or metal oxide nanoparticles. Confocal Raman and photoluminescence spectroscopies further confirm the integrity of the BTC ligand and coordination bond breaking, while high-resolution imaging with chemical and structural analysis over time allows for tracking the dynamics of solid-to-solid transformations. The revealed relationship between the initial and resulting structures and the stability of the obtained phase and its photoluminescence over time contribute to the design of new amorphous MOF-based optical nanomaterials.

An octahedral polyoxomolybdate-organic molecular cage.

An unprecedented Mo-organic molecular cage built on interesting {MoVI2O5} secondary building blocks and BTC ligands, which has been successfully synthesized and systematically characterized, presents the first example of an isopolyoxomolybdates(vi)-organic molecular cage. An investigation into the related Cs+-exchange experiment was performed in detail.

Two new diverse 3D MOFs induced by ligand salt type: Photocatalytic performance

Self-assembly of Zn(Ac)2·2H2O with π-conjugated and rigid multicarboxylate ligand 1,3,5-benzenetricarboxylic acid (H3BTC) and flexible N-donor linker 1,3-bis(2-methylimidazolyl)propane generated two new metal-organic frameworks (MOFs), [Zn7 (μ3-OH)2(BTC)4 (bmp)2(H2O)4·2H2O·2DMF]n (1) and [Zn(BTC) (Hbmp)·H2O]n (2). 1 has a pentanuclear [Zn5 (μ3-OH)2] subunit, which is further connected by the BTC ligands to shape a layer. The 2D layer is further bridged by BTC and monuclear metal to form a 3D framework. The 3D zinc-BTC substructure has 1D open channels filled by bmp ligands. Polymer 2 shows a 4-connected 3D cds network. While a variation of bmp was imported into the zinc-btc system yielding a two different topological networks, demonstrating that the ligand salt type has an apparent effect in the building of the final networks. Their photochemical properties were measured.

Photoluminescent Investigation of the Doping Site of Eu3+-Doped [Zn3(BTC)2∙12H2O] Metal-Organic Framework Prepared by Microwave-Assisted Hydrothermal Synthesis

The [Zn3(BTC)2·12H2O] (BTC = 1,3,5-tricarboxylate) metal-organic framework (MOF) was successfully synthesized using a microwave-assisted hydrothermal synthesis technique, which allowed for significantly decreased reaction time compared to the production of the same compound via conventional heating. In situ doping with Eu3+ ions at concentrations ranging from 1.0 to 5.0 mol% produced doped materials whose emission ranged from blue to red color. The Eu3+ spectroscopic properties were used to study the incorporation of the dopant into the structure of [Zn3(BTC)2·12H2O], even at very low concentrations. These experiments confirmed the usefulness of this ion as a luminescent probe, as it permitted the identification of small variations in structure not perceptible by X-ray diffraction. The variation in the coordination environment induced by increases in doping percentage was analyzed by evaluating changes in the characteristic Eu3+ excitation and emission profiles, using them to calculate luminescence lifetimes, experimental intensity parameters Ωλ (λ: 2 and 4) as well as the intrinsic quantum yield (QEu+3Eu+3) of the 5D0 emitting level of each doped MOF. The excitation and luminescence spectra show that intramolecular energy transfer from the BTC linker to Eu3+ ion, and we could observe the emission color tuning originated from the emissions of the BTC ligand and Eu3+ ion.

Metal-organic frameworks as precursor for metal oxide nanostructures Part I: MOF-derived copper oxide embedded in carbon matrix

Three isostructural metal-organic framework materials (MOFs) formulated as M[(HBTC)(H2O)]ˑH2O(M = Cu for 1, Zn for 2 and Ca for 3) constructed with 1, 3, 5-benzenetricarboxylate (BTC) were synthesised under hydro/solvothermal conditions. The three compounds were characterised on the basis of infrared and UV-Vis spectroscopy and the structure of 3 elucidated with the help of single-crystal x-ray crystallography. The UV-Vis spectrum of 1 exhibited a unique band at 511 nm. In the region 520 – 534 nm, the band splits into two moderately intense peaks at 527 and 531 nm. These absorption peaks along with other bands at 629 and 638 nm were assigned to d-d transitions of the copper (II) ion with distorted square planar geometry. The infrared spectra of the three compounds revealed that the ligand, BTC anion coordinated in a chelating and / or bridging mode to the metal center. The presence of absorption bands at 1699 cm-1 in 1 and 2, (1681 cm-1 in 3) can be attributed to protonated HBTC for 1-3. Single-crystal X-ray crystallographic studies of compound 3 revealed well-ordered structure with BTC ligand linking the individual chains to form a network structure. On heating Cu(HBTC)(H2O)ˑH2O up to 400oC, a copper-oxide embedded in carbon matrix was obtained with uniform particles of 10 -100 nm size.

