HgII Ions Research Articles

Ultrasound-assisted synthesis of a Eu3+-functionalized ZnII coordination polymer as a fluorescent dual detection probe for highly sensitive recognition of HgII and L-Cys

A new ZnII coordination polymer (CP) based on 2,3-pyrazine dicarboxylic acid (H2pzdc) and 4,4′-bipyridine (bpy) (ZCP) was synthesized using a facile slow evaporation method. Single-crystal X-ray diffraction revealed that ZCP is a two-dimensional porous CP, [Zn2(pzdc)2(bpy)(H2O)2] n , with van der Waals forces as the dominant interaction within its layers forming a 63 network. Employing energetic ultrasound irradiation, nanoscale ZCP (nZCP) was successfully synthesized and Eu3+ ions were incorporated within its host lattice (Eu@nZCP). The resulting platform exhibits superior fluorescence characteristics and demonstrates notable optical durability. Therefore, it was used as a dual detection fluorescent sensing platform for the detection of mercury and L-cysteine (L-Cys) in aqueous media through a turn-off/on strategy. In the turn-off process, the fluorescence emission of Eu@nZCP progressively quenches by the addition of HgII via a photo-induced electron transfer (PET) mechanism. The fluorescence of Eu@nZCP is quenched to establish a low fluorescence background through the incorporation of HgII. This devised turn-on fluorescent system is suitable for the recognition of L-Cys (based on the strong affinity of L-Cys to the HgII ion) through a quencher detachment mechanism. This method attained a relatively wide linear range, spanning from 0.001 to 25 µM, with the low detection limit of 5 nM for the sensing of HgII. Also, the corresponding limit of detection (LOD) for L-Cys is 8 nM in a relatively wide linear range, spanning from 0.001 to 40 µM.

Development of colorimetric probe for the selective detection of HgII

A selective sensing technique for HgII ions has been developed utilizing an amino acid based probe. The design, synthesis and efficacy of the chemosensor have been described. The probe (SALTYR) was successfully synthesized from a naturally occurring amino acid after sequential functional group modifications. Recognition studies were performed against a wide variety of metal cations and anions including real water samples. All the analyses were carried out utilizing UV–vis and fluorescence techniques with micromolar concentrations of the probe in HEPES buffer. The selectivity of the probe was found to be very specific for HgII with quenching of the fluorescence in a turn-off mechanism. The detection limit of the probe SALTYR was calculated and found to be 5.9 × 10−6 M. Quantum chemical calculations demonstrated the stability of the HgII complex in the context of binding energy. Furthermore, the change of the pattern of emission spectra has been rationalized with a logic gate model.

Nanoclusters with specific DNA overhangs: modifying configurability, engineering contrary logic pairs and the parity generator/checker for error detection.

The most promising alternative for next-generation molecular computers is biocomputing, which uses DNAs as its primary building blocks to perform a Boolean operation. DNA nanoclusters (NCs) have emerged as promising candidates for biosensing applications due to their unique self-assembly properties and programmability. It has been demonstrated that adding DNA overhangs to DNA NCs improves their adaptability in identifying specific biomolecular interactions. A recent proposal in DNA computing is the concept of "contrary logic pairs (CLPs)" executed by employing a DNA hybrid architecture as a universal platform. We have designed thymine overhang-modified DNA-templated NCs (T-Au/Ag NCs). These NCs serve as a chemosensing ensemble platform, where the presence of HgII ions mediates the formation of M-Au/Ag NCs. The resulting NCs exhibit the capability to drive elementary CLPs (YES, NOT, OR, NOR, INH and IMP) as well as complex logic operations (XOR and XNOR). Additionally, they can be utilized for advanced non-arithmetic DNA logic devices like a parity generator (pG) and a parity checker (pC) for "error detection". Bit errors are an unavoidable and common occurrence during any computing. A cascade of XOR operations was used to evaluate these errors by introducing the pG and pC at the transmitting (TX) and receiving (RX) ends in binary transmission, respectively, which has devastating implications for reliable logic circuits, especially in advanced logic computation. Moreover, an even/odd natural number from 0 to 9 distinguishable pC was designed based on a dual-source responsive computing platform. This work offers inspiring avenues for a cost-effective strategy to construct highly-intelligent DNA computing devices by enhancing the multi-input responsive single DNA platform concept.

