Tricarboxylic Acid Ligand Research Articles

Design of two coordination polymers based on semi-rigid tricarboxylic acid ligands of cobalt (II): Synthesis, structures and properties

In this work, two novel coordination polymers [Co3(L)2(mida)3]n (1) and [Co3(L)2(bimb)3]n (2) have been synthesized using a semi-rigid tricarboxylic acid ligand (H3L: 3-[(1-carbox-ynaphthalen-2-yl)oxy] phthalic acid) and two nitrogen-containing heterocyclic ligands (mida: [1, 4-bis (1H-imidazol-1-yl) benzene] and bimb: {1-[4-(2H-1λ4-imidazol-1-yl) methyl]benzyl}-1H-imidazole). The results of single crystal X-ray diffraction show that the Co-based coordination polymer 1 have a two-dimensional (2D) layered structure, while the coordination polymer 2 presents a three-dimensional (3D) spatial configuration. In addition, the coordination polymers 1 and 2 exihit better selectively catalytic degradation performances of dyes, indicating that Co-based coordination polymers have potential application values in dye degradation.

Multifunctional Lanthanide Metal-Organic Frameworks Are Used for Fluorescence Sensing of Bi3+, HPO42-, Flu, and PNBA and Application.

Using a nitrogen-containing tricarboxylic acid ligand (imidazole-1-yl) benzene-2,4,6-tricarboxylic acid (H3ttc) and lanthanide metal elements (Dy, Eu, Nd, and Gd), four lanthanide metal organic frameworks (Ln-MOFs) with the same structure, namely, {[Dy2 (Httc)3]·1.5DMF}n(1), {[Eu2 (Httc)3]·1.5DMF}n(2), {[Nd2 (Httc)3]·1.5DMF}n(3), and {[Gd2 (Httc)3]·1.5DMF}n(4), were synthesized under solvothermal conditions. The characterization analysis showed that the four isomorphic Ln-MOFs were trigonal crystals of the R3̅c space group, with good phase purity and thermal stability. Fluorescence analysis showed that complex 1 can be an excellent fluorescence sensor for Bi3+, HPO42-, and fluridine (Flu), while complex 2 can be an excellent fluorescence sensor for p-nitrobenzoic acid (PNBA). And their sensing mechanisms were discussed in detail. The fluorescent test paper and fluorescent seal were prepared by using the excellent luminescence properties of 1 and 2, and the pesticide on the surface of cherry tomato was detected. The applicability of these MOFs as fluorescence sensors was proved. Therefore, Ln-MOFs are expected to have unpredictable application prospects in the field of environmental detection.

Two Cd(II) complexes: Fluorescence performances and loaded with paclitaxel-hydrogel on oral cancer treatment

In this study, two unique three-dimensional Cd(II)-based coordination polymers, [Cd3L12(H2O)4]∙(CH3CN)∙(H2O) (1) and [Cd3L22(H2O)2] (2), were successfully synthesized under solvothermal conditions. The organic linkers selected were two tricarboxylic acid ligands, H3L1 and H3L2 (H3L1 = 4,4′,4″-((benzene-1,3,5-tricarbonyl) tris(azanediyl)) tribenzoic acid, H3L2 = 4,4′,4″-(benzene-1,3,5-triyltris(azanediyl))tribenzoic acid). Furthermore, fluorescence performance tests of the complexes indicated that through coordination with the metal center and the semi-rigid triangular ligand, as well as the formation of a highly rigid network involving the framework and free solvent molecules in a hydrogen bond network, complexes 1 and 2 exhibited excellent blue fluorescence. Building upon this, given the poor biocompatibility of metal–organic frameworks (MOFs) as carriers, we employed hyaluronic acid (HA)/carboxymethyl chitosan (CMCS) hydrogel for encapsulation and paclitaxel loading. A novel paclitaxel drug delivery system, HA/CMCS-MOFs@paclitaxel, was developed, and the effects of the two systems on the expression of the cancer proliferation marker gene Ki-67 in OSCC cells (CAL27) were evaluated. Results demonstrated that the synthesized paclitaxel-loaded metal gel particles exhibited potent inhibitory activity against Ki-67, showcasing their potential as therapeutics for oral cancer.

