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Four rhodamine-based fluorescent probes M1-M4 were synthesized in one step using Mannich reaction. The Mannich reaction based approach has the advantages of simplicity, good yield and excellent atomic economy. The structures were determined by 1 H NMR, 13 C NMR, IR and HRMS. The probe M3 as a representative compound was characterized by single-crystal X-ray analyses. The fluorescence and absorbance spectra research of the probes demonstrated that they could be used as Fe 3+ -selective fluorescent probes with good sensitivity, excellent linearity, and outstanding anti-interference in acetonitrile/Tris-HCl buffer solution (3:7, V/V; pH = 7.4). Moreover, confocal laser scanning microscopy experiments have proven that the probe M3 was successfully used for fluorescence imaging in MCF-7 cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

4,5-Bis(phtalimidomethyl)acridine (L) was studied as a chemosensor for metal ions in alcoholic matrices and showed to be selective for Al 3+ , through a linear fluorescence enhancement of 230% in the concentration range of 10-70 μmol L -1 . Benesi-Hildebrand and Job's formalisms indicated the formation of a 1:1 (Al 3+ :L) complex with a binding constant of 6.30 × 10 3 L mol -1 . DFT/TDDFT calculations allowed access to the energies of frontier orbitals and could explain the fluorescence augmentation upon complex formation, due to the restraining of PET process. Limit of detection and limit of quantification (R 2  = 0.998, least squares method) are 1.130 and 3.768 μmol L -1 , respectively, and validation was verified based on the variation of several analytical conditions. Practical application in spiked Brazilian sugarcane spirit showed recovery of (84 ± 0.42)% with no effect of interfering ions., Competing Interests: Declaration of competing interest We declare that there is no conflict of interest regarding this manuscript., (Copyright © 2020 Elsevier B.V. All rights reserved.)

New pyrazole bearing imidazole derivative was successfully synthesized and thoroughly characterized by various spectroanalytical techniques. The sensor DIBI shows a highly selective and sensitive fluorescent response with the addition of Al 3+ /Fe 3+ ions in acetonitrile-water mixture. The strong fluorescent molecule exhibits a notable ratiometric emissions at 462 nm and 470 nm for Al 3+ and Fe 3+ ions, respectively (λ ex  = 280 nm). Job's plot studies conclude that the coordination between DIBI with Al 3+ /Fe 3+ was 1:1 binding stoichiometry. The limit of detection of DIBI with Al 3+ /Fe 3+ was calculated as 2.12 × 10 -7  M and 1.73 × 10 -6  M, respectively. The TD-DFT calculations further supported the photonics performances of the free probe and its complexes. The reversibility and reusability of the sensor molecule are studied using EDTA. The probe was used to track Al 3+ /Fe 3+ in cancer cells via fluorescence microscopy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier B.V. All rights reserved.)

It's of vital importance to detect heavy metals in environment and living cells. In this work, four near-infrared regions boron dipyrromethene (BODIPY) probes (QBPH, PBPH, QBP and PBP) are constructed based on two BODIPY precursors (QB, PB) for sensing of Fe 3+ . As expected, these four probes exhibit obvious colorimetric and ratiometric response to Fe 3+ . In addition, QBP and PBP display highly sensitive and selective performance for detection of Fe 3+ . More importantly, QBP and PBP are successfully applied to near infrared imaging and detection of Fe 3+ in living A549 cells; it indicates that these novel designed probes could be a useful tool for the studies of Fe 3+ in living cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A highly sensitive and selective indole-based probe IHT exhibited obvious color change from colorless to violet easily detected by naked eye as well as 'turn on' fluorescence response to Cu 2+ ion at physiological pH condition. The detection limit was determined to be as low as 8.93 × 10 -8  M, which was much lower than drinking water permission concentrations by the United States Environmental Protection Agency. The 1:2 binding mechanism was well confirmed by fluorescence titration, Job's plot, HRMS, IR analysis and DFT calculations. Furthermore, the probe IHT was successfully used for fluorescence imaging of Cu 2+ ion in living cells., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this work, we designed a novel Schiff-base probe from the condensation reaction of 3,5-diiodosalicylaldehyde with isoniazid. Treatment of the sensor molecule with different metal ions like K + , Ba 2+ , Ca 2+ , Mg 2+ , Fe 2+ , Mn 2+ , Co 2+ , Cu 2+ , Cd 2+ , Ni 2+ , Hg 2+ , Zn 2+ , Pb 2+ and Al 3+ in visual inspection and absorption measurements explained its colorimetric sensing ability. The sensor DISN displays a remarkable color variation from pale yellow to brownish-orange towards Co 2+ ion. The absorption and emission spectra of DISN, upon treating with various anions including F - , Br - , Cl - , I - , HSO 4 - , NO 3 - , H 2 PO 4 - , and CN - were tested. The addition of the fluoride ion to the receptor caused not only the intense color variation from pale yellow to orange but also a significant fluorescence turn-on response. Job's plot method fixed the binding of Co 2+ and F - to DISN separately, in 2:1 and 1:1 binding stoichiometry, respectively. The detection limit of 1.24 × 10 -7  M and 0.108 × 10 -6  M was attained for Co 2+ and F - , respectively. The TD-DFT calculations further supported the photophysical properties involved in the free probe and its complexes. The YES and INHIBIT logic function was found to operate from modulation in the absorbance and fluorescence behavior of Co 2+ and F - ions with DISN. Furthermore, DISN displays its practical applicability in filter-paper strips, live cell imaging, and real sample analyses., (Copyright © 2019. Published by Elsevier B.V.)

