Theoretical estimate of the stability constants of metal complexes of aliphatic and heterocyclic amines in aqueous solutions

The stability constants of 1: 1 complexes of Mg²⁺, Ca²⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe²⁺, Mn²⁺, Ni²⁺, and Zn²⁺ with 29 N-donor ligands (ammonia, alkylamines, aniline, pyridine, imidazole, pyrazole, benzimidazole, isoquinoline, and their alkyl-and halogen-substituted derivatives) in aqueous solutions at 298 K were calculated by integration of the ligand distribution function. The stability constants are determined by the effective charge on the electron donor atom of the ligand and by the sizes of the cation and ligand, as well as by the degree of covalence of the coordination bond.     

Quantum yields and quantitative spectra of firefly bioluminescence with various bivalent metal ions

We measured quantitative spectra of firefly (Photinus pyralis) bioluminescence in the presence of Zn²⁺ and other bivalent metal ions to investigate the effects of these metal ions on luciferin‐luciferase reaction. We studied the dependence of the quantum yield and spectrum on quantity and kind of bivalent metal ions. Adding various amounts of Mg²⁺, Mn²⁺ and Ca²⁺ produced virtually no change in the quantum yields or the spectra of bioluminescence. In contrast, increasing amounts of ions such as Zn²⁺ and Cd²⁺ decreased quantum yields and changed the bioluminescence color from yellow‐green to red. Quantitative analysis showed that the sensitivities of the quantum yield and color to various metal ions were in the order of Hg²⁺>Zn²⁺, Cd²⁺>Ni²⁺, Co²⁺, Fe²⁺≫Mg²⁺, Mn²⁺, Ca²⁺. We propose that the changes in quantum yield and spectrum caused by the metal ions are due to their effect on luciferase that surrounds oxyluciferin during its radioactive decay. We also found that having more metal ions accelerated bioluminescence reactions. The sensitivity of the reaction rate had no correlation with those of the quantum yield and spectrum.     

A Highly Copper‐Selective Ratiometric Fluorescent Sensor Based on BODIPY

A new ratiometric fluorescent sensor ( 1 ) for Cu²⁺ based on 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) with di(2‐picolyl)amine (DPA) as ion recognition subunit has been synthesized and investigated in this work. The binding abilities of 1 towards different metal ions such as alkali and alkaline earth metal ions (Na⁺, K⁺, Mg²⁺, Ca²⁺) and other metal ions ( Ba²⁺, Zn²⁺, Cd²⁺, Fe²⁺, Fe³⁺, Pb²⁺, Ni²⁺, Co²⁺, Hg²⁺, Ag⁺) have been examined by UV‐vis and fluorescence spectroscopies. 1 displays high selectivity for Cu²⁺ among all test metal ions and a ～10‐fold fluorescence enhancement in I₅₈₂/I₅₅₈ upon excitation at visible excitation wavelength. The binding mode of 1 and Cu²⁺ is a 1:1 stoichiometry determined via studies of Job plot, the nonlinear fitting of the fluorometric titration and ESI mass.     

Metal complexes of ethylenediaminetetraacetamide

Summary A convenient synthesis of the ligand ethylenediaminetetraacetamide (L) is described, and a number of metal complexes of the general formula MLCl_n · xH₂O (Mⁿ⁺=Ca^II, Mn^II, Fe^II, Co^II, N^II, Cu^II, Zn^II, Mg^II, Ba^II, Cd^II, Hg^II and La^III) prepared. The deprotonated Cu(L-H)₂ · 2 H₂O complex has been characterised and the associated pK values determined. I.r., conductivity, magnetic susceptibility and electronic spectral data are discussed.     

