Photoproducts of 7-Hydroxycoumarins in Aqueous Solution

2012 ◽  
Vol 65 (10) ◽  
pp. 1451 ◽  
Author(s):  
Gerald J. Smith ◽  
Roderick J. Weston ◽  
Ying Tang ◽  
Yinrong Lu ◽  
Jolon M. Dyer
Keyword(s):  
Mass Spectrometry ◽  
Aqueous Solution ◽  
Excited State ◽  
Mass Spectrum ◽  
Solid State ◽  
Aqueous Solutions ◽  
Fluorescence Spectra ◽  
Major Product ◽  
Structural Assignment ◽  
Esi Mass Spectrometry

Near-UV irradiation of aqueous solutions of 7-hydroxy-6-methoxycoumarin (scopoletin) and 6,7-dihydroxycoumarin (esculetin) resulted in the formation of dimers. Substantially greater amounts of the 7-hydroxy-6-methoxycoumarin photodimer were produced compared with that of 6,7-dihydroxycoumarin. Fluorescence spectra indicated that the initial photolytic reaction involves the excited state of the phenolate form of the monomeric coumarin. The electro-spray ionization (ESI) mass spectrum suggested that the major product (with a sodiated quasimolecular ion at m/z 405) from the photolysis of scopoletin in water had formed by oxidative dimerisation and possibly had a 3,3′-bond. A second dimer (with a sodiated quasimolecular ion at m/z 407) was probably a 2 + 2 cyclodimer. This work concluded that photolysis of coumarins in water results in oxidative dimerisation whereas photolysis in the solid state or in organic solvents results in cyclodimerisation. Minor monomeric photoproducts were a dihydroxy-6-methoxycoumarin from 7-hydroxy-6-methoxycoumarin and a trihydroxycoumarin from 6,7-dihydroxycoumarin. During ESI-mass spectrometry (ESI-MS), sodiated quasimolecular ions of the photodimer formed more readily than protonated quasimolecular ions and the sodiated ions did not fragment readily. Protonated quasimolecular ions of the monomeric coumarins formed more readily than their sodiated counterparts and the protonated ions fragmented to create daughter ion spectra that were useful for chemical structural assignment.

Imidazolato-bridged complexes of copper(II)

1970 ◽  
Vol 23 (10) ◽  
pp. 1973 ◽  
Author(s):  
ME Bridson ◽  
WR Walker
Keyword(s):  
Aqueous Solution ◽  
Solid State ◽  
Aqueous Solutions ◽  
Electronic Spectra ◽  
Empirical Formula ◽  
Spectroscopic Data ◽  
Bridging Ligand

Compounds of the empirical formula Cu(HIm)2(Im)X [where X = NO3-, ClO4-, Cl-, Br-, and I-; HIm = imidazole and Im- = anion of imidazole] have been prepared and investigated. Evidence for the imidazolato anion acting as a bridging ligand in the solid state is based on magnetic and spectroscopic data. The electronic spectra of aqueous solutions of tetrakisimidazolecopper(11) compounds suggest the presence of the binuclear hydroxy-bridged cation (1) : (See diagram in article) which is also furnished by the imidazolato-bridged species in aqueous solution.

scholarly journals Order in disorder: solution and solid-state studies of [MIII2MII5] wheels (MIII = Cr, Al; MII = Ni, Zn)

2018 ◽  
Vol 47 (34) ◽  
pp. 11834-11842 ◽  
Author(s):  
Hector W. L. Fraser ◽  
Gary S. Nichol ◽  
Dušan Uhrín ◽  
Ulla Gro Nielsen ◽  
Marco Evangelisti ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Single Crystal ◽  
Solid State Nmr ◽  
Squid Magnetometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solid State Nmr Spectroscopy ◽  
Esi Mass Spectrometry

Heterometallic species with Anderson-like structures are characterised by single-crystal X-ray diffraction, solution- and solid-state NMR spectroscopy, ESI mass spectrometry and SQUID magnetometry.

Free-Radical Reductions of Arenediazonium Ions in Aqueous Solution. VI. On Iododediazoniation

1985 ◽  
Vol 38 (6) ◽  
pp. 991 ◽  
Author(s):  
JE Packer ◽  
RER Taylor
Keyword(s):  
Aqueous Solution ◽  
Free Radical ◽  
Aqueous Solutions ◽  
Major Product ◽  
Chain Reaction ◽  
Γ Irradiation ◽  
A Chain

γ-Irradiation of aqueous solutions of p-ClC6H4N2+BF4- and KI initiates a chain reaction in which dichloroazobenzene is the major product. When iodine is also present the chain reaction is longer and the major product is chloroiodobenzene . The reaction � ������������������������� I2-·+ArN2+ → I2+Ar·+N2 is suggested to be propagation step in both reactions, with Ar · reacting with I3- in the presence of iodine and with ArN2+ in its absence. The relevance of these reactions to iododediazoniation is discussed.