Synthesis and chelation induced fluorescence emission from two imidazo[1,2-a]pyridine derivatives are described. The nonfluorescent molecule 1 containing N and O donor atoms, achieves coplanarity upon interactions with trivalent cations Al 3+ , Fe 3+ and Cr 3+ , that favors fluorescence emission. Molecule 2 containing two N donor atoms attains coplanarity upon interaction with the only Zn 2+ and becomes fluorescent. Both molecules 1 and 2 form a 1:1 complex with interacting metal ions. Other trivalent metal ions (including Bi 3+ and In 3+ ) and common divalent metal ions (including Hg 2+ and Cd 2+ ) fail to form any complex with 1 or 2, and they do not interfere in the detection of Zn 2+ , Al 3+ , Fe 3+ or Cr 3+ ions. Noninterference of other metal ions renders 1 and 2 suitable for the detection of fungal cells contaminated with Zn 2+ , Al 3+ , Fe 3+ or Cr 3+ ions., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A novel quinoline-based Schiff-base probe QL had been synthesized, which could sequentially monitor Al 3+ and F - in MeOH-H 2 O solution (v/v = 8/1, 0.01 M, HEPES buffer, pH = 7.3). The probe QL expressed a high selective and sensitive "OFF-ON-OFF" fluorescent response for Al 3+ and F - (excitation at 460 nm and emission at 530 nm) accompanying visible color changed, which was ascribed to intramolecular charge transfer (ICT) process and chelation-enhanced fluorescence (CHEF) mechanism. The binding stoichiometry of QL with Al 3+ was 2:1 counting on Job's plot and HRMS, while F - could pull Al 3+ to depart from the complexation 2QL-Al 3+ and released free QL. The limit of detections of probe QL for Al 3+ and F - ions were calculated to be 0.10 μM and 0.50 μM. The 1 H NMR experiments and density functional theory (DFT) calculations were carried out to further prove the binding mode between QL and Al 3+ . Furthermore, fluorescence imaging studies demonstrated that the probe QL was low cytotoxicity and could be applied to detect Al 3+ and F - in living PC12cells., (Copyright © 2019 Elsevier B.V. All rights reserved.)

An effective morpholine-type naphthalimide chemsensor, N-p-chlorophenyl-4-(2-aminoethyl)morpholine-1,8-naphthalimide (CMN) has been developed as a lysosome-targeted fluorometric sensor for trivalent metal ions (Fe 3+ , Al 3+ and Cr 3+ ). Upon the addition of Fe 3+ , Al 3+ or Cr 3+ ions, the probe CMN showed an evident naked-eye color changes which pale yellow solution of CMN turned deepened and it displayed turn-on fluorescence response in methanol. CMN showed a significant selective and sensitive toward Fe 3+ , Al 3+ or Cr 3+ ions, while there was no obvious behavior to other monovalent or divalent metal ions from the UV-vis and fluorescence spectrum. Based on the Job's plot analyses the 1:1 coordination mode of CMN with Fe 3+ , Al 3+ or Cr 3+ was proposed. The limit of detection (LOD) observed were 0.65, 0.69 and 0.68 μM for Fe 3+ , Al 3+ and Cr 3+ ions, respectively. The N-atom of morpholine directly involved in complex formation, CMN emitted fluorescence through inhibition of photoinduced electron transfer (PET). This probe exhibited excellent imaging ability for Fe 3+ , Al 3+ and Cr 3+ ions in living cells with low cytotoxicity. Significantly, the cellular confocal microscopic research indicated that the lysosome-targeted group of morpholine moiety was introduced which realized the capability of imaging lysosomal trivalent metal ions in living cells for the first time., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This paper describes a new fluorescent chemosensor (DSH) based on dipeptide conjugated with dansyl group, which was synthesized by solid phase peptide synthesis (SPPS) technology. DSH exhibited a highly selective and sensitive toward Zn 2+ ions by "turn-on" response based on generation of monomer-excimer mechanism in aqueous solutions, and the detection limit was calculated at 11.2 nM. In addition, the reversible of DSH-Zn with Na 2 EDTA establishes the reuse of DSH, and the circulation effect was very good. Moreover, DSH had good water solubility, and was successfully applied to bioimage intracellular Zn 2+ ions and Na 2 EDTA in two different living cells with exciting cellular permeability and low cytotoxicity, which indicated that DSH had great potential in the application of biological imaging., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Palladium (Pd) has drawn worldwide attentions because its connections to industry, chemistry, biological material and public health. Quantitative and selective detection tools for Pd and its ion forms are in urgent necessity. Here an umbelliferone derivative Umb-Pd2 was provided as a small, steady, safe and selective sensor for detecting Pd(II). It indicated advantages including sensitive (LOD 1.1 nM), wide pH tolerance (5.0-10.0), applicable linear range (0-1.8 equivalent) and low toxicity. The most attractive point was its explicit selectivity towards Pd(II) from Pd(0) in both independent and coexistence systems. This distinguishing ability was further utilized in imaging in living cells, raising this work as a rare and important example among all the published papers on palladium sensing. Thus, Umb-Pd2 supplied a potential approach for further improvement and applications in both daily chemistry and public health., (Copyright © 2019. Published by Elsevier B.V.)

