Cd Coordination Polymers Research Articles

Novel anthracene and pyrene containing Cd(II)-based coordination polymers for adsorptive removal of toxic dyes from aqueous medium

In the present work, we have synthesized two new one- and two-dimensional Cd(II) coordination polymers (CPs), formulated as [Cd(L1)(Formamide)2]n (1) and [Cd2(L2)2(MeOH)2]n (2), by the solvothermal reactions of Cd(NO3)2·4H2O with the anthracene and pyrene group bearing carboxylic acids 5-{(anthracen-9-ylmethyl)amino}isophthalic acid (H2L1) and 5-{(pyren-1-ylmethyl)amino}isophthalic acid (H2L2), respectively. The newly synthesized CPs were characterized by FT-IR, elemental, thermogravimetry and single-crystal and powder X-ray diffraction analyses. The single-crystal X-ray diffraction analysis demonstrates that CPs 1 and 2 have one-dimensional double chain and two-dimensional structures, respectively. These novel CPs were employed for the adsorptive removal of various toxic cationic and anionic organic dyes in aqueous medium. Both CPs are highly effective for the removal of cationic dyes in comparison to anionic ones. However, the two-dimensional pyrene group containing CP 2 shows a higher efficiency (removal efficiency of 75–97 %) in removing three different 6 × 10−5 M cationic dyes. In addition, the adsorption kinetics and isotherms for both CPs were determined. An insight into the removal of the organic dyes is provided by in silico studies. Moreover, the stability and recyclability of both CPs were tested under adsorption conditions.

Two new coordination polymers containing 1,4-bis(2-ethylbenzimidazole) as luminescent chemosensors for Fe3+ ions and tetracycline

Two new ternary Cd(II) coordination polymers, [Cd2(L)(tbip)2] n (1) and {[Cd(L)0.5(1,4-NDC)]·0.4H2O} n (2) (H2tbip = 5-tert-butylisophthalic acid, 1,4-H2NDC = 1,4-naphthalenedicarboxylic acid and L = 1,4-bis(2-ethylbenzimidazol-1-ylmethyl)benzene), were hydrothermally synthesized and characterized via single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetric analysis. 1 is a 1-D linear chain, while 2 exhibits a 3-D framework, which can be defined as a 3-D xah (sqc320) topology with the Schläfli symbol of {42.62.82}{46.64}. 1 and 2 remained stable in a pH range of 4.0–13.0 and 3.0–13.0, respectively. 1 and 2 displayed excellent luminescent sensing abilities for Fe3+ ions and tetracycline with high sensitivity and selectivity.

An insight into the controllable synthesis of Cd(II) coordination polymers with packing-assistant luminescent property

Three luminescent materials, {[Cd(m-bix)(2,5-tdad)]·H2O}n(1), [Cd(m-bix)(1,4-bda) (H2O]n(2), [Cd(m-bix)(Cl)2]n(3) [m-bix = 1,3-bis-(imidazol-1-ylmethyl) benzene, 2,5-H2tdad = 2,5-thiophenedicarboxylic acid; 1,4-H2bda = 1,4-benzenedicarboxylic acid] have been hydrothermally synthesized by mixed ligands and characterized by single crystal X-ray diffraction, infrared (IR), elemental analysis and thermogravimetric analysis (TGA). Single-crystal X-ray diffraction analysis reveals that 1–3 exhibit three different structural types: 1 displays a wavelike 2D structure constructed from [CdO5N2] clusters with the help of 2,5-H2tdad. 2 is defined as a 3D supramolecular structure based on π⋯π stacking interactions. Both 1 and 2 display remarkable alternate π⋯π stacking interactions, providing the effective distance for transmission of MLCT. 3 can be regarded as a 6-connected pcu net with the Schläfli symbol {412·63}, featuring binuclear [Cd2Cl6N4] Cl-bridge clusters. Coordination polymers 1–3 display tunable luminescence from deep blue, blue, light blue to green with the red-shift at 298 K and 77 K. 3 displays remarkable narrow band emission with a smaller full width at half-maximum (FWHM) (77 K: 46.98 nm; 298 K: 72.63 nm) in the solid state, which endows the excellent monochromaticity. The mechanism of fluorescence has been explained and verified by density functional theory (DFT) calculations.

