Fluorescent chemosensor for Ag(I) based on amplified fluorescence quenching of a new phthalocyanine bearing derivative of benzofuran

Oxidation of diclofenac in the presence of iron(II) octacarboxyphthalocyanine

This paper presents the results of the research on the influence of catalytic activity of iron(II) octacarboxyphthalocyanines (FePcOC) on the transformation of diclofenac (DCF) which is the most popular anti-inflammatory analgesic. Diclofenac poses a serious threat to the natural environment. The paper demonstrates that diclofenac, in the presence a monomeric form of iron octacarboxyphthalocyanine and hydroxyl radicals (HO^•) (from H₂O₂), undergoes a transformation into diclofenac-2,5-iminoquinone (DCF-2,5-IQ), causing distinct changes in the UV-Vis absorption spectrum. In the presence of iron octacarboxyphthalocyanine and H₂O₂, the previously colourless diclofenac solution becomes intense orange. As a result, a new band at approx. 450 nm appears in the absorption spectrum. HPLC analysis has shown that the concentration of diclofenac decreases with time. TD-DFT calculations using the CAM-B3LYP/6-31+G (d, p) method have been conducted to confirm experimental data concerning the formation of a new band at λ_max = 450 nm.

Metal (Mn, Fe, Co, Ni, Cu, and Zn) Phthalocyanine-Immobilized Mesoporous Carbon Nitride Materials as Durable Electrode Modifiers for the Oxygen Reduction Reaction

In the search for alternative sources to replace fossil fuels, carbon nitride materials can be used in a variety of ways. In the present work, porosity is introduced to the carbon nitride material using mesoporous silica material, MCM-41, as a hard template, and a mesoporous carbon nitride (MCN) material is synthesized. Further, the MCN is modified by immobilizing metal phthalocyanine (MPc, where M = Mn, Fe, Co, Ni, Cu, and Zn). The resulting MPc-incorporated MCN materials (MPc@MCN) were tested for the electrocatalytic oxygen reduction reaction (ORR) in acidic and basic media. Detailed studies reveal that the FePc@MCN and CoPc@MCN materials exhibit higher ORR activity than the other composites in 0.1 M KOH. FePc@MCN follows a direct four-electron oxygen reduction mechanism and shows ORR onset potential (vs RHE) at 0.93 V (in 0.1 M KOH), which is very close to the onset potential exhibited by the state-of-the-art material, Pt-C (1.0 V), and higher than several similar composites of MPc with carbon supports tested in similar environments. Besides, due to the inherent property of coordination through nitrogen present on the MCN, FePc@MCN shows excellent stability even after 3000 cyclic voltammetry (CV) cycles. FePc@MCN was found to have a better methanol tolerance in comparison to Pt-C in basic medium. CoPc@MCN shows a highly selective two-electron reduction reaction in both acidic and basic media at lower overpotential than many of the reported catalysts for the two-electron oxygen reduction. Therefore, these materials (FePc@MCN and CoPc@MCN) can be used as suitable alternatives to replace Pt and other expensive materials in ORR and related applications.

Elucidation of Selectivity for Silver Ion Based on Metal-Induced H-Type Aggregation of Fluorescent Receptor

In present work, a new substituted phthalonitrile derivative was prepared by the nucleophilic displacement reaction and then highly soluble zinc phthalocyanine (ZnPc) with four peripheral 1-hydroxyhexan-3-ylthio groups was synthesized by cyclotetramerization and characterized by FTIR, ¹H and ¹³C NMRs spectroscopies, fluorescence and UV-vis measurements. The optical property and quantum yield of ZnPc were elucidated in mixed solvent of ethanol/water with varying compositions. The pH-dependent fluorescence and absorbance spectra of ZnPc in the absence and presence of Ag⁺ ions were obtained to elucidate the optimum pH value that is convenient for stable complex formation in predetermined mixture. A comparative study for recognition of Ag⁺ ion has been carried out to evaluate the effect of the solution parameters on selective sensing ability of ZnPc as a fluorescent receptor. Interference effect was investigated by spectrofluorometric titration based on fluorescence quenching of ZnPc upon addition of Ag⁺ ion in the presence of foreign metal ions. Stepwise complexation/decomplexation cycles with Na₂S-titration by fluorescence quenching/enhancement were investigated to establish the reversible response rate and reusability of ZnPc toward Ag⁺ ions. Graphical Abstract Selective determination of silver ion based on H-type aggregation of zinc phthalocyanine.

