Chemosensors For Metal Ions Research Articles

Fabricating a super stable luminescent chemosensor with multi-stimuli-response to metal ions and small organic molecules through turn-on and turn-off effects

A multi-stimuli-responsive luminescent Ln-MOF (1), with a combination of exceptionally high thermal, air and chemical stabilities, as a turn-on/turn-off chemosensor for metal ions and small organic molecules is reported.

Naphthoquinone based chemosensors for transition metal ions: experiment and theory

Naphthoquinone based chemosensors are studied for metal ion binding in methanol–water–triethylamine solvent mixtures. pH effect, M : L stoichiometry and competitive binding of metal ions is studied.

Aggregation induced enhanced and exclusively highly Stokes shifted emission from an excited state intramolecular proton transfer exhibiting molecule.

The inner filter effect due to self-quenching dominates the normal emission of dyes at higher concentrations, which would limit their applications. Since normal emission was also observed with aggregation induced emission enhancement (AIEE) active excited state intramolecular proton transfer (ESIPT) exhibiting molecules, two new molecules are synthesized and studied to obtain normal emission free AIEE. The molecules are 4-(3-(benzo[d]thiazol-2-yl)-5-tert-butyl-4-hydroxybenzyl)-2-(benzo[d]thiazol-2-yl)-6-tert-butyl phenol (bis-HPBT) and its oxazole analogue (bis-HPBO). Of these molecules, bis-HPBT, which is weakly fluorescent in tetrahydrofuran solution, shows a sudden high enhancement in fluorescence upon addition of 70% water due to the formation of aggregates. Though the normal emission is also observed in tetrahydrofuran, it is completely eliminated in the aggregates, and the aggregates display exclusive tautomer emission. However, bis-HPBO does not emit such an exclusive tautomer emission in the water/tetrahydrofuran mixture. The enhancement in the fluorescence quantum yield of bis-HPBT in 70% water is ∼300 times higher than that in tetrahydrofuran. The modulated molecular structure of bis-HPBT is the cause of this outstanding AIEE. The observation of almost exclusive tautomer emission is a new additional advantage of AIEE from bis-HPBT over other ESIPT molecules. Since the tautomer emission is highly Stokes shifted, no overlap with the absorption spectrum occurs and therefore, the inner filter effect is averted. The aggregated structure acts as a good fluorescence chemosensor for metal ions as well as anions. The aggregated structure is cell permeable and can be used for cell imaging.

Semi-Interpenetrating Polymer Networks with Predefined Architecture for Metal Ion Fluorescence Monitoring.

The development of new synthetic approaches for the preparation of efficient 3D luminescent chemosensors for transition metal ions receives considerable attention nowadays, owing to the key role of the latter as elements in biological systems and their harmful environmental effects when present in aquatic media. In this work, we describe an easy and versatile synthetic methodology that leads to the generation of nonconjugated 3D luminescent semi-interpenetrating amphiphilic networks (semi-IPN) with structure-defined characteristics. More precisely, the synthesis involves the encapsulation of well-defined poly(9-anthrylmethyl methacrylate) (pAnMMA) (hydrophobic, luminescent) linear polymer chains within a covalent poly(2-(dimethylamino)ethyl methacrylate) (pDMAEMA) hydrophilic polymer network, derived via the 1,2-bis-(2-iodoethoxy)ethane (BIEE)-induced crosslinking process of well-defined pDMAEMA linear chains. Characterization of their fluorescence properties demonstrated that these materials act as strong blue emitters when exposed to UV irradiation. This, combined with the presence of the metal-binding tertiary amino functionalities of the pDMAEMA segments, allowed for their applicability as sorbents and fluorescence chemosensors for transition metal ions (Fe3+, Cu2+) in solution via a chelation-enhanced fluorescence-quenching effect promoted within the semi-IPN network architecture. Ethylenediaminetetraacetic acid (EDTA)-induced metal ion desorption and thus material recyclability has been also demonstrated.

Luminescence tuning of the Dy–Zn metal–organic framework and its application in the detection of Fe(iii) ions

A single-component Dy–Zn MOF with white-light emission was used to detect Fe(iii) with the combination of f–f transitions and ligand-based emission, which provides a platform for the design and application of the white-light emitting materials and chemosensors for metal ions.