A photoinduced electron transfer (PET) and chelation-enhanced fluorescence (CHEF) regulated rhodamine-azobenzene chemosensor (L) was synthesized for chemoselective detection of Al 3+ , Cr 3+ , and Cu 2+ by UV-Visible absorption study whereas Al 3+ and Cr 3+ by fluorimetric study in EtOH-H 2 O solvent. L showed a clear fluorescence emission enhancement of 21 and 16 fold upon addition of Al 3+ and Cr 3+ due to the 1:1 host-guest complexation, respectively. This is first report on rhodamine-azobenzene based Cr 3+ chemosensor. The complex formation, restricted imine isomerization, inhibition of PET (photo-induced electron transfer) process with the concomitant opening of the spirolactam ring induced a turn-on fluorescence response. The higher binding constants 6.7 × 10 3  M -1 and 3.8 × 10 3  M -1 for Al 3+ and Cr 3+ , respectively and lower detection limits 1 × 10 -6  M and 2 × 10 -6  M for Al 3+ and Cr 3+ , respectively in a buffered solution with high reversible nature describes the potential of L as an effective tool for detecting Al 3+ and Cr 3+ in a biological system with higher intracellular resolution. Finally, L was used to map the intracellular concentration of Al 3+ and Cr 3+ in human lymphocyte cells (HLCs) at physiological pH very effectively. Altogether, our findings will pave the way for designing new chemosensors for multiple analytes and those chemosensors will be effective for cell imaging study., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Polysiloxanes have excellent stability and biological relevance and are suitable for biological research. However, there were few polysiloxane-based fluorescent probes for bioimaging. This report successfully designed a new polysiloxane-based polymer fluorescent probe (RB-1) for the first time as a "turn-on" fluorescent probe response to Al 3+ ion with highly sensitive and selectivity. Importantly, this probe could also apply both in cell and zebrafish imaging, indicating the huge application development prospects of polysiloxane-based fluorescent probes in future., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Developing high performance fluorescent chemo-sensors for in vitro and in vivo Al 3+ detection is highly desirable, because Al 3+ accumulation has been involved to various diseases. Herein, we report a highly selective and sensitive Schiff base fluorescent probe, H 3 L, based on 2-hydroxynaphthalene, which can recognize aluminum ions and exhibit an "off-on" mode with high selectivity in methanol solutions. The detection limit of the probe for Al 3+ is as low as 10 -7  M which was determined by fluorescent titration. The high selectivity and high sensitivity of H 3 L for Al 3+ are attributed to the inhibition of ESIPT. Additionally, the distribution of intracellular Al 3+ ions could be observed under confocal fluorescence microscopy. Moreover, we also applied H 3 L for in vivo detection of Al 3+ ions in living zebrafish larvae., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Three naphthol Schiff base-type fluorescent sensors, 1,3-Bis(2-hydroxy-1-naphthylideneamino)propane (L1), 1,3-Bis(1-naphthylideneamino)-2-hydroxypropane (L2) and 1,3-Bis(2-hydroxy-1-naphthylideneamino)-2-hydroxypropane (L3), have been synthesized. Their recognition abilities for Al(3+) are studied by fluorescence spectra. Coordination with Al(3+) inhibited the CN isomerization of Schiff base which intensely increase the fluorescence of L1-L3. Possessing a suitable space coordination structure, L3 is a best selective probe for Al(3+) over other metal ions in MeOH-HEPES buffer (3/7, V/V, pH=6.6, 25°C, λem=435nm). A turn-on ratio over 140-fold is triggered with the addition of 1.0 equiv. Al(3+) to L3. The binding constant Ka of L3-Al(3+) is found to be 1.01×10(6.5)M(-1) in a 1:1 complex mode. The detection limit for Al(3+) is 0.05μM. Theoretical calculations have also been included in support of the configuration of the L3-Al(3+) complex. Importantly, the probe L3 has been successfully used for fluorescence imaging in colon cancer SW480 cells., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A novel rhodamine-based dual probe Rh-2 for trivalent ferric ions (Fe(3+)) was successfully designed and synthesized, which exhibited a highly sensitive and selective recognition towards Fe(3+) with an enhanced fluorescence emission in methanol-water media (v/v=7/3, pH=7.2). The probe Rh-2 could be applied to the determination of Fe(3+) with a linear range covering from 3.0×10(-7) to 1.4×10(-5)M and a detection limit of 1.24×10(-8)M. Meanwhile, the binding ratio of Rh-2 and Fe(3+) was found to be 1:1. Most importantly, the fluorescence and color signal changes of the Rh-2 solution were specific to Fe(3+) over other commonly coexistent metal ions. Moreover, the probe Rh-2 has been used to image Fe(3+) in living cells with satisfying results., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A structurally modified quinazoline derivative (L) acts as highly selective chemosensor for Al(3+) ions in DMSO-H2O (1:9, v/v) over the other competitive metal ions. L shows a red shifted fluorescence after the addition of Al(3+) ions and later the further fluorescence enhancement is due to chelation enhanced fluorescence (CHEF) through inhibition of photoinduced electron transfer (PET). This probe (L) detects Al(3+) ions as low as 9nM in DMSO-H2O (1:9, v/v) at biological pH. The non-cytotoxic probe (L) can efficiently detect the intercellular distribution of Al(3+) ions in living cells under a fluorescence microscope to exhibit its sensible applications in the biological systems., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A trivalent chromium (Cr(3+)) fluorescence probe (RhC) was designed and synthesized via Schiff base reaction based on rhodamine-crown ether conjugate. This probe displayed a favorable selectivity for Cr(3+) over a range of other common metal ions in DMF/H2O (3:7, v/v; PBS buffer 50 mmol L(-1); pH=6.8) solution, leading to prominent fluorescence "OFF-ON" switching of the rhodamine fluorophore. The limit of detection was calculated to be 1.5 μmol L(-1) (S/N=3). The binding ratio of RhC-Cr(3+) complex was determined to be 1:2 according to the Job's plot and HR-MS. The probe was successfully applied to examination of Cr(3+) in drinking water spiked samples. The average recoveries ranged from 104.9% to 106.9% at spiked concentration level of 10.00 μmol L(-1), and the obtained results were consistent with those obtained using atomic absorption spectrometry (AAS). Moreover, bioimaging experiments showed that RhC can sense the Cr(3+) in living cells with a fluorescence enhancement signal., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Two Schiff-base fluorescent sensors have been synthesized, which both can act as fluorescent probes for Al(3+), upon addition of Al(3+), they exhibit a large fluorescence enhancement which might be attributed to the formation of 1:1 ligand-Al complexes which inhibit photoinduced electron transfer (PET) progress, and that the proposed binding modes of the sensors and Al(3+) are identified by theoretical calculations., (Copyright © 2015 Elsevier B.V. All rights reserved.)

