Cd-based Coordination Polymers Research Articles

Luminescent coordination polymers with mixed carboxylate and triazole ligands for rapid detection of chloroprene metabolite

Chloroprene is a monomer widely used in the production of neoprene, and 1-hydroxy-2-butanone (1H2B) is one of the metabolites of chloroprene in urine, which can place a significant impact on human health by disrupting the normal structure and function of DNA. Herein, a three-dimensional Zn-based coordination polymer (1) and a two-dimensional Cd-based coordination polymer (2) were synthesized with mixed ligands of 2,5-furandicarboxylic acid (H2FDA) and 1,2,4-triazole (Htrz) and fully characterized. 2 exhibits excellent stability and superior sensing performance for 1H2B with fast response within 15 s, good recyclability and a detection limit of 9.24 μM. In addition, 2 demonstrates good selectivity in presence of main coexisting compounds in urine. In-depth investigations of the sensing mechanism revealed that the luminescence sensing is based on the competitive absorption and photoelectron transfer processes.

Structure and photochromic properties of two cadmium coordination polymers derived from viologen ligands

AbstractTwo novel 1D Cd‐based coordination polymers (CPs) {[Cd(MQ)(HBTC)(H2O)2] ⋅ (H2BTC) ⋅ 4H2O}n (1) and {[Cd(AQ)(HBTC)(H2O)Br] ⋅ 2H2O}n (2) have been prepared in the reaction of Cd2+ with different viologen ligands such as 1‐methyl‐4,4′‐bipyridinium bromide (MQBr) or 1‐amyl‐4,4′‐bipyridinium bromide (AQBr) in the presence of 1,3,5‐benzenetricarboxylic acid (H3BTC). The Cd2+ ions are bridged by HBTC2− anions to take shape a 1D configuration for two CPs. Additionally, 1 and 2 both show photochromism due to the photoinduced electron transfer (ET) from electron‐rich O atoms to electron‐deficient viologen moieties. Compared with 2, compound 1 has a rapid photoresponsive rate. The different photochromic behaviors have been discussed adequately.

A Multifunctional Coordination Polymer Constructed by Viologen Derivatives: Photochromism, Chemochromism, and MnO4- Sensing.

A multifunctional Cd-based coordination polymer based on a viologen derivative and a secondary carboxylic ligand, namely, {[Cd2(bcbp)(pta)2 (H2O)]·2H2O}n (1, H2bcbpCl2 = 1,1'-bis(4-carboxyphenyl)-(4,4'-bipyridinium) dichloride, H2pta = p-phthalic acid), has been solvothermally synthesized and structurally characterized. Compound 1 is a 3D framework built on {Cd2(pta)2 (H2O)}n net with square channels which intalls bcbp ligands at the diagonal position of the two adjacent square channels. Notably, compound 1 exhibits a reversible photochromic transformation between yellowish gray and dark green under xenon light irradiation, which should be attributed to the formation of free viologen radicals. Furthermore, compound 1 also displays a chemochromic phenomenon from yellowish gray to dark green after exposure to ammonia and hydrazine, which could be ascribed to the generation of viologen radicals and charge-transfer complexes triggered by nucleophilic attack of electron-rich ammonia and hydrazine molecules to the electron-deficient viologen moiety in the bcbp ligand. Moreover, compound 1 is capable of quickly and selectively detecting MnO4- with a high quenching coefficient and a low limit of detection via a luminescent quenching process caused by the competitive absorption of excitation energy.

A new two-dimensional cadmium(II) coordination polymer based on Cd6(CHADC)6 clusters (H2CHADC is cyclohexane-1,2-dicarboxylic acid): synthesis, structure and properties.