A bis(pyridine-2-ylmethyl)amine-based selective and sensitive colorimetric and fluorescent chemosensor for Cu2+

A new bis(pyridine-2-ylmethyl)amine derivative (1) was synthesized as a colorimetric and fluorescent chemosensor for metal ions. Experimental results indicate that 1 displays significant colorimetric and fluorescent changes upon binding of Cu2+. Since 1 has a high water solubility as well as good cell-permeability, it successfully applied to detect the presence of Cu2+ ion in HepG2 cells in culture medium. Thus, 1 can be used as a potential Cu2+ chemosensor in aqueous solution and mammalian cells. Further, the fluorescence behavior of 1 upon Cu2+ binding was well explained by our quantum calculation based on electronic structure.

Correction: Fluorescent metal ion chemosensors via cation exchange reactions of complexes, quantum dots, and metal–organic frameworks

Correction for 'Fluorescent metal ion chemosensors via cation exchange reactions of complexes, quantum dots, and metal-organic frameworks' by Jinghui Cheng, et al., Analyst, 2015, DOI: 10.1039/c5an01398d.

Fluorescent metal ion chemosensors via cation exchange reactions of complexes, quantum dots, and metal-organic frameworks.

Due to their wide range of applications and biological significance, fluorescent sensors have been an active research area in the past few years. In the present review, recent research developments on fluorescent chemosensors that detect metal ions via cation exchange reactions (transmetalation, metal displacement, or metal exchange reactions) of complexes, quantum dots, and metal-organic frameworks are described. These complex-based chemosensors might have a much better selectivity than the corresponding free ligands/receptors because of the shielding function of the filled-in metal ions. Moreover, not only the chemical structure of the ligands/receptors but also the identity of the central metal ions have a tremendous impact on the sensing performances. Therefore, sensing via cation exchange reactions potentially provides a new, simple, and powerful way to design fluorescent chemosensors.

A novel 1,10-phenanthroline based chemosensor for differential metal ion sensing and constructing molecular logic gates

A simple tailor-made amidic functionality based on 1,10-phenanthroline unit (1) gave differential absorption changes with only metal ions viz. Cd2+, Zn2+, and Cu2+ ions. In CH3CN solution of 1, addition of Cd2+ and Zn2+ ions resulted in bathochromic shift of ∼65nm, whereas Cu2+ ions resulted in hyperchromic effect with only ∼15nm bathochromic shift. These differential changes observed with Cd2+ and Cu2+ ions addition enabled chemosensor 1 to construct ‘IMLICATION’ and ‘TRANSFER’ logic gates. The observed binding constant values were found to be in order of Cd2+>Zn2+>Cu2+.

Calixarene-Based Fluorescent Chemosensors for Metal Ions via Clicking

Calixarene-based fluorenscent chemosenors, owing to its simplicity, high sensitivity and high detection limits for metal ions in biology and the environment, has been received much attention. Via cliking, calixarene derivations has the group of triazoles, which can bind to metol ions, but also can be modified by various fluorophores. This in-depth review provides an overview of calixarene-based fluorescent chemosensors for metal ions via clicking.

Heterocyclic ring based colorimetric and fluorescent chemosensor for transition metal ions in an aqueous medium

Heterocyclic ring based R1–R3 have been synthesized from the simple condensation method. R1–R3 exhibit highly selective and sensitive recognition towards transition metal ions in an aqueous medium via visual color change and were further confirmed by UV–vis and fluorescent spectroscopic methods. Fluorescent turn on and turn off behavior was observed for receptors tested with transition metal ions. The interaction of transition metal ions and receptors R1–R3 was confirmed to adopt 1:1 binding stoichiometry. Micromolar detection limit was found for R1–R3 with metal ions. DFT theoretical calculations were employed to understand the sensing mechanism of the sensors towards the metal ions. R1 and R2 were also successfully demonstrated as a fluorescent probe for detecting Cu2+ ions in living cells.

2-Aminotryptanthrin Derivative with Pyrene as a FRET-based Fluorescent Chemosensor for Metal Ions

