Cation Sensor Research Articles

Synthesis, characterization, and application of a novel water-soluble polyethyleneimine-based Schiff base colorimetric chemosensor for metal cations and biological activity

A novel colorimetric cation sensor based on polyethyleneiminehydrochloride (PEI.HCl) as Schiff base was synthesized. The molecular structure of the PEI.HCl-Schiff base was characterized via FT-IR, 1H NMR, 13C NMR, LC-MS and UV–vis spectroscopic methods The chromogenic sensing ability of PEI.HCl-Schiff base was investigated with colorimetric and UV–vis spectroscopy. The designed sensor exhibited highly selective recognition for Fe2+, Co2+, Cu2+, Cr3+, and Fe3+ amongst a wide range of metal ions tested in water. In the presence of these cations, the sensor underwent a dramatic colour change from yellow to green, while the presence of other metal cations such as Mn2+, Ni2+, Zn2+, Cd2+, Hg2+ and Pb2+ produced no effect on the colour. The absorption spectral changes were observed upon the addition of Fe2+, Co2+, Cu2+, Cr3+, and Fe3+ with impressive naked eye detectable colour change from yellow to dark-gray, light-brown, green, light-green and brown, respectively. The most discernable colour change in the PEI.HCl-Schiff base was caused by Fe2+, Co2+, Cu2+, Cr3+, and Fe3+ suggesting the selective detection of these metal cations. Surprisingly, PEI.HCl-Schiff base behaves as highly selective chemical sensor for the oxidation of Fe2+ to Fe3+ cations. Moreover, the antimicrobial activity of PEI.HCl-Schiff base was tested for its minimum inhibitory concentration (MIC), and the interaction with calf thymus DNA (CT-DNA) was investigated using UV–vis spectroscopy. DNA cleavage study showed that PEI.HCl-Schiff base can successfully cleave DNA without any external agents.

Trace electrochemical detection of Ni2+ ions with bidentate N,N′-(ethane-1,2-diyl)bis(3,4-dimethoxybenzenesulfonamide) [EDBDMBS] as a chelating agent

The heavy metals are naturally occurring elements and becoming the main source of pollution in our eco-environment due to their commercial applications. So, for the probe of heavy metal cations, bidentate chelating agents N,N′-(ethane-1,2-diyl)bis(4-methoxybenzene sulfonamide) [EDBMBS] and N,N′-(ethane-1,2-diyl)bis(3,4-dimethoxybenzenesulfonamide) [EDBDMBS] were synthesized in this study. These chelating agents were characterized by UV/Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H-NMR &13C-NMR), in addition to single-crystal X-ray diffraction and X-ray photoelectron spectroscopy (XPS) analysis. After the characterization, I-V technique was executed using electrometer to check the affinity of our synthesized chelating agents against the wide range of heavy metal cations (Ag+, Al3+, Au3+, Ba2+, Ce4+, Co2+, Ni2+, Pb2+, Sn2+ & Y3+). It was found that it has selective affinity with Nickel (Ni2+) cations. Ni2+ is one of the most toxic heavy metal presents in the environmental contaminants. EDBMBS and EDBDMBS onto flat-glassy carbon electrode were fabricated with conducting coating agents to fabricate a sensitive and selective Ni2+ ions sensor in short response time in phosphate buffer phase. The comparative study of EDBMBS/Nafion/GCE and EDBDMBS/Nafion/GCE was performed and found that fabricated EDBDMBS/Nafion/GCE cationic-sensor exhibited higher sensitivity, large-dynamic concentration ranges, long-term stability, and improved electrochemical performances towards nickel ions. The calibration plot is linear (r2=0.9929) over the large Ni2+ concentration ranges (1.0nM to 1.0mM). The sensitivity and detection limit is ∼2.3417µA.µM.cm−2 and ∼0.78nM (signal-to-noise ratio, at a SNR of 3) respectively. This novel effort initiated a well-organize way of efficient cationic sensor development with nafion conducting binder deposited on GCE for toxic pollutants in environmental and health-care fields in large scales. Therefore, the proposed EDBDMBS/Nafion/GCE offers a cost-effective compound that can be considered as a viable alternative for effectively detecting and removing toxic Ni2+ from water samples.

