Flexible Carboxylic Acid Research Articles

Three Metal Organic Frameworks of Cd(II) with Tri (4‐Carboxybenzyl) Amine and their Photoluminescence Properties

AbstractUtilizing the flexible carboxylic acid ligand, tri (4‐carboxybenzyl) amine (H3L), three new metal organic frameworks Na[Cd(L)]n ⋅ 3nH2O (1), [Cd(HL)(4,4’‐bipy)0.5(H2O)]n (2) (4,4’‐bipy=4,4’‐bipyridine) and [Cd(HL)(2,2’‐bipy)]n (3) (2,2’‐bipy=2,2’‐bipyridine) have been successfully synthesized. Compounds 1 and 2 are 2D structures with (3,6) 2‐nodal as kgd topology, while compound 3 is a 1D chain structure. The powder X‐ray diffraction and thermal stability of 1–3 were studied. In addition, the solid‐state luminescence properties of compounds 1–3 at room temperature were also tested, indicating their application prospects in fluorescent materials.

Two Mixed-Ligand Co(II) Complexes as Luminescent Materials and Loaded with Temozolomide-gel Particles in Nursing Against Glioma.

By employing a mixed-ligand strategy, we synthesized two new coordination polymers (CPs) featuring Co(II): {Co(H2L)(bib)]·2H2O}n (1) and {Co(L)(bib)2]·2H2O}n (2), where H4L represents 5-(3,5-dicarboxybenzyloxy) isophthalic acid, and bib denotes 1,4-bis(1-imidazolyl)benzene. These CPs were obtained through the reaction of H4L, a flexible carboxylic acid ligand, with Co(NO3)2·6H2O in various solvent mixtures, along with the N-donor co-ligand bib. Complexes 1 and 2 are formed through distinct coordination modes, resulting in their distinct structural features and excellent fluorescent properties. Based on ligand-centered fluorescence emission and the blue shift (CP 1) along with red shift (CP 2) characteristics, both complexes show promise for applications in fields such as blue fluorescence sensing materials and luminescent materials. After successfully synthesizing two CPs, CP 1 was chosen as the carrier for loading temozolomide (TMZ). Subsequently, leveraging the unique advantages of hydrogels, we developed a novel metal gel formulation loaded with TMZ. The inhibitory effect of this formulation on the growth of glioblastoma was evaluated. Our results demonstrate a significant suppression of glioblastoma cell proliferation by this system, providing an effective avenue for glioblastoma treatment.

Enhancing visual fluorescence detection of tetracycline antibiotics through nitrogen containing ligand regulation and antenna effect of Ln3+

Two fluorescent Cd-MOFs were obtained by solventhermal process using flexible carboxylic acid ligand of 4-(3,5-dicarboxylatobenzyloxy) benzoic acid (H3L) and flexible/rigid tripodal N-containing ligand 1,3,5-tris(1,2,4-tiazol-1-ylmethyl)-2,4,6-Trimethylbenzene (ttytb) and 2,4,6-tris(4-pyridyl)-1,3,5-triazine(tpytz), namely, {[Cd(HL)(ttytb)]·DMF·3H2O}n (LCU-127)...

Photocatalytic Oxidation of Benzylamine by Cadmium‐Based MOF Constructed with Flexible Carboxylic Acid

AbstractMOFs (Metal organic frameworks) have diverse structures that present great potential for light capture and light conversion. Therefore, MOFs are widely used in the study of photocatalysis. However, there still are some challenges in photocatalytic organic conversion upon MOFs under mild conditions, such as poor light absorption performance. Here, we successfully synthesized a new Cd‐connected two‐dimensional MOF by a simple hydrothermal method, termed [Cd(PLA)(4,4’‐bipy)0.5 ]⋅(DMF) (Cd‐PLA) (PLA= phenylene‐diacetic acid, 4,4’‐bipy= 4,4’‐bipyridine and DMF= N,N’‐dimethyl formamide). The bpy‐containing Cd‐PLA possesses excellent light harvest ability and suitable photocatalysis energy potential, allowing it to be a remarkable photocatalyst with highly efficiency and selectivity for the photo‐oxidation of benzylamine. This work provides an efficient, economical, and green way for oxidation of amines to produce imines under ultraviolet light irradiation.

