Cd Coordination Polymers Research Articles

Naphthalenedisulfonate-based Cd(II) CPs as fluorescent sensors for turn-on and red-shift sensing of tryptophan

Tryptophan (Trp) is one of the essential amino acids in human body, which is important for human health. Therefore, convenient strategies for the detection of Trp are very significant. Coordination polymers (CPs) have presented great importance as fluorescent sensors in recent years. Herein, two Cd(II) CPs were synthesized as fluorescent sensors for turn-on and red-shift sensing of tryptophan, namely, {[Cd(1,4-bbix)2(1,5-NDS)]·(H2O)2}n (1) and {[Cd(bmbp)2(H2O)2]·(1,5NDS)(H2O)4}n (2), (1,5-NDS = 1,5-naphthalenedisulfonate, 1,4-bbix = 1,4-bis(benzimidazol-1-yl-methyl)benzene, bmbp = 4,4′-bis(2-methylimidazole-1-yl-methyl)biphenyl). 1 shows a three-dimensional (3D) structure with 6-connected pcu topology. 2 shows a 1D chain, which is connected by hydrogen-bonds to form the 3D supramolecular structure. Both CPs can effectively detect Trp via fluorescence enhancement and red-shift in aqueous solution with the limits of detection being 1.11 μM and 0.69 μM for 1 and 2, respectively. Two CPs also can be applied for the detection of Trp in milk with good sensitivity. The sensing mechanisms toward Trp were investigated via experimental and theoretical calculation methods. The test films were prepared for the visual detection of Trp.

A stable 2D Cd (II) coordination polymer based on mixed ligands as a fluorescence sensor for detection of tetracycline antibiotic in milk and honey

An innovative two-dimensional Cd (II) coordination polymer, namely, [Cd(L)(dibp)] (CP 1) (dibp= 4,4′-di(1H-imidazol-1-yl)-1,1′-biphenyl; H2L= 5-(1-oxoisoindolin-2-yl)isophthalic acid), have been successfully synthesized under solvothermal condition and characterized by X-ray single crystal diffraction, PXRD, IR, TGA, elemental analysis and solid-state fluorescence analysis. Single-crystal X-ray structural analysis suggests that CP 1 crystallizes in monoclinic system with a space group of P21/c and displays a 2D layer based on centrosymmetric binuclear [Cd2(CO2)4N4] units. Sensing experiments have shown that CP 1, as an emerging fluorescent sensor, can selectively, sensitively and quickly detect Tetracycline antibiotic (TC) with fantastic reusability and low detection limit (LOD = 0.092 μM). At the same time, the fluorescence quenching mechanism of CP 1 may be the FRET and PET. Excitingly, CP 1 as a novel fluorescent sensor can detect TC in milk and honey with recovery rates of 96.8–101.2 % and 97.2–100.8 %, respectively.

Practicality and Compatibility of Cd(II) Coordination Polymer as Luminescent Sensor in Selective and Sensitive Detection of 3‐Nitrotyrosine Biomarker

AbstractBased on the mixed ligands of 1,4‐bis(2,4,6‐tricarboxylpyrid‐5‐yl)benzene (H6BTPB) and 1,4‐bis(imidazol‐1‐yl)benzene (bib), a new cadmium(II) coordination polymer with the molecular formula of {[Cd(bib)(μ2‐H2O)(H2O)2](H4BTPB)0.5(bib)0.5}n (CdCP) was constructed under solvothermal condition, and displayed a 3D supramolecular structure expanded by the hydrogen bonds between the 1D [Cd(bib)(μ2‐H2O)(H2O)2]n ladder chain and the guests. Profiting from its superior stability and inherent luminescence, the prepared CdCP dispalyed great potential as a highly sensitive and selective luminescent sensor in trace detection of 3‐NT biomarker in both water and real bodily fluids through the luminescence quenching effects, with the Ksv and LODs being 2.408×105 M−1 and 30.3 nM in water, 2.230×105 M−1 and 44.7 nM in diluted urine, 2.249×105 M−1 and 43.9 nM in diluted serum, respectively. Subsequent mechanism studies indicated the synergistic effect of internal filtering effect, photo‐induced electron transfer, and fluorescence resonance energy transfer determining the luminescence quenching response of CdCP towards 3‐NT biomarker.