Synthesis, structure, fluorescence, and magnetic studies of a series of transition metal complexes with oxygen-bridged phenylene tricarboxylic acid ligand

In this work, 4-(2-carboxyphenoxy)phthalic acid ligand (H3bppa), 4,4′-dipyridyl (4,4′-dipy), 1,10-phenanthroline (phen), 2,2′-dipyridyl (2,2′-dipy) and transition metal ions Zn2+, Cu2+, Mn2+, Ni2+, Co2+ were used to synthesize metal complexes by solvothermal reaction. Ten complexes were synthesized, namely, [Zn(H2bppa)2(H2O)4]·4H2O (1), [Mn(H2bppa)2(H2O)4]·4H2O (2), [Co(H2bppa)2(H2O)4]·4H2O (3), [Mn(H2bppa)2 (2,2′-dipy) (H2O)]n (4), [Cu(H2bppa)2 (2,2′-dipy) (H2O)]n (5), [Mn3(bppa)2(4,4′-dipy)2 (H2O)6]n (6), [Co(Hbppa) (phen)2 (H2O)] (7) and [Ni(Hbppa) (phen)2 (H2O)] (8), [Mn(Hbppa) (phen) (H2O)]n (9), [Cu(Hbppa) (phen) (H2O)]n (10). Structural datas were collected by X-ray single crystal diffractometer, the results show that complexes 1, 2, 3, 7 and 8 are zero-dimensional mononuclear structure, 4, 5, 9 and 10 are one-dimensional chain structure, 6 is three-dimensional network structure. Furthermore, solid state fluorescence properties were performed on complexes H3bppa and 1–8, magnetic properties were performed on complexes 2–8. The fluorescence experiment results show that the fluorescence intensity of complexes 1–8 is weaker than that of H3bppa, and the fluorescence emission spectrum of complex 1 undergoes a blue shift relative to the H3bppa. Magnetic testing data analysis shows that complexes 2, 3 and 8 have antiferromagentic properties and complexes 4, 5, 6 and 7 have ferromagentic properties.

Co(II) Metal-Organic Complex: Fluorescence Performances and Loaded With Drug Vitamin B2 Hydrogels Against Recurrent Oral Ulcers.

A new coordination polymer (CP) based on Co(II), namely, {[Co3(L)2(4,4'-bipy)(DMA)2]·H2O}n(1) has been synthesized after reacting Co(NO3)2·6H2O with H3L ligand in the existence of N-donor ligand 4,4'-bipyridine (4,4'-bipy), via utilizing a flexible tricarboxylic acid ligand 5-((formic acid-3-sulfur)methyl)isophthalic acid (H3L) with -S-CH2- joint. Additionally, the excellent blue fluorescence properties of CP 1 were confirmed through fluorescence spectroscopy compared to the original ligand. Using natural polysaccharide hyaluronic acid (HA) and carboxymethyl chitosan (CMCS) as raw materials, HA/CMCS hydrogel was prepared by chemical synthesis method. Taking vitamin B2 as the drug model, we designed and synthesized gels loaded with vitamin B2 metal framework and evaluated their efficacy in the treatment of recurrent oral ulcer.

Three new alkaline earth-based metal-organic frameworks based on two tricarboxylic acid ligands: Structural diversity, stability study and luminescent properties

The alkaline earth-based metal-organic frameworks (MOFs) have attracted more and more attention for their beautiful structure and environmental friendliness. In this work, three alkaline earth-based MOFs, namely [Ba(HL1)]n (1), [Ca(HL1)(H2O)2]n (2), and [Ba(HL2)]n (3) (H3L1 = 1-(3-carboxyphenylmethyl)-1H-pyrazol-3,5-dicarboxylic acid and H3L2 = 1-(4-carboxyphenylmethyl)-1H-pyrazol-3,5-dicarboxylic acid), were synthesized under hydrothermal conditions. Compounds 1-3 reveal structural diversity owing to different metal ions and organic ligands. Thermal and solvent stability were characterized by thermogravimetric analyses (TG) and powder X-ray diffraction (PXRD), respectively. The solid-state luminescent properties were also investigated. The result shows a clear correlation between emission bands and excitation wavelengths of compounds 1-3.