Synthesis and characterization of bioplastic curdlan esters with an introduced flexible carboxylic acid side chain

Curdlan, a linear β-1,3-glucan, was reacted with glutaric anhydride and heptanoyl chloride to afford thermoplastic curdlan esters (CrdE(HepGlu)) with a carboxylic acid side chain. CrdE(HepGlu) with a degree of substitution of the glutaric acid monoester moiety (DSGlu) in the range of 0–0.58 and that of the heptanoate moiety (DSHep = 3 − DSGlu) was prepared. The esterification of the hydroxy groups in the glucan skeleton effectively caused the cleavage of the interchain hydrogen bonds of curdlan and enhanced the formability of CrdE(HepGlu). Moreover, the flexible carboxylic acid side chain moderately affected hydrogen bonding. Thus, the glass transition temperature of CrdE(HepGlu), estimated by differential scanning calorimetry, increased with increasing DSGlu. CrdE(HepGlu) with DSGlu between 0 and 0.58 displayed high solubility in organic solvents and thermoplasticity, enabling the formation of homogeneous and free-standing films by solution casting. The mechanical properties of CrdE(HepGlu) films were evaluated by a stress−strain test, which showed that Young's modulus and the maximum stress increased with increasing DSGlu. CrdE(HepGlu) exhibited higher mechanical strength than non-hydrogen-bonded curdlan triheptanoate and hydrogen-bonded curdlan alkylcarbamates, with thermal stability comparable to that of thermally stable curdlan esters. In addition, these properties can be regulated by controlling DSGlu.

Solvent induced synthesis of uranium organic frameworks: From 1D→2D based on a flexible carboxylic acid ligand

The development of nuclear energy gives lots of spent fuel which do harm to the environment and human health. There are numerous researchers focused on the disposal of the spent fuel with the adsorption method by selecting different materials as adsorbents. This work aims to handle the waste by using Lewis acid to accumulate and solidify the uranium. In this study, to remove the uranium from the spent fuel, a novel flexible tripod carboxylic acid based on sulfur was used to react with the uranium to form the interesting uranium organic framework with a one-dimensional chain and two-dimensional network. To our knowledge, this is the first case of the MOFs (Metal-Organic Frameworks) based on the ligand H3TTTTA, and the ligand in the compounds gives different coordination styles. All the UOFs exhibit outstanding stability in the solution with pH from 1 to 14, which shows brilliant application potential in the extreme environment. The methyl violet was selected to verify the adsorption properties of the materials, and UOF-1 shows the best removal rate of 96.98% in 24 h.

Characterization of Bioplastic Curdlan Esters with an Introduced Flexible Carboxylic Acid Side Chain

Characterization of Bioplastic Curdlan Esters with an Introduced Flexible Carboxylic Acid Side Chain

Structure and photocatalytic performance of a metallacycle complex based on flexible carboxylic acid ligand

A new compound of {[Cu2(L)2(2,2′-bipy)2(H2O)2]·2H2O}n (1) (H2L = 1,3-bis(4′-carboxylatophenoxy)benzene, 2,2′-bipy = 2,2′-bipyridine), was prepared and full characterized. 1 shows a metallacycle unit, which was further extended into 3D supramolecular motif through the π-π packing and H-bonded interactions. 1 obtained effectively photocatalytic performance to the disintegration of Rhodamine B (Rh B) compared to the dyes of basic green (BG), methyl violet (MV) and methylene blue (MB). In addition, the plausible mechanism displayed by 1 for the catalytic degradation toward Rh B was proposed using the trapping method and LC-MS studies.