基于苯并噻唑Zn2+荧光探针及其细胞造影应用

设计合成基于苯并噻唑Zn²⁺荧光增强型探针BHP,在HEPES缓冲液中测其对Zn²⁺识别性能。实验结果表明,BHP对Zn²⁺有较高的选择性,对其他金属离子如Cd²⁺,Fe²⁺,Ni²⁺,Pb²⁺,Hg²⁺,Al³⁺,Mn²⁺,Ag⁺,Cu²⁺,Co²⁺,Na⁺,K⁺,Mg²⁺和Ca²⁺无明显荧光增强响应。BHP与Zn²⁺按1：1计量比配位,在生理条件下荧光强度不受pH值影响。在HeLa细胞中对Zn²⁺的造影表明BHP可用于生物体Zn²⁺检测。     

Tridentate benzimidazole ligand and its metal complexes: Synthesis,characterization, photo physical and sensor properties

A tridentate bisbenzimidazole-pyridine ligand (L-C⁵) with two pentyl side-units and its metal complexes with Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ metal ions were synthesized and characterized. The structures of the ligand (L-C⁵) and its five coordinate [Mn(L-C⁵)Cl₂] were elucidated by single crystal X-ray diffraction studies. The absorption and photoluminescence properties of the compounds were studied in solution media. The ligand is highly fluorescent, and binding of the metal ions to the ligand has caused significant changes in the emission band (shift or quenching). Moreover, the effect of aggregation on UV–Vis. absorption and emission properties was examined in MeOH-water mixtures. The ligand was found to show aggregation-induced quenching in the MeOH-water mixture. The ligand was also screened for its colorimetric and fluorometric sensing ability of several metal ions [Na⁺, K⁺, Mg²⁺, Al³⁺, Ca²⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Hg²⁺, Pb²⁺]. The ligand showed selective sensing ability towards Zn²⁺, and the limit of detection was calculated as 3.09 × 10⁻⁷ m . The ligand also showed a distinguishable color change in the presence of Fe²⁺ under daylight.     

The Stability of Metal N,N,N′,N′‐Tetrakis(2‐aminoethyl)ethane‐ 1,2‐diamine (=penten) Complexes and the X‐Ray Crystal Structure of [Tl(NO3)(penten)](NO3)2

Complex formation between N,N,N′,N′‐tetrakis(2‐aminoethyl)ethane‐1,2‐diamine (penten) and the metal ions Mn²⁺, Co²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Ag⁺, Pb²⁺, and Tl³⁺ (in 1.00M NaNO₃ and 25°) was investigated by potentiometry and spectrophotometry. These are the first reported values of the stability constants for this ligand with Ag⁺, Pb²⁺, and Tl³⁺. The X‐ray crystal structure of [Tl(NO₃)(penten)](NO₃)₂ was determined. In this structure, Tl³⁺ shows a coordination number of seven made up of the six N‐donors and one O‐atom of NO.     

Rhodamine-Appended Bipyridine: XOR and OR Logic Operations Integrated in an Example of Controlled Metal Migration

A new bipyridyl derivative 1 bearing rhodamine B as visible fluorophore was designed, synthesized and characterized as a fluorescent and colorimetric sensor for metal ions. Interaction with Cu²⁺, Zn²⁺, Cd²⁺, Hg⁺, and Hg²⁺ ions was followed by UV/Vis and emission spectroscopy. Upon addition of these metal ions, different colorimetric and fluorescent responses were observed. “Off-on-off” (Cu²⁺, Zn²⁺, and Hg²⁺) and “off-on” (Hg⁺ and Cd²⁺) systems were obtained. Probe 1 was explored to mimic XOR and OR logic operations for the simultaneous detection of Hg⁺–Cu²⁺ and Hg⁺–Zn²⁺ pairs, respectively. DFT calculations were also performed to gain insight into the lowest-energy gas-phase conformation of free receptor 1 as well as the atomistic details of the coordination modes of the various metal ions.     

ESI‐MS studies of the non‐covalent interactions between biologically important metal ions and N‐sulfonylcytosine derivatives

The aim of this report is to present the electrospray ionization mass spectrometry results of the non‐covalent interaction of two biologically active ligands, N‐1 ‐ (p‐toluenesulfonyl)cytosine, 1‐TsC, 1 and N‐1 ‐ methanesulfonylcytosine, 1‐MsC, 2 and their Cu(II) complexes Cu(1‐TsC‐N3)₂Cl₂, 3 and Cu(1‐MsC‐N3)₂Cl₂ and 4 with biologically important cations: Na⁺, K⁺, Ca²⁺, Mg²⁺ and Zn²⁺. The formation of various complex metal ions was observed. The alkali metals Na⁺ and K⁺ formed clusters because of electrostatic interactions. Ca²⁺ and Mg²⁺ salts produced the tris ligand and mixed ligand complexes. The interaction of Zn²⁺ with 1–4 produced monometal and dimetal Zn²⁺ complexes as a result of the affinity of Zn²⁺ ions toward both O and N atoms. Copyright © 2016 John Wiley & Sons, Ltd.     