A family of Cd(II) coordination polymers constructed from 6-aminopicolinate and bipyridyl co-linkers: study of their growth in paper and photoluminescence sensing of Fe3+ and Zn2+ ions.

In this work, we report on five novel coordination polymers (CPs) based on the linkage of the [Cd(6apic)2] building block [where 6apic = 6-aminopicolinate] by different bipyridine-type organic spacers, forming different coordination compounds with the following formulae: [Cd(μ-6apic)2]n (1), {[Cd(6apic)2(μ-bipy)]·H2O}n (2), {[Cd(6apic)2(μ-bpe)]·2H2O}n (3), [Cd(6apic)(μ-6apic)(μ-bpa)0.5]n (4) and {[Cd2(6apic)4(μ-tmbp)]·7H2O}n (5) [where bipy = 4,4'-bipyridine, bpe = 1,2-di(4-pyridyl)ethylene, bpa = 1,2-di(4-pyridyl)ethane (bpa) and tmbp = 1,3-di(4-pyridyl)propane]. Most of the synthesized compounds form infinite metal-organic rods through the linkage of the building block by the bipyridine-type linker, except in the case of compound 4 whose assembly forms a densely packed 3D architecture. All compounds were fully characterized and their photoluminescence properties were studied experimentally and computationally through density functional theory (DFT) calculations. All compounds display, upon UV excitation, a similar blue emission of variable intensity depending on the linker employed for the connection of the building units, among which compound 2 deserves to be highlighted for its room temperature phosphorescence (RTP) with an emission lifetime of 32 ms that extends to 79 ms at low temperature. These good photoluminescence properties, in addition to its stability in water over a wide pH range (between 2 and 10), motivated us to study compound 2 as a sensor for the detection of metal ions in water, and it showed high sensitivity to Fe3+ through a fluorescence turn-off mechanism and an unspecific turn-on response to Zn2+. Furthermore, the compound is processed as a paper-based analytical device (PAD) in which the phosphorescence emission is preserved, improving the sensing capacity toward Fe3+ ions.

New 1D Cd(II) coordination polymer based on L‒arginine ligand; Synthesis, X−ray structure, Hirshfeld analysis, DFT studies, and biological activity

The structural aspects of the newly synthesized 1D coordination polymer, [Cd(μ–L–Arg)(OSO3)(H2O)2]n with L−arginine (L−Arg) are presented. The Cd(II) is hepta−coordinated with one L‒Arg as a bridged bidentate ligand in addition to two water molecules and one sulphate group where both are monodentate ligands. The expansion of the coordination polymer along a–direction is occurred via two extra Cd–O bonds with the carboxylate group from another L−Arg in a neighboring complex unit. The significant interactions that controlled the molecular packing are O···H (52.8%) and H···H (32.2%) based on Hirshfeld topology analysis. The 1D polymeric structure of the Cd(II) is confirmed by the presence of obvious red spots in dnorm map related to the Cd−O coordinate bonds with the neighbouring molecule. The AIM investigation revealed that the Cd–O and Cd–N bonds have low covalent characters. The charge of Cd(II) is changed to 1.374 e as a consequence of complexation with the ligand groups. The orbital-orbital interactions included in the Cd–N and Cd–O bonds are analyzed using NBO calculations. The anticancer activity of the studied complex and L−Arg were screened versus human colorectal cell line (HCT−116). The results show that, the Cd(II) complex has better activity towards the tested cell line (IC50 = 166.15 ± 6.95 µg/mL) than its free ligand (IC50 = 224.42 ± 8.34 µg/mL). Also, the complex exhibits somewhat higher antibacterial activity compared with L‒Arg.

