Selective Detection Of Cd2 Research Articles

An effective procedure used metal–organic framework for determination of cadmium ions in real tap water and human blood plasma samples

A newly developed 2H5MA-MOF sensor by covalently linking NH2-MIL-53(Al) with 2′-Hydroxy-5′-methylacetophenon, designed for highly sensitive and selective detection of Cd2+ ions using fluorometric methods. Detailed structural and morphological analyses confirmed the sensor’s unique properties. It demonstrated an impressive linear detection range from 0 to 2 ppm, with an exceptionally low detection limit of 5.77 × 10−2 ppm and a quantification limit of 1.75 × 10−1 ppm, indicating its high sensitivity (R2 = 0.9996). The sensor also responded quickly, detecting Cd2+ within just 30 s at pH 4. We successfully tested it on real samples of tap water and human blood plasma, achieving recovery rates between 96 % and 104 %. The accuracy of these findings was further validated by comparison with ICP-OES. Overall, the 2H5MA-MOF sensor shows great potential for fast, ultra-sensitive, and reliable detection of Cd2+ ions, making it a promising tool for environmental and biomedical applications.

A 3D photoluminescent Eu(iii)-MOF sensor supported by a tetracarboxylate ligand for the sensitive and selective detection of Cd2+ and o-nitrophenol

A novel 3D luminescent metal–organic framework (MOF) denoted as [Eu(BTA)0.5(H2BTA)0.5(H2O)]n (Cj-2) has been constructed from a π-conjugated ligand with a tetracarboxylate group, 1,2,4,5-benzenetetracarboxylic acid (BTA), via solvothermal synthesis.

Label-free and sensitive determination of toxic Cd(II) in environmental waters using a Fe3O4-PEI-Au based electrochemical aptasensor

A novel electrochemical strategy was presented using gold nanoparticles decorated on polyethyleneimine-modified iron oxide nanoparticles (Fe3O4-PEI-Au) as a nanocomposite modifier for sensitive and selective detection of Cd(II). The aptasensor was fabricated by immobilizing a thiol-terminated Cd(II) aptamer onto a screen-printed carbon electrode modified with the Fe3O4-PEI-Au nanocomposite. This nanocomposite provided high surface area for enhanced aptamer loading, excellent biocompatibility, and good conductivity to promote the signal amplification at the sensing interface. Differential pulse voltammetry was used for quantitative measurement of Cd(II), demonstrating a dynamic linear detection range from 0.04 nM to 25 nM. The limit of detection was found to be 0.01 nM, which is lower than the safe limit in drinking water defined by the U.S. Environmental Protection Agency. The label-free aptasensor showed high selectivity, reproducibility, stability and reliability for real-time Cd(II) monitoring in environmental water samples. This work successfully demonstrates the development of a novel electrochemical aptasensor utilizing a Fe3O4-PEI-Au nanocomposite modifier for sensitive and selective detection of trace levels of Cd(II) in water resources.

Competitive fluorescence assay for Cd2+ based on aptamer structure-switching

Cadmium ion (Cd2+) is a heavy metal pollutant that causes serious effects on human health. Development of a simple and specific Cd2+ detection method is of great significance in food safety and environmental monitoring. In this work, we demonstrated a fluorescence assay for Cd2+ based on aptamer structure-switching. A short 17-mer aptamer against Cd2+ with fluorescein (FAM) labeled at the 5′ end was used as an affinity ligand, and a partially complementary DNA (cDNA) with black hole quencher 1 (BHQ1) labeled at the 3′ end was used as quencher. In the absence of Cd2+, the aptamer hybridized with the cDNA, forming a duplex helix structure that showed low fluorescence intensity as FAM was quenched by adjacent BHQ1. In the presence of Cd2+, the aptamer specially bound to Cd2+, and the FAM-labeled aptamer dissociated from the aptamer-cDNA duplex, showing high fluorescence intensity. We examined the effects of different lengths of cDNA, the composition of binding buffer, incubation time, and incubation temperature on the performance of the sensing system. Under the optimal experimental conditions, we achieved sensitive and selective detection of Cd2+ with a detection limit of 2.4 nM by using the 17-mer aptamer and 13-mer cDNA. The FAM-labeled aptamer exhibited a large fluorescence increase upon Cd2+, with a maximum change about 51.6-fold. The developed assay also showed good responses to Cd2+ in actual water samples, showing the potential for practical application.