The highly effective recognition and detection of metal ions and anions in water has attracted much attention with respect to environmental safety. Herein, a novel Cd-based coordination polymer, poly[[4,4'-bis(2-methylimidazol-1-yl)biphenyl]bis(cyclohexane-1,2-dicarboxylato)dicadmium(II)], [Cd2(C8H10O4)2(C20H18N4)]n or [Cd(CHADC)(4,4'-BMIBP)0.5]n, (I), has been synthesized employing cis-cyclohexane-1,2-dicarboxylic acid (H2CHADC) and 4,4'-bis(2-methyl-1H-imidazol-1-yl)biphenyl (4,4'-BMIBP). Single-crystal X-ray analysis reveals that (I) presents a 6-connected hxl two-dimensional layer based on Cd6(CHADC)6 clusters with the point symbol (36·46·53). Furthermore, (I) has been characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and fluorescence spectroscopy, and exhibits good stability and excellent photoluminescence properties. Coordination polymer (I) was chosen as a fluorescent probe to sense different target analytes and shows an obvious selective recognition response to Fe3+ cations and Cr2O72-/CrO42- anions through luminescence-quenching effects in aqueous solution. The sensing mechanism was investigated and showed that the detection mechanism was resonance energy transfer between (I) and the Fe3+, Cr2O72- and CrO42- ions.

Effect of Hydrogen Bonding on the Luminescence Lifetime and Device Resistance: A Case Study Based on Two New Related Cd-Based Coordination Polymers

Two new coordination polymers of formulas [Cd2(2,3-pzdc)(tz)2] (1) and [Cd2(2,3-pzdc)(dtz)2] (2) {2,3-pzdc = 2,3-pyrazine dicarboxylate, tz = 1,2,4-triazolate, dtz = 3,5-diamino-1,2,4-triazolate)} were synthesized via hydrothermal techniques. Both the compounds were characterized by single-crystal X-ray analysis, powder X-ray diffraction, Fourier transform infrared (FTIR), and thermogravimetric analysis (TGA). Single-crystal X-ray analysis shows that both the structures are three-dimensional in nature and connectivity-wise they are similar to each other. In compound 2, the presence of N–H···O hydrogen-bond interactions further stabilized the structure. Aqueous dispersion of both the compounds showed a strong dual emission─one at around 353 nm and another at 369 nm upon excitation at 280 nm. Lifetime studies from time-resolved spectra show 0.82 and 0.60 ns for compound 1 and 2.02 and 1.78 ns for compound 2. The higher lifetimes of the excited states in the case of compound 2 establish the role of hydrogen-bond interactions in reducing the nonradiative decay processes. To explore the junction properties at the Al/material interface of these Schottky barrier diodes, the dark J–V characteristics of both of the devices (ITO/PEDOT/compound 1/Al and ITO/PEDOT/compound 2/Al) were analyzed using the well-known Shockley diode equation. In both the devices (with compound 1 and compound 2), asymmetric behavior is observed under forward and reverse bias, indicating rectification. However, in the compound 2 device, the overall current magnitude is 10 times higher than that of the compound 1 device. The series resistance extracted for the compound 2 device is ≈ 22 times lower than that of the compound 1 device, indicating the higher conductivity of compound 2. This behavior indicates a probable role of hydrogen-bond interactions in the lower resistance and higher conductivity of compound 2 compared to compound 1.

Two dual functional 3D Cd-based coordination polymers for the highly luminescent sensitive detection of Fe3+ and norfloxacin

Two new Cd(II) coordination polymers(CPs) [Cd2.5(L1)(Htbip)(tbip)2]n (1) and {[Cd(L2)0.5(1,4-chdc)]·H2O}n (2) (L1 ​= ​1,2-bis(2-ethylbenzimidazol-1-ylmethyl)benzene, L2 ​= ​1,4-bis(2-ethylbenzimidazol-1-ylmethyl)benzene, H2tbip ​= ​5-tert-butylisophthalic acid; 1,4-H2chdc ​= ​1,4-cyclohexanedioic acid) were hydrothermal synthesized and structural characterized. 1 can be defined as a 3D 6,8T13 network with the point symbol of {32.410.52.6}{34.412.58.64}. 2 reveals an unusual 3D xww-3,4-P21/c topological frameworks with the point symbol of {4.82.103}{4.82}. Both CPs possessed highly thermal and chemical stability. 1 and 2 can be as bifunctional luminescent sensors for effective detection of Fe3+ and norfloxacin.

