Collision-Induced Dissociation Studies of Alkali Metal Adducts of Tetracyclines and Anti-Viral Agents by Electrospray Ionization, Hydrogen/Deuterium Exchange and Multiple Stage Mass Spectrometry

2008 ◽  
Vol 14 (5) ◽  
pp. 281-297 ◽  
Author(s):  
Amin Kamel ◽  
Burnaby Munson
Keyword(s):  
Metal Ions ◽  
Metal Complexes ◽  
Metal Ion ◽  
Mass Spectra ◽  
Collision Induced Dissociation ◽  
Guanine Derivatives ◽  
Product Ions ◽  
Hydrogen Deuterium ◽  
Cleavage Reactions ◽  
Metal Adducts

The collision-induced dissociation (CID) mass spectra were obtained for the X+-adducts (X = Na+ or Li+) of five tetracyclines, four pyrimidine and three purine derivatives and their fully D-exchanged species in which the labile hydrogens were replaced by deuterium by either gas- or liquid-phase exchange. The CID spectra were obtained for [M + Na]+ and [M + Li]+ and the exchanged analogs, [M(D) + Na]+ and [M(D) + Li]+, and compositions of product ions and mechanisms of decomposition were determined by comparison of the MS n spectra of the undeuterated and deuterated species. Metal ions are bound to the base of purine and pyrimidine anti-viral agents and dissociate primarily to give the metal complexes of the base [B + X]+. For vidarabine monophosphate, however, the metal ions are bound to the phosphate group, resulting in unique and characteristic cleavage reactions not observed in the uncomplexed system and dissociate through the loss of phosphate and/or a phosphate metal ion complex. The [B + X]+ of these anti-viral agents are relatively stable and show little or no fragmentation compared to [B + H]+. The CID of [B + X]+ of guanine derivatives occurs mainly through elimination of NH3 and that of trifluoromethyl uracil dissociates primarily through the loss of HF. For tetracyclines, metal ions are bound to ring A at the tricarbonylmethyl group and dissociate initially by the loss of NH3/ND3 from [MH + X]+ and [MD – X]+. The CID spectra of [M + X]+ of tetracyclines are somewhat similar to those of [M + H]+. The dominant fragments from the metal complexes of these compounds are charge remote decompositions involving molecular rearrangements and the loss of small stable molecules. Additionally, tetracyclines and the anti-viral agents show more selectivity towards the Li+ ion than the corresponding complexes with Na+ or K+.

scholarly journals Synthesis and Spectral Analysis of Some Metal Ions Complexes with Mixed Ligands of Schiff Base and 1, 10-Phenanthroline

2017 ◽  
Vol 14 (1) ◽  
pp. 135-147
Author(s):  
Baghdad Science Journal
Keyword(s):  
Schiff Base ◽  
Metal Ions ◽  
Metal Complexes ◽  
Mass Spectrometer ◽  
Schiff Base Ligand ◽  
Metal Ion ◽  
Molecular Structures ◽  
Spectroscopic Techniques ◽  
Metal Ion Complexes ◽  
Free Schiff Base

The free Schiff base ligand (HL1) is prepared by being mixed with the co-ligand 1, 10-phenanthroline (L2). The product then is reacted with metal ions: (Cr+3, Fe+3, Co+2, Ni+2, Cu+2 and Cd+2) to get new metal ion complexes. The ligand is prepared and its metal ion complexes are characterized by physic-chemical spectroscopic techniques such as: FT-IR, UV-Vis, spectra, mass spectrometer, molar conductivity, magnetic moment, metal content, chloride content and microanalysis (C.H.N) techniques. The results show the formation of the free Schiff base ligand (HL1). The fragments of the prepared free Schiff base ligand are identified by the mass spectrometer technique. All the analysis of ligand and its metal complexes are in good agreement with the theoretical values indicating the purity of Schiff base ligand and the metal complexes. From the above data, the molecular structures for all the metal complexes are proposed to be octahedral

scholarly journals Synthesis and Spectroscopic Characterization for Some Metal ion Complexes with 2-Hydroxy-3-((5-Mercapto-1,3,4-Thiadiazol-2-yl)Diazenyl)-1-Naphthaldehyde