Copper oxide nanocomposite particles supported on sodium alginate-g-polyallylamine based reduced graphene oxide: An efficient electrochemical sensor for sensitive detection of cadmium ions in water

A highly sensitive and selective electrochemical sensor, sodium alginate-g-polyallylamine/reducedgrapheneoxide/CuO nanocomposite particles (SAGPMRGO@CuO NPs) has been synthesized for the detection of Cd2+ ions in the aqueous environment. The graft copolymer/reduced graphene oxide supported CuO nanocomposite particles are prepared through bioreduction of graphene oxide by a novel synthesized graft copolymer sodium alginate-g-PAAM (SAG-g-PAAM) to reduced graphene oxide (SAGPMRGO) followed by using it as both a reductant and a stabilizing agent to obtain SAGPMRGO@CuO hybrid nanocomposite particles. The graft copolymer is prepared via free radical solution phase graft copolymerization technique. The graphene oxide (GO) is prepared by the oxidation of graphite using modified Hummer's method. The prepared nanocomposite particles are characterized by UV-VIS, FTIR and Raman spectroscopy, powder X-ray diffraction (PXRD), HRTEM-EDS, FESEM, XPS and DLS analysis with zeta potential measurement in colloidal suspension. The prepared graft copolymer is characterized by 1H and 13C NMR spectroscopy, PXRD and FESEM analysis and the SAMPGRGO is characterized by UV-VIS and Raman spectroscopy, PXRD and FESEM analysis. The CuO nanocomposite particles are spindle shaped with an average particle size ranges from 15.6 nm to 32.1 nm and are well polydispersed. Metal ion (Cd2+) sensing is carried out by cyclic voltammetry (CV) and chronoamperometry (CA) analysis under optimum conditions. The limit of detection (LOD) and limit of quantitation (LOQ) is found to be 1.27 nM and 4.24 nM respectively which is lower than some other reported works. The reproducibility and stability properties of the developed sensor are examined where the results are found to be satisfactory. The selective detection of Cd2+ ions in a river water sample is also evaluated with an excellent performance.

Selective detection of Cd (II) and Cr (VI) ions using rGO functionalized metal doped SnO2 nanocomposites

This research gives a valuable insight for understanding the effect of doping on morphology and rGO functionalization on electrochemical sensing. Firstly, hydrothermal method was used to synthesize pure SnO2, cobalt (Co) doped and iron (Fe) doped SnO2 nanocomposites. Doping of Co/Fe into SnO2, gradually attract spherical nanoparticles together to form a three-dimension cube-like structure. Considering the potential of these morphological changes, their heavy metal ions (HMIs) sensing properties have been further investigated. The results revealed that the type of dopants (Co/Fe) and their morphologies have a significant impact on the HMIs sensing performance. 1 wt% doping of Co and Fe into SnO2 shows highest selectivity (∼2.3 – 8.4 (Co doping); ∼2–13 (Fe doping)) and sensitivity (∼1.4 µA/ppb (Co doping); ∼2.6 µA/ppb (Fe doping)) toward cadmium (Cd (II)) and chromium (Cr (VI)) ions respectively as compared to other HMIs. Furthermore, reduced graphene oxide (rGO) functionalized Co doped and Fe doped SnO2 nanocomposites were synthesized using ultrasonication method. The rGO functionalized metal doped nanocomposites improve HMIs sensing performance than pure and metal doped SnO2 nanocomposites. According to electrochemical studies, the synthesis of nanocomposites with strong electrocatalytic activity and enhanced active surface area is primarily responsible for improved sensor response.

Simple, universal colorimetric strategy for amplified detection of nanomolar toxic heavy metal ions based on multi-component complexation and Tyndall effect

This work describes a new class of universal nanoprobe-free colorimetric assay with Tyndall effect (TE) signaling for amplified detection of nanomolar heavy metal ions based on analyte-triggered multi-component complexation. In the presence of NH2OH·HCl, Cu2+ (model analyte) is reduced to Cu+ which in turn reacts with KSCN and CHClN2O3 to form colloidal three-component complexation particles unexpectedly producing an enhanced TE signal with the aid of a 635 nm laser pointer. The results show that the developed method could detect Cu2+ in a linear concentration range of 156 nM ∼ 120 µM with a limit of detection (LOD) of ∼38 nM (3σ) using a smartphone for quantitative readout. The generality of the new equipment-free strategy was demonstrated well with selective detection of Cd2+ as the second model analyte with a LOD down to ∼1.27 nM where KI and CHClN2O3 were adopted as the three-component complexation reagents. In addition, satisfying recovery results obtained from analysis of Cu2+ and Cd2+ in several polluted real water samples ranged from 93.1% to 104.67% and 93.21–101.85%, respectively. To the best of our knowledge, this may be the first report of nanoprobe-free TE-based colorimetric assay based on multi-component complexation.

