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001-es BibID:BIBFORM085641
Első szerző:Kéki Sándor (polimer kémikus)
Cím:Matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometric study of 2,3-dihydro-1,4-benzoxazepines / Sándor Kéki, Lajos Nagy, György Deák, Albert Lévai, Miklós Zsuga
Dátum:2005
ISSN:0951-4198 1097-0231
Megjegyzések:Fragmentations of the protonated adduct ions [M?H]? of seven 1,4-benzoxazepine derivatives were studied using ♭post-source decay' matrix-assisted laser desorption/ionization (PSD MALDI) and electrospray nozzle-skimmer collisionally induced dissociation (ESI-CID) mass spectrometric methods. It was found that both methods generated mainly product ions arising from the crossring cleavages of the benzoxazepine ring. Similar product ions were generated under MALDI and ESI conditions; however, it was observed that the loss of the alkylene unit from the N-substituted benzoxazepine, and the loss of a H2X molecule (where X?O or S), are more preferred under ESI conditions. Based on the experimental results a mechanism is also proposed for the fragmentation of the oxazepines studied.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Rapid Communications In Mass Spectrometry. - 19 : 10 (2005), p. 1263-1267. -
További szerzők:Nagy Lajos (1979-) (vegyész) Deák György (1954-) (polimer kémikus) Lévai Albert (1941-) (kémikus) Zsuga Miklós (1944-) (polimer kémikus)
Pályázati támogatás:T037448
OTKA
T042740
OTKA
T049468
OTKA
M 28369
OTKA
M 36872
OTKA
MU-00204/2001
OTKA
Internet cím:Szerző által megadott URL
DOI
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2.

001-es BibID:BIBFORM023373
Első szerző:Kéki Sándor (polimer kémikus)
Cím:Cationization of simple organic molecules by singly-charged Ag3+ cluster ions in matrix-assisted laser desorption/ionization mass spectrometry: Metal cluster-molecule interactions / Sándor Kéki, Lajos Nagy, György Deák, Miklós Zsuga, László Somogyi, Albert Lévai
Dátum:2004
Megjegyzések:It was found earlier that under matrix-assisted laser desorption/ionization (MALDI) conditions several organic compounds which produce adduct with silver ions, are also capable of forming adducts with Ag3+ cluster ions under appropriate conditions. The Ag3+ cluster ion can be in situ generated under the MALDI analysis conditions from silver trifluoroacetate cationization agent in the presence of organic MALDI matrices. In this article the fragmentation of a commercial plasticizer, a peracetylated isoflavone glycoside and a pyrazolylphenyl disulfide derivative cationized with silver ions and Ag3+ cluster ions are compared. It was observed that the complexes of Ag3+ are less fragmented than the corresponding adduct ions with Ag+. The presumable fragmentation channel of [M + Ag3+] is the elimination of Ag2 units from these complexes. No significant dissociation of [M + Ag3+], into M and Ag3+ takes place, indicating a tight connection between the corresponding molecule and Ag3+ cluster ion. However, with a compound carrying very labile groups, such as the pyrazolylphenyl disulfide derivative, intramolecular cleavages can occur prior to significant dissociation of the Ag3+ cluster ion.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal of The American Society for Mass Spectrometry. - 15 : 6 (2004), p. 879-883. -
További szerzők:Nagy Lajos (1979-) (vegyész) Deák György (1954-) (polimer kémikus) Zsuga Miklós (1944-) (polimer kémikus) Somogyi László (1928-) (vegyész) Lévai Albert (1941-) (kémikus)
Pályázati támogatás:T 025016, T 037201, T 037448, T 042740, M 28369, M 36872, MU-00204/2001
OTKA
Internet cím:Szerző által megadott URL
DOI
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3.

001-es BibID:BIBFORM001193
Első szerző:Kéki Sándor (polimer kémikus)
Cím:Energy-variable collision-induced dissociation study of 1,3,5-trisubstituted 2-pyrazolines by electrospray mass spectrometry / Sándor Kéki, Lajos Nagy, János Török, Katalin Tóth, Albert Lévai, Miklós Zsuga
Dátum:2007
Megjegyzések:The pathways of the ([M+H]+) ions generated from electrosprayed solutions of nine 1,3,5-trisubstituted 2-pyrazoline derivatives were studied using energy-variable collision-induced dissociation (CID) and pseudo-MS3 (in-source CID combined with MS/MS) methods. It was shown that under CID conditions several structurally important product ions such as the 2,4-substituted azete and 1,2-substituted aziridine ions were formed. The compositions of the product ions were unambiguously supported by accurate mass measurement (mass accuracy was within +/-8 ppm). The fragmentation pathways of 1,3,5-trisubstituted 2-pyrazolines were established by means of pseudo-MS3. It was found that a substituent at the N-1 position greatly affects the fragmentation pathways of the 2-pyrazoline derivatives. The 1-acetyl- and 1-propionyl-2-pyrazoline derivatives dissociate mainly through formation of a pyrazolium cation, while in the case of 1-phenyl-2-pyrazoline derivatives product ions arising from the consecutive fragmentation of 2,4-substituted azete and 1,2-substituted aziridine ions dominate. Another interesting finding is the formation of a radical cation from the 2,4-substituted azete by loss of a methyl radical. The fragmentation yield as a function of the collision energy for each of the 1,3,5-trisubstituted 2-pyrazolines was determined. Based on the fragmentation yield versus collision energy curves the relative fragmentation stabilities for the 1,3,5-trisubstituted 2-pyrazoline derivatives were also evaluated.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Rapid Communications in Mass Spectrometry. - 21 : 11 (2007), p. 1799-1808. -
További szerzők:Nagy Lajos (1979-) (vegyész) Török János Tóth Katalin Zsuga Miklós (1944-) (polimer kémikus) Lévai Albert (1941-) (kémikus)
Internet cím:DOI
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