2016 ◽  
Vol 13 (2) ◽  
pp. 105-114
Author(s):  
Baghdad Science Journal
Keyword(s):  
Metal Complexes ◽  
Metal Ion ◽  
Mass Spectra ◽  
Spectroscopic Characterization ◽  
Bidentate Ligand ◽  
Molar Ratio ◽  
Theoretical Treatment ◽  
Spectroscopic Techniques ◽  
Metal Ion Complexes ◽  
Square Planar

New metal ion complexes were synthesized with the general formula; K[PtLCl4], [ReLCl4] and K[ML(Cl)2] where M = Pd(II), Cd(II), Zn(II) and Hg(II), from the Azo ligand (HL) [2-Hydroxy-3-((5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl)-1-naphth aldehyde] (HL) the ligand was synthesized from (2-hydroxy-1-naphthaldehyde) and (5-amino-1,3,4-thiadiazole-2-thiol). The ligand and its metal complexes are characterized by phisco- chemical spectroscopic techniques (FT.IR, UV-Vis and Mass spectra, elemental analysis, molar conductivity, Atomic Absorption, Chloride contain and magnetic susceptibility). The spectral data suggest that the (HL) behaves as a bidentate ligand in all complexes. These studies revealed tetrahedral geometries for all metal complexes, except square planar for Pd(II) complex and except octahedral geometry for Pt(IV) and Re(V) complexes. The study of complexes formation via molar ratio of (M:L) as (1:1). Theoretical treatment of this ligand and its metal complexes in gas phase using Hyper chem.8 was preformed.

scholarly journals Synthesis and characterization Studies of Metal Complexes with Schiff base derived from 4-[5-(2-hydoxy-phenyl)-[1,3,4-oxadiazol-2-ylimino methyl]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one

2016 ◽  
Vol 13 (2) ◽  
pp. 19-28
Author(s):  
Baghdad Science Journal
Keyword(s):  
Schiff Base ◽  
Metal Ions ◽  
Metal Complexes ◽  
Mass Spectra ◽  
Nmr Spectra ◽  
Electronic Spectroscopy ◽  
Synthesis And Characterization ◽  
Alcoholic Medium ◽  
Tetradentate Schiff Base ◽  
Characterization Studies

New metal complexes of the ligand 4-[5-(2-hydoxy-phenyl)-[1,3,4- oxadiazol -2-ylimino methyl]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (L) with the metal ions Co(II), Ni(II), Cu(II) and Zn(II) were prepared in alcoholic medium. The Schiff base was synthesized through condensate of [4-antipyrincarboxaldehyde] with[2-amino-5-(2-hydroxy-phenyl-1,3,4- oxadiazol] in alcoholic medium . Two tetradentate Schiff base ligand were used for complexation upon two metal ions of Co2+, Ni2+, Cu2+ and Zn2+ as dineucler formula M2L2.4H2O. The metal complexes were characterized by FTIR Spectroscopy, electronic Spectroscopy, elemental analysis, magnetic susceptidbility measurements, and also the ligand was characterized by 1H-NMR spectra, and mass spectra. The Structures of complexes were proposed from the measurements.