Highly stable fluorescent probe based on mesoporous silica coated quantum dots for sensitive and selective detection of Cd2+

Cadmium ions have been of crucial concern due to the high biological toxicity and serious environmental risks. Various fluorescent Cd-sensitive probes have been reported with improved sensing properties, but still severely suffer from poor stability and insufficient selectivity. In this work, a stable fluorescent probe based on silica encapsulated quantum dots (QDs) have been developed for rapid, sensitive and selective detection of cadmium ion. To improve fluorescence stability, the strategy of mesoporous silica encapsulation was adopted, in which the mesoporous silica shell offers numerous channels for Cd2+. Further, the Forster Resonance Energy Transfer (FRET) system, where QDs@mSiO2 and rhodamine B (RB) are used as donors and acceptors respectively, has been constructed, in which the mesoporous silica shell also serves as spacers with tunable thickness for controlling the QD-RB distance. Under optimal conditions, the probes possess a sensitive fluorescence response with a detection limit of 1.25 μM. Visual detection can be realized by the obvious fluorescence changes of the FRET system. In addition, the FRET system shows promising sensing performances both in tap water samples and rice-washed water samples, confirming a great potential for practical application.

Probing How Various Metal Ions Interact with the Surface of QDs: Implication of the Interaction Event on the Photophysics of QDs.

With an aim to understand the mechanism of interaction between quantum dots (QDs) and various metal ions, fluorescence response of less-toxic and water-soluble glutathione-capped Zn-Ag-In-S (GSH@ZAIS) QDs in the presence of different metal ions has been investigated at both ensemble and single-molecule level. Fourier transform infrared (FT-IR) spectroscopy has also been performed to obtain a molecular level understanding of the interaction event. The steady-state data reveal no significant change in QD emission for alkali and alkaline earth metal ions, while there is a decrease in fluorescence intensity for transition metal (TM) and some heavy transition metal (HTM) ions. Interestingly, a significant fluorescent enhancement (FE) (19-96%) of QDs is found for Cd2+ ions. Time-resolved fluorescence studies reveal that all the three decay components of QDs decrease in the presence of first-row TM ions. However, in the case of Cd2+, the shorter component is found to increase while the longer one decreases. The analysis of data reveals that photoinduced electron transfer is responsible for fluorescence quenching of QDs in the presence of first-row TM ions and destruction/removal of trap/defect states in the case of Cd2+ causes the FE. In FT-IR experiments, a prominent peak at 670 cm-1, corresponding to Cd-S stretching vibrations, indicates strong ground-state interactions between the -SH of GSH and Cd2+ ions. Moreover, a decrease in the diffusion coefficient of QDs in the presence of Cd2+ ions during fluorescence correlation spectroscopy (FCS) studies further substantiates the removal of GSH by Cd2+ from the surface of QDs. The optical output of this study demonstrates that ZAIS can be used for fluorescence signaling of various metal ions and in particular selective detection of Cd2+. More importantly, these results also suggest that Cd2+ can effectively be used for enhancing the fluorescence quantum yield of thiol-capped QDs such as GSH@ZAIS.

Ultrasensitive detection of cadmium ions using a microcantilever-based piezoresistive sensor for groundwater.

This paper proposes the selective and ultrasensitive detection of Cd(II) ions using a cysteamine-functionalized microcantilever-based sensor with cross-linked ᴅʟ-glyceraldehyde (DL-GC). The detection time for various laboratory-based techniques is generally 12–24 hours. The experiments were performed to create self-assembled monolayers (SAMs) of cysteamine cross-linked with ᴅʟ-glyceraldehyde on the microcantilever surface to selectively capture the targeted Cd(II). The proposed portable microfluidic platform is able to achieve the detection in 20–23 min with a limit of detection (LOD) of 0.56 ng (2.78 pM), which perfectly describes its excellent performance over other reported techniques. Many researchers used nanoparticle-based sensors for the detection of heavy metal ions, but daily increasing usage and commercialization of nanoparticles are rapidly expanding their deleterious effect on human health and the environment. The proposed technique uses a blend of thin-film and microcantilever (micro-electromechanical systems) technology, which mitigate the disadvantages of the nanoparticle approaches, for the selective detection of Cd(II) with a LOD below the WHO limit of 3 μg/L.