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.

New polymorph for Cd(II) chloro‑bridged coordination polymer based on 3-aminopyrazin-2-carboxylic acid: Synthesis, structural characterization, Hirshfeld surface analysis, thermal properties and molecular docking study on the antifungal activity

A new polymorph of cadmium (II) coordination polymers, namely poly[[(3-aminopyrazin-4-ium-2-carboxylate-k2N1,O)di-μ-chlorido-cadmium(II)] monohydrate], {[CdCl2(C5H5N3O2)]-H2O}n, (PM2), is synthesized from the reaction of cadmium(II) chloride and 3-aminopyrazine-2-carboxylic acid (Hapca). The first P-1 polymorphic (PM1) has already been isolated; it was synthesized by the reaction of Hapca with the hydrated cadmium salt. Meanwhile, for the preparation of the new Pccn polymorph (PM2), the anhydrous metal salt was used. The two polymorphic Cd-based coordination polymers are synthesized in aqueous acidic media. To identify the potential protonation sites in the organic ligand Hapca and determine its coordinating ability, the ionization constants pKa are predicted using ACD/pKa and ChemAxon calculators. The new polymorph is characterized by single-crystal X-ray diffraction and show chloro-bridged zigzag chains with octahedrally coordinated metal ions where Hapca acts as a bidentate N/O chelating ligand. The chains are further interconnected via noncovalent interactions into three dimensional supramolecular networks. The dominant H···O and H···Cl interactions for both polymorphs were quantified using Hirshfeld surface analysis. The thermal properties of the two isolated polymorphic coordination polymers are also discussed. The antifungal activity of the two polymorphs PM1, PM2 and the organic free ligand Hapca against the yeast Candida albicans was screened by the molecular docking approach. The enzyme exo-β- (1,3)-glucanase (Exg) was chosen as a target. The drug-likeness activity and ADMET properties were also evaluated.

A novel three-fold interpenetration 3D Cd-based coordination polymer for the sensing of glutamate in aqueous medium and calf serum

As a special biomarker for many nervous system diseases, Glutamate (Glu) plays an important role in clinical application. Therefore, it is of great significance to sense Glu sensitively in aqueous medium or serum. Here, a novel three-fold interpenetration 3D framework of {[Cd (HTCPB) (4,4′-bbib)]·2H2O}n (1) (H3TCPB ​= ​1,3,5-tris(4-carbonylphenyloxy)benzene, 4,4′-bbib ​= ​4,4′-bis(benzoimidazo-1-yl)biphenyl) (1) has been successfully synthesized and characterized by single-crystal X-Ray diffraction (SCXRD), X-ray powder diffraction analyses (PXRD), thermogravimetric (TG) and X-ray photoelectron spectroscopy (XPS). Stability experiments show that 1 has excellent water and thermal stability. And luminescence experiments demonstrated that 1 can selectively and sensitively sense Glu in aqueous solution with the limit of detection (LOD) being 1.15 ​× ​10-7 ​M. Meanwhile, the detection concentration of 1 towards Glu in serum is 4.31 ​× ​10-5 ​M, which is far lower than that of Glu (4 ​× ​10-4 ​M) in the blood of patients with glioma. In addition, the interaction between carboxylate groups (-COOH) of H3TCPB ligands in 1 and amino-groups (−NH2) of Glu is mainly responsible for the turn-on phenomenon of 1. These results provide a platform of 1 for sensing Glu in clinical application.

Programmable Triboelectric Nanogenerators Dependent on the Secondary Building Units in Cadmium Coordination Polymers.