Synthesis, Structural Characterization and Hirshfeld Surface Analysis of a Novel Cd(II) Coordination Polymer with Mixed N- and O-donor Linker

Synthesis, Structural Characterization and Hirshfeld Surface Analysis of a Novel Cd(II) Coordination Polymer with Mixed N- and O-donor Linker

Metal complex hydrogel loaded with paclitaxel for photocatalytic and fluorescence-responsive drug control on ampullary carcinoma by modulation of HHLA2

Despite accounting for only 0.2 % of gastrointestinal malignancies, ampullary carcinoma is the second most common malignant tumor in the peripelvic area after pancreatic head cancer, highlighting the need for new drug delivery systems, as pancreaticoduodenectomy remains the primary treatment. In this study, we synthesized a novel Cd(II) coordination polymer (CP1), {[Me4N]2[Cd3(4,4′-bpdc)4]}n (4,4′-H2bpdc = 4,4′-biphenyldicarboxylic acid), under hydrothermal conditions using tetramethylammonium cations as templates. The photocatalytic performance of CP1 was investigated under UV light irradiation. Hyaluronic acid (HA) and carboxymethyl chitosan (CMCS) were chemically synthesized to retain the biocompatibility of natural polysaccharides, resulting in HA/CMCS hydrogels with a three-dimensional porous structure, as revealed by scanning electron microscopy. This structure makes the hydrogel an excellent drug carrier. We recombined CP1 and the drug paclitaxel (PTX) within the hydrogel, constructing a HA/CMCS-CP1@PTX nanodrug platform. This platform exhibited excellent drug-loading performance and allowed effective temperature control through light sources, enabling controlled release rates. In vitro cell tests demonstrated that the system promoted apoptosis by modulating the expression of apoptosis-related factors and HHLA2, thereby inhibiting the progression of ampullary carcinoma.

Three robust luminescent Cd(II) coordination polymers as multi-responsive fluorescent sensors for Cu2+, Hg2+, levofloxacin, and acetylacetone in water

Employing coordination polymers (CPs) developing effective organic contaminants and heavy metal ions luminescent detection systems is an ongoing challenge. Three ternary Cd(II) CPs namely [Cd(MIP)(L)0.5(H2O)]n (1), [Cd2(TPA)2(L)(H2O)]n (2), and [Cd2(DCTP)2(L)(H2O)]n (3), (L = 1,6-bis(2-((1H-imidazol-1-yl)methyl)-1H-benzo[d]imidazol-1-yl)hexane, H2MIP = 5-methylisophthalic acid, H2TPA = terephthalic acid, and H2DCTP = 2,5-dichloroterephthalic acid) containing new L ligands, were hydrothermally synthesized and characterized. 1 displays a (4,4)-connected 4,4L28 layer and further extended into the 3D supramolecular framework via π−π stacking interactions. 2 exhibits a (4,4,5)-connected trinodal network with the point symbol of {42.5.62.8}{42.52.72}{42.53.62.73}2. 3 takes on a (3,5,6)-connected framework with the point symbol {3.42.52.7}{3.82}2{33.44.5.62.82.92.10}2. 1 − 3 show highly good thermal stability, and highly acid-base tolerance. The limits of detection (LOD) of 1 − 3 were calculated as follows: for Cu2+, the LODs are 8.92 × 10−8, 5.74 × 10−7, and 9.37 × 10−8 mol L−1, respectively; for Hg²⁺, the LOD values are 3.73 × 10−7, 5.22 × 10−7, and 8.45 × 10−7 mol L−1, respectively. Regarding levofloxacin (LEV), the LODs for 1 − 3 were found to be 5.11 × 10−8 mol L−1, 2.45 × 10−8 mol L−1, and 8.54 × 10−8 mol L−1, respectively. Finally, for acetylacetone (acac), the LODs of 1 − 3 are 5.53 × 10−6, 5.66 × 10−6, and 1.23 × 10−6 mol L−1, respectively. 1 − 3 represent the first examples of exceptional multi-responsive sensing platforms for the detecting of Cu2+, Hg2+, LEV, and acac with high sensitivity, outstanding anti-interference abilities, and low LODs. The possible sensing mechanisms were investigated in detail.