PH-controlled preferential binding of cucurbit[7]uril-coated iron-oxide nanoparticles to 6-mercaptonicotinic acid for fluorescent detection of cadmium ions in the solid state.

A host-guest complex of 6-mercaptonicotinic acid (MNA) and cucurbit[7]uril (CB7) was prepared and conjugated to γ-Fe3O4 nanoparticles (NPs) to detect toxic cadmium ions in water as a solid-state sensor. The formation of an inclusion host-guest complex with CB7 was confirmed by UV-vis absorption and proton NMR spectroscopy. CB7 preferentially binds the protonated MNA form compared to the neutral form, demonstrated by a binding constant for the protonated form that is four orders of magnitude higher than that ofthe neutral form. An increase in the pKa of MNA by 1.2units was demonstrated after the addition of CB7, which further supports preferential binding between MNA and CB7. The NMR results confirm binding to cadmium via the carboxylic acid moiety. Stationary and time-resolved fluorescence results, in solution and in the solid state, indicate that cadmium and CB7 cause a blue shift in the MNA emission bands and extend its excited-state lifetime due to dissociation of the MNA dimer. In the solid state, switching the emission signals between Cd2+-MNA/CB7NPs (ON state) and MNAH+/CB7NPs (OFF state) was achieved by controlling the pH. An efficient, regenerable, and stable sensor device was fabricated for sensitive and selective detection of Cd2+ in contaminated water samples. Graphical abstract Regeneration of MNA/CB7 nanoparticles for the detection of cadmium ions in the solid state by a visible blue emission signal upon suppression of photoinduced electron transfer (PET).

Synthesis of 9-ethyl-3-isothiacyanato carbazole for turn on fluorescence for rapid and selective detection of Cd2+ in aqueous system

A remarkable instantaneous visual change from colorless to faint blue coloration is observed selectively for cadmium cation (Cd2+) using a simple carbazole derivative 9-ethyl-3-isothiocyanatocarbazole (CIT) in aqueous medium in presence of other heavy transition metal ions. Chemical characterization of synthesized 9-ethyl-3-isothiocyanatocarbazole is fully performed by FT-IR, 1H NMR, 13C NMR and single crystal XRD. The theoretical result and experimental values were found to be satisfactorily support each other. From the HOMO-LUMO energy calculation and different thermodynamic parameter, chemical activity and kinetic stability of the molecule has been established by studying density functional theory (DFT). No significant changes found in fluorescence intensity for CIT with varying temperature and pH in medium. The addition of Cd2+ ion in CIT solution exhibits a significant enhancement in fluorescence intensity at 482 nm (ФF = 0.16) and the colour changes instantaneously within a few second. The stoichiometric ratio of the sensing moiety formed in situ was found to be 2:1 from Job's plot and shows the presence of stable Chelation Enhanced Fluorescence (CHEF) mechanism. The average life time of the stable combined CIT with Cd2+ moiety is remarkably higher by 3.29 ns than the native ligand and with other metals. The detection limit is 0.95 μM (S/N = 2). Thus, reported carbazole derivative has excellent promptness, sensitivity and selectivity for the detection of Cd2+ ion in water medium.

Capillary electrophoretic determination of heavy-metal ions using 11-mercaptoundecanoic acid and 6-mercapto-1-hexanol co-functionalized gold nanoparticle as colorimetric probe

Capillary electrophoresis (CE) and gold nanoparticle aggregation based-colorimetric detection (AuNP/ABCD) were incorporated to provide rapid, sensitive and selective detection of Cd2+, Pb2+, and Hg2+. CE and AuNP/ABCD were interfaced by a pressurized electric field decoupler to isolate the colorimetric reaction solution from the separation voltage. The AuNPs co-functionalized with 11-mercaptoundecanoic acid (MUA) and 6-mercapto-1-hexanol (MCH) were used as colorimetric probes, which provided enhanced sensitivity and good selectivity toward the heavy-metal ions. Under optimal conditions, good linearities were obtained for the analytes, and the detection limits for Cd2+, Pb2+, and Hg2+ were 0.214, 0.150, and 0.0214 μg/mL, respectively. The method was successfully applied to cosmetic samples, with recoveries of 87.8% to 103% for the heavy-metal ions spiked. Our results suggested the great potential of the CE-AuNP/ABCD strategy in determining heavy-metal ions in complicated matrices.

