Nickel(II) and iron(III) selective off-on-type fluorescence probes based on perylene tetracarboxylic diimide

Unravelling the Metal Sensing Activity of a Biologically Relevant Fluorescent Crown Ether: A Unified Experimental and Theoretical Study

1,4-dihydropyridines (DHPs) are biologically active. 1,4-DHP analogs with appropriate substituents also show characteristic fluorescence activity. Here, for the first time, we report a simple and easy synthesis of a novel fluorescent 1,4- DHP derivative of dibenzo[18]-crown-6 (2), which showed promising sensing ability towards physiologically important metal ions. The covalent linking of 1,4-DHP analog with dibenzo[18]-crown-6 instigates its fluorescence activity in (2) and makes it biologically relevant. (2) shows a noteworthy enhancement of fluorescence intensity toward Fe3+ and Ba2+ in methanol medium. DFT studies revealed that metal binding by the crown ether-O atoms leads to structural rigidity, enhancing the fluorescence intensity. Interestingly, (2) shows utility in the quantitative detection of Fe3+ ions in the biological (human blood serum) and food samples.

Two-Dimensional Graphitic Carbon Nitride (g-C3N4) Nanosheets and Their Derivatives for Diagnosis and Detection Applications

The early diagnosis of certain fatal diseases is vital for preventing severe consequences and contributes to a more effective treatment. Despite numerous conventional methods to realize this goal, employing nanobiosensors is a novel approach that provides a fast and precise detection. Recently, nanomaterials have been widely applied as biosensors with distinctive features. Graphite phase carbon nitride (g-C₃N₄) is a two-dimensional (2D) carbon-based nanostructure that has received attention in biosensing. Biocompatibility, biodegradability, semiconductivity, high photoluminescence yield, low-cost synthesis, easy production process, antimicrobial activity, and high stability are prominent properties that have rendered g-C₃N₄ a promising candidate to be used in electrochemical, optical, and other kinds of biosensors. This review presents the g-C₃N₄ unique features, synthesis methods, and g-C₃N₄-based nanomaterials. In addition, recent relevant studies on using g-C₃N₄ in biosensors in regard to improving treatment pathways are reviewed.

Synthesis and bioimaging of a BODIPY-based fluorescence quenching probe for Fe3

Iron is the main substance for maintaining life. Real-time determination of ferric ion (Fe³⁺) in living cells is of great significance for understanding the relationship of Fe³⁺ concentration changes with various physiological and pathological processes. Fluorescent probes are suitable for the detection of trace metal ions in cells due to their low toxicity and high sensitivity. In this work, a boron-dipyrromethene-based fluorescent probe (BODIPY-CL) for selective detection of Fe³⁺ was synthesized. The fluorescence emission of BODIPY-CL was determined at 516 nm. In a pH range of 1 to 10, the probe BODIPY-CL exhibits a quenching response to Fe³⁺. Meanwhile, BODIPY-CL showed a highly selective response to Fe³⁺ compared with 16 kinds of metal ions. The stoichiometry ratio of BODIPY-CL bound to Fe³⁺ was nearly 2 : 1. The fluorescence quenching response obtained by the sensor was linear with the Fe³⁺ concentration in the range of 0-400 μM, and the detection limit was 2.9 μM. BODIPY-CL was successfully applied to image Fe³⁺ in cells. This study provides a promising fluorescent imaging probe for further research on the physiological and pathological effects of Fe³⁺.

Synthesis, Computational and cytotoxicity studies of aryl hydrazones of β-diketones: Selective Ni2+ metal Responsive fluorescent chemosensors