Oligonucleotides Featuring a Covalently Mercurated 6-Phenylcarbazole Residue as High-Affinity Hybridization Probes for Thiopyrimidine-Containing Sequences.

Short oligonucleotides incorporating either 1-mercuri-6-phenylcarbazole, 8-mercuri-6-phenylcarbazole, or 1,8-dimercuri-6-phenylcarbazole C-nucleoside in the middle of the chain have been synthesized and studied for their potential as hybridization probes for sequences containing thiopyrimidine nucleobases. All of these oligonucleotides formed very stable duplexes with complementary sequences pairing the organometallic moiety with either 2- or 4-thiothymine. The isomeric monomercurated oligonucleotides were also able to discriminate between 2- and 4-thiothymine based on the different melting temperatures of the respective duplexes. DFT-optimized structures of the most stable mononuclear HgII -mediated base pairs featured a coordinated covalent bond between HgII and either S2 or S4 and a hydrogen bond between the carbazole nitrogen and N3. The dinuclear HgII -mediated base pairs, in turn, were geometrically very similar to the one previously reported to form between 1,8-dimercuri-6-phenylcarbazole and thymine and had one HgII ion coordinated to a thio and the other one to an oxo substituent.

New Europium(III)-TTA Complex Containing 2-Pyrrolidone as Coligand to Application as Luminescent Sensor: PbII and Ethanol in Gasoline

This work describes the synthesis and application of an europium(III) complex, [Eu(TTA)3(2-pyr) (H2O)], containing 2-thenoyltrifluoroacetonate (TTA) and 2-pyrrolidone (2-pyr) as ligands, obtained as white solid and soluble in ethanol. In solution, the complex showed red emission, characteristic of the EuIII emission in the solid state (λexc = 375 nm and λem = 612 nm). The complex was tested with PbII, CdII, and HgII ions in water. The effect of metal ions was monitored and evaluated by hypersensitive transition 5D0 → 7F2 (612 nm). The results show that PbII suppresses the complex luminescence and present high sensitivity, according to the values for the Stern-Volmer constant (KSV = 2300 L mol-1), showing good linearity, i.e., determination coefficient (R2 ) of 0.9913, and low limit of detection (LOD = 6.03 µM). Luminescence quenching increased with the increasing concentration of PbII. These results indicate that the synthesized complex is a potential luminescent sensor for detecting PbII in a simple and fast way, being applicable for routine environmental analysis. When applied as an ethanol sensor in gasoline, the complex hypersensitive transition intensity decreased with the increasing volume of ethanol in gasoline, reaching the values of R2 = 0.9815 and LOD = 4.94% v/v.

Crystal structure and Hirshfeld surface analysis of bis-[(eth-oxy-methane-thio-yl)sulfanido](N,N,N',N'-tetra-methyl-ethane-1,2-di-amine)-mercury(II).

The title four-coordinate mononuclear complex, [Hg(C3H5OS2)2(C6H16N2)] or [Hg(C3H5OS2)2(tmeda)] (tmeda: N,N,N',N'-tetra-methyl-ethane-1,2-di-amine), has a distorted tetra-hedral geometry. The HgII ion is coordinated to two N atoms of the N,N,N',N'-tetra-methyl-ethylenedi-amine ligand and two S atoms from two ethylxanthate xanthate ligands. In the crystal, mol-ecules are linked by weak C-H⋯S hydrogen bonds, forming a two-dimensional supra-molecular architecture in the ab plane. The most important contributions for the crystal packing are from H⋯H (59.3%), S⋯H (27.4%) and O⋯H (7.5%) inter-actions.

Structural characterization of the derivatives of bis{[2,6-(dimethylamino)methyl]phenyl} selenide with palladium(II) and mercury(II).