Zinc(ii), copper(ii) and cadmium(ii) complexes as fluorescent chemosensors for cations

The fluorescence chemosensing behavior of Zn(ii), Cu(ii), and Cd(ii) based complexes toward cations has been described. Cation detection via conventional mechanisms, metal-metal exchange and chemodosimetric approaches along with the importance of metal ions and the scope, significance, and challenges with regard to the detection of cations by metal complex based probes will be discussed in detail. The fundamentals of photophysical behavior and mechanisms involved in the fluorescence detection of analytes will also be described. This article provides a detailed overview of Zn(ii), Cu(ii), and Cd(ii) based complexes as fluorescent probes for cations, together with essential discussions pertaining to detection mechanisms.

A Fluorescent Turn-On Carbazole-Rhodanine Based Sensor for Detection of Ag+ Ions and Application in Ag+ Ions Imaging in Cancer Cells

Carbazole - Rhodanine conjugate is an effective fluorescent host for silver ions through fluorometric transformation from green to red color with a hyperchromic emission. An intramolecular charge transfer process derived from carbazole towards rhodanine favors interaction of thiocarbonyl S and carboxylic acid O of the rhodanine moiety towards Ag⁺ ion. Carbazole - rhodanine dyad accomplishes the lowest detection limit of 12.8 × 10^-9 M and high quantum efficiency. A fluorescence reversibility of the probe with I^- ion surges reutilization of sensor molecule as an Ag⁺ ion probe with minimal loss in the fluorescent efficiency. This fluorescent ligand is a biocompatible probe and is also a proficient candidate for fluorescent imaging of Ag⁺ ion in live cells.

A New Pathway for the Synthesis of a New Class of Blue Fluorescent Benzofuran Derivatives

In this study an efficient and straightforward method for obtaining a new class of blue fluorescent bezofuran derivatives, under microwave irradiation, as well as under conventional thermal heating, is presented. Under conventional TH the reactions occur selectively, and a single type of benzofuran ester derivative was obtained. The synthesis under MW irradiation also led to benzofuran derivatives, but in a time-dependent manner. Irradiation for a short period of time led to a mixture of two types of benzofuran derivatives (3a⁻c and 4a⁻c), while MW irradiation for a longer period of time led to a single type of benzofuran (3-methylbenzofuran), the reaction becoming highly selective. Taking into consideration the advantages offered by MW irradiation in terms of a substantial decrease of solvent consumed, a substantial reduction in reaction time (from days to hours), and a consequent diminution in energy consumption, these methods could be considered environmentally friendly. Here, feasible reaction mechanisms for the benzofuran derivatives formation are described. The absorption and fluorescence emission of the obtained benzofuran derivatives were studied, with part of these compounds being intense blue emitters. A certain influence of the benzofuran substituents concerning absorption and fluorescent properties was observed. Only compounds anchored with a carbomethoxy group of furan ring have shown good quantum yields.

Sequential detection of Fe3+/2+ and pyrophosphate by a colorimetric chemosensor in a near-perfect aqueous solution

A colorimetric chemosensor was developed for Fe^3+/2+ and pyrophosphate with low detection limit and practical application for Fe³⁺ in water samples.

Polyoxy-Derivatized Perylenediimide as Selective Fluorescent Ag (I) Chemosensor

Recent investigations indicated that same concentrations of the ionic silver have harmful effects on aquatic life, bacteria and human cells. Herein we report chemosensory properties of N,N ^' -Bis(4-{2-[2-(2-methoxyethoxy)ethoxy] eth- oxy}phenyl) -3,4:9,10-perylene tetracarboxydiimide (PERKAT) towards ionic silver. The dye doped sensing agents were prepared utilizing ethyl cellulose (EC) and poly (methylmethacrylate) (PMMA) and then forwarded to electrospinning to prepare sensing fibers or mats. The PERKAT exhibited bright emission in embedded forms in EC or in the solvents of N,N-Dimethylformamide (DMF), Dichloromethane (DCM), Tetrahydrofurane (THF) and in the mixture of DCM/ethanol. The PERKAT exhibited selective and linear response for ionic silver in the concentration range of 10^-10 - 10^-5 M Ag (I) at pH 5.5. Detection limits were found to be 2.6 × 10^-10 and 4.3 × 10^-11 M, in solution phase studies and PERKAT doped sensing films, respectively. Cross sensitivity of the PERKAT towards pH and some metal ions was also studied. There were no response for the Li⁺, Na⁺, K⁺, Ca²⁺, Ba²⁺, Mg²⁺, NH₄⁺, Ni²⁺, Co²⁺, Cu²⁺,Pb²⁺, Al³⁺, Cr³⁺,Mn²⁺, Sn²⁺, Hg⁺, Hg²⁺, Fe²⁺ and Fe³⁺ in buffered solutions. To the best of our knowledge, this is the first study investigating silver sensing abilities of the PERKAT.

