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Coumarins and metal ligands

Esther S Areas, Bruna Juliana da S Bronsato, Thiago M Pereira, Guilherme P Guedes, Fábio da S Miranda, Arthur E Kümmerle, Antônio G B da Cruz, Amanda P Neves
A series of new Co(III) complexes of the type [Co(dien)(L1-L3)]ClO4 (1-3), containing fluorescent coumarin-N-acylhydrazonate hybrid ligands, (E)-N'-(1-(7-oxido-2-oxo-2H-chromen-3-yl)ethylidene)-4-R-benzohydrazonate [where R=H (L1(2-)), OCH3 (L2(2-)) or Cl (L3(2-))], were obtained and isolated in the low spin Co(III) configuration. Single-crystal X-ray diffraction showed that the coumarin-N-acylhydrazones act as tridentate ligands in their deprotonated form (L(2-)). The cation (+1) complexes contain a diethylenetriamine (dien) as auxiliary ligand and their structures were calculated by DFT studies which were also performed for the Co(II) (S=1/2 and S=3/2) configurations...
June 27, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Peng Wang, Yu Fang, Jun Jiang, Yujin Ji, Youyong Li, Junwei Zheng, Qingfeng Xu, Jianmei Lu
Owing to the demands of state-of-the-art information technologies that are suitable for vast data storage, the necessity for organic memory device (OMD) materials is highlighted. However, OMDs based on metal complexes are limited to several types of transition-metal complex systems containing nitrogen-donor ligands. Herein, attempts are made to introduce novel alkynylgold(III) materials into memory devices with superior performance. In this respect, an alkynyl-containing coumarin gold(III) complex, [(C19 N5 H11 )Au-C≡C-C9 H5 O], has been synthesized and integrated into a sandwiched Al/[(C19 N5 H11 )Au-C≡C-C9 H5 O]/indium tin oxide device...
May 2, 2017: Chemistry, An Asian Journal
Nayan Roy, Abhijit Dutta, Paritosh Mondal, Pradip C Paul, T Sanjoy Singh
A new coumarin based Schiff-base chemosensor-(E)-7-(((8-hydroxyquinolin-2-yl)methylene) amino)-4-methyl-2H-chromen-2-one (H 11 L) was synthesized and evaluated as a colorimetric sensor for Fe(3+) and fluorescence "turn on-off" response of Zn(2+) and Cu(2+) using absorption and fluorescence spectroscopy. Upon treatment with Fe(3+) and Zn(2+), the absorption intensity as well as the fluorescence emission intensity increases drastically compared to other common alkali, alkaline earth and transition metal ions, with a distinct color change which provide naked eye detection...
March 15, 2017: Journal of Fluorescence
Jingjing Deng, Guoyue Shi, Tianshu Zhou
This study demonstrates a new strategy for colorimetric detection of alcoholic strength (AS) in spirit samples based on dual-responsive lanthanide infinite coordination polymer (Ln-ICP) particles with ratiometric fluorescence. The ICP used in this study are composed of two components: one is the supramolecular Ln-ICP network formed by the coordination between the ligand 2,2'-thiodiacetic acid (TDA) and central metal ion Eu(3+); and the other is a fluorescent dye, i.e., coumarin 343 (C343), both as the cofactor ligand and as the sensitizer, doped into the Ln-ICP network through self-adaptive chemistry...
October 26, 2016: Analytica Chimica Acta
Muhammad Saleem, Muhammad Rafiq, Muhammad Hanif
Due to the deleterious effects of mercury on human health and natural ecosystems, high reactivity, non-degradability, extreme volatility and relative water and tissue solubility, it would consider as one of the most toxic environmental pollutants among the transition metals. In the present investigation, we have tried to summarized the several organic material based fluorescent sensor including rhodamine, boron-dipyrromethene (BODIPYs), thiourea, crown-ether, coumarine, squaraines, pyrene, imidazole, triazole, anthracene, dansyl, naphthalenedimide/ naphthalene/ naphthalimide, naphthyridine, iridium (III) complexes, polymeric materials, cyclodextrin, phthalic anhydride, indole, calix [4]arene, chromenone, 1,8-naphthalimides, lysine, styrylindolium, phenothiazine, thiocarbonyl quinacridone, oxadiazole, triphenylamine-triazines, tetraphenylethene, peptidyl and semicarbazone for the trace mercury detection in the aqueous, aqueous-organic and cellular media...
