- Anthracene coupled adenine for the selective sensing of copper ions
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Anthracene-based adenines 1 and 2 have been designed and synthesized, and their metal ion recognition properties have been established fluorometrically. Both molecules exhibit Cu 2+ induced ON-OFF type signaling patterns over the other representative metal ions studied. Compound 1 exhibits 97% quenching of emission in the presence of Cu 2+ whilst derivative 2 shows 81% quenching under similar experimental conditions.
- Ghosh, Kumaresh,Sen, Tanushree
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- Dual Fluorophore Containing Efficient Photoinduced Electron Transfer Based Molecular Probe for Selective Detection of Cr3+ and PO43- Ions through Fluorescence " Turn-On-Off" Response in Partial Aqueous and Biological Medium: Live Cell Imaging and Logic Application
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The present work describes a new photoinduced electron transfer (PET) based molecular probe in which naphthalimide (NPI) and anthracene (AN) chromophores are linked through a molecular bridge of piperazine and triazole units by the Click reaction. A typical meaningful structural variation has made the present probe highly selective for Cr3+ ion (limit of detection (LOD), 5.567 × 10-8 M) that displayed enhanced, "turn-On" emission (due to the PET-Off photophysical mechanism) and naked-eye sensitive bright green color fluorescence in the environment of interfering and competitive ions, in Tris-HCl buffer. The minimum energy structure obtained through theoretical calculations (density functional theory (DFT) and time-dependent (TD)-DFT) revealed a "tub" shape structure for probe 10. Upon complexation, the conformation of piperazine fragment changes from chair to boat in which the triazole and piperazine units create a cavity to tether Cr3+. Moreover, the probe showed excellent biocompatibility and cell permeability to sense Cr3+ sensitively in live cells and, thus, holds great promise for application in biological and environmental sciences. Additionally, the sensitive "Off-On-Off" sensing behavior of probe 10 providing two chemical inputs (Cr3+ and PO43-) helps to construct an INHIBIT logic gate. Also the probe has been utilized as printing material to decode secret information through the Cr3+ ion containing "marker ink" under UV light.
- Dwivedi, Sushil K.,Gupta, Ramesh C.,Srivastava, Priyanka,Singh, Priya,Koch, Biplob,Maiti, Biswajit,Misra, Arvind
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- Intramolecular stacking of two aromatic rings in the platinum(II) coordination sphere: Preparation, crystal structures, and 1H NMR spectra of bipyridine(N-arylmethyl-1,2-ethanediamine)platinum(II) nitrate
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Square-planar complexes with the formula [Pt(L1)(L2)](NO3)2·nH2O, where L1 is bipyridine (bpy) and L2 is N-benzyl-1,2-ethanediamine (Been) (1) (n = 0), N-(1-naphthyl)methyl-1,2-ethanediamine (Npen) (2) (n = 2), and N-(9-anthryl)methyl-1,2-ethanediamine (Aten) (3) (n = 2), were prepared and X-ray crystal-structure determinations were carried out. The molecular structures of the complex cations revealed that the N-arylmethyl groups are forced to take pseudo axial dispositions due to an intramolecular repulsion from hydrogen atoms of bpy. The aromatic-aromatic interaction between the aromatic rings of ethanediamine derivatives and coordinated bpy caused 2 and 3 to take a conformation where the aromatic ring and bpy stack face-to-face to each other intramolecularly. An intermolecular aromatic-aromatic face-to- face interaction was also observed for 1, 2, and 3 in the crystals. The latter interaction occurs between bpy and the aryl substituent, except for 1. For D2O solutions of 1 through 3, significant upfield shifts due to the intramolecular stacking were observed in the 1H NMR spectra for the protons on the half ring of bipyridine, depending on the size of the aromatic ring. The crystal data of 1: monoclinic, P21/c, a = 9.884(2), b = 24.717(2), c = 9.560(5) A, β = 113.83(3)°, Z = 4, and R = 0.029. 2: monoclinic, Ia, a = 17.030(5), b = 10.461(4), c = 14.727(4) A, β = 94.72°, Z = 4, and R = 0.023. 3: monoclinic, P(n), a = 10.471(2), b = 8,844(5), c = 15.332(3)A, β = 98.61(2)°, Z = 2, and R = 0.034.