Levofloxacin capped Ag-nanoparicles: A new highly selective sensor for cations under joint experimental and DFT investigation

A very new and alternate function of an antibiotic drug levofloxacin (Lv), as a highly selective, colorimetric turn-OFF/turn-ON chemosensor for metal-ions Hg2+ and Fe3+, has been reported in this study. An extremely easy, very less time consuming, economical one-pot method of synthesis has been developed for the production of silver nanoparticles (AgNPs). The AgNPs that are stabilized and surface functionalized by Lv. Functionalization of AgNPs by antibiotic drug Lv has been thoroughly confirmed using FTIR spectrophotometry. Two carbonyl oxygen moieties, one belongs to the pyridine oxygen group and another one from the carboxylate oxygen group of Lv together form the binding site over the nanoparticle surface. The Lv-AgNPs system has shown naked eye detectable colour change, as well as significant change via both UV–Vis and fluorescence spectroscopy. The limits of detection (LODs) are predicted to be 6.86×10−8M for Hg2+ and 2.52×10−9M for Fe3+ using UV–Vis spectroscopy and 2.35×10−9M for Fe3+ using fluorescence spectroscopy. UV–Vis spectroscopy, fluorescence spectroscopy, FTIR, TEM, DLS etc. have been used for the physico-chemical characterization of Lv-AgNPs system and the nanoparticle mediated sensing process. Detailed experimental and theoretical studies employing FTIR spectrophotometry and density functional theory (DFT) studies have been used for the elucidation of drug-nanoparticle based sensing mechanism. It is also demonstrated that the Lv-AgNPs system can show real time application using Test-Paper Kit to establish the drug-nanoparticle assembly as a potential colorimetric turn-OFF/turn-ON sensing system for Hg2+ and Fe3+ respectively.

Hg2+ Sensor Development Based on (E)-N'-Nitrobenzylidene-Benzenesulfonohydrazide (NBBSH) Derivatives Fabricated on a Glassy Carbon Electrode with a Nafion Matrix.

Three novel derivatives of (E)-N′-nitrobenzylidene-benzenesulfonohydrazide (NBBSH) were synthesized by a condensation method from nitrobenzaldehyde and benzenesulfonylhydrazine reactants in low to moderate yields, which crystallized in methanol, acetone, ethyl acetate, and ethanol. NBBSH derivatives were totally characterized using various spectroscopic techniques, such as Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, proton nuclear magnetic resonance spectroscopy (1H NMR), and carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy. The molecular structure of the NBBSH derivates was confirmed by the single crystal X-ray diffraction method and used for potential detection of a selective heavy metal ion, mercury (Hg2+), by a reliable I–V method. A thin coating of NBBSH derivatives was deposited on a glassy carbon electrode (surface area = 0.0316 cm2) with a binder (nafion) coating to modify a sensitive and selective Hg2+ sensor with a short response time in phosphate buffer. The modified cationic sensor exhibited enhanced chemical performances, such as higher sensitivity, linear dynamic range, limit of detection (LOD), reproducibility, and long-term stability toward Hg2+. The calibration curve was found to be linear over a wide range of Hg2+ concentrations (100.0 pM–100.0 mM). The sensitivity and LOD were considered to be ∼949.0 pA μM–1cm–2 and 10.0 ± 1.0 pM (S/N = 3), respectively. The sensor was applied to the selective measurement of Hg2+ in spiked water samples to give acceptable and satisfactory results.

Spirooxazine molecular switches with nonlinear optical responses as selective cation sensors

Spirooxazine, a photochromic material, can transform into metallic open-form merocyanine by molecular switching, giving rise to large contrasts in its second-order nonlinear optical (NLO) properties.

Fabrication of cadmium ionic sensor based on (E)-4-Methyl-N′-(1-(pyridin-2-yl)ethylidene)benzenesulfonohydrazide (MPEBSH) by electrochemical approach

We synthesized a very simple and new molecule with good yield to develop heavy metallic sensor for the detection of selective Cd2+ ions in aqueous solutions. (E)-4-Methyl-N′-(1-(pyridin-2-yl)ethylidene)benzenesulfonohydrazide (MPEBSH) was prepared following a simple condensation method, which was characterized in details using well known spectroscopic techniques like 1HNMR, 13CNMR, IR, UV-Vis and finally single crystal diffraction studies gave the structure of target molecule. The molecule was crystalized in monoclinic crystal system (β = 102.59°) with P21/c space group. The thin-layer of MPEBSH onto glassy carbon electrode (GCE) was fabricated with conducting coating agents (5.0% ethanolic nafion solution) to fabricate a sensitive and selective Cd2+ ions sensor in short response time in phosphate buffer phase. The fabricated heavy cationic-sensor exhibited high sensitivity, large-dynamic concentration ranges, long-term stability, and improved electrochemical performances towards cadmium ions. The calibration plot is linear (r2 = 0.9915) over the large Cd2+ concentration ranges (0.35 nM ∼ 0.35 mM). The sensitivity and detection limit is ∼2.2215 μA μM−1 cm−2 and ∼0.14 nM (signal-to-noise ratio, at a SNR of 3) respectively. This novel effort initiated a well-organize way of efficient cationic sensor development with conducting binder deposited on GCE for toxic pollutants in environmental and health-care fields in large scales.