7-Methyl-6-furylpurine forms dinuclear metal complexes with N3,N9 coordination

2018 ◽  
Vol 73 (11) ◽  
pp. 813-817 ◽  
Author(s):  
Indranil Sinha ◽  
Lukas Heller ◽  
Jutta Kösters ◽  
Jens Müller
Keyword(s):  
Metal Ions ◽  
Metal Complexes ◽  
Metal Ion ◽  
Dinuclear Complexes ◽  
Purine Derivatives ◽  
Purine Derivative ◽  
Coordination Environment ◽  
Bridging Ligand ◽  
Dinuclear Metal Complexes ◽  
Argentophilic Interaction

AbstractTwo dinuclear metal complexes bearing the purine derivative 7-methyl-6-furylpurine (1b) as a ligand are reported. In [Ag2(1b)2(DMSO)2](ClO4)2·DMSO and [Cu2(1b)2(NO3)2], two bridging purine derivatives coordinate the two metal ions via their N3 and N9 positions. In the silver(I) complex, the coordination environment of each metal ion is completed by a DMSO ligand, whereas an additional nitrato ligand coordinates to each copper(I) ion. The intramolecular Ag···Ag distance of 3.1069(5) Å is in agreement with the presence of a weak argentophilic interaction, whereas the Cu···Cu distance of 2.9382(4) Å is too long to be indicative of a cuprophilic interaction. The compounds represent the first examples of dinuclear complexes comprising two N3,N9-bridging purine derivatives without any additional bridging ligand.

Chemical reactivities of tetrapyrrole pigments: a comparison of experimental behaviour with the results of s.c.f.-π-m.o. calculations

1976 ◽  
Vol 273 (924) ◽  
pp. 335-352 ◽  
Keyword(s):  
Metal Ions ◽  
Metal Complexes ◽  
Experimental Work ◽  
Oxidation Potential ◽  
Central Metal ◽  
Reversible Reactions ◽  
Specific Reactivity ◽  
Cleavage Reactions ◽  
Recent Experimental Work ◽  
Experimental Behaviour

Porphyrins are highly σ-electron donating bases and very weak π-acids. Hence they increase the electron density on central metal ions, e.g. iron, which leads to the specific reactivity of haem cytochromes, haemoglobin and oxidizing enzymes. The macrocyclic chlorin ligand behaves similarly but to a lesser degree which explains the comparably low oxidation potential of chlorophyll. Phlorins, oxophlorins, oxa- and aza-porphyrins, tetradehydrocorrins, corrins and biliverdins all produce metal complexes which have a similar geometry to that of metalloporphyrins, but their reactivity patterns are different. In contrast to themetalloporphyrins which undergo many fully reversible reactions, these compounds tend to irreversible addition and cleavage reactions. These tetrapyrrole ligands are stronger π-acids than porphyrins. Results of some recent experimental work and π-electron s.c.f. calculations are presented in support of these generalizations.

scholarly journals Synthesis, Characterization and Antimicrobial Screening of Novel Hydrazide Ligand & It’s Transition Metal Complexes

2019 ◽  
Vol 31 (4) ◽  
pp. 938-942
Author(s):  
S.P. Bhale ◽  
A.R. Yadav ◽  
S.U. Tekale ◽  
R.B. Nawale ◽  
R.P. Marathe ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Metal Ion ◽  
Octahedral Geometry ◽  
Tetrahedral Geometry ◽  
Metal Acetate ◽  
Spectral Techniques ◽  
Chloride Salts

Different transition metal complexes were synthesized from novel 3-bromo-2-[1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)ethylidene]hydrazide ligand (H2L) and characterized by spectral techniques. The synthesized ligand was found to act mono as well as di deprotonated (OH, NH) manner and stoichiometry of the ligand to metal ions was confirmed to be 1:1 in case of complex using metal chloride salts, whereas 1:2 in case of metal(II) complexes using metal acetate(II) salt. Structures of metal complexes were confirmed by IR, 1H NMR, TGA, XRD, elemental analysis and UV technique which revealed that Mn(II), Co(II), Ni(II), Cu(II) complexes were octahedral geometry and those of Cu(II), Zn(II) showed square planner and tetrahedral geometry around metal ion respectively. Furthermore H2L and its metal complexes were screened for antimicrobial activity which showed that ligand enhanced its biological activity after coordination with metal ions. In particular, Cd(II) and Mn(II) complexes exhibited excellent antifungal activity.