A Simple Spectrofluorimetric Method Based on Quenching of a Nickel(II)-Phthalocyanine Complex to Determine Iron (III)

A new nickel(II)-phthalocyanine complex (NiPc) was synthesized and used as a fluorescent ligand in determination of iron in real samples. The NiPc compound, when excited at 350 nm, decreases of emission with increases of the iron(III) concentration at 425 nm were used analytical response in a modified standard addition method. The method was validated by analyzing two certified reference materials (CRM-SA-C Sandy Soil C and Mixed Polish Herbs (INCT-MPH-2). Food and drug samples were digested in a closed microwave system using nitric acid and hydrogen peroxide. Therefore, all iron in the samples converted to iron(III) ion. These solutions were used directly in determination of iron(III) ion. No cleanup or enrichment of the solutions was required. The calibration graph was linear until 14.00 μg mL(-1). Detection limit and quantification limit were 1.29 μg mL(-1) and 3.88 μg mL(-1), respectively. The method provided accurate results for the majority of the food samples tested, including spanich, dill, mint, purslane, rocket, red lentils, dry beans and two iron medicinal tablets. Also, the high recovery (95.6 %) was obtained for a fortified stream water sample. The simple and cost-effective method is suitable for monitoring total iron concentration in foods and drug samples.

Tuning of azine derivatives for selective recognition of Ag+ with the in vitro tracking of endophytic bacteria in rice root tissue

X-ray structurally characterized probes to track Ag⁺ in in vitro endophytic bacteria at rice root tissue and human breast cancer cells (MCF7).

Structural, molecular orbital and optical characterizations of binuclear mixed ligand copper (II) complex of phthalate with N,N,N',N'-tetramethylethylenediamine and its applications

A new binuclear mixed ligand complex, [Cu2(Phth)(Me4en)2(H2O)2(NO3)2]·H2O (where, Phth=phthalate, and (Me4en)=N,N,N',N'tetramethylethylenediamine) was synthesized and characterized using analytical, spectral, magnetic, molar conductance, thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and transmission electron microscope (TEM) measurements. The XRD data of Cu(II)-complex was analyzed on the basis of Williamson-Hall (W-H) and compared with TEM results. The results indicate that the complex is well crystalline and correspond to hexagonal crystal structure. Analysis of the absorption coefficient near the absorption edge reveals that the optical band gaps are indirect allowed transition with values of 1.17 and 1.78 eV. The d-d absorption bands of the complex (dissolved in various solvents) exhibit a color changes (solvatochromic). Specific and non-specific interactions of solvent molecules with the complex were investigated using Multiple Linear Regression Analysis (MLRA). Transient photocurrent characteristics of Cu(II)-complex/n-Si heterojunctions indicate that photocurrent under illumination increase with increasing of light intensity and explained by continuous distribution of traps. Structural parameters of the free ligands and their Cu(II)-complex were calculated on the basis of semi-empirical PM3 level and compared with the experimental data. The present copper (II) complex was screened for its antimicrobial activity against some Gram-positive and Gram-negative bacteria and fungus strain.

Synthesis and spectroscopic-electrochemical properties of novel ratiometric Hg (II) chemosensor containing Bodipy and the N-phenylaza-15-crown-5 moiety

The aryl-amine containing azacrown ether ring and alkyl-chloro boradiazaindacene (Bodipy) were synthesized by Schiff base condensation. The absorption and emission of a novel Schiff base derivative (based on azacrown-Bodipy ) were performed in presence of different cations such as Zn²⁺, Ga³⁺, Pb²⁺, Hg²⁺, NH₄⁺ Ca²⁺, Cu²⁺, Na⁺, Ni²⁺, Cd²⁺ and Cr³⁺. The complexation property of the Schiff base was studied in dimethylformamide (DMF) by interacting azacrown-ether group and transition metal nitrates-ammonium chloride. The electrochemical behavior of the Schiff base has also been investigated by cyclic voltammetry. All experimental results indicated that the new compound act as a selective ratiometric chemosensor for Hg²⁺.