September 19, 2016: Journal of Fluorescence
Qiongqiong Zhang, Cankun Zhang, Lingyun Cao, Zi Wang, Bing An, Zekai Lin, Ruiyun Huang, Zhiming Zhang, Cheng Wang, Wenbin Lin
Metal-organic frameworks (MOFs) with light-harvesting building blocks designed to mimic photosynthetic chromophore arrays in green plants provide an excellent platform to study exciton transport in networks with well-defined structures. A step-by-step exciton random hopping model made of the elementary steps of energy transfer between only the nearest neighbors is usually used to describe the transport dynamics. Although such a nearest neighbor approximation is valid in describing the energy transfer of triplet states via the Dexter mechanism, we found it inadequate in evaluating singlet exciton migration that occurs through the Förster mechanism, which involves one-step jumping over longer distance...
April 27, 2016: Journal of the American Chemical Society
Chetan T Prabhakara, Sangamesh A Patil, Shivakumar S Toragalmath, Shivashankar M Kinnal, Prema S Badami
The impregnation of halogen atoms in a molecule is an emerging trend in pharmaceutical chemistry. The presence of halogens (Cl, Br, I and F) increases the lipophilic nature of molecule and improves the penetration of lipid membrane. The presence of electronegative halogen atoms increases the bio- activity of core moiety. In the present study, Co(II), Ni(II) and Cu(II) complexes are synthesised using Schiff bases (HL(I) and HL(II)), derived from 8-formyl-7-hydroxy-4-methylcoumarin/3-chloro-8-formyl-7-hydroxy-4-methylcoumarin with 2,4-difluoroaniline/o-toluidine respectively...
April 2016: Journal of Photochemistry and Photobiology. B, Biology
Pablo Rivera-Fuentes, Stephen J Lippard
Nitroxyl (HNO) is a biological signaling agent that displays distinctive reactivity compared to nitric oxide (NO). As a consequence, these two reactive nitrogen species trigger different physiological responses. Selective detection of HNO over NO has been a challenge for chemists, and several fluorogenic molecular probes have been recently developed with that goal in mind. Common constructs take advantage of the HNO-induced reduction of Cu(II) to Cu(I). The sensing mechanism of such probes relies on the ability of the unpaired electron in a d orbital of the Cu(II) center to quench the fluorescence of a photoemissive ligand by either an electron or energy transfer mechanism...
November 17, 2015: Accounts of Chemical Research
Muhammad Mujahid, Agnieszka Foltyn-Arfa Kia, Brian Duff, Denise A Egan, Michael Devereux, Siobhán McClean, Maureen Walsh, Natasha Trendafilova, Ivelina Georgieva, Bernadette S Creaven
Silver(I) complexes of coumarin-based ligands and one of their phenanthroline (phen) adducts have been prepared and characterized using microanalytical data, molar conductivity, IR, (1)H and (13)C NMR, UV-Vis, and atomic absorption (AAS) spectroscopies. The binding modes of the coumarin-based ligands and the most probable structure of their Ag(I) complexes were predicted by means of molecular modeling and calculations of their IR, NMR, and absorption spectra using density functional theory (DFT). The cytotoxicity of the compounds studied against human-derived hepatic carcinoma cells (Hep-G2) and a renal cancer cell line (A498) showed that the complexes were more cytotoxic than the clinically used chemotherapeutic, mitoxantrone...