Complexing Properties of Phenolic Diazacrown Ethers with Transition and Heavy Metal Ions

The complexation equilibria of the phenolic diazacrown ether derivatives L1–L11 with transition and heavy metal ions (Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺ and Pb²⁺) have been studied in methanol using UV absorption spectrophotometry. A majority of the systems studied formed only ML complexes. Using a ligand with a different position of the substituents on the phenolic side arms (denoted L7) leads to ML₂ formation with most of the metal ions. Every ligand forms very strong ML and ML₂ complexes with Pb²⁺, and, in nearly all cases, only a lower limit could be derived for the stability constant. The stability of the complexes generally increases as the length of the para-substituents on the phenol groups increases. Among the metal ions tested, Zn²⁺ and Hg²⁺ are the least preferred by alkyl and alkoxy derivatives, respectively.     

1,8-萘酰亚胺为发色团的Zn2+荧光探针的合成及性能研究

合成了以1,8-萘酰亚胺为发色团,以联吡啶为离子受体的Zn²⁺荧光探针,并进行了表征及离子识别性能的研究。研究表明该化合物对Zn²⁺具有良好的识别性能,同时相对于Ca²⁺, Cd²⁺, Co²⁺, Cu²⁺, Hg²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺等金属离子具有良好的选择性。     

Synthesis of a Dithiocarbamate Chelate Resin and Its Oxidized form and Their Adsorption Properties for Heavy Metal Ions

A series of macroporous dithiocarbamate chelate resins, III and V, and an oxidized resin, VI, with high adsorption capacity were prepared. The influence of various reaction conditions of amination, dithiocarboxylation, and oxidation were examined. The structure and the conversion of functional groups of resins were confirmed by IR spectra and elemental analysis. The adsorption capacities of Resin II for Hg²⁺, Cu²⁺, Zn²⁺, and Cd²⁺ are 4.40, 2.44, 1.77, and 1.36 mmol/g, respectively. The adsorption capacities of Resins V and VI for Cu²⁺. Zn²⁺, Ni²⁺, Co³⁺, Ag⁺, Hg²⁺, Cd²⁺, Pb²⁺, and Au³⁺ are 4.07–0.51 and 3.81–0.59 meq ion/g, respectively. The adsorption rate and the influence of pH on the adsorption percentage of the resins for metal ions were examined. Noble metal, transitional metal, and heavy metal ions can be quantitatively adsorbed by the resins. The adsorbed Cu²⁺, Pb²⁺, Cd²⁺, Co³⁺, and Ni²⁺ can be quantitatively eluted with 5N HNO₃, and the presence of large amounts of Ca²⁺, Mg²⁺, Fe³⁺, and Al³⁺ did not interfere.     

A New Fluorescent Chemosensor for Metal Ions Based upon 1,8‐Naphthalimide and 8‐Hydroxyquinoline

A new fluorescent chemosensor based upon 1,8‐naphthalimide and 8‐hydroxyquinoline was synthesized, and its fluorescent properties in the presence of different metal cations (Hg²⁺, Ag⁺, Zn²⁺, Fe²⁺, Cd²⁺, Pb²⁺, Ca²⁺, Cu²⁺, Mg²⁺, and Ba²⁺) were investigated. It displayed fluorescence quenching with some heavy and transition metal (HTM) ions, and the quenching strongly depended on the nature of HTM ions.     