1-(2-tryptanthrinylaminoacetoxy)-14-(1-pyrenecarboxy)-3,6,9,12-tetraoxatetradecane (T2NH-P5P) was synthesized as a fluorescent chemosensor for metal ions. We investigated the metal-ion recognition of T2NH-P5P by separately adding Mg(2+), Ca(2+), Ba(2+), Fe(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Ag(+), Zn(2+), Cd(2+), Hg(2+), Al(3+), and Pb(2+) in an acetonitrile solution. When using excitation at 325 nm, which corresponds to the absorption of the pyrene unit of T2NH-P5P, emission at 600 nm, from the 2-aminotryptanthrin unit, was observed, indicating that intramolecular fluorescence resonance energy transfer (FRET) occurs in T2NH-P5P (FRET-on). However, when Fe(2+), Fe(3+), Ni(2+), Cu(2+), Cd(2+), Hg(2+), and Al(3+) were added to an acetonitrile solution of T2NH-P5P, the behavior changed from FRET-on to FRET-off, which means that the fluorescence of 2-aminotryptanthrin was quenched, whereas that of the pyrene group was revived (FRET-off). Especially, this behavior was remarkable for Fe(2+), Fe(3+), Cu(2+), and Hg(2+). T2NH-P5P is suitable for use as a fluorescent chemosensor for Fe(2+), Fe(3+), Cu(2+), and Hg(2+).

A Colorimetric and “Turn-On” Fluorescent Chemosensor for Metal Ion Based on Rhodamine Derivative

The recognition and sensing of biologically and environmentally important species has emerged as a significant goal in the field of chemical sensors in recent years1. Fluorogenic methods in conjunction with suitable probes are preferable approaches for the measurement of these analytes because fluorimetry is rapidly performed, is nondestructive, is highly sensitive, is suitable for high-throughput screening applications2,3. We synthesized rhodamine derivatives compounds by a Schiff base reaction.

Highly stable antibacterial silver nanoparticles as selective fluorescent sensor for Fe3+ ions

Calix[4]resorcinarene polyhydrazide (CPH) protected water dispersible fluorescent silver nanaoparticles (AgNps) were prepared by one-pot method using water soluble CPH and AgNO3. (CPH) bearing hydrazide group on its periphery acts as a reducing agent and its web type of structure as a stabilizing agent for the formation of calix protected silver nanoparticles (CPH-AgNps). CPH-AgNps were found to be highly stable over 120 days at room temperature and at varied pH. CPH-AgNps were characterized by UV/Vis-spectroscopy, particle size analyzer (PSA), transmission electron microscopy (TEM) and Energy dispersive X-ray analysis (EDX). Duly characterized nanoparticles were explored for their application as sensitive and selective fluorescent chemosensors for various metal ions. It was found that nanoparticles were selective and sensitive only for Fe3+ ions with the linear range of detection from 0.1μM to 10μM. CPH-AgNps were also found to exhibit good antimicrobial activity when compared with standard Chloramphenicol. The selectivity and antimicrobial activity of CPH-AgNps suggests its potential use as a sensor for Fe(III) ions in ecosystems prone to industrial pollution and as an antimicrobial agent in biological applications.

A dansyl–rhodamine chemosensor for Fe(III) based on off–on FRET

A novel fluorescent chemosensor bearing a rhodamine and a dansyl moiety was developed for highly selective detection of Fe3+ based on fluorescence resonance energy transfer (FRET) mechanism. Binding of Fe3+ to the chemosensor induced spirolactam ring opening in the rhodamine moiety and subsequent off–on FRET from the dansyl energy donor to the rhodamine energy acceptor due to the spectral overlap between the emission of the dansyl moiety and the absorption of the ring opened rhodamine moiety. Job’s plot analysis indicated a 1:1 binding stoichiometry between the chemosensor and Fe3+. The association constant was estimated to be 2.72×103M−1 according to the Benesi–Hildebrand method. With the feature of easy synthesis, simple structural skeleton and excellent sensing ability, the newly synthesized chemosensor provided the potential for applying as a highly selective fluorescent probe in complex samples containing various competitive metal ions and developing other metal ion chemosensors to fulfill various needs of biological and environmental field.

Superaromatic terpyridines based on corannulene responsive to metal ions

Two superaromatic terpyridine ligands (1 and 2) incorporating a corannulene unit at the 4'-position are reported. The optical and metal sensing properties of both ligands were investigated by the naked eye, and UV-vis and fluorescence spectroscopy in this work. In 1, the corannulene motif is directly connected to the 4'-phenylterpyridine domain, while in 2, the corannulene motif and the 4'-phenylterpyridine domain are separated by an acetylene linker. Both 1 and 2 can work as chemosensors for metal ions and display different optical responses to various metal ions. It is shown that both ligands exhibit a colorimetric sensing ability for Fe(2+) through an obvious color change from colorless to magenta, and this color change can be observed easily by the naked eye. The addition of Fe(2+) also leads to significant changes in the absorption spectra of the ligands. A characteristic red shift in the emission spectra is observed in the presence of Zn(2+), which facilitates the discrimination of Zn(2+) from other metal ions. In addition, density functional theory (DFT) and time-dependent-density functional theory (TD-DFT) calculations were performed and shown to be consistent with the observed experimental results.