Bis(tetraethylthiophosphoramidoyl)methylamine as an electrochemical ligand for the simultaneous detection of iron and copper bivalent cations

A new thiophosphoramide-based electrochemical ligand was synthesized and used as a bivalent metallic cation sensor. Electrochemical studies reveal a sensitive detection process toward various cations such as Fe 2+ , Co 2+ , Ni 2+ , Cd 2+ , Cu 2+ and Ca 2+ . The chelation process was accompanied by dramatic changes in the redox properties of the free ligand. Interestingly, the ligand shows a simultaneous sensing behavior towards iron and copper cations. The oxidation peak potentials of the two complexes can be well separated, allowing sensitive detection. Furthermore, UV–Visible spectra showed redshifts of absorbance bands of the free ligand in the presence of cations due to the coordination of the thiophosphoryl groups. Electrochemical and UV–Visible studies confirmed that the metal-ligand complexes have 1:2 stoichiometry. Dans ce travail, un nouveau ligand électrochimique à base de thiophosphoramide a été synthétisé pour la détection des cations métalliques bivalents. Les études électrochimiques ont montré que la présence de différents cations métalliques tels que Fe 2+ , Co 2+ , Ni 2+ , Cd 2+ , Cu 2+ et Ca 2+ provoque un changement considérable au niveau des propriétés électrochimiques du ligand libre. Par ailleurs, le ligand a montré la possibilité de détecter d'une manière simultanée les ions Fe 2+ et Cu 2+ . En outre, les investigations UV–Visible montrent un déplacement considérable des bandes d'absorption du ligand vers les longueurs d'onde infrarouge. Ceci est dû à la coordination des groupements thiophosphoryles présents dans la structure du ligand. Les études électrochimiques et par UV–Visible confirment que les complexes formés ont une stœchiométrie 1:2.

Fluorescent Protein-Based Ca2+ Sensor Reveals Global, Divalent Cation-Dependent Conformational Changes in Cardiac Troponin C.

Cardiac troponin C (cTnC) is a key effector in cardiac muscle excitation-contraction coupling as the Ca2+ sensing subunit responsible for controlling contraction. In this study, we generated several FRET sensors for divalent cations based on cTnC flanked by a donor fluorescent protein (CFP) and an acceptor fluorescent protein (YFP). The sensors report Ca2+ and Mg2+ binding, and relay global structural information about the structural relationship between cTnC’s N- and C-domains. The sensors were first characterized using end point titrations to decipher the response to Ca2+ binding in the presence or absence of Mg2+. The sensor that exhibited the largest responses in end point titrations, CTV-TnC, (Cerulean, TnC, and Venus) was characterized more extensively. Most of the divalent cation-dependent FRET signal originates from the high affinity C-terminal EF hands. CTV-TnC reconstitutes into skinned fiber preparations indicating proper assembly of troponin complex, with only ~0.2 pCa unit rightward shift of Ca2+-sensitive force development compared to WT-cTnC. Affinity of CTV-TnC for divalent cations is in agreement with known values for WT-cTnC. Analytical ultracentrifugation indicates that CTV-TnC undergoes compaction as divalent cations bind. C-terminal sites induce ion-specific (Ca2+ versus Mg2+) conformational changes in cTnC. Our data also provide support for the presence of additional, non-EF-hand sites on cTnC for Mg2+ binding. In conclusion, we successfully generated a novel FRET-Ca2+ sensor based on full length cTnC with a variety of cellular applications. Our sensor reveals global structural information about cTnC upon divalent cation binding.

