The photochemistry of bis(18-crown-6)-containing 1,3-distyrylbenzene and its 2 : 2 bis-pseudo-sandwich complex with ethane-1,2-diammonium was studied. The UV irradiation of the supramolecular complex resulted in the formation of three geometric isomers of tetracrown-containing dicyclobutano[2.2]metacyclopane, differing in the orientation of the cyclobutane moieties, with the unsymmetrical isomer (>50%) predominating. The diammonium cations used as the template could be removed after photolysis by simple extraction, and the product was obtained in high yield (82%). The 1H NMR signals of a mixture of geometric isomers of [2.2]metacyclophane derivative were assigned resorting to quantum chemistry methods (DFT). The kinetic and thermodynamic parameters of thermal isomerization between the endo,endo- and exo,exo-isomers were measured. Tetracrown-containing dicyclobutano[2.2]metacyclophanes are homotetratopic ligands that contain four binding sites for metal and ammonium cations, which is of interest for the design of photo- and thermo-switchable supramolecular devices with a variable complex formation behavior and supramolecular machines owing to the butterfly-type thermal isomerization.

This work is devoted to the analysis of the results obtained during the separation of the mass spectra of apamin and its complex after the deutero-hydrogen substitution of these molecules when leaving the electrospray ion source. The goal of the work was to determine the origin of the structural components identified in apamin and its complex. The separation method assumes that the substitution of labile hydrogen atoms with deuterium ones occurs independently, while charge carriers are retained independently too by various amino acid residues of a polypeptide with a specific structural form. This method also includes an indirect assessment of the contribution of natural isotopes to the measured data, without requiring knowledge of the elemental composition or other structural features of the biomolecule under study. Previously, we performed similar calculations by directly accounting for the contribution of natural isotopes. For apamin electrosprayed ions, after introducing a gas flow of ND3 into the molecular ion reactor of the mass spectrometer, three main components were identified, with contributions of approximately 57, 39, and 5

Using a flow reactor with a movable insert and mass-spectrometric control of the gas composition, methane soot samples are treated with O 3 and NO 2 reagents until the surface is completely poisoned. A solution of the initial methane soot in acetonitrile and solid products of its reaction with oxidizing reagents O 3 and NO 2 is analyzed using high-resolution mass spectrometry with an electrospray ion source and gas chromatography (GC)–mass spectrometry (MS) with electron ionization. It is established that the original soot contains a number of aromatic compounds, including polycyclic compounds, which are completely consumed in the reaction with these oxidizing agents. Compounds from the paraffin class remain inert with respect to NO 2 and O 3 . The products of the ozonization of prenitrated soot are the same as those of simple ozonation. The number of ozonation products is much higher than similar nitration products. This is the reason for the reactivity of nitrated soot with respect to the ozone uptake.

Complexation between (18-crown-6)stilbene and alkanediammonium ions + H 3 N(CH 2 ) n NH 3 + ( n = 2−4) resulting in the pseudo-sandwich 2:1 stilbene—dication complexes and 1:1 stilbene—dication complexes was studied by NMR spectroscopy. The stability of the complexes decreases as the methylene chain length in the alkanediammonium ion increases. UV photolysis of the bis-ligand complexes produces two major products, viz. , the rctt isomer of a biscrown-containing cyclobutane derivative formed as a result of intra-supramolecular [2+2] photocycloaddition and a crown-containing phenanthrene derivative (product of electrocyclization reaction). The effective quantum yields of both cyclization reactions occurring in the pseudo-sandwich complexes increase as the number of methylene units in the dication decreases.

С использованием проточного реактора с подвижной вставкой и масс-спектрометрическим контролем газового состава была проведена обработка образцов метановой сажи реагентами O 3 и NO 2 до момента полного прекращения их захвата поверхностью. Анализ растворов исходной метановой сажи и твердых продуктов ее реакции с окисляющими реагентами O 3 и NO 2 в ацетонитриле проводился с использованием масс-спектрометрии высокого разрешения с электроспрейным ионным источником и газовой хроматографии–масс-спектрометрии с электронной ионизацией. Установлено, что исходная сажа содержит ряд ароматических соединений, включая и полициклические, которые полностью расходуются в реакции с этими окислителями. Соединения из класса парафинов остаются инертными по отношению к NO 2 и О 3 . В качественном отношении продукты нитрования и озонирования одинаковы как по своему составу, так и по содержанию основных функциональных групп. Количество продуктов озонирования значительно больше аналогичных продуктов нитрования. Это является причиной высокой реакционной способности нитрованной сажи по отношению к захвату озона.