Metal ions optical sensing by semiconductor quantum dots

Colloidal semiconductor nanocrystals or quantum dots (QDs) have been facilitating the development of sensitive fluorescence sensors over the past decade, due to their unique photophysical properties, versatile surface chemistry and ligand binding ability, and the possibility of the encapsulation in different materials or attachment to different functional materials, while retaining their native luminescence property. The optical metal ion chemosensors with high sensitivity and selectivity have been developed due to the importance of the metal ions' fundamental roles, possessed in a wide range of biological processes and the aquatic environment. This review addresses the different sensing strategies with chemically modified QD hybrid structures for the sensing of metal ions in aqueous solution or an in vivo environment, and discusses the photophysical mechanisms in the different sensor systems while comparing their detecting/sensing selectivity. The perspectives for the future potential developments in QD based optical sensing for metal ions are discussed.

Cover Picture: Polyamine Ligand‐Mediated Self‐Assembly of Gold and Silver Nanoparticles into Chainlike Structures in Aqueous Solution: Towards New Nanostructured Chemosensors (ChemistryOpen 5‐6/2013)

Cover PictureAdrián Fernández-Lodeiro, Javier Fernández-Lodeiro, Cristina Núñez*, Rufina Bastida, José Luis Capelo, and Carlos Lodeiro*The cover picture shows the formation of one-dimensional nanochains of silver nanoparticles (AgNPs) upon addition of a polyamine molecular linker. In the present work, the binding ability of this linker was exploited, bearing different functional groups, which favors the self-assembly of silver and gold nanoparticles (AuNPs) into one-dimensional nanochains in aqueous solution. These nanochains visually resemble the artistic work of “calceteiros” (pavers) to build the “calçada Portuguesa” (Portuguese pavements) in Portugal (Photography “calçada Portuguesa”, Jose M. G. Pereira). Polyamine ligands are very versatile materials due to their water solubility and flexibility. The study of AgNPs and AuNPs in one-dimensional nanostructured formations are finally used as new sophisticated heavy metal (Hg2+) ion chemosensors. For more details, see the Full Paper by Carlos Lodeiro, Christina Núñez and co-workers, on p. 200 ff.

Selective recognition by novel calix system: ICT based chemosensor for metal ions

A new calix[4]pyrrole derivative bearing four dansyl groups through hydroxyl groups has been synthesized and duly characterized by FT-IR, NMR and ESI-MS. Tetra dansylated calix[4]pyrrole (TDCP) shows selective behavior for U(VI), Th(IV) and Fe(III) ions among all other metal ions, e.g. Li(I), Na(I), K(I), Ca(II), Ni(II), Cd(II), Cu(II), Zn(II), Pb(II), Hg(II) and Ag(I), in the absorption spectra as well as in the emission spectra. The absorption spectra show a bathochromic shift while the emission spectra along with red-shift exhibit quenching for U(VI), Th(IV) and Fe(III) ions. The binding constants, stoichiometry and quantum yields have been determined. The mechanism of quenching by Stern–Vohmer equation has also been discussed.

An electrochemically prepared sky-blue light emitting ether functionalized polyfluorene as chemosensor for metal ions

Synthesis and electrochemical polymerization of 9,9-bis(2-(2-(2-methoxy ethoxy)ethoxy)ethyl)-fluorene (EO-F) into poly[9,9-bis(2-(2-(2-methoxy ethoxy)ethoxy)ethyl)-fluorene] (EO-PF) films are reported. The boron trifluoride diethyl etherate electrolyte enables facile preparation of EO-PF films at lower potential compared to LiClO4/MeCN and the electrochemical polymerizations are discussed. The EO-PF shows good electrochemical behavior and can be dissolved in solvents such as DMSO and THF. The solubility of EO-PF in THF is 2 mg·mL−1 and the number average molecular weight is 35300 with a polydispersity index of 1.65. The side chains on C9 position of the monomer maintain unchanged after electrooxidation into corresponding polymer. The EO-PF dissolved in THF under 365 nm ultraviolet light is sky blue light emitting with the Commission Internationale de L’Eclairage-CIE coordinates of (0.19, 0.15). The electropolymerized EO-PF is used for the first time in chemosensing metal ions, demonstrating fluorescence quenching for Mn2+ and Fe3+ while fluorescence enhancement for Cr6+ ions.