One-dimensional La(III) coordination polymer displaying multi-responsive luminescence activities towards Fe3+, acetone and benzothiozoles

Through reaction of La(NO3)3 with a flexible carboxylic acid ligand named 3,5-bis[(2-carboxyphenyl)oxy]benzoic acid (H3L) under solvothermal condition, the complex with the formula of [La(L)(DMF)2] (1) was obtained. One-dimensional chain of the complex was generated through the connection of binuclear units of La2(COO)4 across the flexible acid ligands. Luminescence results showed that different pollutants (Fe3+, acetone and benzothiophene organic compounds) could quench the luminescence of the blue emission of the complex in DMF with much low detection limit. Among several 2-substituted benzothiophene compounds, 2,2′-dithiobisbenzothiazole (DM) has a strongest binding constant of 10.8 ​× ​104 ​M−1 and lowest detection limit of 0.332 ​μM (0.110 ​ppm). All quenching effect was found within 15 ​s. The sensing mechanism was investigated through a series of experiments and theoretical calculation. Complex 1 could be employed as a multi-responsive chemsensor for detection of different pollutants with high sensitivity and fast response.

A new Cu(II)-based coordination polymer: protective activity against ulcerative colitis via regulating the level of pro-inflammatory and anti-inflammatory cytokines

A new one-dimensional (1-D) copper(II) coordination polymer, namely, {[Cu(L)(2,2’-bipy)]·0.5DMF}n (1) (H2L= 2,2’-[benzene-1,4-diylbis(methanediylsulfanediyl)]dibenzoic acid, 2,2’-bipy= 2,2’-bipyridine), has been synthesized using Cu(NO3)2·3H2O with long flexible carboxylic acids and N-containing ligands. Furthermore, a green hand grinding technique has been implemented to reduce the particle size of the compound 1 to generate nanoscale 1 (denoted as nano 1 hereafter). Furthermore, the protective effect of the compound on the ulcerative colitis was evaluated. Firstly, the Colon Tissue Mucosal Injury Score (CMDI) of the ulcerative colitis rat was measured after compound treatment. Then, the pro-inflammatory and anti-inflammatory cytokines in the UC rat model after compound treatment was measured with ELISA detection assay.

Coordination Assemblies of Zn(II) Coordination Polymers: Positional Isomeric Effect and Optical Properties

Two Zn(II) coordination polymers (CPs) [Zn(L)(pphda)] (1) and [Zn(L)(ophda)]·H2O (2) were prepared by reactions of ZnSO4·7H2O based on the N-donor 1,4-di(1H-imidazol-4-yl)benzene (L) ligand and two flexible carboxylic acids isomers of 1,4-phenylenediacetic acid (H2pphda) and 1,2-phenylenediacetic acid (H2ophda) as mixed ligands, respectively. Structures of CPs 1 and 2 were characterized by elemental analysis, Infrared spectroscopy (IR), thermogravimetric analysis and single-crystal X-ray diffraction. The CP 1 is a fourfold interpenetrating 66-diamond (dia) architecture, while 2 is a 2D (4, 4) square lattice (sql) layer based on the Zn2(cis-1,2-ophda2−)2 binuclear Zn(II) subunits. The luminescent property, including luminescence lifetime and quantum yield (QY), have been investigated for CPs 1 and 2.

Polyoxomolybdates functionalized by a flexible carboxylic acid and their photochromic properties

Two inorganic-organic hybridized polyoxomolybdates, Cs8NaH [(SeMo6O21)C6H3O3(CH2CO2)3]2·10H2O (1) and Cs8H4 [(AsMo6O21)C6H3O3(CH2CO2)3]2·10H2O (2), functionalized by a flexible tri-podal multicarboxylic ligand 1,3,5-tris (carboxymethoxy)benzene (TCMB) have been synthesized and characterized. Single-crystal X-ray diffraction analysis reveals that each of the two hybrids consists of two {XMo6} (X = Se, As) units supported by two TCMB molecules. The photochromism and thermochromism behaviors of the two compounds have been explored. The color of compound 2 could change dramatically from white to black within just 1 min of irradiation by a Xe lamp. During thermochromic experiments the two compounds change their color at 423 K for 1 and 393 K for 2, respectively.

