Nail L. Asfandiarov
Bio: Nail L. Asfandiarov is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Ion & Electron capture. The author has an hindex of 14, co-authored 75 publications receiving 592 citations. Previous affiliations of Nail L. Asfandiarov include Latvian Academy of Sciences & Pedagogical University.
Papers published on a yearly basis
TL;DR: The twisting of 5-and 6-membered rings in bicyclic cis-diaziridines is a rapid process in the time scale of 1H- and 13C-NMR even at -80°.
Abstract: The twisting of 5- and 6-membered rings in bicyclic cis-diaziridines—1,5-diazabicyclo hexanes 12–17 and l,6-diazabicycloheptane 18—is a rapid process in the time scale of 1H- and 13C-NMR even at -80° According to the 1H- and 13C-NMR spectra, 1,5-diazabicyclo hexanes 12,13,15a,15b and 16a,16b do, exist mostly in the boat form ; only the introduction of endo substituents into position 3 or 6 leads to the population of the chair, as is the case with 14 and 17 2,4-Dialkyl substituted 1,5-diaza- and 1,3,5-triazabicyclohexanes are formed via a transition cyclization state similar in its geometry to the initial chair-shaped N-chlorodi(tri)azanes
TL;DR: An attempt to use Dissociative Electron Attachment Spectroscopy data for evaluation of the EAs of twelve naphthoquinone (NQ) derivatives and a simple Arrhenius approximation seems to be adequate to describe the process of electron detachment from molecular anions.
Abstract: RATIONALE: Electron Affinity (EA) is one of the fundamental properties of a molecule. EA values can be measured with various experimental methods, although their availability is still relatively limited. We make an attempt to use Dissociative Electron Attachment Spectroscopy (DEAS) data for evaluation of the EAs of twelve naphthoquinone (NQ) derivatives. METHODS: Naphthoquinone (NQ) and eleven of its hydroxyl derivatives were investigated by means of DEAS. A combined investigation of NQ and juglone by means of the Electron Transmission Spectroscopy (ETS) and DEAS techniques, with the support of density functional theory (DFT) calculations, allowed us to elucidate the empty-level structures of NQ and its hydroxyl derivatives. RESULTS: All molecules under investigation form extremely long-lived molecular anions associated with three resonant states (except for NQ, where only two long-lived resonances were observed). The hydroxyl substituents of NQ cause an increase in EA and number of internal degrees of freedom (N), and, as a result, an increase in the mean electron autodetachment lifetimes of the molecular negative ions (NIs). Evaluation of the EAs from the measured lifetimes of the molecular NIs through a simple Arrhenius approximation gives results in reasonable agreement with those obtained with DFT calculations. CONCLUSIONS: NI lifetime measurements by means of a modified DEAS instrumentation can provide quantitative data of EA. A simple Arrhenius approximation seems to be adequate to describe the process of electron detachment from molecular anions. Copyright © 2014 John Wiley & Sons, Ltd.
TL;DR: In this article, electron transmission spectroscopy (ETS), dissociative electron attachment spectrograph (DEAS) and negative ion mass spectrometry (NIMS) were used to investigate the energy of electron attachment to π* MOs.
Abstract: The nitrobenzene derivatives 1,2-nitrotoluene, 1,3-nitrotoluene, 1,2-fluoronitrobenzene, 1,3-fluoronitrobenzene, 1,4-fluoronitrobenzene, 1,2-chloronitrobenzene, 1,3-chloronitrobenzene and 1,4-chloronitrobenzene are investigated by means of electron transmission spectroscopy (ETS), dissociative electron attachment spectroscopy (DEAS) and negative ion mass spectrometry (NIMS). The observed energies of electron attachment to π* MOs were interpreted with the support of the empty level structures of the neutral molecules supplied by HF/6-31G and B3LYP/6-31G* calculations. In the chlorine-substituted derivatives three main long-lived negative ions (NIs) (M − , Cl − , and NO 2 − ) are observed, only M − and NO 2 − in the other investigated compounds. The detection of the metastable NIs corresponding to the process M* − → R − + (M–R) suggests that the molecular NIs formed near thermal electron energy dissociate on a microsecond timescale. Mean autodetachment lifetimes of the molecular NIs as a function of electron energy are evaluated.
TL;DR: A series of seven typical matrix-assisted laser desorption/ionization matrices has been investigated by means of electron capture negative ion mass spectrometry (ECNI-MS) and it has been shown that the most effective matrices form deprotonated negative ions predominantly in the low-energy region.