Frustrated magnetism in Cu(II) based metal–organic framework

A Cu(II) based metal–organic framework (MOF), [Cu2(TPT)2(BTC)Cl]·(solvent)x, (TPT = 2,4,6-tris(4-pyridyl)-1,3,5-triazine, BTC = benzene-1,3,5-tricarboxylic acid) has been solvothermally synthesized and characterized using single crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis and magnetic measurements. This compound adopts three-dimensional connectivity where Cu2+ dimers are linked with BTC ligand to form the layered architecture. This layered motif is pillared by TPT linker to form the three-dimensional structure. Magnetic studies show that the compound undergoes a magnetic long-range ordering at TN ≈ 5 K. A large value of Curie–Weiss temperature compared to TN suggests strongly frustrated nature of the magnetic compound.

Nucleation and growth of oriented metal-organic framework thin films on thermal SiO2 surface

Assembly of metal-organic framework (MOF) thin-films with well-ordered growth directions enables many practical applications and is likely part of the future of functional nanomaterials. Insights into the formation pathway of the MOF thin films would allow better control over the growth directions and possibly the amount of guest molecules absorbed into the MOF pores. Here, we investigate the nucleation and growth of oriented Cu3(BTC)2∙xH2O MOF (HKUST-1, BTC = benzene-1,3,5-tricarboxylic acid) thin films on the thermal SiO2 surface using a room temperature stepwise layer-by-layer (LBL) method. Initial stages of LBL growth were characterized with X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analysis in order to understand nucleation and growth kinetics. HKUST-1 thin films with preferred growth along the [111] direction on the thermal SiO2 surface were obtained in the absence of not only a gold substrate, but also organic-based self-assembled monolayers (SAMs). It is found that the formation of HKUST-1 is initiated by deposition of copper acetate on the thermal SiO2 surface followed by ligand exchange between coordinated acetate from the copper precursor and the BTC ligands. As the LBL growth cycle is increased, HKUST-1 crystals on the thermal SiO2 surfaces are continuously forming and growing and finally the crystallites coalesce into a continuous film. Highly oriented HKUST-1 thin films on thermal SiO2 surface with complete surface coverage and ~90 nm thickness were obtained at ~80 cycles of LBL growth under the conditions used in this study.

The Power of Heterometalation through Lithium for Helix Chain-Based Noncentrosymmetric Metal–Organic Frameworks with Tunable Second-Harmonic Generation Effects

We demonstrate herein a general strategy for developing acentric or chiral nonlinear optical MOFs from centrosymmetric ligands by shifting the asymmetrical roles to the metal centers through heterometalation. With 1,3,5-benzenetricarboxylic acid (H3BTC), a very common polyfunctional centric ligand, the Li+/Zn2+, Li+/Co2+, or Li+/Cd2+ heterometallic combinations successfully led to five new noncentrosymmetric metal–organic frameworks, namely, {[Zn(HBTC)(H2O)]}n (SNNU-71), {Li4[Cd2(HBTC)(BTC)2]}n (SNNU-72), {CoLi(BTC)(DMA)2}n (SNNU-73), {CdLi2(BTC)4/3(H2O)3}n (SNNU-74), and {Li2[Zn3Li5(BTC)4(MTAZ)(H2O)4]}n (MTAZ = 5-methyl tetrazole, SNNU-75). All these MOFs are acentric or chiral on the base of helical chain building blocks and four colorless members of them show remarkable and tunable SHG effects. Remarkably, more than 1000 metal-BTC frameworks are reported to date and most of them are centrosymmetric due to the C3-symmery of BTC ligands. Clearly, our heterometalation approach greatly increases the possib...

Understanding the Inhibiting Effect of BTC on CuBTC Growth through Experiment and Modeling

The room temperature growth kinetics of the commonly studied metal–organic framework CuBTC (HKUST-1) is investigated with UV/vis absorption spectroscopy. Contrary to chemical intuition, increased concentrations of the BTC ligand slows down the formation of CuBTC. Based on the time-resolved experimental data, a kinetic model is proposed for CuBTC growth. This model is based on a chemical reaction equation sequence for the production of CuBTC including an overcoordinated, slowly reacting Cu-BTCx species. This growth model excellently captures the temporal CuBTC development over the entire range of concentration conditions.