Two chemically robust coordination polymers as fluorescent probes for effective sensing of sulfadiazine/ornidazole and Cd2+ ions

Two new ternary Cd(II) coordination polymers (CPs), namely [Zn(bdc)(L)]n (1) and {[Cd(bta)0.5(L)]·H2O}n (2) (H2bdc = 1,4-dicarboxybenzene, H4bta = 1,2,4,5-benzenetetracarboxylic acid, and L = 1,6-bis(benzimidazol-2-yl)hexane) were synthesized through the hydrothermal reactions. 1 displays a 1D infinite chain while 2 reveals a 3D moganite (mog) network. The as-prepared functionalized 1/2 exhibit remarkable thermal and chemical stabilities. The two CPs can be utilized as the dual fluorescence chemosensors for the detection of sulfadiazine (SDZ)/Cd2+ (for 1) and ornidazole (ORN)/Cd2+ (for 2) through fluorescence quenching effect with high sensitivity and selectivity.

Tailoring Enhanced Elasticity of Crystalline Coordination Polymers.

The approach for enhancing the elasticity of crystals with suboptimal elastic performances through a rational design was presented. A hydrogen-bonding link was identified as a critical feature in the structure of the parent material, the Cd(II) coordination polymer [CdI2(I-pz)2] n (I-pz = iodopyrazine), to determine the mechanical output and was modified via cocrystallization. Small organic coformers resembling the initial organic ligand but with readily available hydrogens were selected to improve the identified link, and the extent of strengthening the critical link was in an excellent correlation with the delivered enhancement of elastic flexibility materials.

A stable luminescent Cd(II) coordination polymer for selective detection of chlortetracycline in aqueous medium

A 1D zigzag chain Cd(II) coordination polymer (CP), [Cd(L)2(tcpa)]n(1) (L = 1,3-bis(2-methylbenzimidazol-1-yl)-2-propanol, H2tcpa = tetrachloroterephthalic acid) was hydrothermally synthesized and characterized. 1 can be a promising fluorescence probe to detect chlortetracycline (CTC) with a limit of detection of 2.3 × 10−8 mol/L. 1 could be reused five times. Further, the fluorescent sensing mechanism of 1 was discussed.

Polyaromatic Group Embedded Cd(II)-Coordination Polymers for Microwave-Assisted Solvent-Free Strecker-Type Cyanation of Acetals.

In this work, two new 1D Cd(II) coordination polymers (CPs), [Cd(L1)(NMF)2]n (1) and [Cd(L2)(DMF)(H2O)2]n·n(H2O) (2), have been synthesized, characterized and employed as catalysts for the microwave-assisted solvent-free Strecker-type cyanation of different acetals. Solvothermal reaction between the pro-ligand, 5-{(pyren-1-ylmethyl)amino}isophthalic acid (H2L1) or 5-{(anthracen-9-ylmethyl)amino}isophthalic acid (H2L2), and Cd(NO3)2.6H2O in the presence of NMF or DMF:THF solvent, produces the coordination polymer 1 or 2, respectively. These frameworks were characterized by single-crystal and powder X-ray diffraction analyses, ATR-FTIR, elemental and thermogravimetry analysis. Their structural analysis revealed that both CPs show one-dimensional structures, but CP 1 has a 1D double chain type structure whereas CP 2 is a simple one-dimensional network. In CP 1, the dinuclear {Cd2(COO)4} unit acts as a secondary building unit (SBU) and the assembly of dinuclear SBUs with deprotonated ligand (L12-) led to the formation of a 1D double chain framework. In contrast, no SBU was observed in CP 2. To test the catalytic effectiveness of these 1D compounds, the solvent-free Strecker-type cyanation reactions of different acetals in presence of trimethylsilyl cyanide (TMSCN) was studied with CPs 1 and 2 as heterogenous catalysts. CP 1 displays a higher activity (yield 95%) compared to CP 2 (yield 84%) after the same reaction time. This is accounted for by the strong hydrogen bonding packing network in CP 2 that hampers the accessibility of the metal centers, and the presence of the dinuclear Cd(II) SBU in CP 1 which can promote the catalytic process in comparison with the mononuclear Cd(II) center in CP 2. Moreover, the recyclability and heterogeneity of both CPs were tested, demonstrating that they can be recyclable for at least for four cycles without losing their structural integrity and catalytic activity.