- Goto, Masafumi,Matsumoto, Takashi,Sumimoto, Masamitsu,Kurosaki, Hiromasa
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- A Fluorescent Silver(I) Carbene Complex with Anticancer Properties: Synthesis, Characterization, and Biological Studies
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The silver(I) N-heterocyclic carbene (NHC) complex bis(1-(anthracen-9-ylmethyl)-3-ethylimidazol-2-ylidene) silver chloride ([Ag(EIA)2]Cl), bearing two anthracenyl fluorescent probes, has been synthesized and characterized. [Ag(EIA)2]Cl is stable in organic solvents and under physiological conditions, and shows potent cytotoxic effects in vitro toward human SH-SY5Y neuroblastoma cells. The interactions of [Ag(EIA)2]Cl with a few model biological targets have been studied as well as its ability to be internalized in cells. The in vitro anticancer activity is apparently related to the level of drug internalization. Notably, [Ag(EIA)2]Cl does not react with a few model proteins, but is capable of binding the C-terminal dodecapeptide of thioredoxin reductase hTrxR(488–499) and to strongly inhibit the activity of this enzyme. Binding occurs through an unconventional process leading to covalent binding of one or two carbene ligands to the C-terminal dodecapeptide with concomitant release of the silver cation. To the best of our knowledge, this mode of interaction is reported here for the first time for Ag(NHC)2 complexes.
- Fabbrini, Maria Giulia,Cirri, Damiano,Pratesi, Alessandro,Ciofi, Lorenzo,Marzo, Tiziano,Guerri, Annalisa,Nistri, Silvia,Dell'Accio, Alfonso,Gamberi, Tania,Severi, Mirko,Bencini, Andrea,Messori, Luigi
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p. 182 - 188
(2019/01/04)
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- Reductive Amination by Photoredox Catalysis and Polarity-Matched Hydrogen Atom Transfer
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The excitation of a RuII photosensitizer in the presence of ascorbic acid leads to the reduction of iminium ions to electron-rich α-aminoalkyl radical intermediates, which are rapidly converted into reductive amination products by thiol-mediated hydrogen atom transfer (HAT). As a result, the reductive amination of carbonyl compounds with amines by photoredox catalysis proceeds in good to excellent yields and with broad substrate scope and good functional group tolerance. The three key features of this work are 1) the rapid interception of electron-rich α-aminoalkyl radical intermediates by polarity-matched HAT in a photoredox reaction, 2) the method of reductive amination by photoredox catalysis itself, and 3) the application of this new method for temporally and spatially controlled reactions on a solid support, as demonstrated by the attachment of a fluorescent dye on an activated cellulose support by photoredox-catalyzed reductive amination.
- Guo, Xingwei,Wenger, Oliver S.
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supporting information
p. 2469 - 2473
(2018/01/27)
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- Synthesis and inclusion ability of anthracene appended β- cyclodextrins: Unexpected effect of triazole linker
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A new fluorescent β-cyclodextrin has been synthesized by coupling an anthracene moiety to the cyclic oligosaccharide via click chemistry. The influence of the triazole spacer was compared to the simple amino and amido linkers. While a sensing ability toward adamantan-1-ol was observed with the latter two spacers, the absence of inclusion capacity prevents the triazole modified cyclodextrin from showing any fluorescence variations. The difference in the binding behaviors studied by Isothermal Titration Calorimetry, UV-vis and fluorescence spectroscopies, was highlighted by the NOESY NMR spectra of the modified cyclodextrins: whereas a free cavity was observed for the amino and amido linkers, an important obstruction was obtained in the case of the triazole.