Four New Coordination Polymers Constructed by 2-(4-Thiazolyl)benzimidazole and 1,3,5-Benzenetricarboxylic Acid

Through using mixed N/S-containing ligand 2-(4-thiazolyl)benzimidazole (L), four new metal–organic coordination polymers, namely, [Co2 L 4(HBTC)(H2O)2] (1), [Cu2 L 2(HBTC)2]·H2O (2), [NiL 3]·(HBTC)·H2O (3) and [NiL 3]·H2O (4), have been synthesized under hydrothermal conditions, further assisted by a second organic ligand, benzenetricarboxylic (H3BTC). The structures of 1–4 have been determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses and IR spectra. Compound 1 contains two {CoL 2(H2O)} fragments, which are connected by a BTC molecule to form a discrete “V”-type subunit. The hydrogen bonding interactions between N3⋯O1 atoms induce a 1D chain of 1. Complex 2 includes bi-nuclear CuII subunits, which are linked by BTC ligands to form a 2D layer. Each bi-nuclear Cu subunit is linked by four BTC molecules. Both complexes 3 and 4 are based on [NiL 3] subunits. In complex 3, when NiCl2·6H2O was used as reactant, a discrete BTC molecule is captured as a counter anion. In contrast, when using reactant NiSO4·6H2O, [NiL 3]·H2O (4) is formed. Both complexes 3 and 4 contain abundant hydrogen bonding interactions. In these complexes, the N donors in L ligand coordinate with transition metals and the S atoms participate in hydrogen bonding interactions. Through using mixed N/S-containing ligand 2-(4-thiazolyl)benzimidazole (L), four new metal-organic coordination polymers, namely, [Co2 L 4(HBTC)(H2O)2] (1), [CuL(HBTC)] (2), [NiL 3]·(HBTC)·H2O (3) and [Ni(L)3]·H2O (4), have been synthesized under hydrothermal conditions further assisted by the second organic ligand benzentricaboxylate (H3BTC).

Electro-Synthetic Optimization of Host Material Based on MIL-100(Fe)

Electro-synthesis of Metal-Organic Frameworks types of MIL-100(Fe) (MIL = Material Institute of Lavoisier) in ethanol: water (1: 1) with electrolyte TBATFB 0.1 M has been optimized by varying voltage (12, 13, 14 and 15 Volt) and temperature (room temperature, 40, 60 and 80 °C). The product showed light brown powder which upon activation becomes dark brown. Optimum condition achieved during use voltage of 15 Volts and at a temperature of 40 °C with 33% yield. The obtained material was characterized by XRD and compared to CCDC 640536 simulated patterns to confirm the phase purity of the product. As comparison hydrothermal and reflux method have been carried out. Characterization by FTIR has also undertaken to ensure the coordination between the metal cation (Fe3+) and the BTC ligand (BTC = 1,3,5-Benzene Tri Carboxylate). Meanwhile pore analysis using SAA confirmed that MIL-100(Fe) obtained by electrolysis method has a BET surface area reached till 569.191 m²/g with a total pore volume of 0.4540 cc/g and an average pore diameter reached 16 Å. Based on SEM analysis, morphology material show particle size between 0.4-8.6 μm and has a thermal stability up to 350 °C according thermo-gravimetric analysis. Due to the presence of Lewis acid sites on Fe-trimeric unit, porosity features on MIL-100(Fe) and a fairly high thermal stability, this material is potentially used as the host material for the catalyst in the conversion reactions model for green diesel production.

Three‐Dimensional Porous Heterometallic‐Organic Frameworks: Synthesis, Luminescent, Magnetic, Adsorption and Hydrogen Storage Properties