State-of-the-art with the prospects of cobalt-based metal-organic frameworks for solar cell applications

The characteristics of metal–organic framework (MOF) composites make them the most significant materials for energy conversion applications. MOFs are hybrid molecular frameworks synthesized using metal ions like Copper, Cobalt, Zinc, Nickel, etc and organic ligands such as BTC, NDC, etc. To meet and fulfill futuristic energy demands and needs, it is feasible to expand cost-effective energy conversion solar cell devices using MOF materials, therefore in the present work, the Cobalt-based MOFs (Co-MOF) are synthesized by coordinating Cobalt nitrate and 1,3,5 Benzene tricarboxylic acid (BTC or Trimesic acid) ligand using the Solvothermal method. To study the physiochemical properties of synthesized Co-BTC MOFs, these have gone through a variety of characterization processes where the structural exploration unveils that the intensity of the dominant peak obtained at 18.7° gradually decreases with a decrease in the concentration of trimesic acid ligand. First and second weight losses, corresponding to release of the solvent molecules and breakdown of the frameworks, respectively, were detected by thermogravimetric analysis (TGA) measurements. In the FTIR spectra, metal-oxide, modified benzene, carboxylic, and hydroxyl groups with different modes of vibrations are observed. Analysis of surface morphology demonstrated creation of rod-like geometry to the synthesized materials, whereas elemental studies inveterate effective formation of the Co-BTC MOFs. Additionally, the optimized Co-BTC MOF is applied as a potential interfacial layer in solar cells and the outcome implies that the device designed with 10 Co-BTC LBL cycle evolutions provided relatively desirable solar cell performance parameters. The present findings recommended that material progression is necessary to develop cost-effective and high-performance MOF-based solar cell devices.

Crystal structure and fluorescence-based sensor properties of a Metal-Organic Framework

Abstract A Metal-Organic Framework (MOF) based on a tricarboxylic acid ligand (H3L = biphenyl-2,4′,5-tricarboxylic acid), namely [Cd3(L)2(H2O)4] (1), had been prepared and characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analyses (TGA), and single-crystal X-ray diffraction. Fluorescence studies showed that 1 has high quenching efficiency for testing acetone and Fe3+ ions in aqueous systems. Therefore, it can be used as a new type of fluorescence probe to detect solvent molecules and metal ions in water.

Metal-organic-frameworks passivated CuBi2O4 photocathodes boost CO2 reduction kinetics

Photoelectrochemical reduction of CO2 to produce CO with metal-organic frameworks (MOFs) is recognized as a desirable technology to mitigate CO2 emission and generate sustainable energy. To achieve highly efficient electrocatalyst, it is essential to design a new material interface and uncover new reaction mechanisms or kinetics. Herein, we developed two metal-organic Cu-MOF and Bi-MOF layers using benzene tricarboxylic acid (H3BTC) ligands on CuBi2O4 photocathodes. Both MOF layers drastically improved the photoelectrochemical stability by suppressing the photo-corrosion through conformal surface passivation. The Cu-MOF modified CuBi2O4 showed more significant charge separation and transfer efficiencies than the Bi-MOF modified control. Based on the transient photocurrent curves under the applied potential of 0.6 V vs. RHE, the rate-law analysis showed the CO2 photoreduction took place through a first-order reaction. Further, the photoelectrochemical impedance spectra (PEIS) revealed this reaction order, representing an “operando” analysis. Moreover, the reaction rate constant on Cu-MOF modified sample was higher than that on Bi-MOF modified one and bare CuBi2O4. Combined with the density functional theory calculation, the surface absorption of CO2 and CO molecules and the higher energy barrier for ∗COOH intermediates could significantly determine the first order reaction.