Gamma Irradiation of Uridine and Uridylic Acid in Aerated A queous Solutions: Identification of the Major Product

1974 ◽  
Vol 29 (9-10) ◽  
pp. 643-644 ◽  
Author(s):  
R Ducolomb ◽  
J Cadet ◽  
R Teoule
Keyword(s):  
Mass Spectrometry ◽  
Aqueous Solution ◽  
Thin Layer ◽  
Gamma Irradiation ◽  
Optical Rotation ◽  
Hydrolytic Degradation ◽  
Major Product ◽  
Gel Chromatography ◽  
Spectroscopic Methods ◽  
Silica Gel Chromatography

Abstract The major product of uridine gamma irradiation in aerated aqueous solution (10-3 ᴍ, pH ~6) has been identified: N-(β-ᴅ-ribofuranosyl) -formamide. Thin-layer silica gel chromatography and spectroscopic methods (mass spectrometry. NMR, IR, optical rotation) enabled us to isolate and characterize this product. It may be assumed that this substance resulted from the hydrolytic degradation of unstable hydroxy-hydroperoxides. It was also prepared by uridine oxydation with pertrifluoracetic acid. A similar major compound in the radiolysis of uridylic acid has been found

scholarly journals Cytotoxicity of doxorubicin conjugated with C60 fullerene. Structural and in vitro studies

2019 ◽  
Vol 30 (6) ◽  
pp. 2327-2338
Author(s):  
Kamila Butowska ◽  
Witold Kozak ◽  
Magdalena Zdrowowicz ◽  
Samanta Makurat ◽  
Michał Rychłowski ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Aqueous Solution ◽  
Fluorescence Spectra ◽  
C60 Fullerene ◽  
Absorption And Fluorescence Spectra ◽  
H Nmr ◽  
Low Toxicity ◽  
Pass Through ◽  
The Impact

Abstract Conjugating an anticancer drug of high biological efficacy but large cytotoxicity with a “transporting” molecule of low toxicity constitutes a valuable approach to design safe drug delivery system. In the present study, doxorubicin (DOX) a drug of large cardiotoxicity was chemically conjugated to a C60-fullerene. The synthesized molecule, a fullerene-doxorubicin conjugate (Ful-DOX), was characterized using the 1H NMR and MALDI TOF mass spectrometry. The absorption and fluorescence spectra and dynamic light scattering of the conjugate were recorded in an aqueous solution, while the impact on viability of several cancer cell lines of the free DOX and the conjugate was compared using the SRB and WST-1 assays. A low antiproliferative activity of the conjugate as compared to the free DOX is a consequence of the presence of fullerene moiety in the former, which is also responsible for the conjugate aggregation in an aqueous solution. Unlike free DOX, these aggregates cannot pass through the nuclear membrane (as demonstrated by the confocal microscopy measurements), which makes them marginally cytotoxic.

scholarly journals Synthesis and characterization of 2-pyridineformamide 3-pyrrolidinylthiosemicarbazone

2013 ◽  
Vol 29 ◽  
pp. 28-33
Author(s):  
B. Shakya ◽  
P. N. Yadav
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrum ◽  
Nmr Spectroscopy ◽  
13C Nmr Spectroscopy ◽  
Synthesis And Characterization ◽  
Ionization Mass ◽  
Transamination Reaction ◽  
Ionization Mass Spectrum ◽  
Esi Mass Spectrometry

Pyrrolidine-1-carbothiohydrazide was prepared by the transamination reaction of 4-methyl-4-phenyl-3-thiosemicarbazide with pyrrolidine in MeCN. 2-pyridineformamide 3-pyrrolidinyl-thiosemicarbazone (HAmPyrr) was synthesized by the reduction of cyanopyridine in the presence of pyrrolidine-1-carbothiohydrazide in MeOH with Na metal. The synthesized compound was characterized by elemental analysis, IR, 1H-NMR, 13C-NMR spectroscopy and ESI mass spectrometry. The prominent (M+1) peak (m/z) of HAmPyrr in the electron spray ionization mass spectrum was found at 250.09 which correspond to the molecular ion plus H. DOI: http://dx.doi.org/10.3126/jncs.v29i0.9234Journal of Nepal Chemical SocietyVol. 29, 2012Page: 28-33Uploaded date : 12/3/2013

scholarly journals Heteroleptic [Cu(P^P)(N^N)][PF6] Compounds with Isomeric Dibromo-1,10-Phenanthroline Ligands

Inorganics ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 4 ◽  
Author(s):  
Isaak Nohara ◽  
Aramis Keller ◽  
Nikolai Tarassenko ◽  
Alessandro Prescimone ◽  
Edwin C. Constable ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Excited State ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Single Crystal ◽  
Quantum Yields ◽  
Excited State Lifetime ◽  
X Ray ◽  
Multinuclear Nmr Spectroscopy ◽  
Phenanthroline Ligands