Precisely controlling the coordination microenvironment and electronic features of polynuclear secondary building units (SBUs) in coordination polymers (CPs) is an efficient approach to governing their fundamental performance. Here, different multinuclear SBUs (binuclear, trinuclear, and pentanuclear SBUs for 1-3, respectively) were introduced into Cd-based CPs, which were used as frictional electrode materials, to clarify the contributions of polynuclear Cd-SBUs through the output of triboelectric nanogenerators (TENGs). The results demonstrated that 1-TENG with binuclear Cd-SBUs possessed the highest output, whereas 3-TENG with the pentanuclear Cd-SBUs indicated the minimum output, suggesting that the binuclear Cd-SBUs in 1 lost electrons most readily and generated much more charge, which was further confirmed by density functional theory calculations. This work opened a new prospect to confirm the gaining/losing capability of polynuclear Cd-SBUs in CPs and provided an effective approach to tuning both the stability and functionality of polynuclear CPs as frictional pair materials to regulate the output of CPs-based TENGs.

Multiresponsive Luminescent Sensitivities of a 3D Cd-CP with Visual Turn-on and Ratiometric Sensing toward Al3+ and Cr3+ as Well as Turn-off Sensing toward Fe3.

By using the reduced Schiff base tricarboxylate ligand H3cip, one novel 3D Cd-based coordination polymer (Cd-CP) with the formula [Cd(Hcip)(bpea)0.5(H2O)]n (H3cip = 5-(3-carboxybenzylamino)isophthalic acid, bpea = 1,2-bis(4-pyridyl)ethane) has been solvothermally synthesized. The prepared Cd-CP possesses a 4-connected CdSO4 net based on dinuclear {Cd2} units. Luminescence measurements revealed that the complex exhibited ratiometric turn-on luminescence responses toward Al3+ and Cr3+ with a significant color change, which could be easily distinguished by the naked eye under ultraviolet light. Cd-CP can also respond to Fe3+ through a turn-off mechanism. Interestingly, the luminescence quenched by Fe3+@Cd-CP can be recovered and increased significantly by adding some competitive Al3+, while Cr3+ can only marginally increase the luminescence intensity of Fe3+@Cd-CP. Moreover, the detection of the three aforementioned metal ions can be realized by using Cd-CP-coated test papers, extending the potential application regions of the reported material to point-of-care tests and environmental field studies.

Influence of pH on the structures of two Cd phosphonate compounds

Two novel Cd-based coordination polymers Cd(H2BCP)2(phen)2 1 and {[Cd6(BCP)4(phen)3]·2H2O}n 2 (Phen=1,10-phenanthroline) have been hydrothermally synthesized from a combination of 4-(phosphonomethyl) benzoic acid 4-HOOCC6H4CH2PO3H2 (H3BCP) and 1,10-phenanthroline. The X-ray crystal structure analyses revealed that 1 is a 0D mononuclear molecular structure and 2 is a 3D structure existing the novel Cd6 cluster unit. It is worth mentioning that 1 and 2 have the same constitutional units, namely the Cd ion, H3BCP ligand and second ligand- Phen. However, their structures are different and it results from the different solution pH value. In order to explore the structural characteristics, FTIR, photo-luminescent and solid UV-Vis spectra are employed. Synthesis and properties of two novel Cd-based coordination polymers Cd(H2BCP)2(phen)2 1 and {[Cd6(BCP)4(phen)3]·2H2O}n 2 are reported. It is worth mentioning that 1 is zero-dimensional structure and forms super-molecular layers via O–H···O under the condition of solution pH = 2.1, 2 is a three-dimensional framework and contains the novel Cd6 cluster unit under the condition of solution pH = 5. So controlling the pH of the solution plays an important role in the structure of the compound.

Triggering Lewis Acidic Nature through the Variation of Coordination Environment of Cd-Centers in 2D-Coordination Polymers.