A luminescent 2D Tb-calixarene aggregate: Synthesis, structure and CH4 separation from C3H8 and C2H2

By introducing a triangular tricarboxylic acid ligand to the Tb-H4TC4A system, a two dimensional (2D) metal-organic layer {[Tb4(TC4A)2(μ4OH)(TATB)(CH3OH)(H2O)3 (DMF)]}n (CIAC-266) (H4TC4A = p‑tert‑butylthiacalix[4]arene, H3TATB = 2, 4, 6-tris(4-carboxyphenyl)-1, 3, 5-triazine) was successfully synthesized by solvothermal method. It exhibits green photoluminescence with an average decay time of 5.7 × 105 ns and a quantum yield of 9.9%. The N2 sorption measurement indicates that CIAC-266 is a microporous material with the Brunauer–Emmett–Teller (BET) and the Langmuir surface areas being of 444 and 504 m2·g−1, respectively. CIAC-266 has strong affinity towards C3H8 and C2H2 but weak affinity towards CH4, providing the opportunity for the CH4 separation from these gas mixtures.

Synthesis, crystal structures and electrocatalytic properties of 2D and 3D Co(Ⅱ) Coordination polymers based on semi-rigid tricarboxylic acid ligand

The tricarboxylic ligand, 4′,4′,4′-[(trimethylamino)]-tris[(1,1′-biphenyl)-2-carboxylic acid] (H3TMCA), is designed and synthesized to self-assembly two novel cobalt coordination polymers, formulated as {[Co2(TMCA)(OH)(DMF)(H2O)]}n (1), {[Co3(TMCA)2]}n (2). Interesting, due to the flexibility of the H3TMCA, the final frameworks of 1-2 can change depending on the reaction of temperature and solvents. Complex 1 is a (3, 6)-connected of type kgd two-dimensional (2D) network with a point (Schlafli) symbol of {43}2{46. 66. 83}. Complex 2 is a (4, 6)-connected 2-nodal three-dimensional (3D) net with point (Schlafli) symbol of {415}2{42. 84}3. In addition, the electrocatalytic activity of these Co-CPs were studied in detail.

Electrochemical Conversion of Cu Nanowire Arrays into Metal-Organic Frameworks HKUST-1

We explore the conversion of free-standing Cu nanowire arrays produced by electrodeposition in polymer etched ion-track membranes into metal-organic frameworks KHUST-1 by electrochemical oxidation. HKUST-1 particles are built up when the as-formed Cu2+ ions bind to the benzene tricarboxylic acid ligands (BTC3−) in the electrolyte solution. The morphology and crystallinity of the samples at different transformation stages are investigated by scanning and transmission electron microscopy. X-ray diffraction data taken at different conversion times confirm the formation of HKUST-1 particles. The conversion process resulted in octahedral structures of several μm in size. Comparison of the Raman spectra with the band positions derived from density functional theory (DFT) calculations, suggests that vibrations involving Cu atoms appear only below 490 cm−1 wavenumbers and involve the entire HKUST-1 lattice rather than vibrations of single bonds.

Synthesis, crystal structures and selective luminescence sensing property of Zn(II) coordination polymers based on semi-rigid tricarboxylic acid ligands

Herein, two novel Zn-based coordination polymers [Zn(HL)(1,10-phen)(H2O)]n (1) and [Zn2(HL)2(2,2′-bipy)2]n (2) have been successfully synthesized via solvothermal method by using the semi-rigid tricarboxylic acid ligand (H3L:3-[(1-carboxynaphthalen-2-yl)oxy] phthalic acid) and two different nitrogen-containing heterocyclic ligands (1,10-phenanthroline, 2,2′-bipyridine). A single-crystal X-ray analysis reveals that these two novel Zn-based coordination polymers 1 and 2 exhibit a one dimensional (1D) chain structures. Moreover, two novel Zn-based coordination polymers 1 and 2 exihit excellent fluorescence performances, and selectively recognition response to Ni2+, MnO4−, Cr2O72−, nitrobenzene and nitromethane through the luminescence quenching effects in aqueous solutions. The possible fluorescence recognition mechanism of 1 and 2 toward Ni2+, MnO4−, Cr2O72- are investigated, which may be attribute to the synergistic effects of energy competitive absorption and weak interaction. Whereas the fluorescence quenching behaviors of 1 and 2 toward nitrobenzene and nitromethane, owing to the existence of a strong electron-withdrawing group which can obtain excited-state electrons, and leading to the occurence of electrons transfer. These results indicating that Zn-based coordination polymers have potential application values in fluorescent recognition.