Synthesis of highly fluorescent silver clusters on gold(I) surface

Evolution of fluorescence from a giant core-shell particle is new and synergistic, which requires both gold and silver ions in an appropriate ratio in glutathione (GSH) solution. The formation of highly fluorescent Ag(2)/Ag(3) clusters on the surface of Au(I) assembly results in giant Au(I)(core)-Ag(0)(shell) water-soluble microparticles (~500 nm). Here, Au(I) acts as the template for the generation of fluorescent Ag clusters. The presence of gold under the synthetic strategy is selective, and no other metal supports such synergistic evolution. The core-shell particle exhibits stable and static emission (emission maximum, 565 nm; quantum yield, 4.6%; and stroke shift, 179 nm) with an average lifetime of ~25 ns. The drift of electron density by the Au(I) core presumably enhances the fluorescence. The positively charged core offers unprecedented long-term stability to the microparticles in aqueous GSH solution.

Synthesis of 2-(1-Benzofuran-2-yl)-4-(1,3-benzoxazol-2-yl/ 1,3-benzothiazol-2-yl) Quinolines as Blue Green Fluorescent Probes

A series of novel 2-(1-benzofuran-2-yl)-4-(1,3 benzoxazol-2-yl/1,3-benzothiazol-2-yl) quinoline derivatives4(a–d)were synthesized in one step by the reaction of 2-(1-benzofuran-2-yl) quinoline-4-carboxylic acids3(a-b)with o-aminophenol and o-amino thiophenol, respectively, using polyphosphoric acid (PPA) as a cyclizing agent. The fluorescent properties of newly synthesized compounds were investigated in three different organic solvents like chloroform (CHCl3), tetrahydrofuran (THF), and dimethyl sulfoxide (DMSO). The photophysical constants such as quantum yield and stokes shift were determined. From the results of fluorescence study, it is evident that all synthesized compounds are fluorescent in solution. Compound4aemitted green light (490.4 nm, 518.2 nm, and 522.4 nm) with high quantum yield in all the three solvents, while compounds4b, 4c, and4demitted green light (512 nm, 499 nm, 510 nm) only in polar solvent DMSO. All fluorescent probes exhibited a bathochromic shift on increase in polarity of the solvent.

Synthesis and photophysical properties of metallophthalocyanines substituted with a benzofuran based fluoroprobe

The synthesis, characterization and photophysical properties of the tetra- {6-(-benzofuran-2-carboxylate)-hexylthio} substituted copper(II), cobalt(II), manganese(III) and zinc (II) phthalocyanines, {M[Pc(β-S(CH(2))(6)OCOBz-Furan)(4)], which were derived from 6-(3,4-dicyanophenylthio)-hexyl-2-benzofuranate (BzF) (1-4) are reported for the first time. The new compounds have been synthesized and fully characterized by elemental analysis, FTIR, UV-vis, (1)H- and (13)C NMR, MS (Maldi-TOF). In this work, we also report the effects of peripherally bound BzF substituent on the photophysical properties of metallo phthalocyanine derivatives. The effects of changing the central metal ions on quantum yield are discussed. It was found that the substitution of BzF groups on the framework of phthalocyanines diminished the fluorescence quantum yield of these complexes depending on paramagnetic behavior of central metal atoms. In addition, central metal atoms like Co and Cu also caused to decrease in quantum yield of phthalocyanine backbone.

Recent progress in fluorescent and colorimetric chemosensors for detection of precious metal ions (silver, gold and platinum ions)

Due to the wide range of applications and biological significance, the development of optical probes for silver, gold and platinum ions has been an active research area in the past few years. This tutorial review focuses on the recent contributions concerning the fluorescent or colorimetric sensors for these metal ions, and is organized according to their structural classifications (for Ag(+) detection) and unique mechanisms between the sensors and metal ions (for Au(3+) and Pt(2+) detection).