Development of highly efficient Co2+ ions sensor based on N,N′-(ethane-1,2-diyl)bis(2,5-dimethoxybenzenesulfonamide) (EBDMBS) fabricated glassy carbon electrode

Two bis-sulfonamides, N,N′-(ethane-1,2-diyl)bis(2,5-dimethoxybenzenesulfonamide) (EBDMBS) and N,N′-(ethane-1,2-diyl)bis(2-methoxy-5-bromobenzenesulfonamide) (EBMBBS) were synthesized to study their applications as heavy metal sensors. These molecules were prepared via very environment friendly methodology using diaminoethane and respective sulfonyl chlorides as reactants. Aromatic rings were ornamented with electron donating and withdrawing groups for comparison studies and to choose a best ligand for sensor preparation. The synthesized molecules were well characterized using UV/VIS, IR and NMR (1H &13C) spectroscopic techniques. Finally, single crystal X-Ray diffraction studies prove the structures of our designed molecules. For the selective and sensitive potential sensor application, EBDMBS and EBMBBS were fabricated onto glassy carbon electrode (GCE; surface area, 0.0316 cm2) with conducting nafion binders to develop a Co2+ ions sensor in phosphate buffer phase. The fabricated ionic-sensor with EBDMBS/GCE is exhibited higher sensitivity, large-dynamic concentration ranges, long-term stability, and improved electrochemical performances towards cobalt ions. The calibration plot is linear (r2 = 0.9891) over the large Co2+ concentration ranges (0.35 nM–3.5 mM). The sensitivity and detection limit is ∼1.87 μAμM−1cm−2 and ∼0.17 ± 0.02 nM (signal-to-noise ratio, at a SNR of 3) respectively. This novel effort is initiated a well-organize way of efficient cationic sensor development for toxic pollutants in environmental and health-care fields in large scales.

Sensitive and selective Cu2+ sensor based on 4-(3-(thiophen-2-yl)-9H-carbazol-9-yl)benzaldehyde (TPCBZ) conjugated copper-complex

4-(3-(thiophen-2-yl)-9H-carbazol-9-yl)benzaldehyde (TPCBZ) was synthesized under microwave irradiation with auto generated pressure (at 130.0 °C) and characterized by 1H NMR, 13C NMR, Mass and FTIR spectroscopy, thin-layer chromatography (TLC), and elemental analyses. Here, a thin-layer of TPCBZ onto glassy carbon electrode (GCE) is fabricated with conducting coating agents (5% nafion) to fabricate a selective and selective Cu2+ sensor in short response time in phosphate buffer phase. The fabricated sensor (TPCBZ/Nafion/GCE) is exhibited higher sensitivity, large-dynamic concentration ranges, long-term stability, and improved electrochemical performances towards TPCBZ-conjugated copper complex for selective Cu2+ sensor. The calibration plot is linear (r2: 0.9979) over the large Cu2+ ions concentration ranges (1.0 nM–1.0 mM). The sensitivity and detection limit is ∼1.12974 μAcm−2 μM−1 and ∼0.84 ± 0.02 nM (signal-to-noise ratio, at a SNR of 3) respectively, which is calculated from the slope of the calibration plot. This novel effort is initiated a well-organize way of efficient cationic sensor improvement with carbazide for heavy metallic pollutants in environmental and health-care fields in large scales.

Microwave-assisted synthesis of novel amide based chiral tripodal receptors for recognition of cation and anion sensors

Microwave-assisted synthesis of novel amide based chiral tripodal receptors for recognition of cation and anion sensors

Inner and Outer Coordination Shells of Mg(2+) in CorA Selectivity Filter from Molecular Dynamics Simulations.

Structural data of CorA Mg(2+) channels show that the five Gly-Met-Asn (GMN) motifs at the periplasmic loop of the pentamer structure form a molecular scaffold serving as a selectivity filter. Unfortunately, knowledge about the cation selectivity of Mg(2+) channels remains limited. Since Mg(2+) in aqueous solution has a strong first hydration shell and apparent second hydration sphere, the coordination structure of Mg(2+) in a CorA selectivity filter is expected to be different from that in bulk water. Hence, this study investigated the hydration structure and ligand coordination of Mg(2+) in a selectivity filter of CorA using molecular dynamics (MD) simulations. The simulations reveal that the inner-shell structure of Mg(2+) in the filter is not significantly different from that in aqueous solution. The major difference is the characteristic structural features of the outer shell. The GMN residues engage indirectly in the interactions with the metal ion as ligands in the second shell of Mg(2+). Loss of hydrogen bonds between inner- and outer-shell waters observed from Mg(2+) in bulk water is mostly compensated by interactions between waters in the first solvation shell and the GMN motif. Some water molecules in the second shell remain in the selectivity filter and become less mobile to support the metal binding. Removal of Mg(2+) from the divalent cation sensor sites of the protein had an impact on the structure and metal binding of the filter. From the results, it can be concluded that the GMN motif enhances the affinity of the metal binding site in the CorA selectivity filter by acting as an outer coordination ligand.