Luminescent Cd coordination polymer based on thiazole as a dual-responsive chemosensor for 4-nitroaniline and CrO42− in water

A novel highly fluorescent cadmium metal–organic framework, [Cd (DPTTZ) (OBA)] (IUST-3), synthesized by using two linkers 2, 5-di (pyridine-4-yl) thiazolo [5, 4-d] thiazole (DPTTZ) and 4, 4′-oxybis (benzoic acid) (OBA) simultaneously, which exhibits a two-dimensional framework. The characteristics of this Cd-MOF were investigated by single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, elemental analysis, powder X-ray diffraction, and thermogravimetry analysis. The IUST-3 exhibits excellent luminescence property and good stability in water. Luminescent experiments indicate that the IUST-3 has remarkable sensitivity and selectivity for the detection of 4-nitroaniline (4-NA), and CrO42− anion with KSV = 1.03 × 105 M-1 (4-NA) and KSV = 2.93 × 104 M-1 (CrO42−) and low limit of detection 0.52 µM (4-NA) and 1.37 µM (CrO42−). In addition, the possible fluorescence quenching mechanism was explored in this paper.

A viologen-based Cd(II) coordination polymer as a multifunctional platform for photochromism, chemochromism and a broad range of fluorescence pH sensing.

A multi-responsive Cd(II) coordination polymer (1) has been constructed by introducing a viologen derivative as both the framework backbone and ligand side pendant. Notably, compound 1 exhibits intriguing properties, including photochromism, methanol-assisted photochromism and chemochromism to ammonia. Furthermore, compound 1 also displays fluorescence pH sensing ability in a wide pH range.

The high fluorescence sensitivity property and quenching mechanism of one-dimensional Cd-HCIA-1 sensor for nitrobenzene.

The sensing of nitroaromatic compounds in aqueous solution is closely related to environmental sustainability and human health. In this study, a novel Cd(II) coordination polymer (Cd-HCIA-1) was designed and prepared, and its crystal structure, luminescence performance, detection of nitro pollutants in water, and fluorescence quenching mechanisms were studied. Cd-HCIA-1 exhibited a one-dimensional ladder-like chain based on a T-shape ligand of 5-((4-carboxybenzyl) oxy) isophthalic acid (5-H3CIA). The H-bonds and π-π stacking interactions were then used to construct the supramolecular skeleton in common. Luminescence studies revealed that Cd-HCIA-1 can detect nitrobenzene (NB) in aqueous solution with high sensitivity and selectivity, and the limit of detection was 3.03 × 10-9 mol L-1. The fluorescence quenching mechanism of the photo-induced electron transfer for NB by Cd-HCIA-1 was obtained through an investigation of the pore structure, density of states, excitation energy, orbital interactions, hole-electron analysis, charge transfer, and electron transfer spectra by using density functional theory (DFT) and time-dependent DFT methods. NB was absorbed in the pore, π-π stacking increased the orbital overlap, and the LUMO was mainly composed of NB fragments. The charge transfer between ligands was blocked, resulting in fluorescence quenching. This study on fluorescence quenching mechanisms can be used to develop efficient explosive sensors.