- Mallard, Isabelle,Landy, David,Bouchemal, Nadia,Fourmentin, Sophie
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experimental part
p. 35 - 42
(2011/02/25)
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- Control between TICT and PET using chemical modification of N-phenyl-9-anthracenecarboxamide and its application to a crown ether type chemosensor
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Both twisted intramolecular charge transfer (TICT) and photoinduced electron transfer (PET) relaxation processes of N-phenyl-9-anthrylcarboxamide derivatives can be characterized by modified substitution of the phenyl group. Introduction of a methoxy group to phenyl moiety quenched fluorescence of the anthracene using TICT or PET process, and was not retrieved even using highly viscous media. The introduction of a methylene unit induced fluorescence emissions using a solvent with both viscosity and polarity. This phenomenon demonstrates that the effects of both TICT and PET are involved in this system. Based on these data, we synthesized a novel crown ether derivative 7: its analytical usefulness as a fluorescent chemosensor for alkaline earth metal ions is reported herein.
- Kim, Jeongsik,Morozumi, Tatsuya,Nakamura, Hiroshi
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p. 10735 - 10740
(2008/12/23)
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- Aromatic thioesters as protecting groups for thiols against 1,2-didehydrobenzenes
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Divalent sulfur compounds usually react with 1,2-didehydrobenzenes to give a palette of unspecific products. To identify a suitable protecting group for thiols under the reaction conditions typically used for the synthesis of triptycenes, that is, 1,2-didehydrobenzene generated in situ from 2-diazoniobenzenecarboxylate at elevated temperatures, a wide-ranging optimization study was conducted. Of several acyl groups investigated, the benzoyl group turned out to be optimal. The efficiency of this protecting group was demonstrated by the successful transformation of an electron-poor (thus unreactive) anthracene derivative to the corresponding triptycenethiol derivative. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Fowelin, Christian,Schuepbach, Bjoern,Terfort, Andreas
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p. 1013 - 1017
(2008/03/12)
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- Amine-guanidine switch: A promising approach to improve DNA binding and antiproliferative activities
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A series of polyaromatic guanidino derivatives was synthesized and evaluated for growth inhibitory properties in several human carcinoma cell lines. The properties of these guanidino compounds were compared to those of their corresponding synthetic amino precursors. The size of the polyaromatic ring system as well as the length of the tether attached to the ring had a direct impact on the observed antiproliferative profiles, compound 14 having the broadest spectrum of activity. As both series intercalate DNA, guanidine derivatives showed a remarkable affinity for DNA and the guanidinium group appeared to be essential, yet not sufficient for caspase-3/7 activation. Compound 14 also showed significant in vivo activity against breast cancer cell xenografts in NOG/SCID mice. These results suggest that the electronic nature of chain tethering an intercalator not only influences the DNA-binding process but also controls the antitumoral activity of the whole compound.
- Ohara, Keiichiro,Smietana, Michael,Restouin, Audrey,Mollard, Séverine,Borg, Jean-Paul,Collette, Yves,Vasseur, Jean-Jacques
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p. 6465 - 6475
(2008/04/12)
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- Conversion of hydrazones to alkyl chlorides under Swern oxidation conditions
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The unsubstituted hydrazones derived from aromatic ketones and aldehydes were converted in high yield to the corresponding alkyl chlorides under Swern oxidation conditions. In this unusual oxidation/reduction sequence the substrate undergoes a net reduction under the well established Swern oxidation conditions. Unsubstituted hydrazones derived from cyclohexyl ketones returned elimination products.