A series of [Cu(P^P)(N^N)][PF6] compounds are reported in which N^N is 2,9-dibromo-1,10-phenanthroline (2,9-Br2phen), 3,8-dibromo-1,10-phenanthroline (3,8-Br2phen) or 4,7-dibromo-1,10-phenanthroline (4,7-Br2phen) and P^P is bis(2-(diphenylphosphano)phenyl)ether (POP) or 4,5-bis(diphenylphosphano)-9,9-dimethylxanthene (xantphos). The compounds were characterized by solution multinuclear NMR spectroscopy, mass spectrometry and a single-crystal X-ray analysis. Each compound underwent a partially reversible or irreversible copper-centred oxidation, the highest potential being for 2,9-Br2phen-containing compounds. In solution, the compounds are weak yellow or orange emitters, whereas powdered samples exhibit yellow emissions with photoluminescence quantum yields of up to 45% for [Cu(xantphos)(2,9-Br2phen)][PF6] with an excited state lifetime τ1/2 = 9.9 μs. Values of λemmax for [Cu(POP)(2,9-Br2phen)][PF6] and [Cu(xantphos)(2,9-Br2phen)][PF6] are blue-shifted with respect to compounds with the 3,8-and 4,7-isomers, both in solution and in the solid state.

Tetranitroquinodimethane (Tnq)—Electron-Deficient Prototype for a New Series of Organic Solid State Materials

1989 ◽  
Vol 173 ◽  
Author(s):  
David J. Vanderah ◽  
A. T. Nielsen ◽  
R. A. Hollins ◽  
Chris Baum
Keyword(s):  
Mass Spectrometry ◽  
Solid State ◽  
Title Compound ◽  
Radical Anion ◽  
H Nmr ◽  
Structural Assignment ◽  
Spectral Evidence ◽  
Vacuum Pyrolysis ◽  
Organic Solid ◽  
Solid State Materials

ABSTRACTRecently we have synthesized several new aryl compounds substituted with two or more trinitromethyl groups. Vacuum pyrolysis of one of these—±,±,±,±’,±’,±’-hexanitro-p-xylene (p-HNX)—gave the title compound via 1,6-elimination of N2O4. Structural assignment of TNQ is based on spectral evidence (UV, 1H NMR and mass spectrometry) and conversion to the known l,4-bis(bromodinitromethyl)benzene. Evidence for the formation of the TNQ radical anion has been obtained.

Multiple Fluorescence of 7-Hydroxylepidone

1978 ◽  
Vol 33 (2) ◽  
pp. 238-239 ◽  
Author(s):  
Otto S. Wolfbeis ◽  
E. Lippert
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Title Compound ◽  
Fluorescence Spectra ◽  
Neutral Molecule ◽  
Fluorescence Band ◽  
Fluorescence Maximum ◽  
Visible Part ◽  
Orange Region

The fluorescence spectra of the title compound have been measured in ethanol and in aqueous solutions of different pH. In ethanol the neutral molecule's fluorescence (at 360 nm) is observed, whereas in aqueous solutions emission occurs from the anion (at 428 nm) and from a "tautomeric" species (at 460 nm), but not from the neutral molecule. An aqueous solution at pH 3, which contains about 30% of ethanol gives a broad fluorescence band ranging from the near uv to the orange region of the spectrum. Contrarily, 7-methoxylepidone has no fluorescence maximum in the visible part of the spectrum.

Visualization and Manipulation of Molecular Motion in Solid State through Photo-Induced Clusteroluminescence

2019 ◽  
Author(s):  
Haoke Zhang ◽  
Lili Du ◽  
Lin Wang ◽  
Junkai Liu ◽  
Qing Wan ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
Excited State ◽  
Solid State ◽  
Light Source ◽  
Molecular Motion ◽  
Molecular Machine ◽  
Conjugated Molecules ◽  
Time Resolved ◽  
Packing Structure ◽  
New Strategy

<p>Building molecular machine has long been a dream of scientists as it is expected to revolutionize many aspects of technology and medicine. Implementing the solid-state molecular motion is the prerequisite for a practical molecular machine. However, few works on solid-state molecular motion have been reported and it is almost impossible to “see” the motion even if it happens. Here the light-driven molecular motion in solid state is discovered in two non-conjugated molecules <i>s</i>-DPE and <i>s</i>-DPE-TM, resulting in the formation of excited-state though-space complex (ESTSC). Meanwhile, the newly formed ESTSC generates an abnormal visible emission which is termed as clusteroluminescence. Notably, the original packing structure can recover from ESTSC when the light source is removed. These processes have been confirmed by time-resolved spectroscopy and quantum mechanics calculation. This work provides a new strategy to manipulate and “see” solid-state molecular motion and gains new insights into the mechanistic picture of clusteroluminescence.<br></p>

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