The intramolecularly coordinated homoleptic diorgano selenide bis{2,6-bis[(dimethylamino)methyl]phenyl} selenide, C24H38N4Se or R2Se, where R is 2,6-(Me2NCH2)2C6H3, 14, was synthesized and its ligation reactions with PdII and HgII precursors were explored. The reaction of 14 with SO2Cl2 and K2PdCl4 resulted in the formation of the meta C-H-activated dipalladated complex {μ-2,2'-bis[(dimethylamino)methyl]-4,4'-bis[(dimethylazaniumyl)methyl]-3,3'-selanediyldiphenyl-κ4C1,N2:C1',N2'}bis[dichloridopalladium(II)], [Pd2Cl4(C24H38N4Se)] or [{R(H)PdCl2}2Se], 15. On the other hand, when ligand 14 was reacted with HgCl2, the reaction afforded a dimercurated selenolate complex, {μ-bis{2,6-bis[(dimethylamino)methyl]benzeneselanolato-κ4N2,Se:Se,N6}-μ-chlorido-bis[chloridomercury(II)], [Hg2(C12H19N2Se)Cl3] or RSeHg2Cl3, 16, where two HgII ions are bridged by selenolate and chloride ligands. In palladium complex 15, there are two molecules located on crystallographic twofold axes and within each molecule the Pd moieties are related by symmetry, but there are still two independent Pd centers. Mercury complex 16 results from the cleavage of one of the Se-C bonds to form a bifurcated SeHg2 moiety with the formal charge on the Se atom being -1. In addition, one of the Cl ligands bridges the two Hg atoms and there are two terminal Hg-Cl bonds. Each Hg atom is in a distorted environment which can be best described as a T-shaped base with the bridging Cl atom in an apical position, with several angles close to 90° and with one angle much larger and closer to 180°.

1,8-Dimercuri-6-Phenyl-1H-Carbazole as a Monofacial Dinuclear Organometallic Nucleobase.

A C-nucleoside with 6-phenyl-1H-carbazole as the base moiety has been synthesized and incorporated in the middle of an oligonucleotide. Mercuration of this modified residue at positions 1 and 8 gave the first example of an oligonucleotide featuring a monofacial dinuclear organometallic nucleobase. The dimercurated oligonucleotide formed stable duplexes with unmodified oligonucleotides placing either cytosine, guanine, or thymine opposite to the organometallic nucleobase. A highly stabilizing (ΔTm =7.3 °C) HgII -mediated base pair was formed with thymine. According to DFT calculations performed at the PBE0DH level of theory, this base pair is most likely dinuclear, with the two HgII ions coordinated to O2 and O4 of the thymine base.

Colorimetric Detection Based on Localized Surface Plasmon Resonance Optical Characteristics for Sensing of Mercury Using Green-Synthesized Silver Nanoparticles.

Development of selective colorimetric detectors that can use green-fabricated silver nanoparticles' (AgNPs) with localized surface plasmon resonances (LSPRs) to rapidly, simply, and selectively detect Hg(II) ions was undertaken in this study. Onion extract was used for synthesising photo-induced green crystalline silver nanoparticles (NPs). The formation of nanoparticles is enhanced when ultrasound irradiation is present; bioligands could serve as stabilizing and reducing agents. Different methods of measurement, including UV-Vis, TEM, SEM/EDAX, FT − IR, and XRD, are effective for characterization of nanoparticles. The spherical nature of green-fabricated AgNPs is confirmed by TEM. High-density, spherical, and uniformly formed silver nanoparticle shapes were found in silver nanoparticle SEM images. The arrangement of AgNPs in the form of face-centered cubic structures was confirmed by XRD patterns. The formation of impurity-free AgNPs was confirmed using the EDAX analysis results. Hg2+ with excellent sensitivity was sensitively and selectively detected by employing green-synthesized silver nanoparticles. The reduction of Ag (1) to Ag (0) was confirmed by a slight increase in Hg (II) concentration and progressive reduction of green-synthesized AgNPs, whose absorbance changed abruptly. The reduction of LSPRs by the phosphate buffer medium enables AgNPs to sensitively and selectively detect Hg2+ ions by providing good environment. Besides, a selective, sensitive, simple, and rapid method that is proposed for detecting Hg (II) ions in samples of water is presented in the study. Harmful mercury ions in real samples of water (tap and ground water) can colorimetrically and selectively be detected using the AgNPs. The results showed an RSD of below 6% and over 92% of good recovery.