In this paper, a new fluorescent probe has been synthesized and applied as "off-on" sensor for the detection of Al(3+) with a high sensitivity and excellent selectivity in aqueous media. The sensor was easily prepared by one step reaction between rhodamine B hydrazide and pyridoxal hydrochloride named RBP. The structure of the sensor has been characterized by nuclear magnetic resonance and electron spray ionization-mass spectrometry. The fluorescence intensity and absorbance for the sensor showed a good linearity with the concentration of Al(3+) in the range of 0-12.5μM and 8-44μM, respectively, with detection limits of 0.23μM and 1.90μM. The sensor RBP was preliminarily applied to the determination of Al(3+) in water samples from the lake of Henan University and tap water with satisfying results. Moreover, it can be used as a bioimaging reagent for imaging of Al(3+) in living cells., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A novel chemosensor based on pyrazole biscoumarin molecule "4-hydroxy-3-((4-hydroxy-2-oxo-2H-chromen-3-yl)(1,3-diphenyl-1H-pyrazol-4-yl)methyl)-2H-chromen-2-one" (PBC) was synthesized by a simple method. The chemosensing properties of PBC towards transition metal ions like Cu(2+) and Zn(2+) by naked eye, UV-Visible and fluorescence spectroscopic methods were described. The PBC solution with Cu(2+) and Zn(2+) ion showed brown and blue colour respectively. The UV-Visible spectra of PBC with Cu(2+) and Zn(2+) ions exposed their corresponding absorption maxima. Further, the Job's plot method confirmed the 1:1 and 2:1 stoichiometry of the complex formation between the PBC with Cu(2+) and Zn(2+) ions respectively. The fluorescence enhancement of PBC on binding with Cu(2+) and Zn(2+) is due to the inhibition of photo induced electron transfer mechanism., (Copyright © 2015 Elsevier B.V. All rights reserved.)