A new fluorescent sensor 2-(2-(3-chloro-4-fluorophenyl)hydrazono)-5,5-dimethyl cyclohexane-1,3-dione (A) and 2-(2-(4-chloro-2-nitrophenyl)hydrazono)-5,5-dimethyl cyclohexane-1,3-dione (B) composed of a β-diketones of aryl hydrazones synthesized by simple and cost-effective method. Various analytical tools analyzed the structural investigations of the synthesized substituted β-diketones of aryl hydrazones like FT-IR, ¹H, ¹³C NMR and UV-Vis techniques, Single-crystal X-ray diffraction studies (SCXRD) (for A), Scanning electron microscopy (SEM), and fluorescence spectroscopy. SEM also investigates surface morphology modifications of aryl hydrazones and Ni²⁺ complex. Furthermore, the metal sensing (Chemo sensing) behavior of newly prepared aryl hydrazones of β-diketones derivatives was further studied by fluorescence spectroscopy. The aryl hydrazones sensor materials show admirable fluorescence selectivity with enrichment to Ni²⁺ over different cations in an aqueous ethanol solution with a recognition extremity of 4 μM-7 μM. A joint experimental and theoretical investigation was led on the chemical structure employing a density functional theory (DFT) (B3LYP), engaging a 6-31G basis set. The DFT technique's enhanced geometrical bond angles and lengths exhibited great covenant with the experimental results. The highest occupied molecular (HOMO) orbital and lowest unoccupied (LUMO) molecular orbital energy has been concluded. The cytotoxicity studies show these compounds impede the growth of KB cells highly and from the studies to evaluate their capability to accurately dock aryl hydrazones to antibodies of cancer protein such as 4LRH, 4L9K, 4 EKD and 4GIW cancer proteins.

Rapid and sensitive detection of dextran sulfate sodium based on supramolecular self-assembly of a perylene diimide derivative in aqueous solution

Dextran sulfate sodium (DSS) is a heparin polysaccharide, whose overuse would cause many adverse effects, such as stiff and painful joints and loss of hair. It is crucial to search after a rapid and accurate approach for the determination of DSS in the clinical treatment and diagnosis. Regrettably, there are few literatures about analytical methods for detecting DSS at present. In this research, a sensitive and selective method for detecting DSS based on the hydrosoluble perylene diimide (PDI) derivative was established in pure aqueous solution. The sensing mechanism and performance of PDI-PdEC were systematically investigated by ultraviolet and fluorescence spectroscopy. Non-covalent interactions between DSS and PDI-PdEC, like π-π stacking, electrostatic and hydrophobic interaction, promote the aggregation of PDI-PdEC and form supramolecular aggregates, which realize the sensitive and rapid detection of DSS in aqueous system. The detection limit for DSS is as low as 5.51 ng/mL and the linear range is 20-500 ng/mL. Furthermore, this probe was triumphantly applied in the detecting of DSS in serum. To the best of our knowledge, this is the first fluorescent probe for detecting DSS in aqueous media. We consider that our study will not only broaden the range of applications of perylene diimide fluorescent sensors, but also provide valuable reference for the design of new sensors for the rapid determination method of DSS.

Design, synthesis and biological evaluation of novel dual-targeting fluorescent probes for detection of Fe3+ in the lysosomes of hepatocytes mediated by galactose-morpholine moieties

In this work, novel dual-targeting probes composed of galactose and morpholine were designed and synthesized for monitoring Fe³⁺ levels in the lysosome of hepatocyte. MP-Gal-1, MP-Gal-2 and MP-Gal-3 showed good selectivity and sensitivities toward Fe³⁺ with the detection limits of 9.40 × 10^-8 M, 7.68 × 10^-8 M and 7.10 × 10^-8 M, respectively. 1:2 stoichiometry is the most likely recognition mode between probe and Fe³⁺. Low toxic MP-Gal-1, MP-Gal-2 and MP-Gal-3 exhibited favorable hepatic targeting effect in both cell and tissue levels, which was because the galactose group of probe could be recognized by ASGPR overexpressed on the hepatocytes. The hepatocyte-targeting capacity followed MP-Gal-1 < MP-Gal-2 < MP-Gal-3 trend, which was attributed to the galactose cluster effect. MP-Gal-1, MP-Gal-2 and MP-Gal-3 also displayed good lysosomes-targeting capacities, because the basic morpholine moiety of probes could be easily attracted by the acidic lysosome. Therefore, MP-Gal-1, MP-Gal-2 and MP-Gal-3 have good dual targeting capacities (liver and lysosome) and could be used to detect lysosomal Fe³⁺ in the liver, which is great significant for precise diagnosis and treatment of liver lysosomal iron-related diseases.