- Brewer, Matthias
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p. 7731 - 7733
(2007/10/03)
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- Halogenations of Anthracenes and Dibenz[a,c]anthracene with N-Bromosuccinimide and N-Chlorosuccinimide
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Halogenation of dibenz[a,c]anthracene (1) by NBS in CCl4 affords the products of 9- and 10-monobromination in the ratio of 9:1. The reaction is accelerated by iodine, and HBr effects rearrangement of 9-bromo product to the sterically less crowded 10-bromo isomer. The mechanism is proposed to involve reversible addition of Br2, followed by elimination of HBr. Reaction of NCS with 1 in CCl4 requires addition of HCl and affords exclusively 9-chlorination. The different reactivities of NBS and NCS are ascribed to the relative amounts of free halogen produced (due to differences in N-X bond strengths involving Br and Cl), and the different sizes of the halogens. Under similar conditions, NCS chlorinates 9-bromoanthracene (2a) to afford 9,10-dichloroanthracene and 9-bromo-10-chloroanthracene in the ratio of 65:35. This reaction ostensibly occurs by addition of Cl2 to 2a, followed by preferential loss of HBr rather than HCl. 9-Methylanthracene (3) affords exclusively 9-(bromomethyl)anthracene with NBS in the absence of iodine, but mainly (67%) 9-bromo-10-methylanthracene in the presence of iodine. Chlorination of 3 with NCS in the presence of HCl also affords mostly (65%) nuclear halogenation. Nuclear bromination of anthracene, 9-methylanthracene, and dibenz[a,c]anthracene by NBS in the absence of added HBr is accelerated by iodine. This effect is probably due to an increase in the amount of bromine produced from NBS in the presence of iodine.
- Duan, Shaoming,Turk, Jeff,Speigle, Joseph,Corbin, Jean,Masnovi, John,Baker, Ronald J.
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p. 3005 - 3009
(2007/10/03)
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- Synthesis of 5'-polyarene-tethered oligo-DNAs and the thermal stability and spectroscopic properties of their duplexes and triplexes
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Eleven different planar hydroxy alkylated polyarenes 1-11 with different geometry, bulk and electronic characteristics were synthesised, and used for tethering to the 5'-phosphate of a 9-mer and a 18-mer DNA sequences through solid-phase synthesis. The 5'-polyarene-tethered 9-mers 30-40 were tested for their ability to form stable duplexes with four complementary target DNA-strands 25-28 of different length. The 5'-polyarene-tethered 18-mers 44-54 were tested for their ability to form stable triplexes with a 24-mer duplex target 41+42. The T(m) measurements of duplexes at low salt and pH 7.3 showed that the angular nitro phenanthrene and phenanthrene conjugates 31 and 30 gave the highest duplex stabilisations with targets 25 (ΔT(m) 13.8°C and 11.8°C) and 26 (ΔT(m), 12.3°C and 11.9°C). With the mismatch sequence 28, only 30 and 31 gave a high ΔT(m), of 11.6°C and 10.8°C respectively, while lower ΔT(m), values were observed for other conjugates (ΔT(m), -4.0-5.0°C). The T(m) measurements of triplexes between 43-54 and duplex target 41+42 at low salt and pH 7.3, 6.5 and 6.0 without Mg2+ showed that the nitro phenanthrene conjugate 45 gave the best triplex stabilisation (ΔT(m), 4.1-5.4°C). The stabilisation of nitro phenanthrene conjugate 45 compared to phenanthrene conjugate 44 increased more remarkably when Mg2+ was present: 45 (ΔT(m), 15°C), 44 (ΔT(m), 10°C). These results imply that the electron density of the chromophore influences the π-π stacking interactions between the chromophore and nucleobases, and thereby influencing the duplex and triplex stability. Fluorescence measurements on single strand to double strand transition indicated that the 5'-tethered polyarenes are stacked only on the neighbouring nucleobases of the opposite strand. In case of 5'-9-N-ethylphenazinium conjugate 36, a comparative NMR and fluorescence measurement has unambiguously shown that the tethered phenazinium ion is indeed intercalated between the nucleotides of the opposite target strand 26. Thermodynamic calculations showed the most stable ΔG°(298K) for 30, 31(+targets 25, 26, 28) and 35, 36(+targets 25, 26) compared to the blank 29 ΔΔG°(298K) ~-10kJ mol-1). The non-palindromic target 27 was shown by T(m) measurements to form a stable tertiary structure, which was very little affected by addition of any 5'-tethered conjugate, thereby showing the importance of the tertiary structures of an in vivo antisense target and its implication in regard to its bioavailablity to complementary antisense probes.