Luminescence Cd(II) coordination compounds based on a semi-rigid tricarboxylic acid ligand for identifying metal cations, inorganic anions and organic solvents

Highly effective recognition and detection of metal ions, anions and organic small molecules from water have attracted remarkable attention for environmental safety. Herein, a novel Cd-based coordination polymer [Cd(HL)(4,4′-bipy)(H2O)]n (1) and a metal–organic framework {[Cd3(L)2(bip)2(H2O)3]·5H2O}n (2) have been synthesized by employing a semi-rigid tricarboxylic acid ligand (H3L) and different N-containing ligands under hydrothermal conditions, where H3L = 3-[(1-carboxynaphthalen-2-yl)oxy] phthalic acid, 4,4′-bipy = 4,4′-bipyridine, bip = 1,4-di(pyridine-4-yl) benzene. Single crystal X-ray analysis reveals that 1 presents a 4-connected 2D network structure with a Schläfli symbol of (44·62),whilst 2 possesses a (3,4,4)-connected 3D framework with a Schläfli symbol of (4.82)2(42.82.102)(8.104.12). Furthermore, 1 and 2 have been characterized by elemental analyses, FT-IR, powder X-ray diffraction, thermogravimetric analyses, fluorescence and UV spectra, exhibiting good stability and excellent photoluminescence properties. 1 and 2 have been chosen as fluorescent probes to sense different target analytes, showing an obvious selective recognition response to Co2+, Ag+, Cr2O72-, CrO42-, nitrobenzene and nitromethane through luminescence quenching effects in aqueous solutions. The possible fluorescence quenching mechanisms are studied in detail, revealing that fluorescence quenching is mainly related to weak interactions, competitive energy absorption and electron transfer.

Three-pole wheel paddle luminescent metal organic frameworks (LMOFs) based on the oxygen substituted triazine tricarboxylic acid ligand: recognition and detection of small drug molecules and aromatic amine molecules.

Luminescent metal organic frameworks (LMOFs) are considered to be a type of promising optical sensing material due to their designable and tunable functions, and stable pore structures. Therefore, the preparation of LMOFs has become a research hotspot in recent years. As we know, triazine carboxylic acid ligands are conducive for constructing LMOF materials due to their large π electron conjugated system. In this work, two crystalline materials [Cd3(TCPT)2]·0.5DMF·4H2O (1) and (H3O)[Zn2(TCPT)(μ2-OH)2]·0.5DMF·3H2O (2) were obtained by the reaction of the triazine carboxylic acid ligand 2,4,6-tris(4-carboxyphenoxy)-1,3,5-triazine (H3TCPT), as an extended carboxylate arm, and d10 transition metal salts. Their structures were determined by single crystal X-ray diffraction and characterized by infrared spectroscopy (IR), ultraviolet visible spectroscopy (UV-vis), fluorescence spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TG). The experimental results showed that complexes 1 and 2 show excellent fluorescent emission behavior. Thus, we explored their fluorescence sensing properties. To our delight, the results showed that they both had the ability to sense small organic drug molecules and aromatic amine molecules containing o-phenylenediamine (OPD), m-phenylenediamine (MPD) and p-phenylenediamine (PPD). In general, the practical applications of a MOF material are usually limited because of the relatively harsh synthesis methods. In this aspect, we studied the synthesis method in detail to obtain the optimal reaction conditions for the large-scale synthesis of 1 and 2. The preparation of the two LMOF materials only required about 3 hours of heating time and they could be prepared on a large scale, which is significant for the practical applications of LMOFs.

Zn-based coordination polymers with tricarboxylic acid ligand: fluorescence sensor toward Fe3+ and MnO4−

Two new coordination polymers, {[Zn2(HBTC)2(bpy)2(H2O)3]•2H2O}n1 and {[Zn(BTC)(Hdpa)]•H2O}n2 ((H3BTC = 1,2,4-benzenetricarboxylic acid, bpy = 4,4′-bipyridine, Hdpa = 4,4′-dipyridylamine), have been synthesized under pH-controlled hydrothermal conditions. Their structures were characterized by IR spectrum, single-crystal X-ray diffraction, powder X-ray diffraction (XRD), thermal gravimetric analysis (TGA), UV–vis spectroscopy, EDS and ICP-MS. Complexes 1 and 2 exhibit binuclear units. 1 shows 1D chain structure, while in 2 the network is assembled from binuclear units. It was extended into 3D supramolecular framework by π-π stacking interactions and hydrogen bonded interactions. Complex 2 displays excellent luminescence in the solid state and solution. Importantly, it can act as multi-responsive luminescent sensors for Fe3+ and MnO4− with high selectivity and sensitivity.