In the present study, azocalix[4]arenes were prepared by linking 4-methoxy, 4-methyl, 4-ethyl, 4-chloro, 4-bromo and 4-nitroaniline to calix[4]arene through a diazo-coupling reaction. A new family of azocalix[4]arene tetraester derivatives, (4a-f), have been prepared with the incorporation of ethyl ester units to azocalix[4]arene. Characterization of the synthesized azocalix[4]arenes was carried using elemental analyses, UV-vis, FT-IR and (1)H NMR spectroscopic techniques. The effect of varying pH levels and solvent types on the absorption ability of azocalix[n]arenes substituted with electron-donating and electron-withdrawing groups was examined. Thermal decomposition of azocalix[4]arene derivatives (4a-f) was investigated by means of thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) analyses. In conclusion of the examination of the extraction we found a selectivity characteristic of these compounds toward Ag(+), Hg(+) and Hg(2+) cations., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A new rhodamine-based fluorescent turn-on chemosensor (L) for selective detection of Al3+ ion has been developed and characterized. The fluorescent chemosensor L was synthesized by the reaction of intermediate (4) with 2,5-bis (4-phenylacyl chloride)-1,3,4-oxadiazole (3). The chemosensor L displays an excellent selective and sensitive response to Al3+ ion over other metal ions, in which the spirocyclic (non-fluorescent) to ring opened amide (fluorescent) process was utilized and a 1:2 stoichiometry for L-Al3+ complex was formed with an association constant of 2.03×10(3) M(-1). Furthermore, chemosensor L can be applied as a fluorescent probe for monitoring Al3+ in living cells by performing cell imaging studies., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A turn-on fluorescent chemosensor is introduced for the detection of Lu(3+) ion using N-[3-methyl]-2-[pyridine-2-amido] phenyl] pyridine-2-carboxamide (L) molecule. Fluorescent emission intensity of L enhances after binding to Lu(3+) ions in ethanol-water solution (1:9, v/v). The observed enhancement is the result of a strong covalent binding between Lu(3+) ion and L (the binding constant value is 2.0×10(6) mol(-1) L). The proposed optical chemosensor can be applied for the analysis of Lu(3+) ion in a linear range of 3.3×10(-7) to 1.0×10(-5) mol L(-1). The limit of detection was obtained 8.6×10(-7) mol L(-1). The probe exhibits high selectivity toward Lu(3+) ion in comparison with common metal ions. The proposed fluorescent chemosensor was successfully used in the determination of Lu(3+) ion in some water samples., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In this work, a new flavone-based fluorescent probe 3-hydroxy-3'-formylflavone (3HFF) was designed to achieve highly selective relay recognition of HSO3(-) and Al(3+) in DMSO-H2O (2:8, v/v) solution. 3HFF displayed a highly selective response to HSO3(-) with a green fluorescence appearing at 524 nm. Moreover, the in situ generated 3HFF+HSO3(-) system demonstrated eminent relay recognition capability for Al(3+) with a blue fluorescence appearing at 453 nm by the formation of a 1:1 complex between 3HFF and Al(3+) in DMSO-H2O (2:8, v/v) solution. However, only slight change was observed in emission intensity with addition of Al(3+) to 3HFF, and indicated HSO3(-) was essential for the sensing of Al(3+). This work achieves the detection of HSO3(-) and Al(3+) by only one probe and provides another example for this rare combination (anion/metal)., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A novel Schiff base fluorescent probe, 1-phenyl-3-methyl-5-hydroxypyrazole-4-carbaldehyde (2'-methylquinoline-4'-formyl) hydrazone (PMHCH), for selective detection of Al(3+) has been designed and synthesized. Upon addition of various metal ions, the receptor only shows 286-fold enhancement of fluorescence intensity which might be attributed to a 1:1 stoichiometry between PMHCH and Al(3+) and the photo-induced electron transfer progress in the present of Al(3+) at 505n m. More importantly, the detection limit of PMHCH for Al(3+) could reach at 10(-7) M level., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A new Schiff base from the condensation of 5,6-diamino-1,3-dimethyluracil with 5-methylthiophene-2-carboxaldehyde was synthesized. The compound was characterized by spectral data (UV-Vis, IR, (1)H NMR, fluorescence, MS). Ethanolic solutions of the Schiff base exhibit a strong fluorescence emission at 385 nm (λex=341 nm), and have been employed as a "turn-off" fluorescent probe for selective detection of Ag(+), Cu(2+) and Fe(3+) ions in presence of other cations such as Na(+), K(+), Ca(2+) and Mg(2+) ions abundant in natural water. The interaction between the tested compound and copper, silver or iron ions is associated with a significant fluorescence decrease, showing detection limits of 2.1-14.2 ppb. Under optimal conditions, the developed sensor was successfully employed to determine Ag(+), Cu(2+) and Fe(3+) ions in real samples and proved to be selective and sensitive., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Ligand sensitized fluorescence of europium ion using thenoyltrifluoroacetone (TTA) as a sensitizing ligand and dimethyl sulphoxide (DMSO) as a solvent is studied for the first time. TTA ligand enhances the fluorescence of Eu(3+) by a factor of 40000 in DMSO. Linearity is obtained for a concentration range of 0.076-7.6ng/mL of Eu(3+) with a detection limit of 7.6pg/mL. The quenching of Eu(3+)-TTA fluorescence by uranium matrix was studied in different solvents and found to be less in DMSO. Consequently, estimation of Eu(3+) in a large excess of uranium becomes a possibility without the need to separate uranium from the solution, which has been demonstrated in this paper. Satisfactory results are obtained when Eu(3+) is present at a concentration of 0.6μg/g in uranium., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A fluorescence probe, 8-formyl-7-hydroxyl-4-methyl coumarin - (2'-methylquinoline-4-formyl) hydrazone (L) has been synthesized. The chemosensor is found preferential binding to Al(3+) in presence of other competitive ions with associated changes in its optical and fluorescence spectra behavior. Upon addition of Al(3+) to a solution of L, it shows 200-fold enhancement of fluorescence intensity which might be attributed to form a 2:1 stoichiometry of the binding mode of LAl(III) and the chelation enhanced fluorescence (CHEF) process at 479nm in ethanol. The lowest detection limit for Al(3+) is determined as 8.2×10(-7)M., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Hibiscus Sabdariffa (Gongura) plant extracts (leaves (HL) and stem (HS)) were used for the first time in the green synthesis of bio-functionalized silver nanoparticles (AgNPs). The bio-functionality of AgNPs has been successfully utilized for selective colorimetric sensing of potentially health and environmentally hazardous Hg(2+), Cd(2+) and Pb(2+) metal ions at ppm level in aqueous solution. Importantly, clearly distinguishable colour for all three metal ions was observed. The influence of extract preparation condition and pH were also explored on the formation of AgNPs. Both selectivity and sensitivity differed for AgNPs synthesized from different parts of the plant. Direct correlation between the stability of green synthesized AgNPs at different pH and its antibacterial effects has been established. The selective colorimetric sensing of toxic metal ions and antimicrobial effect of green synthesized AgNPs demonstrated the multifunctional applications of green nanotechnology., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A new naphthalene derivative receptor (H2L) was synthesized. The chemosensor (H2L) exhibited a strong fluorescence enhancement in the presence of trace amounts of Al(3+), attributable to chelation-enhanced fluorescence (CHEF) effect, which also displayed high selectivity over a series of other metal cations (Na(+), K(+), Cs(+), Mg(2+), Ba(2+), Pb(2+), Cr(3+), Mn(2+), Fe(3+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Ag(+)) in ethanol., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Simple and sensitive determination of chromium (III) ions (Cr(3+)) has potential applications for detecting trace contamination in environment. Here, the assay is based on the enhancement of resonance Rayleigh scattering (RRS) by Cr(3+)-induced aggregation of citrate-capped gold nanoparticles (AuNPs). Transmission electron microscopy (TEM) and UV-vis absorption spectroscopy were employed to characterize the nanostructures and spectroscopic properties of the Cr(3+)-AuNP system. The experiment conditions, such as reaction time, pH value, salt concentration and interfering ions, were investigated. The combination of signal amplification of Cr(3+)-citrate chelation with high sensitivity of RRS technique allow a selective assay of Cr(3+) ions with a detection limit of up to 1.0 pM. The overall assay can be carried out at room temperature within only twenty minutes, making it suitable for high-throughput routine applications in environment and food samples., (Copyright © 2013 Elsevier B.V. All rights reserved.)