Enhancement of Long-Lived Persistent Room-Temperature Phosphorescence and Anion Exchange with I- and SCN- via Metal-Organic Hybrid Formation.

An in-depth understanding of structure-property relationships and the construction of multifunctional stimuli-responsive materials are still difficult challenges. Herein, we discovered a 4,4'-bipyridinium derivative with both photochromism and dynamic afterglow at 77 K for the first time. A one-dimensional (1D) Cd(II) coordination polymer (1) assembled by only a 4,4'-bipyridinium derivative and cadmium chloride showed photochromism, room-temperature phosphorescence (RTP), and electrochromism. Interestingly, we found that 1 underwent single-crystal-to-single-crystal transformation during the anion exchange process, and the color of the crystal changed from colorless to yellow (1-SCN-) within 10 min. Complex 1 exhibited photochromism, whereas 1-SCN- did not. The difference in the photochromic behavior between the two complexes was ascribed to the electron transfer pathway between the carboxylate groups and viologen. The DFT calculation based on the crystal structure of 1-SCN- indicated that the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were mainly located on bipyridine and cadmium atoms, eliminating the possibility of electron transfer, whereas for complex 1, electron transfer was probable from O and Cl atoms to pyridinium N atoms in viologen as demonstrated by density of states (DOS) calculations. In addition, complex 1 was successfully made into test paper for the rapid detection of I- and SCN- and displayed potential applications in inkless printing, multiple encryption, and anticounterfeiting.

Two Zn(II)/Cd(II) Coordination Polymers as Recyclable Heterogeneous Catalysts for an Efficient Room-Temperature Synthesis of α-Aminonitriles via the Solvent-Free Strecker Reaction.

The α-aminonitriles are versatile building blocks in the synthesis of natural or artificial amino acids as well as important intermediates in organic synthesis. For their synthesis, the three-component Strecker reaction involving an aldehyde or a ketone together with amines and trimethylsilyl cyanide is used. In the literature, hydrothermally produced metal-based heterogeneous Lewis acid catalysts have been utilized in various solvents. In this work, we aimed at a greener approach toward such catalysis by (a) making two precatalysts with d10 metal centers, {[Zn(hipamifba)(H2O)]·2H2O}n (1) and {[Cd(hipamifba)(H2O)2]·2H2O}n (2) (where H2hipamifba = 4-(((4-((carboxymethyl) carbamoyl)phenyl)amino)methyl)benzoic acid), via an easy and scalable room-temperature method, and (b) showcasing the use of these coordination polymers (CPs) as very efficient, recyclable, and heterogeneous catalysts for the Strecker reaction to form α-aminonitriles in high yields under solvent-free reaction at ambient conditions. This has also allowed us to demonstrate the importance of open metal sites in such catalysis through an efficiency comparison between activated 1 and 2. In addition, activated 2 exhibited a wide substrate scope including a natural product Girgensohnine, providing an example of a natural product synthesis by a CP catalyst via an organic transformation such as the Strecker reaction.

Bis(Vinylenedithio)-Tetrathiafulvalene-Based Coordination Networks.

Novel coordination polymers embedding electroactive moieties present a high interest in the development of porous conducting materials. While tetrathiafulvalene (TTF) based metal-organic frameworks were reported to yield through-space conducting frameworks, the use of S-enriched scaffolds remains elusive in this field. Herein is reported the employment of bis(vinylenedithio)-tetrathiafulvalene (BVDT-TTF) functionalized with pyridine coordinating moieties in coordination polymers. Its combination with various transition metals yielded four isostructural networks, whose conductivity increased upon chemical oxidation with iodine. The oxidation was confirmed in a single-crystal to single-crystal X-ray diffraction experiment for the Cd(II) coordination polymer. Raman spectroscopy measurements and DFT calculations confirmed the oxidation state of the bulk materials, and band structure calculations assessed the ground state as an electronically localized antiferromagnetic state, while the conduction occurs in a 2D manner. These results are shedding light to comprehend how to improve through-space conductivity thanks to sulfur enriched ligands.