Abstract: A series of seven typical matrix-assisted laser desorption/ionization (MALDI) matrices has been investigated by means of electron capture negative ion mass spectrometry (ECNI-MS). It has been shown that the most effective matrices form deprotonated negative ions predominantly in the low-energy region. Relative dissociative cross sections have been measured for all molecules under investigation. The relative integrated abundance of [M − H]− ion formation in the series changes by four orders of magnitude. It has been shown that 2,5-DHB (gentisic acid), one of the most effective MALDI matrices, has maximal relative intensity of [M − H]− formation at the energy ∼0.8 eV. This result is in accordance with a finding of Frankevich and Zenobi [Book of Abstracts, Workshop-school “Mass spectrometry in chemical physics, bio-physics and environmental sciences”, Zvenigorod, Russia, April, 25–26, 2002, p. 40] that a probable origin of negative ions in MALDI is the process of low-energy (0.5–1 eV) dissociative electron capture by matrix molecules. Copyright © 2002 John Wiley & Sons, Ltd.
TL;DR: This review summarizes current mechanistic thinking, with emphasis on the most common MALDI variant using ultraviolet laser excitation, and a two-step framework is gaining acceptance as a useful model for many MAL DI experiments.
Abstract: Matrix Assisted Laser Desorption/Ionization (MALDI) is a very widely used analytical method, but has been developed in a highly empirical manner. Deeper understanding of ionization mechanisms could help to design better methods and improve interpretation of mass spectra. This review summarizes current mechanistic thinking, with emphasis on the most common MALDI variant using ultraviolet laser excitation. A two-step framework is gaining acceptance as a useful model for many MALDI experiments. The steps are primary ionization during or shortly after the laser pulse, followed by secondary reactions in the expanding plume of desorbed material. Primary ionization in UV-MALDI remains somewhat controversial, the two main approaches are the cluster and pooling/photoionization models. Secondary events are less contentious, ion–molecule reaction thermodynamics and kinetics are often invoked, but details differ. To the extent that local thermal equilibrium is approached in the plume, the mass spectra may be straightforwardly interpreted in terms of charge transfer thermodynamics.
TL;DR: The 2,1,3-Benzothiadiazole (BTD) is one of the most important nuclei used in the chemistry of photoluminescent compounds and applicable for light technology as discussed by the authors.
Abstract: 2,1,3-Benzothiadiazole (BTD) is one of the most important nuclei used in the chemistry of photoluminescent compounds and applicable for light technology. The understanding of its properties and reactions is fundamental for the design and application of these derivatives in molecular organic electronic devices and for other technologies. As a result of their potential as constituents of organic light-emitting diodes, solar cells, liquid crystals, dyes, photovoltaic cells, and many others, attention has been focused on BTD π-extended derivatives with potential use in this exciting area. Herein, we describe their syntheses, properties, reactions, and selected examples of applications in light technology using by BTD (small molecules) as the core.
TL;DR: A number of processes by which anions can be created and destroyed in these environments are discussed, along with their successes and failings, and an outlook on the future.
Abstract: Until a decade ago, the only anion observed to play a prominent role in astrophysics was H–. The bound–free transitions in H– dominate the visible opacity in stars with photospheric temperatures less than 7000 K, including the Sun. The H– anion is also believed to have been critical to the formation of molecular hydrogen in the very early evolution of the Universe. Once H2 formed, about 500 000 years after the Big Bang, the expanding gas was able to lose internal gravitational energy and collapse to form stellar objects and “protogalaxies”, allowing the creation of heavier elements such as C, N, and O through nucleosynthesis. Although astronomers had considered some processes through which anions might form in interstellar clouds and circumstellar envelopes, including the important role that polycyclic aromatic hydrocarbons might play in this, it was the detection in 2006 of rotational line emission from C6H– that galvanized a systematic study of the abundance, distribution, and chemistry of anions in the...
TL;DR: Applying the ligand electrochemical parameter approach to sandwich complexes and standardizing to the Fe(III)/Fe(II) couple, E(L)(L) values for over 200 pi-ligands are obtained and linear correlations exist between formal potential and summation operator for each metal couple.
Abstract: Applying the ligand electrochemical parameter approach to sandwich complexes and standardizing to the Fe(III)/Fe(II) couple, we obtained E(L)(L) values for over 200 pi-ligands Linear correlations exist between formal potential (E degrees ) and the summation operatorE(L)(L) for each metal couple In this fashion, we report correlation data for many first row transition metal couples The correlations between the E(L)(L) of the substituted pi-ligand and the Hammett substituent constants (sigma(p)) are also explored