Fluorescent chemosensor for mercury(II) cations in an aqueous solution based on 4-acetylamino-1, 8-naphthalimide derivative containing the N-phenylazadithia-15-crown-5-ether receptor

The 4-acetylamino-1,8-naphthalimide derivative containing the N-phenylazadithia-15-crown-5-ether fragment in the N-aryl substituent at the imide nitrogen atom of the naphthalimide core was synthesized, and its cation-dependent spectral properties were studied. The resulting compound in the photoexcited state exhibits low-intensity fluorescence due to the process of electron transfer from the N-aryl group to the naphthalimide residue, which is confirmed by the data of quantum chemical calculations performed using the PM6 method. The binding of Hg²⁺ in an aqueous acetate buffer solution at pH 6.0 is accompanied by the formation of a 1: 1 metal—ligand complex in which the electron transfer is suppressed leading to fluorescence enhancement. The observed spectral changes were used for the determination of the stability constant K of the complex (logK = 6.51±0.03). The found limit of Hg²⁺ detection using the synthesized sensor (28 nmol L^?1) is fairly close the maximum permissible concentration for mercury in drinking water. The study of the selectivity of complexation showed that the presence of Cu²⁺, Zn²⁺, Ni²⁺, Pb²⁺ Cd²⁺, Ca²⁺, Mg²⁺, and Fe²⁺ cations did not impede the determination of Hg²⁺. The presented results indicate that the synthesized chemosensor is promising as a selective and highly sensitive fluorescent reagent for Hg²⁺ ions in an aqueous solution.

     

Bichromophoric naphthalene derivatives of diethylenetriaminepentaacetate (DTPA): fluorescent response to H+, Ca2+, Zn2+, and Cd2+

As an effort to design selective fluorescent sensors toward Ca²⁺, Zn²⁺ and Cd²⁺, synthetic and fluorometric studies were performed on four bichromophores, each of which consists of two naphthyl or methynaphthyl units (1- and 2-isomers) linked with a diethylenetriaminepentaacetate (DTPA) chain. Every bichromophore exhibits naphthalene-monomer emission at 370 nm and excimer emission at 405 nm. Emission intensities show sensitive pH dependence, from which protonation constants were determined. Fluorometric titrations with the metal ions were performed at the physiological pH and the conditional formation constants were determined. Naphthyl rings define the stoichiometry and stability of the complexes. The insertion of CH₂ spacer intensifies the emission and enhances the selective response to metal ions: the excimer emission is strengthened by 70?100 % with Cd²⁺ coordination, weakened by 60 % with Zn²⁺, and insensitive to Ca²⁺. The high response of methylnaphthyl bichromophores to Cd²⁺ is advantageous in fluorometric analyses.     

Syntheses,structures of N‐(substituted)‐2‐aza‐[3]‐ferrocenophanes and their application as redox sensor for Cu2+ ion

Rigid N‐(substituted)‐2‐aza‐[3]‐ferrocenophanes L1 and L2 were easily synthesized from 1,1 ‐dicarboxyaldehydeferrocene and the corresponding amines. Ligands L1 and L2 were characterized by ¹H NMR, ¹³C NMR and single‐crystal X‐ray crystallography. The coordination abilities of L1 and L2 with metal ions such as Cu²⁺, Mg²⁺, Ni²⁺, Zn²⁺, Pb²⁺ and Cd²⁺ were evaluated by cyclic voltammetry. The electrochemical shift (ΔE_1/2) of 125 mV was observed in the presence of Cu²⁺ ion, while no significant shift of the Fc/Fc + couple was observed when Mg²⁺, Ni²⁺, Zn²⁺, Pb²⁺, Cd²⁺ metal ions were added to the solution of L1 in the mixture of MeOH and H₂O. Moreover, the extent of the anodic shift of redox potentials was approximately equal to that induced by Cu²⁺ alone when a mixture of Cu²⁺, Mg²⁺, Ni²⁺, Zn²⁺, Pb²⁺ and Cd²⁺ was added to a solution of L1. Ligand L1 was proved to selectively sense Cu²⁺ in the presence of large, excessive first‐row transition and late‐transition metal cations. The coordination model was proposed from the results of controlled experiments and quantum calculations. Copyright © 2012 John Wiley & Sons, Ltd.     