Synthesis and characterization of 4-Halobenzylidene malanonitriles for optical detection of Nickel (II) ions in aqueous solution

In this work, we have developed fluorescent detection techniques for the determination of Ni²⁺ ions in aqueous medium with sensitivity using metal coordinating fluorescent molecules namely 4-Halobenzylidene malanonitrile. The halogen substituted benzylidene malanonitile were synthesised Knoevenagel condensation reaction of various halogen substituted aromatic aldehydes with malanonitrile and products were characterised by IR and NMR spectroscopy. The obtained benzylidene malanonitiles and are exhibited a fluorescent emission with a peak of 430 nm, 440 nm and 448 nm for chloro, bromo and fluoro substituted compounds, respectively. The intensity of optical emission of the studied molecules is increased proportional to the addition of Ni²⁺ ions. The effect of different halogen substitution on the fluorescence behaviour of benylidene malononitrile has also been investigated. The synthesised title compounds showed a lowest detection limit of 10^-20 M for the Nickel (II) ions in aqueous solution under UV-Vis absorption spectra. The molecule 4- Bromobenzylidene malanonitrile exhibited a lowest detection limit of 10^-19 M for the Nickel (II) ions in, aqueous solution, photoluminescence analysis.

Fluorene Based Ferric Complex as Colorimetric and Fluorometric Probe for Highly Selective Detection of CN- and S2- Anions

A series of new chemosensor molecules bearing benzothiazole-, quinoline- and phthalazine-functionalized fluorene derivatives were synthesized and their complexation behaviors with Fe³⁺ and Sn²⁺ ions were investigated. The sensing abilities of their complexes towards both cyanide and sulfide anions were investigated by colorimetric and fluorometric techniques in detail. The sensing mechanism was investigated by Job's and Scatchard plots evaluations, and also absorption/fluorescence titration experiments. Among the studied dye/metal binary systems, F-BT sensor to Fe³⁺ giving the detection limits of 3.1 µg has also displayed high selectivity and sensitivity towards CN^- and S^2- anions, lead to a significant color change of the solution observable by the naked eye.

Review on application of perylene diimide (PDI)-based materials in environment: Pollutant detection and degradation

Environment pollution is getting serious and various poisonous contaminants with chemical durability, biotoxicity and bioaccumulation have been widespreadly discovered in municipal wastewaters and surface water. The detection and removal of pollutants show great significance for the protection of human health and other organisms. Due to its distinctive physical and chemical properties, perylene diimide (PDI) has received widespread attention from different research fields, especially in the area of environment. In this review, a comprehensive summary of the development of PDI-based materials in fluorescence detection and advanced oxidation technology for environment was introduced. Firstly, we chiefly presented the recent progress about the synthesis of PDI and PDI-based nanomaterials. Then, their application in fluorescence detection for environment was presented and categorized, principally including the detection of heavy metal ions, harmful anions and organic contaminants in the environment. In addition, the application of PDI and PDI-based materials in different advanced oxidation technologies for environment, such as photocatalysis, photoelectrocatalysis, Fenton and Fenton-like reaction and persulfate activation, was also summarized. At last, the challenges and future prospects of PDI-based materials in environmental applications were discussed. This review focuses on presenting the practical applications of PDI and PDI-based materials as fluorescent probes or catalysts (especially photocatalysts) in the detection of hazardous substances or catalytic elimination of organic contaminants. The contents are aimed at supplying the researchers with a deeper understanding of PDI and PDI-based materials and encouraging their further development in environmental applications.