High performance polyaniline/vanadyl phosphate (PANI–VOPO4) nano composite sheets prepared by exfoliation/intercalation method for sensing applications

A new class novel polyaniline/vanadyl phosphate (PANI–VOPO4) composite was synthesized by exfoliation/intercalation method. The sol of polyaniline (PANI) into the gel of VOPO4 by ranging mixing volume ratios concentration of inorganic reactant with a fixed mixing volume ratios i.e.(1:1) of organic polymer. The physico-chemical characterization was carried out by SEM, XRD, FTIR, UV–vis and simultaneous TGA studies. The analytical utility of this membrane was established by employing it as a sensor in electrometric titrations. Lead (Pb2+) is a serious carcinogenic and one of the most toxic heavy metals presents in the environmental contaminants. PANI–VOPO4 onto flat-glassy carbon electrode (GCE; surface area: 0.0316cm−2) was fabricated with conducting coating agents to fabricate a sensitive and selective Pb2+ ions sensor in short response time in phosphate buffer phase. The fabricated cationic-sensor is exhibited higher sensitivity, large-dynamic concentration ranges, long-term stability, and improved electrochemical performances toward lead ions. The calibration plot is linear (r2=0.9798) over the large Pb2+ concentration ranges (2.0nM–2.0mM). The sensitivity and detection limit is ∼2.105μAmMcm−2 and ∼1.36±0.05nM (signal-to-noise ratio, at a SNR of 3) respectively. This novel effort is initiated a well-organize way of efficient cationic sensor development with conducting binder deposited GCE for toxic pollutants in environmental and health-care fields in large scales. Therefore, the PANI–VOPO4/GCE sensor offers a cost effective material that can be considered as a viable alternative for effectively detecting and removing toxic Pb2+ from water samples.

Selective chromo-fluorogenic molecular sensor for dual channel recognition of Cu2+and F−: effect of functional group on selectivity

The amido-Schiff base (3-hydroxy-naphthalene-2-carboxylic acid(4-cyano-benzylidene)-hydrazide) shows dual mode sensibility towards Cu2+and F−. It can detect Cu2+in HEK 293 cells and F−in tooth paste and in solid state.

Cysteine-based silver nanoparticles as dual colorimetric sensors for cations and anions

The synthesis of amide–triazole-based Ag NPs and their sensing ability towards anions and cations in aqueous solution were investigated. The importance of amide–triazole as a binding motif, in conjunction with Ag NPs, and the mode of the sensing ability of these amide–triazole Ag NPs as dual colorimetric sensors have been studied in detail.

Complexation of Donor-Acceptor Substituted Aza-Crowns with Alkali and Alkaline Earth Metal Cations. Charge Transfer and Recoordination in Excited State.

Complexation between two aza-15-crown-5 ethers bearing electron donor and acceptor fragments and alkali and alkaline earth perchlorates has been studied using absorption, steady-state fluorescence and femtosecond transient absorption spectroscopy. The spectral-luminescent parameters, the stability and dissociation constants of the complexes were calculated. The intramolecular charge transfer reaction takes place both in the excited state of the crowns and their complexes 1:1; the latter is subjected to photorecoordination resulting in a weakening or a complete disruption of coordination bond between nitrogen atom and metal cation, disposed within a cavity of the crown. The compounds investigated can be viewed as novel optical molecular sensors for alkali and alkaline-earth metal cations. The photoejection of a metal cation into the bulk was not observed.