The photophysical and photochemical properties of the protonated forms of both covalently bound biphotochromic dyad D44N containing two styrylbenzo[f]quinoline (SBQ) photochromes and corresponding cyclobutane CB44N containing two benzo[f]quinoline (BQ) substituents have been studied. CB44N is formed from D44N as a result of a reversible [2+2] photocycloaddition (PCA) reaction. The dyad and cyclobutane contain the 3-hydroxy-2-naphthoic acid (NA) moiety as a bridging group. It has been shown that the protonation of nitrogen atoms in the SBQ and BQ groups leads to bathochromic shifts in the absorption spectra and bathofloral shifts in the fluorescence spectra of the dyad and cyclobutane. In the protonated dyad, the quantum yield of the PCA reaction decreases, presumably due to the Coulomb repulsion, which prevents the cations of the protonated SBQ photochromes from approaching each other. In protonated cyclobutane, the quantum yield of the reverse four-membered ring opening reaction (retro-PCA), on the contrary, increases due to the absence of a competitive process of energy transfer from BQ to NA, which was previously observed in neutral cyclobutane.

A novel neutral tetranitrosyl iron complex {[Fe(H2O)4]2+[FeR2(NO)2]22-}·4H2O (1) with R = 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiolyls (C7H5N4S), which is a supramolecular ensemble, has been synthesized and studied. As follows from X-ray diffraction analysis, this is an octahedral Fe2+complex (Lewis acid) with two monoanionic dinitrosyl groups [FeR2(NO)2]- (Lewis base) and 4 water molecules as the ligands. As follows from Mössbauer spectra, the coordinating Fe2+ ion is in a low-spin state S = 0, and the dinitrosyl Fe+ ion is in a low-spin state S = 1/2. According to the data of EPR spectroscopy, mass-spectrometry and amperometry, complex 1 in solution forms dinitrosyl particles of [Fe(C7H6N4S-H)2(NO)2]- composition, which are responsible for NO generation. In addition, complex 1 was shown to be a 5-6 times more efficient phosphodiesterase (PDE) inhibitor at 5 × 10-5 M and 10-4 M concentrations than its thioligand. Probable binding sites of the [FeR2(NO)2]- ligand for the bovine PDE1B model have been determined by molecular docking and quantum-chemical calculations.

The accuracy of the ion flight time measurement in the time-of-flight mass spectrometer is critical to achieving high resolution. The pulse amplitude variation of the detector pulses leads to the registration time spread at a given pulse detection threshold. This time spread can be eliminated by determining the position of the pulse apex. To determine the position of the pulse apex, the output of the ion detector is fed simultaneously to the two channels of the time-to-digital converter. In this case, the first channel is set to register the leading edge, and the second channel is set to register the trailing edge of the pulse. Using a simple processing of the received data, the position of the pulse tip is determined. Thus, the dependence of the temporal position of the peak on the pulse amplitude is largely eliminated. Examples are given, and the efficiency of using this algorithm to increase the resolution of time-of-flight mass spectral peak registration is demonstrated.

The reactions of adenosine triphosphoric acid (ATP) with water-soluble binuclear tetranitrosyl iron complexes of the mu-S structural type with functional sulfur-containing ligands (thiosulfate (1) cysteamine (2), and penicillamine (3)) afford products of close structures. The hydrolysis products of the complexes (1-3) in aqueous aerobic solutions are studied by amperometry and mass electrospectrometry. The kinetic regularities of the reactions of the complexes (1-3) with ATP are studied by the spectrofluorimetric method. A generalized kinetic model describing the experimental data of three reactions is proposed for the process. From the qualitative point of view, the reactions of ATP with the studied complexes occur similarly in spite of the difference in the ligands. The rates of particular steps of the process depend on the nature of the ligands. The values determined for the kinetic parameters quantitatively characterize the influence of the ligand nature in complexes 1-3 on the reactivity toward ATP and increase in the order: cysteamine < penicillamine < thiosulfate.