Four coordination compounds constructed from 1,10-phenanthroline and semi-flexible and flexible carboxylic acids: Hydrothermal synthesis, optical properties and photocatalytic performance

Four novel coordination compounds based on d10 metals, 1,10-phenanthroline (phen) and 2,2′,3,3′-oxydiphthalic acid (2,2′,3,3′-odpt), 3,5-di(3,4-dicarboxylphenyloxy)benzoic acid (dcpb) or 1,3-(3′,4′-carboxylphenoxy)benzene (cpb), namely [Co2(phen)4(2,2′,3,3′-H2odpt)2]·14H2O (1), [Co2(phen)4(H4dcpb)2]·14H2O (2), [Cu(phen)(H3dcpb)] (3) and [Mn(phen)2(H2cpb)] (4), have been synthesized under hydrothermal conditions and characterized by the methods of single crystal X-ray diffraction, FTIR, elemental analysis and UV–Vis diffuse spectroscopy. The isostructural compounds 1 and 2 consist of discrete neutral [Co2(phen)4(L)2] (L=2,2′,3,3′-odpt for 1 and dcpb for 2) units and lattice water molecules, forming 3D frameworks with the aid of rich hydrogen bonding interactions. Compounds 3 is built up of discrete neutral [Cu(phen)(H3dcpb)] units to construct a 3D framework via π–π stacking interactions. Compound 4 consists of 1D neutral [Mn(phen)2(H2cpb)] helix chains, further forming a 3D framework via rich hydrogen bonding interactions. The photocatalytic activities of degradation of methylene blue (MB) and methyl orange (MO) in compounds 1–4 under UV light irradiation were determined, and the results revealed that compound 4 can decompose MB and MO efficiently. The different degradation efficiencies of compounds 1–4 implied that the HOMO–LUMO gap should be utilized to describe the discrete character of the light-induced transitions in the coordination compounds.

Solvent-induced synthesis of cobalt(II) coordination polymers based on a rigid ligand and flexible carboxylic acid ligands: syntheses, structures and magnetic properties.

Five new cobalt(ii) coordination architectures, {[Co(L)2(H2O)2]·2H2O·2NO3}n (), {[Co(L)(ppda)]·2H2O}n (), {[Co2(L)(ppda)2]2·H2O}n (), {[Co(L)(nba)]·5H2O}n (), and {[Co(L)(oba)]2·3H2O}n (), have been constructed from the rigid ligand L [L = 2,8-di(1H-imidazol-1-yl)dibenzofuran] and different flexible carboxylic acid ligands [H2ppda = 4,4'-(perfluoropropane-2,2-diyl)dibenzoic acid, H2nba = 4,4'-azanediyldibenzoic acid, and H2oba = 4,4'-oxydibenzoic acid]. Depending on the nature of the solvent systems, these five different coordination polymers were synthesized and characterized by single-crystal X-ray diffraction, IR, PXRD and elemental analysis. Compounds , and were obtained by a one-pot method, and then we utilized the solvent-induced effect to obtain almost pure crystals of , respectively. Compound is an infinite 1D chain which is formed by L ligands and Co atoms. Compound contains a [Co2(CO2)4] secondary building unit (SBU), and can be topologically represented as a 6-connected 2-fold interpenetrating pcu net with the point symbol of {4(12)·6(3)}. Compound can be characterized as a 4-connected sql tetragonal planar network with the point symbol of {4(4)·6(2)}. In compounds and , there is a 1D chain which is formed by flexible carboxylic acid ligands and Co atoms; then the 1D chain is linked by L ligands in the tilting direction, leading to the formation of a 2D layer. Furthermore, UV-vis, TGA and magnetic properties have been investigated in detail.

Four coordination polymers based on flexible carboxylic acid and bis(pyridyl) mixed ligands: synthesis, structures, fluorescent and magnetic properties