Comparison of Electrical Conductivity and Schottky Behavior of 4‐[2‐(9‐anthryl)vinyl]pyridine Based Two 1D Coordination Polymers of Zn(II) and Cd(II)

AbstractWith the increase in demand of electronic devices in the modern civilization, research in material science is being projected to grow in faster rate. In this facet, coordination polymer (CP) based electronic device is one of the promising candidates to the material researchers. Herein, two new Zn(II) and Cd(II) based one‐dimensional (1D) CPs, denoted as [Zn(4‐avp)2(5‐nip)] ⋅ (solvent)x (1) and [Cd(4‐avp)(5‐nip)(CH3OH)] (2) have been synthesized using relatively less explored highly conjugated polycyclic aromatic hydrocarbon (PAH) based monodentate ligand, 4‐[2‐(9‐anthryl)vinyl]pyridine (4‐avp) and bidentate linker 5‐nitroisophthalic acid (H25‐nip). In this instance, the CP 1 creates 1D chain polymer, while CP 2 is made up with 1D ladder polymer. It is interesting to note that both the CPs exhibit semiconducting nature and generate metal‐semiconductor (MS) junction Schottky barrier diodes (SBDs). However, Cd‐based CP 2 shows higher charge transport as compared to Zn‐CP 1, which could be due to stronger π⋅⋅⋅π contacts as well as larger size of Cd metal in CP 2. The experimental results are well corroborated with theoretical density of states (DOS) calculations.

2D Cadmium(II) Coordination Polymer Based on 2,5-Furandicarboxylate and 1,4-Bis(1H-imidazol-1-yl)butane Linkers: Synthesis, Characterization and DFT Studies

As a result of hydrothermal synthesis of 2,5-furandicarboxylate (fdc2−), Cd(II) ion and bis(imidazole) derivative 1,4-bis(1H-imidazole-1-yl)butane (bib) ligand, a novel two-dimensional Cd(II) coordination polymer {[Cd(µ-fdc)(H2O)(µ-bib)]·H2O}n (1) was synthesized. According to the results of single crystal X-ray diffraction analysis, the complex was crystallized in the monoclinic system and in the P21/n space group. In addition, the thermal, luminescence and optical properties of the complex were investigated. The complex emits a maximum at 509 nm and also shows semi-conductor properties according to the solid-state UV–Vis diffuse reflection spectra results. To determine chemical structure, vibrational properties and some chemical properties of complex, theoretical calculations were carried out. All theoretical computations were performed using the DFT method at the B3LYP/LanL2DZ level of theory. The obtained experimental results were in good agreement with theoretical results. To calculate HOMO–LUMO energy values, which provided insights into the material's electronic properties, DFT calculations were used. Detailed information about the local and global chemical activity, as well as the electrophilic and nucleophilic nature of the complex, were also obtained.

An amino acid-functionalized coordination polymer of Cd(II) as a fluorescent probe detecting Cu(II) ion

Cd(II) complex 1, namely {[Cd(HL)]·CH3OH}n was design as a new fluorescence probe for measuring concentration of Cu2+ ion in aqueous solution. Complex 1 is a 3,6-connected double-layered porous metal–organic framework, which was synthesized by optimizing the ratio of Cd(OH)2 and a new ligand 4'-(((1-carboxyethyl)amino)methyl)-[1,1′-biphenyl]-3,5-dicarboxylic acid (H3L) under solvothermal conditions. It not only had good thermal and solvent stabilities, but also displayed a strong solid-state fluorescence centered at 375 nm with a moderate quantum yield of 37.12% under excitation at 275 nm. More importantly, its fluorescence could be obviously quenched by the addition of Cu2+ ion. The fluorescence quenching may be caused by the weak coordination interaction between Cu2+ and the uncoordinated imino N in ligand (HL)2–, as well as the slightly competitive absorption of excitation light by Cu2+. In the low concentration range of Cu2+ ion, the fluorescence quenching efficiency of complex 1 is closely related to the concentration of Cu2+ ion, and the relationship between fluorescence quenching efficiency and the concentration of added Cu2+ ion could be well fitted by Stern-Volmer equation with KSV being 1.589 × 104 M−1 and the detection limit for Cu2+ ion being 5.7 μM. Our case may provide potential applications for the detection of Cu2+ ion in daily domestic water.