"Turn-on" benzophenone based fluorescence and colorimetric sensor for the selective detection of Fe2+ in aqueous media: Validation of sensing mechanism by spectroscopic and computational studies

A diaminobenzophenone Schiff base derived probe 1, was synthesized and structure elucidation was carried out by spectroscopic studies viz., FT-IR, UV-vis, ¹H, and ¹³C NMR and mass spectrometry. The sensing phenomenon with different metal ions (Cr³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺) was investigated by employing absorption and fluorescence titrations, which demonstrated that probe 1 exhibited selective fluorescent sensing behavior towards Fe²⁺ ion among various other metal ions. The porobes selceteclivity towards Fe²⁺ was also examined by colorimetric assay which revealed a change in the color from light yellow to brown upon addition of Fe²⁺ ion. A remarkable increase in the fluorescence intensity of probe 1 was observed towards Fe²⁺ ion, which was found to be associated with the inhibition of photoinduced electron-transfer (PET) and CN isomerization processes, respectively. The chemosensor exhibited an association constant value of 6.173 × 10⁷ M^-2 as determined by using non-linear least square fit data. Job's plot calculated the binding stoichiometry, and the sensing phenomenon of Fe²⁺ towards the probe was further supported by Density Functional Theory (DFT) calculations and ¹H NMR studies. The detection limit of probe 1 was found to be 0.0363 µM, which is below the permissible limits according to the WHO guideline (5 μM) for Fe²⁺ ions in the drinking water. Furthermore, the practical application of probe 1 was studied by analyzing the content of Fe²⁺ in different water samples.

Colorimetric and fluorimetric chemosensor based on upper rim-functionalized calix[4]arene for selective detection of fluoride ion

A new colorimetric and fluorescent chemosensor for fluoride anion based on calix [4]arene bearing four sulfonamide-fluorenone subunits on the upper rim was conveniently synthesized. It showed a remarkable color change as well as the fluorescence quenching upon addition of F^- even in the presence of a wide range of anions in DMSO. The binding property of L with F^- was studied by a combination of various spectroscopic techniques, such as absorption and emission titration, Job's plot and ¹H NMR titration. It is anticipated that this design with functional group attached to upper rim of calix[4]arene platform can provide a new approach for the development of F^- chemosensor.

Fluorescent perylenylpyridine complexes: an experimental and theoretical study

The perylene derivative 2-(3-perylenyl)-4-methylpyridine (HPerPy) was prepared and used to synthesize [Ag(HPerPy)(PPh3)(OClO3)], with the perylene ligand bonded to the metal centre only by the pyridine nitrogen. The treatment of HPerPy with [Pd(OAc)2] in methanol or acetic acid led to acetate bridged dimers (μ-OOCCH3)2[Pd(PerPy)]2, six-membered or five-membered cycled at the perylenyl fragment. Substitution reactions afforded mononuclear compounds [Pd(PerPy)(acac)] (six-member or five-member cycled) and [Pd(PerPy)(S2COMe)] (six-member or five-member cycled). The reaction of HPerPy with a platinum(ii) fragment led to a five-membered cyclometallated Pt(ii) complex [Pt(PerPy)(acac)]. The oxidative addition with MeI gave the corresponding cyclometallated Pt(iv) compound [Pt(PerPy)(acac)MeI]. X-ray single crystal studies of compounds [Ag(HPerPy)(PPh3)(OClO3)], (μ-OOCCH3)2[Pd(PerPy)]2-five-membered, [Pd(PerPy)(acac)]-six-membered, [Pd(PerPy)(S2COMe)]-five-membered, [Pt(PerPy)(acac)]-five-membered, and [Pt(PerPy)(acac)MeI]-five-membered confirmed the proposed structures. The UV-Vis spectra show one intense absorption with vibronic coupling in the visible region with maxima in the range of 448-519 nm. DFT calculations were carried out for the absorption spectra of the HPerPy molecule and representative complexes [M(PerPy)(acac)] (M: Pd, Pt; five and six-membered isomers) and [Pt(PerPy)(acac)MeI], showing that the lowest energy most intense transition in the complexes corresponds to the HOMO → LUMO transition in the perylene moiety, although affected by the metallacycle size and the metal nature. All the compounds are fluorescent in solution, due to the perylene fragment. The emission spectra display maxima in the range of 468-549 nm, with quantum yields from 1.1 to 82%. The attenuation of the intensity of fluorescence by the presence of heavy atoms and the formation of metallacycles has been experimentally determined and sequenced.