The rational design and successful synthesis of novel functional metal-organic frameworks relies on careful selection of metals and versatile organic ligands. A newly designed pyrazole-based dicarboxylate ligand, 5-(3,5-dimethyl-1H-pyrazol-1-yl) 1,3-benzenedicarboxylic acid (H2L), was utilized to obtain two new Cd-based coordination polymers I [Cd(L)(H2O)]·H2O and II [Cd(L)] under similar reaction conditions via solvothermal strategy. Single-crystal X-ray data confirmed that compound I exhibits a two-dimensional (2D) skeleton comprising pentagonal bipyramidal Cd-ions and an organic ligand moiety. Compound II has also formed a two-dimensional layer arrangement with the connectivity between trigonal bipyramidal Cd-ions and the organic ligand. Topological analysis revealed that compound I has formed unique 43.63 net topology while compound II has displayed a 44.62 sql net topology with 2D frameworks. The Lewis acidic nature of both I and II containing a Cd2+ metal center has been correlated with the coordination number through dye adsorption-desorption and catalysis studies. The selective adsorption of anionic dye and the extent of adsorption are interrelated with the Cd-ion geometry. For the first time, the role of coordinated water molecule has been analyzed through heterogeneous catalysis reaction (i.e., cyanosilylation) with Cd-based 2D-coordination polymers (CPs). The plausible mechanisms have been proposed to explain the subsequent role of coordination number and environment in CPs.

Zn- and Cd-based coordination polymers with a novel anthracene dicarboxylate ligand for highly selective detection of hydrogen peroxide.

A one-dimensional {[Zn(L)(DMF)2]}n (1) and a three-dimensional {[Cd(L)(DMF)]·DMF}n (2) coordination polymer based on the novel anthracene derivative H2L (H2L = 4,4'-(9,10-anthracenediyl)dicinnamic acid) were obtained by solvothermal synthesis and charaterised by single-crystal and powder X-ray diffraction, thermogravimetry, and infrared spectroscopy. The anthracene derivative H2L and coordination polymers 1 and 2 were used to modify a glassy carbon electrode and as such served as an active material for detection of H2O2. Cyclic voltammograms in the potential range from 0 to -0.5 V revealed concentration-dependent cathodic current in all three cases with a lower detection limit of 200 μM. The electrode modified with compound 2 showed the best performance towards hydrogen peroxide detection. The results suggest that the development of electrodes modified with inorganic polymers based on highly conjugated ligands can serve as potential electrocatalytic materials.

Ladder chain Cd-based polymer as a highly effective adsorbent for removal of Congo red

Developing of high effective and fast-rate adsorbent materials has been recently attracted intensive attentions all over the world due to organic dye polluted water treatment. However, few studies have been reported on the ultrahigh-capacity and fast-rate removal of Congo red. In this work, a new stable Cd-based coordination polymer exhibits excellent adsorption performance towards Congo Red. This ladder chain [Cd4(H2L)4(H2O)8(NDS)]n·3n(NDS) (I) (H2L = N1,N2-bis(pyridin-3-ylmethyl) ethane-1,2-diamine, 1,5-H2NDS = 1,5-naphthalene disulfonic acid) has been successfully synthesized by the hydrothermal reaction. At room temperature, the experimental adsorption capacity of coordination polymer (I) towards Congo red can reach up to 16,880 mg g−1 in 20 min (pH = 2.0–3.2), and its higher capacity and faster rate are all better than those in reported inorganic and metal-organic frameworks absorbents. The adsorption process is spontaneous and endothermic reaction, and fits well with the second-order kinetics, Langmuir and Scatchard isotherm adsorption models. The excellent adsorption performance of (I) towards Congo red is related to the strong electrostatic, various hydrogen bonding and π-π stacking interactions under acidic conditions.

Anion-Induced Structural Diversity of Zn and Cd Coordination Polymers Based on Bis-9,10-(pyridine-4-yl)-anthracene, Their Luminescent Properties, and Highly Efficient Sensing of Nitro Derivatives and Herbicides.