A 3D coordination polymer of Cd(II) with conformationally flexible mixed ligands as an active filler for silicone elastomers

The electronic configuration of d10 metals enables for a wide range of coordination numbers and geometries which, together with the use of mixtures of ligands for their coordination, allows fine-tuning of the properties of the complexes formed. By treating Cd(ClO4)2 with 1,3-bis(carboxypropyl)tetramethyldisiloxane (H2Cx) and 4,4′-azopyridyne (AzPy) in solution, a 3D coordination polymer, [Cd(Cx)(AzPy)·1.85H2O]n (1), was mostly formed. The compound was investigated by elemental and spectral analysis, as well as by powder and single crystal X-ray diffraction. Thermal behavior of compound 1 was evaluated by TGA and DSC, while the moisture behavior was studied by dynamic vapor sorption (DVS) analysis. Compound 1 contains a five-dentate Cx2− ligand with Cd atoms in a pentagonal-bipyramidal geometry, as determined by X-ray analysis. The conformational flexibility of the ligands allows the establishment of all possible intermolecular interactions in a very dense packing, the resulting structure having an extremely low free volume (14.8%). The compound is hydrophobic, adsorbing up to 2.4 wt% water vapor, thermally stable up to 160 °C, and has a phase transition around 6 °C, which, based on analysis by polarized optical microscopy (POM), is considered as a second-order crystal-to-crystal transition, facilitated by the mobility of the siloxane fragment. Due to the constraints imposed by the covalent 3D architecture, the conformational photoisomerization of 1 is extremely limited, as indicated by UV–Vis spectroscopy studies on solutions with solvents of different polarities as well as dielectric spectroscopy studies on silicone composites in which it is in solid state with 5 and 20 wt% loading. Instead, it was found that compound 1 significantly increases the dielectric strength of the resulting materials (up to 46 V/μm compared to 18 V/μm in the empty matrix) by incorporating it as a filler, making them suitable for dielectric elastomer generators, as the results of theoretical calculations indicate. In the purification process, a 2D coordination polymer, [Cd(Cx)(AzPy)·H2Cx]n (2), was also identified in traces.

TADF Regulation by Tuning Keto‐Energy Levels, ISC/RISC Equilibrium in Coordination Polymers with Excited State Intramolecular Proton Transfer (ESIPT)

AbstractThermally activated delayed fluorescence (TADF) and long persistent luminescence (LPL) are emerging photophysical hotspots, which involve the singlet/triplet excited states and two‐way energy transfer processes between them via intersystem crossing (ISC) or reverse intersystem crossing (RISC). Herein, a new tactic is reported for the regulation of keto‐energy levels and ISC/RISC equilibrium via the introduction of electron‐withdrawing fluorine in a series of excited state intramolecular proton transfer (ESIPT) ligands and corresponding Cd(II) coordination polymers. Among them, the fluorine p‐substituted to the hydroxy group along the nodal plane on the phenol site improves the thermodynamic stability of the keto‐isomers of the ligand, thereby lowering the keto‐energy level and promoting the ESIPT process effectively. Uniquely, the lower‐energy keto excited state makes the ISC/RISC equilibrium shift to the direction of RISC progress, and thus arousing efficient TADF in the constructed coordination polymer. A comprehensive transient photophysical and theoretical study verifies the greatly promoted RISC progress, rather than suppressed ISC is aroused in the p‐substituted system, suggesting a clear‐cut strategy in the design of coordination polymers with good TADF performance.

Two Zn(II)/Cd(II) coordination polymers based on 5-(3,5-dicarboxybenzyloxy)isophthalic acid for selective detection 4-nitrophenol and fluazinam in aqueous medium

Two new Zn(II)/Cd(II) coordination polymers, namely, {[Zn2(L)(CAS)]·H2O}n (1) and {[Cd2(L)(CAS)]·DMF·H2O}n (2) [H4L = 5-(3,5-dicarboxybenzyloxy)isophthalic acid, CAS = 1,2,4,5-tetra(4-pyridyl)benzene] were synthesized by solvothermal method and characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis and powder X-ray diffraction. In complex 1, CAS and Zn(II) are interconnected to form a 2D diamond structure. The 2D layers are interlinked by L4− ligands to generate a 3D network structure. The L4− ligands, CAS and Cd(II) in complex 2 are cross-linked to form a 2D planar structure. The 3D structure is formed by coordination bonds between the two layers. Complexes 1 and 2 could detect p-nitrophenol (4-NP) by fluorescence quenching, and the detection limits were 0.344 and 0.554 μM, respectively. Complex 1 can also be used for sensitive and selective detection of fluazinam (FLU) by fluorescence quenching with the detection limit of 0.185 μM. Additionally, the fluorescence quenching mechanism was also investigated. These new Zn(II)/Cd(II) coordination polymers could be used as dual-functional sensors on NACs and pesticides.