Selective colorimetric detection of HgII using silver nanoparticles modified with Apple and Nigella Sativa seed extracts and β-Cyclodextrin

The surface modification of silver nanoparticles (AgNPs) with natural products could be environmentally friendly method of manufacturing provided that their inherent properties could be substantiated. Therefore, AgNPs were synthesized from AgNO3 using β-Cyclodextrin and seed extracts from Apple (Ap-AgNPs) and Nigella Sativa species (N-AgNPs). AgNPs thus prepared were incorporated as a colorimetric sensor for determining HgII ions and proved to be both selective and adequately sensitive in detecting mercuric ions. These nanoparticles are found to show a limit of detection (LOD) of 29.0 nM and 58.0 nM for Ap-AgNPs and N-AgNPs, respectively. The results demonstrate the higher sensitivity of Ap-AgNPs over N-AgNPs with maximum absorption causing a color shift to blue due to HgII ions and the resulted color change from yellow to pale yellow, even colorless upon addition of HgII in AgNPs solutions. The results validate the applicability of nanoparticles as a sensor with the potential for rapid and on-site detection of HgII ions.

A Novel DNA Helical Wire Containing HgII -Mediated T:T and T:G Pairs.

Numerous applications of metal-mediated base pairs (metallo-base-pairs) to nucleic acid based nanodevices and genetic code expansion have been extensively studied. Many of these metallo-base-pairs are formed in DNA and RNA duplexes containing Watson-Crick base pairs. Recently, a crystal structure of a metal-DNA nanowire with an uninterrupted one-dimensional silver array was reported. We now report the crystal structure of a novel DNA helical wire containing HgII -mediated T:T and T:G base pairs and water-mediated C:C base pairs. The Hg-DNA wire does not contain any Watson-Crick base pairs. Crystals of the Hg-DNA wire, which is the first DNA wire structure driven by HgII ions, were obtained by mixing the short oligonucleotide d(TTTGC) and HgII ions. This study demonstrates the potential of metallo-DNA to form various structural components that can be used for functional nanodevices.

A Novel DNA Helical Wire Containing HgII‐Mediated T:T and T:G Pairs

AbstractNumerous applications of metal‐mediated base pairs (metallo‐base‐pairs) to nucleic acid based nanodevices and genetic code expansion have been extensively studied. Many of these metallo‐base‐pairs are formed in DNA and RNA duplexes containing Watson–Crick base pairs. Recently, a crystal structure of a metal–DNA nanowire with an uninterrupted one‐dimensional silver array was reported. We now report the crystal structure of a novel DNA helical wire containing HgII‐mediated T:T and T:G base pairs and water‐mediated C:C base pairs. The Hg‐DNA wire does not contain any Watson–Crick base pairs. Crystals of the Hg‐DNA wire, which is the first DNA wire structure driven by HgII ions, were obtained by mixing the short oligonucleotide d(TTTGC) and HgII ions. This study demonstrates the potential of metallo‐DNA to form various structural components that can be used for functional nanodevices.

Organically Functionalized Mesoporous SBA-15 Type Material Bearing Fluorescent Sites for Selective Detection of HgII from Aqueous Medium.