A multifunctional and water-stable Cd (II) coordination polymer: Sensitive detection of roxarsone, Fe3+, CrO42− and Cr2O72− in aqueous media

A two-dimensional (2D) water-stable Cd (II) luminescent coordination polymer (1), namely {[CdLCl2]}n, was obtained through assembly of a new 2-deoxy-d-ribose derivative ligand (L) with CdCl2, 1 showed high stability in water. Further investigation showed that 1 can be used as luminescent probe for the organoarsenic compound Roxarsine (ROX) with high selectivity and sensitivity, high quenching constants (KSV = 2.34 × 104 M−1), low limits of detection (LOD) (0.16 μM) and good recyclability in aqueous media. In addition, this luminescent probe can detect some inorganic harmful ions (Fe3+, Cr2O72− and CrO42−) with excellent versatility. The detection mechanism was proved that the quenching was caused by competitive absorption and resonance energy transfer effect between 1 and analytes. More strikingly, a simple 1-based test strip was developed owing to the quick response and recyclability of 1, which shows visible quenching signals under UV light even when analytes concentrations are as low as 5 μM. This work has provided an effective method for the design of multifunctional CP luminescent sensors for pollutants detections in aqueous media.

Synthesis and Crystal Structure of a 3D Cd(II) Coordination Polymer Assembled with Itaconate and 1,2-Bis(4-pyridyl)ethane

Synthesis and Crystal Structure of a 3D Cd(II) Coordination Polymer Assembled with Itaconate and 1,2-Bis(4-pyridyl)ethane

Syntheses, structures and photocatalytic properties of three Cd(II) coordination polymers induced by the dicarboxylate regulator

Three new Cd(II) coordination polymers, with formula {[Cd(bb)(CHDA)]·2H2O}n (1), {[Cd4(bb)4(NO3)4(NPA)2]·4H2O}n (2) and [Cd3(bb)4Cl6]n (3) (bb = 4,4′-bis(imidazolyl) biphenyl; H2NPA = 1,4-naphthalenedicarboxylic acid and H2CHDA = 1,4-cyclohexanedicarboxylic acid) have been synthesized hydrothermally by changing the nature of dicarboxylate regulator. The dicarboxylate regulator affects on the binding degree of nitrate and resulted in the formation of the two different 2D layer networks in polymers 1 and 2, while 3 comprising only bb ligand exhibits 2D double-layered structure. All the CPs have been used as photocatalyst for photodegradation of antibiotic nitrofurantoin (NFT) and CPs 1, 2 and 3 show excellent photocatalytic properties degradation efficiency of 95.51 %, 87.48 % and 79.28 % after 20 min under illumination by UV light. Also, to evaluate the possible photocatalytic mechanism and variations in the photocatalytic performances of CPs, band gap simulations have also been carried out.

Luminescent Zn(II) and Cd(II) coordination polymers based on naphthalene tetracarboxylic acid and 4,4'-bipyridine for sensing of nitrobenzene, Fe3+ and Cr2O7 2− ions

Two luminescent Zn(II) and Cd(II) metal-organic frameworks (MOFs) containing 1,4,5,8-naphthalene tetracarboxylic acid (H4L’) and 4,4'-bipyridine (4bpy), [ZnL(4bpy)0.5(DMA)]n (1) and [CdL(4bpy)0.5]n (2) (L = 1,8-monoanhydride-1,4,5,8-naphthalenetetracarboxylate, DMA = N,N-dimethyl acetamide), were synthesized and characterized through X-ray diffraction, IR, and UV-Vis spectroscopy. 1 shows a 1D linear chain structure, while 2 shows a 2D baluster structure. Both show multiple H bonding and π-stacking interactions. Both compounds show ligand-based luminescence in the range 400-500 nm with contributions from both ligands. The luminescence is strongly dependent on the presence of potentially coordinating molecules. Luminescence quenching experiments show good sensitivities in detecting nitrobenzene (NB), Fe3+ and Cr2O7 2−.