December 2015: Journal of Inorganic Biochemistry
Qingtao Meng, Hongmin Jia, Peter Succar, Liang Zhao, Run Zhang, Chunying Duan, Zhiqiang Zhang
A new complex between coumarin-based ligand (CL) and copper ion has been prepared and applied to be an ON-OFF-ON reversible fluorescence chemosensor for the detection of Cys with high sensitivity and specificity. In HEPES buffer, CL displayed high affinity towards Cu(2+) ion over other physiological and environmental metal ions, accompanied with a 98.4% of fluorescence quenching. In the presence of Cys, the detachment of Cu(2+) ion of CL-Cu(2+) ensemble led to the liberation of the fluorophore, CL, and thus fluorescence was recovered...
December 15, 2015: Biosensors & Bioelectronics
Chetan T Prabhakara, Sangamesh A Patil, Ajaykumar D Kulkarni, Vinod H Naik, M Manjunatha, Shivshankar M Kinnal, Prema S Badami
The Co(II), Ni(II) and Cu(II) complexes have been synthesized with Schiff base (HL), derived from 8-formyl-7-hydroxy-4-methylcoumarin with benzylamine. The Schiff base and its metal complexes were structurally characterized based on IR, (1)H NMR, (13)C NMR, UV-visible, ESR, magnetic, thermal, fluorescence, mass and ESI-MS studies. The complexes are completely soluble in DMF and DMSO. The molar conductance values indicate that, all synthesized metal complexes are non-electrolytic in nature. Elemental analysis reveals [ML2(H2O)2] stoichiometry, here MCo(II), Ni(II) and Cu(II), L=deprotonated ligand...
July 2015: Journal of Photochemistry and Photobiology. B, Biology
Yingying Han, Changqin Ding, Jie Zhou, Yang Tian
It is very essential to disentangle the complicated inter-relationship between pH and Cu in the signal transduction and homeostasis. To this end, reporters that can display distinct signals to pH and Cu are highly valuable. Unfortunately, there is still no report on the development of biosensors that can simultaneously respond to pH and Cu(2+), to the best of our knowledge. In this work, we developed a single fluorescent probe, AuNC@FITC@DEAC (AuNC, gold cluster; FITC, fluorescein isothiocyanate; DEAC, 7-diethylaminocoumarin-3-carboxylic acid), for biosensing of pH, Cu(2+), and pH/Cu(2+) with different ratiometric fluorescent signals...
2015: Analytical Chemistry
A A Abou-Hussein, Wolfgang Linert
Two series of new mono and binuclear complexes with a Schiff base ligand derived from the condensation of 3-acetylcoumarine and diethylenetriamine, in the molar ratio 2:1 have been prepared. The ligand was characterized by elemental analysis, IR, UV-visible, (1)H-NMR and mass spectra. The reaction of the Schiff base ligand with cobalt(II), nickel(II), copper(II), zinc(II) and oxovanadium(IV) lead to mono or binuclear species of cyclic or macrocyclic complexes, depending on the mole ratio of metal to ligand and as well as on the method of preparation...
April 15, 2015: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Marcin T Klepka, Aleksandra Drzewiecka-Antonik, Anna Wolska, Paweł Rejmak, Kinga Ostrowska, Elżbieta Hejchman, Hanna Kruszewska, Agnieszka Czajkowska, Izabela Młynarczuk-Biały, Wiesława Ferenc
The new Cu(II) complexes with 6-acetyl-7-hydroxy-4-methylcoumarin (HL1) and 8-acetyl-7-hydroxy-4-methylcoumarin (HL2) have been obtained by the electrochemical method. The density functional theory calculations and X-ray absorption spectroscopy techniques have been used to geometrically describe a series of new compounds. The studies have been focused on the coordination mode of the hydroxy ligands to the metallic centre. The complexes, Cu(HL1)2 and Cu(HL2)2⋅0.5H2O, have flat square geometry with oxygen atoms in the first coordination sphere...
