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排序方式: 共有105条查询结果,搜索用时 15 毫秒
31.
Dr. Antonela Canneva Prof. Dr. Mauricio F. Erben Prof. Dr. Rosana M. Romano Dr. Yury V. Vishnevskiy Christian G. Reuter Prof. Dr. Norbert W. Mitzel Prof. Dr. Carlos O. Della Védova 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(29):10436-10442
The gas‐phase molecular structure of (CH3)3CSNO was investigated by using electron diffraction, allowing the first experimental geometrical parameters for an S‐nitrosothiol species to be elucidated. Depending on the orientation of the ?SNO group, two conformers (anti and syn) are identified in the vapor of (CH3)3CSNO at room temperature, the syn conformer being less abundant. The conformational landscape is further scrutinized by using vibrational spectroscopy techniques, including gas‐phase and matrix‐isolation IR spectroscopy, resulting in a contribution of ca. 80:20 for the anti:syn abundance ratio, in good agreement with the computed value at the MP2(full)/cc‐pVTZ level of approximation. The UV/Vis and resonance Raman spectra also show the occurrence of the conformational equilibrium in the liquid phase, with a moderate post‐resonance Raman signature associated with the 350 nm electronic absorption. 相似文献
32.
Pirani LS Erben MF Geronés M Ma C Ge M Romano RM Filho RL Della Védova CO 《The journal of physical chemistry. A》2011,115(21):5307-5318
A study of valence electronic properties of S-ethyl chlorothioformate (S-ethyl chloromethanethioate), ClC(O)SCH(2)CH(3), using HeI photoelectron spectra (PES) and synchrotron radiation is presented. Moreover, the photon impact excitation and dissociation dynamics of ClC(O)SCH(2)CH(3) excited at the S 2p and Cl 2p levels are elucidated by analyzing the total ion yield (TIY) spectra and time-of-flight mass spectra acquired in multicoincidence mode [photoelectron-photoion coincidence (PEPICO) and photoelectron-photoion-photoion coincidence (PEPIPICO)]. The HeI photoelectron spectrum is dominated by features associated with lone-pair electrons from the ClC(O)S- group, the HOMO at 9.84 eV being assigned to the n(π)(S) sulfur lone-pair orbital. Whereas the formation of C(2)H(5)(+) ion dominates the fragmentation in the valence energy region, the most abundant ion formed in both the S and Cl 2p energy ranges is C(2)H(3)(+). Comparison with related XC(O)SR (X = H, F, Cl and R = -CH(3), -C(2)H(5)) species reveals the impact of the alkyl chain on the photodissociation behavior of S-alkyl (halo)thioformates. 相似文献
33.
Rodríguez Pirani LS Geronés M Della Védova CO Romano RM Fantoni A Cavasso-Filho R Ma C Ge M Erben MF 《The journal of physical chemistry. A》2012,116(1):231-241
A combination of photoelectron spectroscopy and synchrotron based photoelectron photoion coincidence (PEPICO) spectra has been applied to investigate the electronic structure and the dissociative ionization of the CH(2)ClSCN molecule in the valence region. The PES is assigned with the electronic structure calculations at the outer-valence Green's function and symmetry adapted cluster/configuration interaction (SAC-CI) levels offer an explanation of our experimental results. Upon vacuum ultraviolet irradiation the low-lying radical cation, located at 10.39 eV is formed. The molecular ion is observed in the time-of-flight mass spectra, together with the CH(2)SCN(+) and CH(2)Cl(+) daughter ions. The total ion yield spectra have been measured in the S 2p and Cl 2p regions and several channels have been determined in dissociative photoionization events for the core-excited species. Thus, by using time-of-flight mass spectrometry and synchrotron radiation the relative abundances of the ionic fragments and their kinetic energy release values were obtained from both PEPICO and photoelectron photoion photoion coincidence spectra. Possible fragmentation processes are discussed and compared with that found for the related CH(3)SCN species. 相似文献
34.
Geronés M Erben MF Romano RM Cavasso Filho RL Della Védova CO 《The journal of physical chemistry. A》2012,116(10):2571-2582
In this work we present a study of the dissociative photoionization of S-methyl thioacetate [CH(3)C(O)SCH(3)] by using multicoincidence time-of-flight mass spectrometry and synchrotron radiation in the S 2p, C 1s, and O 1s edges. Total and partial ion yield spectra together with photoelectron-photoion coincidence (PEPICO) and photoelectron-photoion-photoion coincidence (PEPIPICO) spectra were measured. Fragmentation patterns deduced from PEPICO and PEPIPICO spectra at the various excitation energies show a moderate site-specific fragmentation. The dissociation dynamic for the main ion-pair production is discussed. Two-, three-, and four-body dissociation channels have been observed in the PEPIPICO spectra, and the dissociation mechanisms are proposed. The interstellar HCS(+) and H(3)(+) ions can be observed during the synchrotron experiments reported in the present work. 相似文献
35.