This paper reports on the effect of concentration of Eu(3+) ions in K2O-Nb2O5-SiO2-Eu2O3 (KNbSiEu) glasses prepared by the melt quenching technique. By using the Judd-Ofelt (JO) theory, the intensity parameters Ωλ (λ=2, 4, 6) have been determined from the absorption and emission spectra of Eu(3+) ions under different constraints. The radiative properties of some of the excited states of Eu(3+) ions have been calculated. The decay curves of (5)D0 level exhibited single exponential for all the Eu(3+) ions concentrations. From these results, it is suggested that the strong red emission at 616 nm corresponding to the (5)D0→(7)F2 transition could be used for the development of optical display devices., (Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.)

A simple Schiff-base receptor 7-methoxychromone-3-carbaldehyde-(pyridylformyl) hydrazone (MCNH) was prepared. It exhibits an "off-on-type" mode with high sensitivity in the presence of Al(3+). This compound could be used as Al(3+) probe in ethanol and it features visible light excitation (433 nm) and emission (503 nm) profiles. Upon binding of Al(3+), a significant fluorescence enhancement with a turn-on ratio over 800-fold was triggered. However, other metal ions had no such significant effect on the fluorescence. MCNH can also be used as a colorimetric chemosensor for Al(3+), which is easily observed from colorless to yellow-green by the naked-eye. The detection limit of MCNH for Al(3+) was as low as 1.9×10(-7) M., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The present paper undertakes the study of a title compound whose structure is (C6H9N2)2(Hg0.75Cd0.25)Cl4. The centrosymmetric compound crystallizes in the triclinic space group P-1, with a=7.580(7) Å; b=8.572(8) Å; c=15.433(13) Å; α=84.49(5)°; β=89.13(5)°; γ=68.53(5)° and Z=2. The crystal structure was solved and refined to R (int)=0.0212 using 7932 independent reflections. The atomic arrangement shows an alternation of organic and inorganic layers. Between layers, the cohesion is performed via N-H⋯Cl hydrogen bonding, yet in the organic sheets, cations are further connected to classical π-π stacking. The Infrared and Raman spectra of this compound reported from 400 to 4000 cm(-1) confirmed the presence of the principal bands assigned to the internal modes of organic cation. Solid-state (13)C and (111)Cd CP-MAS-NMR spectra are reported. The dielectric study of this compound has been measured, in order to determine the σ(d.c) conductivity which is thermally activated with activation energy about 1.5 eV., (Copyright © 2013 Elsevier B.V. All rights reserved.)

In this study, we reported a new fluorescence sensor for chromium (III) ion, dansyl-L-glutamine (1). The sensor displayed a unique selective fluorescence "turn-on" response to Cr(3+) over other common metal ions in water. Notably, 1 still showed a ratiometric response to Cr(3+) in UV-vis absorption spectra. The binding mechanism of 1 to Cr(3+) was further clarified by using NMR and ESI-MS spectra. The experiment results indicated that the dual-responses of 1 to Cr(3+) should attribute to the coordination of deprotonated sulfonamide group with Cr(3+) and the protonation of the dimethylamino group due to the coordination of Cr(3+) for 1. In addition, two chloride ions also coordinated to the complex of sensor-chromium (III) ion, which further strengthened the conformation of 1-Cr(3+)., (Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.)

Two porphyrinato-zinc derivatives modified with two and four N,N-di(2-pyridylmethyl)amino groups, namely Zn-Porphyrin-2-DPA (1) and Zn-Porphyrin-4-DPA (2), have been designed, synthesized, and characterized. Systemic studies over a series of metal ions reveal that binding with Fe(3+) for the former compound induces the decrease of fluorescence emission intensity by 37.2%, while for the latter one results in a more remarkable decrease in the fluorescence emission intensity by 90.3%, rendering compound 2 the first example of DPA-modified porphyrin fluorescence ON-OFF sensor for Fe(3+)., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A new multicomponent analysis method, based on principal component analysis-multivariate adaptive regression splines (PC-MARS) is proposed for the determination of dialkyltin compounds. In Tween-20 micellar media, dimethyl and dibutyltin react with morin to give fluorescent complexes with the maximum emission peaks at 527 and 520nm, respectively. The spectrofluorimetric matrix data, before building the MARS models, were subjected to principal component analysis and decomposed to PC scores as starting points for the MARS algorithm. The algorithm classifies the calibration data into several groups, in each a regression line or hyperplane is fitted. Performances of the proposed methods were tested in term of root mean square errors of prediction (RMSEP), using synthetic solutions. The results show the strong potential of PC-MARS, as a multivariate calibration method, to be applied to spectral data for multicomponent determinations. The effect of different experimental parameters on the performance of the method were studied and discussed. The prediction capability of the proposed method compared with GC-MS method for determination of dimethyltin and/or dibutyltin., (Copyright © 2013 Elsevier B.V. All rights reserved.)