- Puri, Nitin,Zamaratski, Edouard,Sund, Christian,Chattopadhyaya, Jyoti
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p. 10409 - 10432
(2007/10/03)
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- Multiple-photon chemistry of 9-(phenoxymethyl)- and 9,10-bis(phenoxymethyl)anthracenes in the laser-jet: Generation, photochemistry, and time-resolved laser-flash spectroscopy of anthracenylmethyl radicals and pulse radiolysis of 9-(bromomethyl)anthracene
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In the high-intensity laser-jet (LJ) photolysis of 9-(phenoxymethyl)anthracene (1a) and 9,10-bis(phenoxymethyl)anthracene (1b) multiple-photon chemistry was observed. Thus, while the [4 + 4] photodimer 8a was formed as the one-photon product in the low-intensity conventional photolysis of monoether 1a, the high-intensity irradiation in the laser-jet yielded 1,2-bis(9-anthracenyl)ethane (3a), lepidopterene (4a), biplanene (5a), 9-(chloromethyl)anthracene (6a), and 9-(methoxymethyl)anthracene (7a) as main products. The product distribution depended on the solvent used: after C-O homolysis of the ether 1a, for which at least two photons are required, the resulting arylmethyl radical 2a dimerizes in benzene, in methylene chloride it engages in photoinduced electron transfer, while in methanol it undergoes photoionization. With the help of time-resolved laser-flash photolysis of the monoether 1a it was confirmed that the homolysis of the C-O bond leads to the 9-anthracenylmethyl radical 2a. The authentic radical 2a was generated independently by time-resolved pulse radiolysis and laser-flash photolysis of 9-(bromomethyl)anthracene. Analogous to the monoether 1a, the bisether 1b gave under the high intensity conditions of the laser-jet irradiation tetrabenzo[2.2]paracyclophane (3b), its photodimer (5b), 9,10-(bischloromethyl)anthracene (6b), and 9-(chloromethyl)-10-(phenoxymethyl)anthracene (9b); their distribution depended also on the solvent used. Mechanistic pathways are offered for these multiple-photon processes.
- Adam, Waldemar,Schneider, Katrin,Stapper, Marion,Steenken, Steen
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p. 3280 - 3287
(2007/10/03)
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- New applications of tungsten hexachloride (WCl6) in organic synthesis. Halo-de-hydroxylation and dihalo-de-oxo-bisubstitution reactions
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Tungsten hexachloride (WCl6) has been used for the halo-de-hydroxylation and dihalo-de-oxo-bisubstitution reactions of benzylic alcohols, benzaldehydes, acyloins, and epoxides to their chlorides, gem-dichlorides, vic-trichlorides, and vic-dichlorides respectively.
- Firouzabadi, Habib,Shiriny, Farhad
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p. 14929 - 14936
(2007/10/03)
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- Intramolecular Diels-Alder Additions. 1. Additions to Anthracene and Acridine
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Intramolecular Diels-Alder reaction of suitably 9-substituted anthracenes at temperatures ranging from 25 to 220 deg C yields a wide variety of 9,12-bridged ethano- and ethenoanthracenes.Adducts having tree-, four-, and five-membered bridges, many incorporating heteroatoms such as oxygen, nitrogen, and sulfur, have been prepared.The ease of cyclization decreases with increasing bridge length.Neither the diene nor the dienophile need to carry activating groups; vinyl and ethynyl dienophiles add with equal ease.Cyclization of N-methyl-N-propargyl-9-acridinecarboxamide gives 31, the first thermal adduct of an acridine.
- Ciganek, Engelbert
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p. 1497 - 1505
(2007/10/02)
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