AbstractTwo three‐dimensional (3D) porous heterometal‐organic frameworks (HMOFs) with isostructures, [Zn2Cd(OH)(BTC)2(DMF)(H2O)2]·(H3O) (JUC‐155A) and [ZnCo2(OH)(BTC)2(DMF)(H2O)2]·(H3O) (JUC‐155B) (JUC=Jilin University China, BTC=1,3,5‐benzenetricarboxylate and DMF=N,N‐dimethylformamide), have been successfully synthesized by utilizing two kinds of 3d metal ions (Zn(II) and Cd(II) or Zn(II) and Co(II)) under conformable conditions. X‐ray crystallography reveals that both HMOFs consist of trinuclear metal‐carboxylate secondary building units (SBUs), and these SBUs are interlinked by the phenyl groups of BTC ligands to generate 3D open‐frameworks with two types of channels of about 6.3 and 10.7 Å. Both HMOFs show the multifunctional properties in photoluminescence and adsorption. JUC‐155B also exhibits an antiferromagnetic interaction, owing to the presence of dinuclear cobalt centers. Additionally, the high‐pressure hydrogen storage of JUC‐155A has been also examined at 77 K. By using mixed metal centers in clustered SBUs, it is a good strategy to construct those isostructures with heterometallic systems, and it is believed that the presence of such HMOFs will further facilitate the exploration of multifunctional materials.

Crystal structure of [NaZn(BTC)(H2O)4]·1.5H2O (BTC = benzene-1,3,5-tri-carb-oxy-l-ate): a heterometallic coordination compound.

The title coordination polymer, poly[[μ-aqua-tri­aqua­(μ3-benzene-1,3,5-tri­carboxyl­ato)sodiumzinc] sesquihydrate], {[NaZn(C9H3O6)(H2O)4]·1.5H2O}n, was obtained in ionic liquid microemulsion at room temperture by the reaction of benzene-1,3,5-tri­carb­oxy­lic acid (H3BTC) with Zn(NO3)2·6H2O in the presence of NaOH. The asymmetric unit comprises two Na+ ions (each located on an inversion centre), one Zn2+ ion, one BTC ligand, four coordinating water mol­ecules and two solvent water molecules, one of which is disordered about an inversion centre and shows half-occupation. The Zn2+ cation is five-coordinated by two carboxyl­ate O atoms from two different BTC ligands and three coordinating H2O mol­ecules; the Zn—O bond lengths are in the range 1.975 (2)–2.058 (3) Å. The Na+ cations are six-coordinated but have different arrangements of the ligands: one is bound to two carboxyl­ate O atoms of two BTC ligands and four O atoms from four coordinating H2O mol­ecules while the other is bound by four carboxyl­ate O atoms from four BTC linkers and two O atoms of coordinating H2O mol­ecules. The completely deprotonated BTC ligand acts as a bridging ligand binding the Zn2+ atom and Na+ ions, forming a layered structure extending parallel to (100). An intricate network of O—H⋯O hydrogen bonds is present within and between the layers.

Synthesis, Structure and Property of a 3D Heterometallic Complex Constructed by Trinuclear [In2Co(OH)2(COO)4] Cluster and BTC Ligand

A novel indium–cobalt heterometallic complex, [C6H11N2]2[In2Co(OH)2 (BTC)2Br2], has been synthesized under ionothermal conditions and characterized by elemental analysis, FT-IR, XRD, TG-DTA, and single crystal X-ray diffraction. It crystallizes in the monoclinic system with space group P21/c. Its structure is characterized as a 3D open framework constructed by [In2Co(OH)2(COO)4] cluster subunit and the 1,3,5-benzenetricarboxylate ligand. The used IL cations [C6H11N2]+ are located in the channels and compensate for the negative charges of framework. Furthermore, its fluorescent property and ion exchange property have also been studied.

Solvothermal syntheses, crystal structure, and photoluminescent properties of two Cu(I) coordination polymers constructed by bisimidazole ligands

Two Cu(I) coordination polymers {[Cu2(bibp)2]·bdc·3H2O}n (1) and {[Cu3(bib)3]·btc·5H2O}n (2), where bibp = 4,4′-bis(1-imidazol-1-yl)biphenyl, H2bdc = terephthalic acid, bib = 1,4-bis(1-imidazol-1-yl)benzene, H3btc = benzene-1,3,5-tricarboxylic acid, are synthesized under solvothermal conditions and characterized structurally. Complex 1 crystallizes in the triclinic form with the space group P-1, and Cu(1) is two-coordinated by two N atoms of bibp, Cu(2) is three coordinated from two N atoms of bibp and one water molecule. Complex 2 crystallizes in the triclinic form with the space group P-1; the copper ions are monovalent and two-coordinated by two N atoms of bib. The bdc and btc ligands are not coordinated with Cu ions, but play important roles in the generation of a 3D supramolecular structure of complexes 1 and 2 via weak interactions respectively.