Trace Level Recognition of Zn2+ and Cd2+ by Biocompatible Chemosensor inside Androecium, Diagnosis of Pick's Disease from Urine and Biomimetic β-Cell Exocytosis.

Two chemosensors with varying substitution have been synthesized for selective detection of d10 metal ion analyte Zn2+ and Cd2+ by fluorometric method from aqueous medium at very low limit of detection. Density functional theory (DFT)-based Loewdin spin population analysis reveals that methoxy-substituted chemosensor is much stronger donor than bromo-substituted chemosensor. Eventually, bromo and methoxy substituted chemosensors are moderate and strong donor, respectively, toward selective detection of Cd2+ and Zn2+ by luminescence induced phenomenon (blue for Cd2+ and cyan for Zn2+). The mechanism of sensing could be explained by PET-CHEF-C = N isomerization-ILCT pathway. 1H NMR, ESI-MS and FT-IR has been carried out in order to explore the selective ion sensing mechanism. Intracellular detection of Zn2+ and Cd2+ has been carried out inside androecium (filament and pollens) of Tecoma Stans. Extracellular detection of Zn2+ for yeast cells represents the bio mimetic model experiments toward β-cells exocytosis as a marker of diabetes mellitus. The unprecedented and novel feature of the present biocompatible chemosensor is its application as biosensor to detect in vivo Zn2+ from human urine specimen which could be a next generation diagnostic tool for Pick's disease.

Electrogenerated chemiluminescence behavior of Tb complex and its application in sensitive sensing Cd2+

In this paper, we report a novel rare earth metal complex with the weak ligand of aromatic sulphonic acid (pyridine-3-sulfonic acid, 3-pSO3H), and characterized by FT-IR, UV–vis, energy-dispersive X-ray spectroscopy (EDX), electrochemiluminescence spectra, etc. Then an excellent electrochemiluminescence (ECL) signal was observed with K2S2O8 as the coreactant in NaAc-HAc buffer solution. For another thing, the electrochemical properties of the compound have been thoroughly investigated in acetonitrile solution, the possible ECL reaction mechanism was proposed as well. Furthermore, a simple and straightforward ECL platform was reported for sensitive and selective detection of Cd2+ due to the effective quenching after addition of Cd2+. Other heavy/transition metal ions do not interfere with the sensing. The limit of detection is determined as 0.13nM, the results suggested that as-prepared complex could be a promising material for developing ECL senors to detect the Cd2+ rapidly indwell in environmental and practical samples.

Liquid Crystal Biosensor Based on Cd<sup>2+</sup> Inducing the Bending of PS-Oligo for the Detection of Cadmium

In this study, a novel liquid crystal (LC) biosensor was developed for the highly sensitive and selective detection of Cd2+ based on Cd2+ inducing the bending of PS-oligo. This strategy makes use of the DNA conformational change to enhance the disruption of orientation of LC leading to an amplified optical signal. DNA containing-SH was bound on the glass slide of the LC cell modified with the DMOAP/APTES. The DMOAP can effectively induce the homeotropic alignment of LC. In the presence of Cd2+, Cd2+ can induce DNA to bend and become a 2 nm spherical structure, which can greatly disrupt the orientational arrangement of LC, resulting in the correspond changes of the optical image of LC cell birefringent under the polarizing microscope. When the Cd2+ concentration is low to 0.1 nM, the optical signal of LC biosensor has an obvious change. But in the absence of Cd2+, there is no orientational response of LC and the optical image under the polarizing microscope is still a uniform dark background. Thus, this LC sensing method has a sensitive and clear distinction between positive and negative results and offers a highly sensitive detection of Cd2+ with a low detection limit down to 0.1 nM.