Hg(II) contamination in water resources is one of the major health issues in keeping the purity standard of the municipal water supply. Herein, we report a new mesoporous sensor probe material SBA-ABZ-PEA having a 2D-hexagonally ordered mesoporous framework bearing covalently bonded fluorescent sites, and this has been synthesized through a two-step post-synthesis grafting route. A pure silica mesoporous SBA-15 material has been functionalized with (3-chloropropyl)triethoxysilane (ClPTES) to obtain chloro-functionalized SBA-15, which was further reacted with 4-aminobenzaldehyde followed by treatment with 2-(2-pyridyl)-ethylamine resulting in functionalized 2D-hexagonal mesoporous sensor probe SBA-ABZ-PEA. Small angle PXRD, N2 adsorption/desorption, HRTEM, TGA, and FT-IR studies have been carried out to characterize these materials. Our experimental results suggested successful grafting of the organic moiety on the SBA-15 surface along with preservation of mesoporosity throughout the grafting process. Photoluminescence measurements were carried out in the aqueous suspension of SBA-ABZ-PEA in the presence of different metal cations, like NaI, MgII, AlIII, KI, CaII, MnII, CoII, CuII, ZnII, CdII, PbII, and HgII. This result revealed that, among the various metal-ions, the emission intensity of the mesoporous sensing probe material SBA-ABZ-PEA has been dramatically quenched in the presence of the HgII ion. To check the sensitivity of the sensor probe, the fluorescence emission was also studied in the presence of different concentrations of HgII ions. A perfect linear plot between the concentrations of HgII ions in the aqueous medium with their corresponding fluorescence intensities with a detection limit of 1.2 × 10–6 M has been observed.

Effects of metal ions on thermal stabilities of DNA duplexes containing homo- and heterochiral mismatched base pairs: comparison of internal and terminal substitutions

The effects of metal ions on the stabilities of duplexes containing a D-homochiral and heterochiral mismatched base pairs were studied. In some duplexes containing an internal mismatched base pair, significant stabilization by HgII and AgI ions was observed. While, in duplexes containing a terminal mismatched base pair, only the duplexes containing T-T and LT-T mispairs were significantly stabilized by HgII ions, and the stabilities of the duplexes containing T-T and LT-T mispairs exceeded those of the corresponding homochiral matched duplex. The results suggest that the formation of homo- and heterochiral T-HgII-T base pairs at duplex termini would be useful for the thermal and enzymatic stabilization of DNA-based nanodevice.

An Intramolecular Charge Transfer Induced Fluorescent Chemosensor for Selective Detection of Mercury (II) and its Self‐Turn‐On Inside Live Cells at Physiological pH

AbstractA new turn‐on fluorescence small‐molecular dicarboxylic acid functionalized chemosensor (L2) has been designed strategically. The bidentate ligand (L2) is exceedingly selective for the sensing of HgII ions over other heavy‐metal ions, and exhibits excellent resolution on imaging living cells in‐vitro. The HgII binding mechanism by the probe occurs selectively through lone pair of electrons from imine nitrogens, which was established by using 1H NMR titrations, density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT). The free acid protons facilitated enhanced fluorescence intensity upon shift at deprotonation and gave a 50 nm hypsochromic at slight basic medium. The para‐ and meta‐positions of imine nitrogen atoms with respect to the donor (NH2) inducing the intramolecular charge transfer (ICT). The designed probe has high sensitivity to mercury(II) ions, excellent cell membrane permeability and negligible cytotoxicity, which result in bright and specific detection of HgII in living cells (HeLa cells) by fluorescence turn‐on at physiological pH. Further, the strategic approach executed in this work would be useful to design new chemosensors for sensing of different molecules or ions in future.

Frontispiece: Goal‐Directed Design of Metal–Organic Frameworks for HgII and PbII Adsorption from Aqueous Solutions

Metal-organic frameworks (MOFs) have evolved to be next-generation utility materials because of their usability in diverse applications. In their Concept article on page 17170 ff., F. Rouhani and A. Morsali provide a conceptual review of recent developments in MOFs for the removal of HgII and PbII ions from aqueous media. These porous materials with excellent chemical stability and wide variety of functional groups, have demonstrated their utility to the area of capturing various types of hazardous metal-ion pollutants.