Investigation of the mechanism of alkyl radical elimination from ionised pentenyl methyl and hexenyl methyl ethers by analysis of the collision-induced dissociation mass spectra of C4H7O+ and C5H9O+ ions

1993 ◽  
Vol 71 (7) ◽  
pp. 1073-1085 ◽  
Author(s):  
Andrew D. Wright ◽  
Richard D. Bowen
Keyword(s):  
Alkyl Radical ◽  
Mass Spectra ◽  
General Structure ◽  
Alkyl Substituent ◽  
Frontier Molecular Orbital ◽  
Collision Induced Dissociation ◽  
Methyl Radical ◽  
Distonic Ions ◽  
Product Ions ◽  
Distonic Ion

Collision-induced dissociation (CID) mass spectra are reported for C4H7O+ and C5H9O+ ions generated by loss of an alkyl radical from 11 isomers of C5H9OCH3+• and 8 isomers of C6H11OCH3+• produced by ionisation of alkenyl methyl ethers derived from stable alkenols. The oxonium product ions have acyclic structures (CH=CHCH=O+CH3 for C4H7O+; CH2=CH(CH3)C=O+CH3, CH3CH=CHCH=O+CH3, or CH2=(CH3)CCH=O+CH3 in the case of C5H9O+). Elimination of a methyl radical does not always occur by simple α-cleavage. Expulsion of an alkyl substituent attached to a carbon atom at either end of the C=C double bond also takes place readily; this process sometimes competes with or pre-empts α-cleavage, as is shown by 2H-labelling experiments. Plausible mechanisms for this σ′-cleavage are considered. A route involving a 1,2-H shift to the radical centre of a distonic ion, followed by γ-cleavage of the resultant ionised enol ether, is shown to provide the most accurate unifying description of this unusual fragmentation. The mechanistic significance of this interpretation of the σ′-cleavage is discussed by analysing the reverse reaction (addition of an alkyl radical to a methyl cationated enal) in frontier molecular orbital terms. A comparison is made between the mechanisms by which an alkyl radical is lost from ionised alkenyl methyl ethers by σ′-cleavage and the parallel process starting from ionised carboxylic acids or isomeric distonic ions derived from these CnH2n+1CO2H+• species. Both classes of fragmentation are best understood to occur via γ-cleavage of a distonic ion of general structure R1CH2CH•C+(X)OR2 (R1 = alkyl; X = OH, R2 = H; or X = H, R2 = CH3), thus yielding (R′)• and CH2 = CHC+(X)OR2.

scholarly journals Speciation of Metal Complexes of Medicinal Interest: Relationship between Solution Equilibria and Pharmaceutical Properties

2019 ◽  
Vol 26 (4) ◽  
pp. 580-606 ◽  
Author(s):  
Tamás Kiss ◽  
Éva A. Enyedy ◽  
Tamás Jakusch ◽  
Orsolya Dömötör
Keyword(s):  
Metal Ions ◽  
Metal Complexes ◽  
Metal Ion ◽  
Biological Fluids ◽  
Chemical Species ◽  
Toxic Metal ◽  
Mri Contrast Agents ◽  
Drug Candidate ◽  
Essential Information ◽  
Toxic Metal Ions

Biospeciation of essential and toxic metal ions, metal complexes with biological or medicinal activity are discussed in the paper in order to emphasize the importance of the distribution of metal ions in biological milieu. The exact knowledge of the chemical species present in the different organs/compartments/fluids/cells may provide essential information about the pharmacokinetic properties and the biological effect of the metal ion or the drug candidate metal complex. The transport of essential and toxic metal ions in the blood serum is discussed first, which is followed by the description of biodistribution of several important metal complexes with medicinal interest such as (i) anticancer, (ii) insulin-enhancing and (iii) MRI contrast agents in biological fluids.

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