Hydrothermal reactions of Zn(II), Cd(II), Co(II) or Cu(II) acetates with 2,4-DH and BPP as flexible ligands (2,4-DH = 2,4-dichlorophenoxyacetic acid, BPP = 1,3-bis(4-pyridyl)propane) afforded four new coordination polymers, [Zn(2,4-D)2(BPP)]n (1), [Cd4(2,4-D)8(BPP)4(H2O)2]n (2), [Co2(2,4-D)4(BPP)2(H2O)]n (3) and [Cu4(2,4-D)6(BPP)2(OH)2]n (4). In these complexes, the BPP ligands bridge different secondary building units, forming diverse networks based on different metal centers. Complex 1 displays a 1D chain structure with four-coordinated Zn(II) atoms connected by BPP ligands, and the resulting 1D chains are further assembled into 2D networks through aromatic π–π stacking interactions. In complexes 2 and 3, the binuclear Cd(II) or Co(II) units are bridged by the BPP ligands to generate 2D networks. Complex 4 shows a 1D double-chain structure with the tetranuclear Cu(II) units linked by BPP bridges. The fluorescence and magnetic properties of these complexes have been investigated.

Synthesis, characterization and dielectric properties of sulfonated poly(1,3,4-oxadiazole-ether) sulfone copolymer with functional pendant carboxylic acid groups

This work reports the synthesis and electrical characterization of sulfonated copolymer with flexible carboxylic acid pendants with 1,3,4-oxadiazole unit in the main polymer structure contrived successfully via nucleophilic displacement polycondensation among 2,5-Bis(4-fluorophenyl)-1,3,4-oxadiazole (BFPOx), 4,4′-Bis(4-hydroxyphenyl) valeric acid (BPV) and Disodium-3,3′-disulfonate-4,4′-dichlorodiphenylsulfone (S-DCDPS). The molecular structural characterization of the copolymer was achieved by NMR spectroscopic studies, TGA was performed to verify the thermal stability, dielectric studies were executed by compressing the copolymer sample in to tablets and results were discussed.

Enhancing CO2 Separation Ability of a Metal–Organic Framework by Post‐Synthetic Ligand Exchange with Flexible Aliphatic Carboxylates

A series of porous metal-organic frameworks having flexible carboxylic acid pendants in their pores (UiO-66-ADn: n=4, 6, 8, and 10, where n denotes the number of carbons in a pendant) has been synthesized by post-synthetic ligand exchange of terephthalate in UiO-66 with a series of alkanedioic acids (HO2 C(CH2 )n-2 CO2 H). NMR, IR, PXRD, TEM, and mass spectral data have suggested that a terephthalate linker in UiO-66 was substituted by two alkanedioate moieties, resulting in free carboxyl pendants in the pores. When post-synthetically modified UiO-66 was partially digested by adjusting the amount of added HF/sample, NMR spectra indicated that the ratio of alkanedioic acid/terephthalic acid was increased with smaller amounts of acid, implying that the ligand substitution proceeded from the outer layer of the particles. Gas sorption studies indicated that the surface areas and the pore volumes of all UiO-66-ADns were decreased compared to those of UiO-66, and that the CO2 adsorption capacities of UiO-66-ADn (n=4, 8) were similar to that of UiO-66. In the case of UiO-66-AD6, the CO2 uptake capacity was 34 % higher at 298 K and 58 % higher at 323 K compared to those of UiO-66. It was elucidated by thermodynamic calculations that the introduction of flexible carboxyl pendants of appropriate length has two effects: 1) it increases the interaction enthalpy between the host framework and CO2 molecules, and 2) it mitigates the entropy loss upon CO2 adsorption due to the formation of multiple configurations for the interactions between carboxyl groups and CO2 molecules. The ideal adsorption solution theory (IAST) selectivity for CO2 adsorption over that of CH4 was enhanced for all of the UiO-66-ADns compared to that of UiO-66 at 298 K. In particular, UiO-66-AD6 showed the most strongly enhanced CO2 uptake capacity and significantly increased selectivity for CO2 adsorption over that of CH4 at ambient temperature, suggesting that it is a promising material for sequestering CO2 from landfill gas.