Synthesis, Characterization and the Corrosion Inhibition Study of Two Schiff Base Ligands Derived From Urea and Thiourea and Their Complexes with Cu(II) and Hg(II) Ions

The research includes synthesis of [L1] and [L2] Schiff base ligands by the reaction of vanillin with urea and thiourea respectively in 2:1 mol ratio. The two ligands were reacted with CuII ion in 1:2 mol ratio and HgII ion in 1:1 mol ratio. The prepared compounds have been identified by FTIR, U.V-Vis, 1H-NMR (L1, L2 and HgII complex) spectroscopies, microelemental analysis (C.H.N.S), magnetic susceptibility measurements, atomic absorption, chloride content along with conductivity and melting point measurements. According to applied characterization methods, the proposed general formulas of CuII and HgII complexes were [Cu2LnCl4] and [HgLnCl]Cl, respectively, (where n = 1, 2). The ability of corrosion inhibition with two ligands and their cupper complexes has been studied in diluted hydrochloric acid media.

Fast and Selective Heavy Metal Removal by a Novel Metal‐Organic Framework Designed with In‐Situ Ligand Building Block Fabrication Bearing Free Nitrogen

Fast and effective adsorbents for the selective removal of HgII and PbII ions were prepared by the reaction of Zn(NO3 )2 ⋅6H2 O, H2 BDC, and N1 ,N2 -bis(pyridin-4-ylmethylene) ethane-1,2-diamine (L) that yields an unprecedented two-dimensional layer-based supramolecular framework, {Zn(BDC)(L*)}⋅DMF (TMU-40), by solvothermal reaction. The formation of this framework involved an in situ C=C coupling of L to L* [L*=5,6-di(pyridin-4-yl)-1,2,3,4-tetrahydropyrazine]. As L* contains free nitrogen atoms, direct reaction of L* and metals led to metallated products. Post-synthetic modification of this novel MOF (TMU-40) with H2 O2 gives a new framework (O-TMU-40) by same structure and different ligand, which also bears free nitrogen atoms. FTIR spectra, TGA analysis, X-ray diffraction, Zeta Potential analysis and 1 H NMR spectroscopy were used to characterize the prepared frameworks. The TMU-40 and O-TMU-40 frameworks were used for heavy-metal removal from aqueous solutions. Maximum adsorption values of 269 mg g-1 for HgII with TMU-40 and 215 mg g-1 for PbII with O-TMU-40 were achieved in 10 min at 298 Kwithout changes in the pH of the adsorption medium with pseudo-second order kinetics based on the Langmuir model. The extremely fast kinetics of TMU-40 means this adsorbent can reduce heavily contaminated water containing HgII concentrations of 40 ppm down to the acceptable limit of 2 ppb.

AgI Metallacoronates and HgII Metallacryptates Derived from a Catechol‐Based Aroylbis(N,N‐diethylthiourea)

Reactions of mixtures between Ag(NO3) and alkaline earth nitrates with the bifunctional ligand 2,2′‐{1,2‐phenylenebis[oxyacetyl(N,N‐diethylthiourea)]}, H2Lcat, give {2}‐metallacoronates of the composition {M ⊂ [Ag2(Lcat)2]} (M = Ca2+, Sr2+, or Ba2+). The trinuclear assemblies show further aggregation in the solid state, where they establish dimeric or polymeric entities stabilized by weak Ag···N(amide) interactions. Discrete {2}‐metallacryptate species {M ⊂ [Hg2(Lcat)3]} (M = Sr2+ or Ba2+) result from similar reactions between H2Lcat, Hg(NO3)2, and strontium nitrate or barium nitrate. The complexes contain HgII ions in an uncommon distorted trigonal‐bipyramidal environment with a S3O2 coordination sphere. The central alkaline earth ions are mainly bonded by the six carbonyl oxygen atoms of the three organic ligands.

Rhodol Derivatives as Selective Fluorescent Probes for the Detection of HgII Ions and the Bioimaging of Hypochlorous Acid.

Invited for this month's cover picture is the group of Professor Keith Man‐Chung Wong from the Southern University of Science and Technology (P.R. China). The cover picture illustrates a novel rhodol‐based fluorescence probe from the structural combination of rhodamine and fluorescein motifs. Read the full text of their Full Paper at 10.1002/open.201700154.