Ligand displacement-induced fluorescence switch of quantum dots for ultrasensitive detection of cadmium ions

This paper reports the construction of a simple CdTe quantum dots (QDs)-based sensor with 1,10-phenanthroline (Phen) as ligand, and the demonstration of a novel ligand displacement-induced fluorescence switch strategy for sensitive and selective detection of Cd2+ in aqueous phase. The complexation of Phen at the surface quenches the green photoluminescence (PL) of QDs dominated by a photoinduced hole transfer (PHT) mechanism. In the presence of Cd2+, the Phen ligands are readily detached from the surface of CdTe QDs, forming [Cd(Phen)2(H2O)2]2+ in solution, and as a consequence the PL of CdTe QDs switches on. The detection limit for Cd2+ is defined as ∼0.01nM, which is far below the maximum Cd2+ residue limit of drinking water allowed by the U.S. Environmental Protection Agency (EPA). Two consecutive linear ranges allow a wide determination of Cd2+ from 0.02nM to 0.6μM. Importantly, this CdTe QDs-based sensor features to distinctly discriminate between Cd2+ and Zn2+, and succeeds in real water samples. This extremely simple strategy reported here represents an attempt for the development of fluorescent sensors for ultrasensitive chemo/biodetection.

Simple naphthalimide-based fluorescent sensor for highly sensitive and selective detection of Cd2+and Cu2+in aqueous solution and living cells

A novel naphthalimide-based fluorescent sensor bearing the N,N'-bis(salicylidene)diethylenetriamine receptor was developed, which exhibited dual signaling behaviors for Cd(2+) and Cu(2+), and was applicable to the environmental and biological milieus. Upon addition of Cd(2+), the fluorescence intensity enhanced in a linear fashion with the maximum fluorescence intensity increase of about 4-fold. Moreover, with the sensor 1 and 1-Cd(2+) complex, Cu(2+) was easily recognized by marked fluorescence quenching. The selectivity and sensitivity of the sensor 1 for Cd(2+) were satisfactory and achieving a detection limit at the nanomolar level. The living cell image experiments demonstrated the value of sensor 1 in fluorescent visualization of Cd(2+) ions in biological systems.

Colorimetric detection of Cd2+ using gold nanoparticles cofunctionalized with 6-mercaptonicotinic acid and l-Cysteine

We have developed a colorimetric assay for the highly sensitive and selective detection of Cd(2+) using gold nanoparticles (AuNPs) cofunctionalized with 6-mercaptonicotinic acid (MNA) and L-Cysteine (L-Cys) through the formation of an Au-S bond. In the presence of Cd(2+), the aggregation of functionalized AuNPs occurred by means of a metal-ligand interaction that led to visible color changes. Most importantly, cofunctionalized AuNPs had better responses for Cd(2+) than that functionalized by either MNA or L-Cys. Cd(2+) could be detected by the colorimetric response of AuNPs that could be detected by the naked eye or a UV-vis spectrophotometer. The absorbance ratio (A(620)/A(523)) was linear with the Cd(2+) concentration in the range of 2.0 × 10(-7) to 1.7 × 10(-6) M. Under optimum conditions (2.0 × 10(-5) M MNA, 2.0 × 10(-6) M L-Cys and 0.020 M NaCl at pH 10.0), the detection limit (3σ) of Cd(2+) could be as low as 1.0 × 10(-7) M. Interference experiments showed that Pb(2+) and Cu(2+) caused a slight interference for Cd(2+) determination while other metal ions caused no interference. The proposed method was successfully applied to determine the concentration of Cd(2+) in environmental samples (lake water).

Chemically Converted Graphene Induced Molecular Flattening of 5,10,15,20-Tetrakis(1-methyl-4-pyridinio)porphyrin and Its Application for Optical Detection of Cadmium(II) Ions

Complexation of cationic 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin (TMPyP) and negatively charged chemically converted graphene (CCG) sheets was performed by simply mixing the diluted aqueous solutions of both components. During this process, a large bathochromic shift of porphyrin Soret band from 421 to 458 nm was observed, which is attributed to the flattening of TMPyP molecules induced by CCG through electrostatic and pi-pi stacking cooperative interactions. Furthermore, the coordination reaction between TMPyP and Cd(2+) ions was greatly accelerated from 20 h to 8 min under ambient conditions by introducing CCG sheets. On the basis of this phenomenon, we used the complex of TMPyP and CCG as an optical probe for rapid and selective detection of Cd(2+) ions in aqueous media.