Toxic metal complexes of macrocyclic cyclen molecule – synthesis,structure and complexing properties

Toxic metal (Cd²⁺, Hg²⁺, Pb²⁺, and Ag⁺) complexes with the tetradentate macrocyclic ligand - cyclen (1,4,7,10-tetraazacyclododecane, [12]aneN₄, L) were prepared and studied in the solid state by IR, X-ray diffraction, elemental and thermal analysis. Diffraction results have yielded three molecular structures, [Cd([12]ane-κ⁴N^1,4,7,10)(NO₃)₂)] (1), [Hg([12]ane-κ⁴N^1,4,7,10)(NO₃-κ²O,O`)]NO₃ (2), [Pb₂([12]ane-κ⁴N^1,4,7,10)₂][Pb(NO₃)₆] (3) and one polymeric structure {[Ag₂([12]ane-κ³N^1,4,7)(μ₂-[12]aneN¹⁰)](NO₃)₂?2H₂O)}_n (4) featuring a unique coordination mode not observed before with cyclen as a ligand. The monodentate (1) and chelate (with small bite angle 50.3(3)°, (2) coordination modes of nitrate ligands were confirmed. Stereochemically active 6s² lone pair was suggested in 3 and DFT results confirmed no significant metal–metal covalent bond. The stability constants of the complexes with Cd²⁺ and Pb²⁺ ions were determined by potentiometric methods in aqueous solutions. Additionally, the structures of complexes in solution were observed by ¹H NMR. Both methods confirm similar cyclen complexing properties toward Zn²⁺ biometal and Cd²⁺, Pb²⁺ toxic metals.     

Zn selective luminescent ‘off-on’ probes derived from diaryl oxadiazole and aza-15-crown-5

New photo-induced electron transfer (PET) probes OMOX and OBOX, carrying an additional binding site in the form of ‘oxadiazole nitrogen’ have been designed to evaluate binding interactions with biologically significant Li⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, and Zn²⁺ including environmentally toxic Ba²⁺ and Cd²⁺ using optical spectral techniques. While Li⁺, Na⁺, and K⁺ did not appreciably perturb either the absorption or emission spectra, Ba²⁺, Ca²⁺, Mg²⁺, Zn²⁺, and Cd²⁺ induced slight red shifts (2-8 nm) in the UV-visible spectra as well as pronounced chelation induced enhanced fluorescence (CHEF). Both OMOX and OBOX exhibited the highest CHEF in contact with the zinc ion, whereas Ba²⁺, Ca²⁺, Mg²⁺, and Cd²⁺ induced relatively less emission enhancements. OBOX, which is a poorer emitter (Φ_f=0.0062) than OMOX (Φ_f=0.015), showed highly promising 160-fold emission enhancement in the presence of Zn²⁺. Potential, therefore is available in OBOX to function as a selective luminescent ‘off-on’ sensor for Zn²⁺ in the presence of coordinatively competing Ba²⁺, Ca²⁺, Mg²⁺, and Cd²⁺ ions.     

Study on the synthesis of novel fluorescent macrocyclic sensors and their sensitive properties for Cu2+ and Fe3+ in aqueous solution

In this work, we synthesised and characterised three novel fluorescence macrocyclic sensors containing optically active dansyl groups. The studies for the interaction of the synthesised compounds with various mental ions (Li⁺, Na⁺, K⁺, Ag⁺, Mg²⁺, Ca²⁺, Ba²⁺, Pb²⁺, Zn²⁺, Co²⁺, Cd²⁺, Hg²⁺, Ni²⁺, Cu²⁺, Mn²⁺, Cr³⁺, Al³⁺, Fe³⁺) were performed by fluorescence titration, Job’s plot, ESI-MS and DFT calculations. The results showed that the sensors 1a–1c displayed selective recognition for Cu²⁺ and Fe³⁺ ions and formed stoichiometry 1:1 complex through PET mechanism in DMSO/H₂O solution (1:1, v/v, pH 7.4 of HEPES). The binding constant (K) and detection limit were calculated.     

Amino-substituted gem-diphosphonic acids: structures of complexes with divalent metal cations in aqueous solutions

A comparative study of complexation of acids R₂N(CH₂)_nCR"(PO₃H₂)₂ (R = H or Me; R" = OH or H; n = 1 or 2) with the Ca²⁺, Mg²⁺, Zn²⁺, and Cu²⁺ cations in aqueous solutions was carried out by vibrational (IR and Raman) and electronic spectroscopy using the data of ESR spectroscopy and conformational analysis (molecular mechanics). The MOPCPO chelate ring is formed in all ML and MHL complexes. The involvement of the N atom in coordination was found only in the Cu²⁺ complexes and is determined by the structure of the ligand. The relationship between the stability constants and the structures of the complexes in aqueous solutions is analyzed.