A novel turn-off fluorescent aptasensor for ampicillin detection based on perylenetetracarboxylic acid diimide and gold nanoparticles

Herein, a novel turn-off fluorescent aptasensor was developed for selective detection of ampicillin (AMP) at picomolar level based on 3,4,9,10-perylenetetracarboxylic acid diimide (PTCDI) as an affordable and low-cost fluorophore. This aptasensor was designed using aptamer, its complementary strand (CS) and gold nanoparticles (AuNPs). The principle of the sensing method is a decrease in the fluorescence intensity of PTCDI in the presence of free CS. Following the addition of AMP, Aptamer/CS-modified AuNPs releases CS and so, the fluorescence intensity of PTCDI is reduced. The designed analytical method indicated a good linear range from 100 pM to 1000 pM and a limit of detection (LOD) of 29.2 pM was obtained. Furthermore, the sensing strategy indicated satisfactory results for the detection of AMP in the spiked human serum samples. By changing the sequences of aptamer and its CS, the presented analytical approach can be easily applied for detection of other antibiotics.

A cystine-based dual chemosensor for fluorescent-colorimetric detection of CN- and fluorescent detection of Fe3+ in aqueous media: Synthesis, spectroscopic, and DFT studies

A new dual-responsive chiral cystine based chemosensor, Cys(cou)₂, has been designed and characterized by ¹H NMR, ¹³C NMR, FT-IR, UV-vis as well as elemental analysis. This sensor exhibited an excellent response towards Fe³⁺ and CN^- with high selectivity and sensitivity by fluorescence turn-off mechanism. The binding mode of Cys(cou)₂ with Fe³⁺, and CN^- was confirmed by ESI-MS, ¹H NMR, and fluorescence titration and also quantum chemical calculation. These results showed that the stoichiometric ratio of Cys(cou)₂-Fe³⁺ and Cys(cou)₂-CN is 1:1 and 1:3 in DMSO/Tris aqueous buffer (1:1, v/v), respectively. The linear relationship of the Stern-Volmer plot illustrates the static quenching mechanism at different concentrations. The detection limit (LOD) and binding constant (K_a) for Fe³⁺ and CN^- are 0.029 μM, 1.28 × 10⁴ and 0.51 μM, 9.94 × 10⁶, respectively. Moreover, Cys(cou)₂ can act as a colorimetric sensor for CN^- in DMSO with the color change from colorless to yellow.

Selective binding of Ni2+ and Cu2+ metal ions with naphthazarin esters isolated from Arnebia euchroma

Naphthazarin esters (C1-C4) isolated from the roots of Arnebia euchroma are found as skilled dual chemosensors for Ni²⁺ and Cu²⁺ among Pb²⁺ , Na²⁺ , K²⁺ , Hg²⁺ , Mg²⁺ , and Ca²⁺ metal ions. C1-C4 esters exhibited a red shift of 54 nm with Ni²⁺ and 30 nm with Cu²⁺ metal ions in absorption. There is a formation of red-shifted bands between 517 and 613 nm in the absorption spectrum of C1-C4 sensors on binding with Ni²⁺ and Cu²⁺ ions. The addition of Ni²⁺ and Cu²⁺ ions to sensors C1-C4 stimulates a remarkable color change from reddish pink to purple and light blue, respectively. These color changes can be identified with the naked eye. The significant downfield shifts of CO and OH peaks in nuclear magnetic resonance (NMR) spectrum confirm the chelation as binding mechanism. With ultraviolet-visble and NMR studies, it is found that C1-C4 esters possessed notable selectivity and sensitivity toward Ni²⁺ and Cu²⁺ over other metal ions.

Perylene Diimide-Based Fluorescent and Colorimetric Sensors for Environmental Detection

Perylene tetracarboxylic diimide (PDI) and its derivatives exhibit excellent thermal, chemical and optical stability, strong electron affinity, strong visible-light absorption and unique fluorescence on/off features. The combination of these features makes PDIs ideal molecular frameworks for development in a broad range of sensors for detecting environmental pollutants such as heavy metal ions (e.g., Cu2+, Cd2+, Hg2+, Pd2+, etc.), inorganic anions (e.g., F-, ClO4-, PO4-, etc.), as well as poisonous organic compounds such as nitriles, amines, nitroaromatics, benzene homologues, etc. In this review, we provide a comprehensive overview of the recent advance in research and development of PDI-based fluorescent sensors, as well as related colorimetric and multi-mode sensor systems, for environmental detection in aqueous, organic or mixed solutions. The molecular design of PDIs and structural optimization of the sensor system (regarding both sensitivity and selectivity) in response to varying analytes are discussed in detail. At the end, a perspective summary is provided covering both the key challenges and potential solutions for the future development of PDI-based optical sensors.