An efficient fluorescent chemosensor Al(3+) receptor based on pyrimidine derivative,2-amino-6-hydroxy-4-(4-N,N-dimethylaminophenyl)-pyrimidine-5-carbonitrile (DMAB), has been synthesized by three-component condensation of aromatic aldehyde, ethyl cyanoacetate and guanidine hydrochloride in ethanol under alkaline medium. High selectivity and sensitivity of DMAB towards Aluminum ion (Al(3+)) in water: ethanol and acetate buffer at pH 4.0 makes it suitable to detect Al(3+) with steady-state UV-vis and fluorescence spectroscopy. Method shows good selectivity towards Al(3+) over other coexisting metal ions tested, viz. Fe(2+), Ni(2+), Cu(2+), Co(2+), Pb(2+), Sb(3+), Na(+), Ca(2+), Mg(2+), Zn(2+), Hg(2+), Ba(2+), Cd(2+) and K(+). A good linearity between the Stern-Volmer plots of F0/F versus concentration of Al(3+) was observed over the range from 10 to 60 μg mL(-1) with correlation coefficient of 0.991. The accuracy and reliability of the method were further confirmed by recovery studies via standard addition method with percent recoveries in the range of 101.03-103.44% and lowest detection limit (LOD=7.35 μg mL(-1)) for Al(3+) was established. This method may offer a new cost-effective, rapid, and simple key to the inspection of Al(3+) ions in water samples in the presence of a complex matrix and can be capable of evaluating the exceeding standard of Al(3+) in environmental water samples. The probable mechanism for fluorescence quenching was also discussed., (Copyright © 2013 Elsevier B.V. All rights reserved.)

In this paper, the fabrication and analytical characteristics of fluorescence-based ferric ion-sensing glass slides were described. To fabricate the sensor, a naphthalimide derivative (compound 1) with a terminal double bond was synthesized and copolymerized with 2-hydroxyethyl methacrylate (HEMA) on the activated surface of glass slides by UV irradiation. Upon the addition of Fe(3+) in 0.05 mol/L Tris/HCl (pH 6.02) at 25 °C, the fluorescence intensity of the resulting optical sensor decrease, which has been utilized as the basis for the selective detection of Fe(3+). The sensor can be applied to the quantification of Fe(3+) with a linear range covering form 1.0×10(-5) to 1.0×10(-3) M and a detection limit of 4.5×10(-6) M. The experiment results show that the response behavior of the sensor to Fe(3+) is pH-independent in medium condition (pH 5.00-8.00) and exhibits high selectivity for Fe(3+) over a large number of cations such as alkali, alkaline earth and transitional metal ions. Moreover, satisfactory reproducibility, reversibility and a rapid response were realized. The sensing membrane was found to have a lifetime at least 2 months. The accuracy and the precision of the method were evaluated by the analysis of the standard reference material, iron in water (1.0 mol/L HNO3). The developed sensor is applied for the determination of iron in pharmaceutical preparation samples with satisfactory results., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A new carbazole-based Schiff-base (1) as a multi-functional fluorescent chemosensor was designed, synthesized and characterized, which can selectively recognized Fe(3+) and Cu(2+) ions over a number of other metal ions. Compound 1 could detect Fe(3+) and Cu(2+) by UV-Vis method and fluorescence method. The stoichiometry ratio of 1-Fe(3+) and 1-Cu(2+) are 2:1 and 1:1, respectively, by the method of Job's plot. Moreover, the detection limits were calculated to be 4.23×10(-6) mol/L for Fe(3+) ion and 5.67×10(-6) mol/L for Cu(2+) ion. In the presence of Fe(3+)/Cu(2+) ions, the fluorescence enhancement was attributed to the inhibited C=N isomerization and the obstructed excited state intramolecular proton transfer (ESIPT) of compound 1. At the same time, the interactions of compounds 1 with other ions were also investigated and unobvious UV-Vis absorption and fluorescence spectral changes were observed. Thus a new kind of chemosensor for Fe(3+)/Cu(2+)with high sensitivity and selectivity was introduced., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A novel and simple Schiff base based on 2-pyridine formaldehyde and 4-aminoantipyrine was synthesized and characterized as a fluorescent probe. In the presence of Al(3+), the fluorescent intensity has a dramatic enhancement over other examined metal ions in aqueous solution. The method of Job's plot indicated the formation of 1:1 complex between probe and Al(3+), and the possible binding mode of the system was also proposed. Moreover, other examined metal ions had no effect on the detection of Al(3+)., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A novel and simple Schiff base composed with 9-anthraldehyde and 4-aminoantipyrine was synthesized and characterized as a fluorescent probe. In the presence of Fe(3+), the fluorescent intensity has a dramatic enhancement over other examined metal ions in aqueous solution. The method of Job's plot indicated the formation of 1:1 complex between probe and Fe(3+), and the possible binding mode of the system was also proposed. Moreover, other examined metal ions had no effect on the detection of Fe(3+)., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The synthesis and spectral characterization of a schiff base, 2-pyridinecarbaldehyde-p-phenylenedihydrazone (short for 2PC-PPH), were described. It was found that ferric ion (Fe(3+)) could selectively quench the fluorescence of 2PC-PPH, whereas many other metal ions, such as Mn(2+), Zn(2+), Cu(2+), K(+), Al(3+), Ca(2+), Ni(2+), Co(2+), Cr(3+) and Fe(2+), could not quench its fluorescence. Based on this, a sensitive method for ferric ion selective detection was established. Under the optimum conditions, the decreasing fluorescence intensity of 2PC-PPH is proportional to the concentration of Fe(3+) within the range of 6.0×10(-7)-1.0×10(-5) mol L(-1). The detection limit (3σ) for Fe(3+) determination is 3.6×10(-7) mol L(-1). The proposed method was successfully applied to determine iron in tea and milk powder., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Two new Schiff base derivatives {2,2'-diphenyl-N,N'-bis(2-pyridylmethylene)biphenyl-4,4'-diamine} (1) and {2,2'-diphenyl-N,N'-bis(salicylidene)biphenyl-4,4'-diamine} (2) were synthesized and characterized by means of elemental analysis, (1)H NMR, FT-IR, and standard spectroscopy techniques. The molecular structure of 2 has been determined by X-ray single crystal analysis. The analyses of fluorescence properties of the compounds revealed that 1 and 2 are both poorly fluorescent and display sensitive fluorescence responses to a panel of 24 monovalent, divalent, and trivalent metal ions in CH(3)CN-DMSO (9:1, v/v). Results with imine 1 showed that Fe(3+), Cu(2+), Zn(2+), Cd(2+), Mn(2+), Zr(4+), Hg(2+), Cr(2+), Pb(2+), Sn(2+), Bi(2+), Al(3+), Ce(3+), La(3+), Sm(3+), Gd(3+), Nd(3+), Eu(3+) and Dy(3+) yields red shifts in emission and increases in intensity. And the greatest spectral changes for imine 2 include enhancements in emission intensity coupled with red shifts (Zr(4+), Sn(2+), Al(3+) and Zn(2+)) and strong quenching (Fe(3+)). The fluorescence enhancement mechanism of 1 and 2 for metal ions is based on: (i) CN isomerization; (ii) chelation-enhanced fluorescence (CHEF) effect; and (iii) excited-state intra/intermolecular proton transfer (ESPT)., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A new dyad containing two 1,8-naphthalimides has been synthesized. N,N-Dimetylaminoethylamino group has been used as substituent at C-4 position of the 1,8-naphthalimide chromophore structure. The photophysical characteristics of the dyad have been investigated in organic solvents with different polarity. In acetonitrile solution the newly synthesized dyad enhance its fluorescent intensity in the presence of metal cations (Ni(2+), Co(2+), Cu(2+), Pb(2)(+), Zn(2+), Fe(3+)) and protons due to quenching of photoinduced electron transfer., (Copyright 2010 Elsevier B.V. All rights reserved.)