RETRACTED:Treatment effects and mechanisms of Cu(II) coordination polymer in hypotension after anesthesia

A Cu(II) coordination polymer (CP) (that is, [Cu2(OH)(H2O)2(cbca)·2H2O]n (1)) has been obtained with the reaction between Cu(II) salt and 4′-(1-carboxyethoxy)-[1,1′-biphenyl]-3,5-dicarboxylic acid (H3cbca), a semi-rigid tricarboxylic acid ligand under the hydrothermal reaction condition. Prevention activity of the new compound on hypotension after anesthesia surgery was evaluated and the related mechanism was researched at the same time. The noninvasive blood pressure monitor was firstly conducted to measure the blood pressure of the animal after compound treatment. Besides, the real time RT-PCR assay was also used to determine theα receptor relative expression on vascular endothelial cells after compound treatment.

Synthesis, crystal structure and Near-infrared luminescence of rare earth metal (YIII, ErIII, HoIII) complexes containing semi-rigid tricarboxylic acid ligand

Three new isostructural rare earth metal coordination polymers, [Re (L)(H2O)2]•n H2O (Re=Y, n=1 for 1; Ho, n=2 for 2; and Er, n=0 for 3), have been successfully synthesized via solvothermal reactions with three rare earth metal nitrates and a semirigid multi-carboxylate ligand H3L [H3L=4-(2-carboxyphenoxy)isophthalic acid]. Single crystal X-ray analysis reveals that complexes 1-3 are isostructural and show 2D layer frameworks connected by O atoms of the carboxyl group from H3L ligand. The near-infrared luminescence properties of complexes 2 and 3 were initially explored, which provided a possibility for further development of near-infrared photoluminescence materials and their exciting use in biomedical field.

Luminescence tuning and sensing properties of stable 2D lanthanide metal–organic frameworks built with symmetrical flexible tricarboxylic acid ligands containing ether oxygen bonds

New Ln-MOFs were yielded by a flexible ligand and lanthanide ions. The colors can be regulated by adjusting the molar ratios of Eu3+/Tb3+, showing promising applications in NB sensing, tunable photoluminescence and pH sensing.

Four new coordination polymers with a Y-shaped tricarboxylic acid ligand: Structural diversities, luminescence sensing and magnetic properties

A new aromatic tricarboxylic acid with pyridine core, 4,4′-(4-(3-carboxyphenyl) pyridine-2,6-diyl)dibenzoic acid (H3cpdba), was used as a Y-shaped building block for the hydrothermal syntheses of four coordination polymers (CPs), namely [M(H2cpdba)2] (M = Zn, 1; Co, 2), [Zn4(cpdba)2(μ-OH)2(py)4]∙H2O (3), and [Co3(cpdba)2(py)6] (4). 1–4 were fully characterized by IR, elemental analyses, TGA, PXRD, and single-crystal X-ray diffraction. Their dimensionality ranges from 2D networks (1 and 2) to 3D frameworks (3 and 4), showing the dimensional/structural diversity of 1–4 is influenced by the level of deprotonation of H3cpdba ligand adjusted via organic solvent types, and the type of metal nodes (ZnII or CoII). Interestingly, 1 and 3 can serve as multi-responsive sensing materials for detecting Fe3+, Cr2O72− and nitrobenzene (NB). Moreover, the mechanism of the selective luminescence quenching response for Cr2O72− can be mainly ascribed to the competitive adsorption of excitation wavelength energy between 1 or 3 and Cr2O72−, meanwhile, Fe3+ ions and NB molecules contact with Lewis-base sites and aromatic rings respectively of H3cpdba ligand in 1 or 3, leading to the luminescent quenching. Furthermore, the magnetic properties of two Co-based CPs (2 and 4) have been investigated. The present work provides a promising approach to design and construct CPs or MOFs by adjusting types of solvents and/or metal nodes.