Urolithin A and B Derivatives as ON-OFF Selective Fluorescent Sensors for Iron(III)

The detection and sensing of environmentally crucial metal ions has always been of great significance in various fields such as biological and environmental cycles. Our previous studies have indicated a new coumarin based lactone, Urolithin B (i.e., 3-Hydroxy[c]chromen-6-one) as a potent fluorescent probe for the selective detection of Iron (III). In order to question the extension of this application to other urolithins, we have synthesized the major urolithins that humans are exposed to through regular diet. Following the structure identifying studies, the compounds were tested in fluorescence titration to investigate their interaction with various metals. The results have indicated that each title compound is selective to interact with Iron (III) in ON-OFF mode, independent from the presence of another metal. Similar to the previous findings, the Job's plots displaying the ratio of complex formation 3:2 UROs:Fe³⁺ have indicated the significance of the lactone group solely.

Mito-targeted "turn-on" fluorescent probe for nickel (II) detection

In this paper, we unveil a new highly selective and sensitive mito-tracker (NiP) for Ni²⁺ detection. NiP itself held very weak fluorescence and exhibited a high selectivity (≥160-fold) toward Ni²⁺ over other metal ions, with a limit of detection of 21.6 nmol. We demonstrate the practicality of NiP for the rapid determination of Ni²⁺ levels in mitochondria of living cells. This approach offers advantages by being fast, simple and low cost.

Strongly luminescent 5d/4f heterometal–organic macrocycles with open metal sites: post-assembly modification and sensing

Strongly luminescent 5d/4f heterometal–organic macrocycles featuring open metal sites have been constructed, along with their post-assembly modification and sensing properties.

Water-soluble and highly emissive near-infrared nano-probes by co-assembly of ionic amphiphiles: towards application in cell imaging

Highly emissive near-infrared nano-emitters formed by co-assembly of ionic amphiphiles were applicable in cell imaging.

A small molecular boron-phenylpyrrin sensor for H+/Fe3+ and its application as a digital demultiplexer

A julolidine-based boron-phenylpyrrin small molecule has been designed and synthesized through a one-pot condensation-complexation procedure. Systematic optical studies show that this compound displays two distinct optical responses to the addition of HCl and Fe[Formula: see text] in succession: the addition of HCl induces an obvious red shift in its maximum absorption and fluorescence emission bands accompanied with the fluorescence quenching, whereas after synchronously adding H[Formula: see text] and Fe[Formula: see text], the maximum absorption and fluorescence emission wavelength were found to shift little but with an obvious decrease in the absorbance and fluorescence intensity, suggesting the dual-detecting nature of this compound to H[Formula: see text] and Fe[Formula: see text] under acid conditions. More interestingly, based on the HCl/Fe[Formula: see text]-mediated absorption and fluorescence signal features, JBPP can function as AND, NAND, INH and IMP logic gates which can be further developed into a 2:4 digital demultiplexer These will endow this small molecule compound with great potential for applications in molecular logic material, chemosensors and biological fields.

Sensing study of quinoxaline analogues with theoretical calculation, single-crystal X-ray structure and real application in commercial fruit juices

Single-crystal X-ray structures of dimeric quinoxaline aldehyde (QA), quinoxaline dihydrazone (DHQ) and HQNM (Goswami S et al. 2013 Tetrahedron Lett.54, 5075-5077. (doi:10.1016/j.tetlet.2013.07.051); Goswami S et al. 2014 RSC Adv.4, 20 922-20 926. (doi:10.1039/C4RA00594E); Goswami S et al. 2014 New J. Chem.38, 6230-6235. (doi:10.1039/C4NJ01498G)) are reported along with the theoretical study. Among them, QA is not acting as an active probe, but DHQ and HQNM are serving as selective and sensitive probe for the Fe³⁺ cation and the Ni²⁺ cation, respectively. DHQ can also detect the Fe³⁺ in commercial fruit juices (grape and pomegranate).