Characterization of Molecular Complexes of 1,4-Naphthoquinone Derivatives

The structures of sulphur atom tethered quinone containing flexible carboxylic acid (3-methyl-1,4-dioxo-1,4-dihydronaphthalen-2-ylsulfanyl)acetic acid (1) and its molecular complex with 4,4′-bipyridine (3) are determined. The compound 1 crystallizes in P-1 (triclinic, a = 7.5378(6) A, b = 7.6413(7) A, c = 10.3101(9) A; α = 89.779 (7)°, β = 81.042 (5)°, γ = 89.101(7)°) and the molecular complex 3 crystallises in P2(1)/n (monoclinic, a = 9.3383(7) A, b = 3.970(3) A, c = 42.130(3) A, β = 91.056(5)°) space groups, respectively. The R 2 2 (8) type hydrogen bonding between dicarboxylic acid groups present in the parent compound 1 is lost on interaction with 4, 4′-bipyridine; in the molecular complex 3 R 2 2 (7) type of O···H–C and O–H···N interactions are present between the pyridine rings and carboxylic acid groups. The molecular complex (4) derived from 3-carboxymethylsulfanyl-1,4-dihydroxynaphthalen-2-yl-sulfanyl) acetic acid (2) with triphenylphosphine oxide in 1:2 ratio, crystallises in C2/c space group have monoclinic, a = 26.0494(13) A, b = 10.5402(5) A, c = 17.1023(8) A, β = 108.719 (5)°). The triphenylphosphine oxide molecules are preferentially held by O–H···O interactions between carboxylic acid and P=O bond. The structures of (3-methyl-1,4-dioxo-1,4-dihydronaphthalen-2-ylsulfanyl) acetic acid , its molecular complex with 4,4′-bipyridine and molecular complex of 3-carboxymethylsulfanyl-1,4-dihydroxy naphthalen-2-yl-sulfanyl)acetic acid with triphenylphosphine oxide are presented

Structural diversity in a series of metal–organic frameworks (MOFs) composed of divalent transition metals, 4,4′-bipyridine and a flexible carboxylic acid

A series of flexible metal–organic frameworks (MOFs) have been successfully synthesized under hydrothermal condition using 1,3-adamantanediacetic acid (C14H20O4, H2ADA) as a flexible dicarboxylate building block, 4,4′-bipyridine and transition metal ions [Cd(II), Zn(II), and Mn(II)] as metal centers in DMF and aqueous media. These MOFs formulated as [Cd(ADA)(4,4′-bipy)0.5]·(DMF) (Cd-ADA-1), [Mn(ADA)(4,4′-bipy)0.5]·(DMF) (Mn-ADA-1), Zn(ADA)(4,4′-bipy)0.5 (Zn-ADA-1), and [Mn(HADA)2(4,4′-bipy)(H2O)2] (Mn-ADA-2) (ADA = 1,3-adamantanediacetate, 4,4′-bipy = 4,4′-bipyridine and DMF = N,N′-dimethyl formamide) display interesting 1D, 2D and 3D structural features depending on the solvent of synthesis. All these MOFs were structurally determined by single-crystal X-ray diffraction. The coordination modes of this ligand are discussed and in addition, thermal stability and hydrogen (H2) and carbon-dioxide (CO2) adsorption properties of Cd-ADA-1, Mn-ADA-1 and Zn-ADA-1 are also presented. Hydrogen sorption at 77 K and up to 1 atm is found to be 0.42, 0.72 and 1.36 wt% without saturation for Zn-ADA-1, Mn-ADA-1 and Cd-ADA-1 samples.

Crystal packing in some flexible carboxylic acids and esters attached to a naphthalene ring

A structural study of four dicarboxylic acids and four esters attached to a naphthalene ring is presented. (4-Carboxymethoxy-naphthalen-2-yloxy)-acetic acid (1) has a chain structure in the lattice while (6-carboxymethoxy-naphthalen-1-yloxy)-acetic acid (2) and (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid (3) adopt a sheet-like structure through weak intermolecular interactions, C–H⋯O and C–H⋯π hydrogen bonds. (3-Carboxymethylsulfanyl-1,4-dihydroxy-naphthalen-2-ylsulfanyl)-acetic acid has two symmetrically non-equivalent molecules per unit cell. The asymmetry is caused by weak C–H⋯S interactions. The packing pattern of the methyl esters differs significantly from the parent carboxylic acids and the packing patterns in each case were found to be determined by the C–H⋯O and C–H⋯π interactions.