Luminescent coordination polymers (CPs) of Zn2+ or Cd2+ and bis-9,10-(pyridine-4-yl)-anthracene (BA) show different 1D and 2D topologies depending on the anion used in the precursor. Compounds {[Zn(μ2-BA)(MeOH)2(p-Tos)2]} n (1) and {[Zn(μ2-BA)(MeOH)2(CF3CO2)2]} n (2) form linear structures and {BA@[Zn(μ2-BA)(MeOH)2(H2O)2](CF3SO3)2} n (3) featuring intercalation of uncoordinated BA molecules into linear ribbons. Cd-based CPs {[Cd(μ2-BA)2(ClO4)2]· n(DCM)} n (4) and {[Cd(μ2-BA)(MeOH)2(Dioxane)(η2-SiF6)]·mDioxane} n (5) form porous structures with 2D lattices. All complexes exhibit strong blue emission in the solid state with average lifetimes between 8 and 13 ns. The emission of compound 4 is sensitive to the presence of nitro aromatics, simazine, and trichloroanisole (TCA) and demonstrates nonlinear Stern-Volmer quenching kinetics. Limits of detection (LOD) of 15 and 16 ppb for picric acid and TCA were achieved, respectively.

An anionic Cd-based coordination polymer exhibiting ion-exchange behavior for photoluminescence and selective dye adsorption

Abstract A 2D anionic Cd-based coordination host was constructed from the linkage of the metal ions and 6-sulfonicotinic acid (SNA, in situ generated from the breaking of disulfide bond in 6,6’-dithiodinicotinic acid) whose interior spaces are occupied with cationic [(CH3)2NH2]+ guests. The compound exhibits an interesting ion-exchange behavior for both encapsulation of lanthanide (Ln) ions and organic dye. Through the fixation of Ln3+ within the host, the designed composite can be endowed with high photoluminescence property. Moreover, the free cations could be readily substituted by methylene blue (MB), with more than 90% of MB (10−5 M) being selectively absorbed after 12 h, making the title compound to be a great medium for dye adsorption and separation.

A new pillared-layer 3D coordination polymer involving in situ generated formate

A new Cd-based coordination polymer, [Cd(cpt)(HCOO)]n (1), has been synthesized from 1-(4-carboxyphenyl)-1,2,4-triazole) ligand (Hcpt). The structure was characterized through X-ray crystallography, elemental analysis, and IR spectrum. Compound 1 presents a three-dimensional (3D) pillared-layer structure constructed by metal-formate layers and cpt− ligands. Moreover, the unusual formate anions are generated in situ from the decomposition of DMF precursors. The fluorescence property of 1 in solid state was also researched.

Synthesis, structure and luminescence properties of a cadmium(ii)-based coordination polymer with (S)-4,4′-bis(4-carboxyphenyl)-2,2′-bis(diphenylphosphinoyl)-1,1′-binaphthyl as chiral linker

Solvothermal reaction of cadmium(II) nitrate with (S)-4,4'-bis(4-carboxyphenyl)-2,2'-bis(diphenylphosphinoyl)-1,1'-binaphthyl (H2L) in dimethylformamide (dmf) gave the two-dimensional chiral coordination polymer [{Cd2(L)2(H2O)}·18 dmf]n (1), which is thermally stable up to 400 °C according to DTA/TG analysis. According to single-crystal X-ray analysis, 1 forms layers in the [1[combining macron]01] direction, which are relatively well separated from each other. Compound L exhibits ligand-based bluish luminescence, assigned to the S1→S0 transition of the aromatic units in L. Emission spectra consist of nearly Gaussian shaped bands with maxima at 25,574 and 24,767 cm(-1) for H2L and 1, respectively. Quantum efficiency reaches a remarkably high value of 42% for the Cd-based coordination polymer and 33% for the respective ligand. Emission intensity of increases from 10 K to room temperature and decreases exponentially for temperatures up to 650 K.

A Three-Component 1D/2D → 2D Interpenetrated Coordination Network: Structure and Gas Adsorption Studies

We herein report a Cd-based coordination polymer containing three integrated polymeric components: two neutral and entangled two-dimensional (6,3) nets and one zwitterionic one-dimensional polymer with corner-sharing double-stranded chains propagating along the c-direction to lock the consecutive ligand struts of the (6,3) nets. Despite a sophisticated entanglement, this coordination polymer is porous to selectively adsorb CO2.