A pyrene based fluorescent turn-on chemosensor: aggregation-induced emission enhancement and application towards Fe3+ and Fe2+ recognition

A pyrene-based probe bearing benzothiazole ionophore (Py-BTZ) was synthesised as a "turn-on" fluorescent chemosensor for the detection of Fe³⁺ and Fe²⁺ ions in CH₃CN : H₂O (1 : 1, v/v) solvent mixes. The chemosensor showed optical as well as colorimetric changes towards Fe³⁺ and Fe²⁺ ions along with a remarkable enhancement in fluorescence emission. The detection limit of Py-BTZ towards Fe³⁺ and Fe²⁺ ions was found to be 2.61 μM and 2.06 μM, respectively. The binding of Py-BTZ with Fe³⁺ and Fe²⁺ was determined by using FT-IR experiments. Interestingly, Py-BTZ shows aggregation induced emission enhancement (AIEE) properties in polar solvent mixes such as CH₃CN : H₂O (1 : 1, v/v).

Highly uniform supramolecular nano-films derived from carbazole-containing perylene diimide via surface-supported self-assembly and their electrically bistable memory behavior

For electrical memory applications, two perylenetetracarboxylic diimide (PDI) derivatives were synthesized and their surface-supported self-assembly behaviors were investigated.

A highly selective fluorescent probe for Fe3+ in living cells: a stress induced cell based model study

A rhodamine–phenanthroline conjugated fluorescent probe 4 has been designed and synthesized for selective sensing and imaging of endogenous Fe³⁺ ions in living cells under different stress conditions.

A new fluorescent sensor containing glutamic acid for Fe3+ and its resulting complex as a secondary sensor for PPi in purely aqueous solution

A new fluorescence sensor L with benzimidazo[2,1-α]benz[de]isoquinoline-7-one as the fluorophore and glutamic acid moiety as the receptor was synthesized and characterized.

Highly Efficient Organic Photocatalyst with Full Visible Light Spectrum through π-π Stacking of TCNQ-PTCDI

Self-assembled TCNQ-PTCDI composite photocatalysts can not only degrade phenol at a rate of 0.154 h^-1, which is 10.4 times higher than that of pure PTCDI, but also produce oxygen at a rate of ∼14 μmol·g^-1·h^-1 without cocatalysts. The π-π interactions between TCNQ and PTCDI result in fast transfer of carriers and reduced carrier recombination. The interaction lowers the valence band and narrows the band gap, thus leading to a stronger oxidizability and a broad spectral response (∼730 nm). Moreover, the presence of TCNQ stabilizes the composite to decrease the accumulation of negative charge, which results in an excellent stability of the composite. The high catalytic activity can potentially be utilized in the fields of environmental and energy applications.

A benzo-15-crown-5-modifying ratiometric-absorption and fluorescent OFF-ON chemosensor for Cu(2.)

One new benzo-15-crown-5-modifying fluorene Schiff base (FBC), together with the CN-linked fluorene-3,4-dimethoxybenzene (FBDMO) and fluorene-benzene (FB) references, has been designed and facilely synthesized. The binding of Cu(2+) with nitrogen atom of CN moiety in these three compounds can inhibit the photo-induced electronic transition process and induce the ratiometric-absorption and fluorescent OFF-ON response to Cu(2+). Whereas the employment of benzo-15-crown-5 moiety in FBC as additional binding platform for Cu(2+) not only amplifies the fluorescent enhancement of FBCvia preventing the isomerization of CN moiety, but also endows this compound high selectivity and rapid response towards Cu(2+) over the references FB and FBDMO. These results render FBC highly sensitive ratiometric-absorption and fluorescent OFF-ON detecting potential for Cu(2+) with the detection limit of 3.91 × 10(-6) M.