Geronés M Erben MF Romano RM Cavasso Filho RL Della Védova CO 《The journal of physical chemistry. A》2012,116(28):7498-7507
The electronic transitions and the dissociative ionic photoionization mechanisms of gaseous ClC(O)SCH(3) have been investigated at the VUV and soft X-ray energy regions of S 2p, Cl 2p, C 1s, and O 1s core edges using tunable synchrotron radiation and time-of-flight mass spectrometry. The relative abundances of the ionic fragments were obtained from both PEPICO (photoelectron photoion coincidence) and PEPIPICO (photoelectron photoion photoion coincidence) spectra. The presence of a moderate site- and element-specific fragmentation effects and its implication regarding chemical reactions were analyzed. The relationship of the current results with the interstellar chemistry is also a goal of this piece of work. 相似文献
36.
Tobias Frank Johannes CM Schlachetzki Bettina G?ricke Katrin Meuer Gundula Rohde Gunnar PH Dietz Mathias B?hr Armin Schneider Jochen H Weishaupt 《BMC neuroscience》2009,10(1):49-10
Background
The hematopoietic Granulocyte-Colony Stimulating Factor (G-CSF) plays a crucial role in controlling the number of neutrophil progenitor cells. Its function is mediated via the G-CSF receptor, which was recently found to be expressed also in the central nervous system. In addition, G-CSF provided neuroprotection in models of neuronal cell death. Here we used the retinal ganglion cell (RGC) axotomy model to compare effects of local and systemic application of neuroprotective molecules. 相似文献37.
Matija Sambol Patricia Ben
i Antonija Erben Marija Matkovi Branka Mihaljevi Ivo Piantanida Marijeta Kralj Nikola Basari 《Molecules (Basel, Switzerland)》2021,26(11)
Quinone methide precursors 1a–e, with different alkyl linkers between the naphthol and the naphthalimide chromophore, were synthesized. Their photophysical properties and photochemical reactivity were investigated and connected with biological activity. Upon excitation of the naphthol, Förster resonance energy transfer (FRET) to the naphthalimide takes place and the quantum yields of fluorescence are low (ΦF ≈ 10−2). Due to FRET, photodehydration of naphthols to QMs takes place inefficiently (ΦR ≈ 10−5). However, the formation of QMs can also be initiated upon excitation of naphthalimide, the lower energy chromophore, in a process that involves photoinduced electron transfer (PET) from the naphthol to the naphthalimide. Fluorescence titrations revealed that 1a and 1e form complexes with ct-DNA with moderate association constants Ka ≈ 105–106 M−1, as well as with bovine serum albumin (BSA) Ka ≈ 105 M−1 (1:1 complex). The irradiation of the complex 1e@BSA resulted in the alkylation of the protein, probably via QM. The antiproliferative activity of 1a–e against two human cancer cell lines (H460 and MCF 7) was investigated with the cells kept in the dark or irradiated at 350 nm, whereupon cytotoxicity increased, particularly for 1e (>100 times). Although the enhancement of this activity upon UV irradiation has no imminent therapeutic application, the results presented have importance in the rational design of new generations of anticancer phototherapeutics that absorb visible light. 相似文献
38.
The synthesis, spectroscopic characterization, and electrochemistry of As, Sb, and Bi corroles are reported. The investigated complexes are represented by [(OEC)AsV(CH3)]+ClO4- and (OEC)M where M = As(III), Sb(III), or Bi(III) and OEC is the trianion of octaethylcorrole. The products of each redox reaction are characterized by UV-vis and ESR spectroscopy. The first one-electron oxidations of (OEC)As and (OEC)Sb are metal-centered and result in the formation of [(OEC)AsIV]+ and [(OEC)SbIV]+. A second one-electron oxidations generates [(OEC)AsV]2+ and [(OEC.)SbIV]2+, the latter of which is slowly converted to a Sb(V) corrole, [(OEC)SbV]2+. The first one-electron oxidation of (OEC)Bi leads only to the Bi(III) pi-cation radical, but a second one-electron oxidation is proposed to give a Bi(IV) complex, [(OEC)Bi]2+. The first reduction of [(OEC)AsV(CH3)]+ClO4- is accompanied by loss of the sigma-bonded methyl ligand and formation of an As(III) complex. 相似文献
39.
40.
Trautner F Gholivand K García P Willner H Erben MF Della Védova CO Oberhammer H 《Inorganic chemistry》2003,42(9):3079-3085
The conformational properties and the geometric structure of perfluoromethyl fluorocarbonyl peroxide, CF(3)OOC(O)F, have been studied by matrix IR spectroscopy, gas electron diffraction, and quantum chemical calculations (HF, B3LYP, and MP2 methods with 6-311G* basis sets). Matrix IR spectra imply a mixture of syn and anti conformers (orientation of the C=O bond relative to the O-O bond) with DeltaH degrees = H(anti) degrees - H(syn) degrees = 2.16(22) kcal/mol. At room temperature, the contribution of the anti rotamer is about 3.0%. The O-O bond (1.422(15) A) is within the experimental uncertainties equal to those in related symmetrically substituted peroxides CF(3)OOCF(3) and FC(O)OOC(O)F (1.419(20) and 1.419(9) A, respectively), and the dihedral angle delta(COOC) (111(5) degrees ) is intermediate between the values in these two compounds (123(4) degrees and 83.5(14) degrees, respectively). 相似文献