Cucurbit[7]uril-improved recognition by a fluorescent sensor for cadmium and zinc cations

The host–guest interaction of cucurbit[7]uril (Q[7]) with the new fluorescent sensor guest molecule (BIBPAH+), formed by alkylation of the secondary amine site in N,N-bis(2-pyridylmethyl)amine with 2-(bromomethyl)benzimidazole, was investigated by fluorescence and 1H NMR spectroscopy. The results indicate the formation of an inclusion complex in a 1:1 ratio with an association constant of Ka = (2.9 ± 0.7) × 105 L ∙ mol−1. There is minimal difference in the fluorescence intensities upon the introduction of each of Mn2+, Ni2+, Co2+, Cr3+, Ho3+ and Lu3+. However, the emission was slightly quenched on the addition of Cu2+ or Fe3+ whether Q[7] is present or not. Further investigation showed that encapsulation of BIBPAH+ in Q[7] improves Cd2+ and Zn2+ recognition by enhancing the fluorescence intensity, leading to an improvement in the limits of detection. In contrast, comparative parallel experiments in which Cu2+, Mn2+, Ni2+, Co2+, Fe3+, Cr3+, Ho3+ or Lu3+ were substituted for Zn2+ or Cd2+ resulted in minimal changes in the fluorescence that occurs for the corresponding metal-free system. The natures of the encapsulated Zn2+ and Cd2+ complexes have been investigated using fluorescence and 1H NMR spectroscopy as well as by quantum chemistry.

A novel Ag+ cation sensor based on polyamidoamine dendrimer modified with 1,8-naphthalimide derivatives

In this study, 4-amino-1,8-naphthalimide-conjugated polyamidoamine dendrimer was synthesized and characterized and its potentiality as a cation sensor was investigated. 4-Amino-1,8-naphthalic anhydride reacted with polyamidoamine dendrimer and the product was characterized using FTIR, 1H NMR, 13C NMR and melting point analysis method. The synthesized compound was applied to detect various cations in water media and N,N-dimethylformamide (DMF) via monitoring the quenching of the fluorescence intensity. Furthermore, various metal cations including Cu2+, Ni2+, Zn2+, Pb2+,Ca2+, Ba2+, Cd2+, Hg2+, Fe2+, Fe3+ and Ag+ were tested. The complexes formed between the synthesized compound and metal cations in solution and their effects on Photoinduced Electron Transfer (PET) process were investigated regarding the potential application of the newly-synthesized dendrimer as a colorimetric and fluorescent sensor for such cations. The results clearly confirmed that the 1,8-naphthalimide groups surrounding the central dendrimer core showed strong green fluorescence emission at 553nm. This effect considerably decreased with the introduction of all cations, except Ag+ where the fluorescence quenching effect was remarkable and more dominant. Therefore, it can be concluded that the synthesized dye has the potentiality of being a highly sensitive and selective fluorescence sensor for Ag+ cation.

Polypyrrole-based amperometric cation sensor with tunable sensitivity

This article presents a novel technique to quantify the kinetics of faradaic response in polypyrrole (doped with dodecylbenzenesulfonate) (PPy(DBS)) and its application in developing a cation sensor. This technique is based on the analysis of the impedance/admittance transfer function of PPy(DBS) and the representation of its reduction chronoameprometric response using system poles and residues. The results presented in this paper demonstrate that the pole of the transfer function is an intrinsic quantity and the residue corresponding to the system pole is an extrinsic quantity. The residue of the system pole for a redox-step potential is dependent on the concentration of cations and is observed to have linear dependence on electrolyte concentration ( R2 > 0.9). Thus, the residues can be used to accurately estimate the concentration of cations in an electrolyte solution and enables the use of PPy(DBS) as a high-precision cation sensor. The experimental investigation supporting this analysis demonstrates that the sensitivity of residue to concentration can be varied by equilibrating PPy(DBS) a priori in the cation containing solution of known concentration and by varying the morphology of PPy(DBS).

Synthesis of benzoazacrown ethers by transformation of benzocrown macrocycle and preparation of related complexing agents

The results of studies aimed at producing and developing a new methodology of synthesis of functional derivatives of benzoazacrown ethers by stepwise transformation of the benzocrown macrocycle are generalized. The comprehensive study of the spatial structure and complexation properties of the starting benzocrown ethers, target benzoazacrown ethers, and their nearest structural analogs shows that the N-alkylbenzoazacrown derivatives exhibit a much higher ability to bind metal and ammonium cations compared to the corresponding N-phenylazacrown ethers. They are comparable with benzocrown ethers in complexation properties and exceed them in some cases. A new approach to the synthesis of dinitrodibenzodiazacrown ethers is proposed based on the one-step transformation of the macrocycle of the dinitrodibenzo18-crown-6 cis-isomer under the action of aliphatic diamines. The synthesis of styryl dyes containing the N-methylbenzoazacrown fragment is described. The detailed studies by electron spectroscopy, NMR spectroscopy, and X-ray diffraction analysis revealed a high potential of these dyes as optical molecular sensors for alkaline and alkaline-earth metal cations.