In the present paper, we describe the fabrication and analytical characteristics of fluorescence-based zinc ion-sensing glass slides. To construct the sensor, a benzoxazole derivative 4-benzoxazol-2'-yl-3-hydroxyphenyl allyl ether (1) with a terminal double bond was synthesized and copolymerized with 2-hydroxyethyl methacrylate (HEMA) on the activated surface of glass slides by UV irradiation. In the absence of Zn(2+) at pH 7.24, the resulting optical sensor emitted fluorescence at 450 nm via excited-state intramolecular proton transfer (ESIPT). Upon binding with Zn(2+), the ESIPT process was inhibited resulting in a 46 nm blue-shift of fluorescence emission. Thus, the proposed sensor can behave as a ratiometric fluorescent sensor for the selective detection of Zn(2+). In addition, the sensor shows nice selectivity, good reproducibility and fast response time. Cd(2+) did not interfere with Zn(2+) sensing. The sensing membrane demonstrates a good stability with a lifetime of at least 3 months. The linear response range covers a concentration range of Zn(2+) from 8.0x10(-5) to 4.0x10(-3) mol/L and the detection limit is 4.0x10(-5) mol/L. The determination of Zn(2+) in both tap and river water samples shows satisfactory results.

We have applied two-color resonant two-photon mass-analyzed threshold ionization technique to record the vibrational spectra of the selected rotamers of m-cresol. The adiabatic ionization energies of cis and trans m-cresol are determined to be 66,933+/-5 and 67,084+/-5 cm(-1), respectively. Frequencies of the in-plane ring vibrations 6a, 1, and 9b are measured to be 528, 720, 1167 cm(-1) for the cis and 520, 698, and 1153 cm(-1) for the trans m-cresol cation. This indicates that different orientation of the OH group with respect to the CH(3) group slightly influences these ring vibrations.

Cu(2+) and VO(2+) doped ammonium hydrogen oxalate hemihydrate, [(NH(4))HC(2)O(4) . (1/2)H(2)O], single crystals have been studied at room temperature and at 113K in three mutually perpendicular planes. Both ions yield unexpectedly large number of lines. The calculated results of the Cu(2+) and VO(2+) doped in [(NH(4))HC(2)O(4) . (1/2)H(2)O] indicate that both ions substitute with the NH(4)(+) ion in the structure. The EPR spectra of Cu(2+) ions are characteristic of tetragonally elongated octahedral site and the spectra of VO(2+) are characteristic of tetragonally compressed complex. The angular variation of the EPR spectra has shown that two different Cu(2+) and VO(2+) complexes are located in different chemical environments, and each environment contains two magnetically inequivalent Cu(2+) and VO(2+) sites in distinct orientations occupying substitutional positions in the lattice and show very high angular dependence. The principal g and the hyperfine (A) values of both ions are determined.