Synthesis, Structural Characterization and Hirshfeld Surface Analysis of a Novel Cd(II) Coordination Polymer with Mixed N- and O-donor Linker

In the present study, we report the room temperature synthesis of a novel two-dimensional (2D) coordination polymer (CP) having the formula {[Cd(H-PCA)2(H2O)].0.5(H2O).0.5(CH3OH)}n (CP1), where H-PCA represents 4-pyrazolecarboxylate. The synthesis of CP1 was achieved through a one-pot reaction, involving the self-assembly of Cd(OAc)2·2H2O and the multitopic mixed N- and O-donor ligand, 4-pyrazolecarboxylic acid (H2-PCA), in methanol. This method demonstrated high yield and purity, enabling the facile production of multigram quantities of CP1 within a short timeframe. Notably, the synthetic procedure selectively deprotonates the carboxylic acid group while retaining the pyrazole moiety in its protonated form.CP1 has been thoroughly characterized using various analytical techniques, including single-crystal X-ray diffraction, FTIR spectroscopy, elemental analysis, scanning electron microscopy, thermogravimetric analysis, and powder X-ray diffraction. The structural analysis revealed that CP1 features a 3, 5-connected binodal net with the point symbol {4.5.6}{4.55.63.7}, leading to a unique –ths net topology. Through hydrogen bonding connections between adjacent 2D sheets, CP1 further extends into a three-dimensional (3D) supramolecular network due to the presence of coordinated water molecules and the protonated pyrazole group. Additionally, a 3D Hirshfeld Surface analysis accompanied by quantitative 2D fingerprint plots was also investigated to explore the intermolecular interactions.

Cd(ii) coordination polymers constructed from tris-pyridyl-tris-amide and polycarboxylic acid: synthesis, structures and sensing properties

Reactions of a C3-symmetrical ligand and Cd(ii) salts with various polycarboxylic acids afforded three new coordination polymers, demonstrating that the length and shape of the polycarboxylate ligands govern the structural diversity.

Photomechanical responses of coordination polymers regulated by precise organization of the photoactive centers.

Three photoactive Cd(II) coordination polymers (CPs), [Cd (Fsbpe)(DBBA)2]·2DMF (CP1), [Cd(Fepbpe)(DBBA)2]·2DMF (CP2) and [Cd(Fsbpeb)(DBBA)2] (CP3) (DBBA = 3,5-dibromobenzoic acid, DMF = dimethyl formamide) with similar 1D chain motifs exhibited completely different photosalient behaviors (PS) in response to UV light. Mechanical motion was triggered by [2+2] photocycloaddition and regulated by positioning of the photoactive alkene centers relative to the crystal axis. This solid-state reaction was reversed by heating and photomechanical behaviour was repeated over several cycles. A simple photoactuating device was prepared using a CP3-PVA composite.

Engineering of CdS-chain arrays assembled through S⋯S interactions in 1D semiconductive coordination polymers.

One-dimensional (1D) Cd(II) coordination polymers [Cd(x-SPhOMe)2]n (x = ortho, meta, and para; HSPhOMe = methoxybenzenethiol) containing inorganic 1D (-Cd-S-)n chains were synthesized. Among these, the KGF-31 polymer bearing para-SPhOMe featured a three-strand chain structure assembled via interchain S⋯S interactions and exhibited high photoconductivity and longevity.

Effects of the recognition sites of MOFs on turn-off fluorescence detection of Fe3+

Two Cd(ii) coordination polymers are designed to investigate the effect of recognition sites on turn off fluorescence detection of Fe3+.

A new Cd(ii)-based coordination polymer as a luminescent sensor and adsorbent for dichromate ions

A new 3,5-bis(1-imidazol)pyridine-appended Cd(ii) coordination polymer was synthesized and used as a luminescent sensor and adsorbent for dichromate ions.