April 2015: Journal of Inorganic Biochemistry
Bobby Happ, Joachim Kübel, Michael G Pfeffer, Andreas Winter, Martin D Hager, Benjamin Dietzek, Sven Rau, Ulrich S Schubert
Two- and three-component polymethacrylates, featuring a 2-(1-substituted-1H-1,2,3-triazol-4-yl)pyridine-based metal complex as photosensitizer, a viologen-type electron mediator, and a triethylene glycol methyl ether as solubilizing part are synthesized by statistical reversible addition-fragmentation chain transfer (RAFT) radical polymerization allowing the construction of well-defined copolymers. Thereby, heteroleptic ruthenium(II) and iridium(III) complexes serve as charged photosensitizers. In hydrogen evolution experiments, as proof-of-concept, triethylamine is utilized as a sacrificial donor and colloidal platinum as hydrogen evolving catalyst...
April 2015: Macromolecular Rapid Communications
Jingjing Deng, Ping Yu, Yuexiang Wang, Lanqun Mao
This study demonstrates a novel ratiometric fluorescent method for real-time alkaline phosphatase (ALP) activity assay with stimulus responsive infinite coordination polymer (ICP) nanoparticles as the probe. The ICP nanoparticles used in this study are composed of two components; one is the supramolecular ICP network formed with guanine monophosphate (GMP) as the ligand and Tb(3+) as the central metal ion, and the other is a fluorescent dye, i.e., 7-amino-4-methyl coumarin (coumarin) encapsulated into the ICP network...
March 3, 2015: Analytical Chemistry
Wolfgang Brandt, Kerstin Manke, Thomas Vogt
Crystal structure data of cation-dependent catechol O-methyltransferases (COMTs) from mammals and related caffeoyl coenzyme A OMTs (CCoAOMTs) from plants have suggested operative molecular mechanisms. These include bivalent cations that facilitate deprotonation of vicinal aromatic dihydroxy systems and illustrate a conserved arrangement of hydroxyl and carboxyl ligands consistent with the requirements of a metal-activated catalytic mechanism. The general concept of metal-dependent deprotonation via a complexed aspartate is only one part of a more pronounced proton relay, as shown by semiempirical and DFT quantum mechanical calculations and experimental validations...
May 2015: Phytochemistry
Nitesh V Sule, Angel Ugrinov, Sanku Mallik, D K Srivastava
BACKGROUND: Methionyl-7-amino-4-methylcoumarin (MetAMC) serves as a substrate for the Escherichia coli methionine aminopeptidase (MetAP) catalyzed reaction, and is routinely used for screening compounds to identify potential antibiotic agents. In pursuit of screening the enzyme's inhibitors, we observed that 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), utilized to solubilize hydrophobic inhibitors, inhibited the catalytic activity of the enzyme, and such inhibition was not solely due to sequestration of the substrate by HP-β-CD...
January 2015: Biochimica et Biophysica Acta
S Nedd, A N Alexandrova
The mechanism of the formation of coumarins via the Pd-catalyzed intramolecular hydroarylation of the C-C triple bond is elucidated computationally, in corroboration with experimental data. It is shown that the reaction follows the concerted metalation-deprotonation (CMD) mechanism. The typically suspected mechanisms of ambiphilic metal ligand activation (AMLA), electrophilic aromatic substitution (EAS), and oxidative addition (OA) are suggested to be non-competitive, based on predicted conformations and energetics...
January 14, 2015: Physical Chemistry Chemical Physics: PCCP
Na Li, Pengxiang Zhao, María E Igartua, Amalia Rapakousiou, Lionel Salmon, Sergio Moya, Jaime Ruiz, Didier Astruc
Monofunctional triazoles linked to ferrocene, ferricenium, or coumarin (Cou), easily synthesized by copper-catalyzed azide alkyne (CuAAC) "click" reactions between the corresponding functional azides and (trimethylsilyl)acetylene followed by silyl group deprotection, provide a variety of convenient neutral ligands for the stabilization of functional gold nanoparticles (AuNPs) in polar organic solvents. These triazole (trz)-AuNPs are very useful toward a variety of applications to synthesis, sensing, and catalysis...
November 3, 2014: Inorganic Chemistry
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