A new cadmium(ii) coordination polymer with 1,4-cyclohexanedicarboxylate acid and phenanthroline derivate: Synthesis and crystal structure

Abstract A new Cd(ii) coordination polymers, formulated as [Cd(1,4-chdc)(L)] n (1) (L = 1-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)naphthalen-2-ol ligands and 1,4-H2chdc = 1,4-cyclohexanedicarboxylate acid), were successfully synthesized by using L ligand and 1,4-H2chdc acid under hydrothermal conditions and characterized by single crystal X-ray elemental analyses, diffraction, and IR spectroscopy. Each Cd(ii) atom is a distorted pentagonal bipyramidal geometry connecting the deprotonated 1,4-chdc anion to form a 2D layer, and a 2D layer is formed into a 3D supramolecular structure by the π–π stacking interactions between neighboring layers.

A water-stable zwitterionic Cd(II) coordination polymer as fluorescent sensor for the detection of oxo-anions and dimetridazole in milk

Coordination polymers (CPs) constructed by zwitterionic ligands show obvious advantages in the fluorescence sensing of toxic pollutants due to the separated charge centers on the frameworks, where the construction of aqueous-phase stable and multifunctional complexes is crucial for practical applications in environmental or food safety detection. A Cd(II) 2D water-stable porous CPs {[CdL(H2O)2]·(ClO4)·3H2O} (1) (flexible H2LCl = 5-carboxy-1-(4-carboxybenzyl)-2-methylpyridin-1-ium chloride) was solvothermally synthesized from good fluorescent zwitterionic organic linkers and was further characterized by single-crystal X-ray diffraction, Hirshfeld surface analysis, powder X-ray diffraction (PXRD), IR spectra, elemental analysis, and thermogravimetric analysis (TG). Aqueous-phase sensing studies demonstrate that complex 1 can serve as a unique bifunctional luminescent probe for highly selective, quick responsive and multicyclic detection of three noxious high-valent oxo − anions Cr2O72−, CrO42−, MnO4− as well as dimetridazole (DTZ) antibiotic via remarkable fluorescence quenching with low limits of detection (LODs) (Cr2O72− 0.12 μM, CrO42− 0.16 μM, MnO4− 0.29 μM and DTZ 0.09 μM). Moreover, the sensor has a certain practical application potential. It obtains desirable recoveries (96.10–105.35 %) for the determination of oxo-anions and DTZ in milk, respectively. Mechanism for all the turn-off responses between the framework and analytes were elaborately explored by means of the electron transfer analytical methods and density functional theory (DFT) calculations.

A 2D layered Cd(II) coordination polymer supported by in situ generated tetracarboxylate ligand: luminescence sensing for Co2+ ions

AbstractA new Cd(II) coordination polymer of [Cd(H2L)(4,4’‐bipy)(H2O)]n (1, H4L=4‐[(3,4‐dicarboxyphenyl)disulfanyl]benzene‐1,2‐dicarboxylic acid, 4,4’‐bipy=4,4’‐bipyridine) was hydrothermally synthesized. The H4L ligand was in situ generated via the formation of disulfide bond between two 4‐sulfanylbenzene‐1,2‐dicarboxylic acid molecular. The in situ generated H4L ligand deprotonated two protons into H2L2−, which acts as a bidentate ligand to connected Cd(II) ions into a 2D layered structure with the assistance of 4,4’‐bipy ligands. The solids of 1 emits strong blue luminescence, and can be used as a luminescence probe for the detection of Co2+ ions. The limit of detection (LOD) of Co(II) ions by 1 was calculated to be 5.4 μM.