The cytotoxic activity of a series of dinitrosyl iron complexes (DNICs) with thioureas against cells of different origin has been studied in this work. The cytotoxicity of the studied DNICs proved to be substantially different depending on the structure of the complexes and cell line. Complexes with thiourea and 1,3-dimethylthiourea were found to induce notable cell death in different cell lines of both cancerous and non-cancerous origin, while the N-ethylthiourea-bearing complex induced cell death in cells derived from brain tumors. The studied DNICs effectively release NO while decomposing in solutions, as follows from the electrochemical analysis. It was found that the cytotoxic effects of the studied DNICs did not correlate with their NO-donating ability, hence suggesting that their cytotoxic activity is, in a big part, defined by the long-lived nitrosyl iron-sulfur intermediates formed during the decomposition of the complexes. The structures of the products formed upon hydrolytic decomposition of all studied DNICs have been studied by electrospray ionization mass spectrometry. Stable high-molecular cluster ions containing NO groups namely [Fe4S3(NO)7]- (Roussin's "black salt" anion), [Fe4S3(NO)5]-, [Fe4S4(NO)4]-, [Fe4S3(NO)4]- and [Fe4S3(NO)6]- have been detected in the solution of the N-ethylthiourea-bearing complex. The mechanism of Roussin's "black salt" anion formation in a solution of DNIC with N'-ethylthiourea was studied using density functional theory. This moved us near understanding the reasons for the formation of biologically active intermediates upon the decomposition of the complex with N'-ethylthiourea, which are apparently responsible for the unique antiglioma activity of the complex.

Abstract Single-crystal XRD structure of binuclear tetranitrosyliron complex [Fe2(SR)2(NO)4] (1), R = 4-aminothiophenyl, has been described. The properties of 1 were studied by IR, Mössbauer, mass spectroscopy, and amperometry. Complex 1 was shown to form long-living nitrosyl intermediates in solution, which underlies its prolonged NO donor activity. In HeLa cells, 1 caused accumulation of NF-κB p50 but decreased the levels of NF-κB p65 in the nucleus, which led to inhibition of NF-κB dependent genes. The complex also induced increase of p53 protein levels and p21 gene activity, which led to the apoptotic cell death after G2/M cell cycle phase. Graphical Abstract

Two new heptamethine cyanine dye–fullerene C60 covalently- linked dyads, which absorb in far-red and NIR spectral regions, have been synthesized by esterification click reaction and characterized by physicochemical methods. No significant fluorescence quenching was found due to weak electronic coupling between heptamethine moiety and fullerene core, which was confirmed by photophysical and electrochemical methods. Such dyads can be useful for cell imaging and fluorescence diagnostics of various fullerene derivatives.

We report the results of a study of the effect of a supersonic gas jet on the formation and extraction of analyzed ions from a liquid supplied through a capillary to an RF quadrupole connected to a time-of-flight mass spectrometer with orthogonal ion injection. The supersonic gas jet is formed inside a cylindrical channel and passes through an electron ionization ion source. The results confirm the prospects of using a supersonic jet to creating a high-performance ion source from a liquid supplied to the vacuum region under the pressure of ~10–4 Torr.

We report novel heteroleptic lanthanide sandwich complexes (Ln = Lu, Eu, La) and their spectral, electrochemical and computational studies.

The article describes the results of a study of the effect of a supersonic gas jet on the formation and extraction of deuterium-substituted ions from a liquid supplied through a capillary into a radio-frequency quadrupole coupled to a time-of-flight mass spectrometer with orthogonal ion injection. The supersonic gas jet is formed inside a cylindrical channel and passes through an electron ionization ion source. With an increase in the flow rate of the a solution, there was no steady trend in the relative contributions of deuterated ions from the liquid phase. The results confirm the prospects of using a supersonic jet to create a high-performance source of deuterium-substituted ions from a liquid supplied into a vacuum region under residual pressure of 10–4 Torr without using strong electric fields.

A new type of pyropheophorbide-fullerene[60] dyad was synthesized by their attachment by the cyclopropane backbone at the 13(1)-position of the chlorin macrocycle using the Hummelen-Wudl method. Here we report a complex analysis of the structure influence on the photophysical properties of the newly obtained dyad and its comparison with another pyropheophorbide-fullerene[60] dyad. The latter dyad was previously obtained by the attachment of the tetrahydropyrrole backbone at the third position of the macrocycle using the Prato reaction. It was shown by quantum-chemical modeling that the studied dyads have drastically different spatial positions of the fullerene core relative to the dye macrocycle plane: "parallel" for the former and "perpendicular" - for the latter. The influence of structural differences on various properties of dyads was studied: the aggregation properties, absorption spectra, the fluorescence quenching of the dye moiety in the dyads, and the lifetimes of excited states. The data obtained are important for the further development of methods for the directional design of the photoactive fullerene-dye structures - highly effective photosensitizers for photodynamic therapy.

Traditional soft ionization methods are not always suitable for mass spectral analysis of complex compounds. Factors such as laser radiation and heating resulting in fragmentations of sample molecules in the case of matrix-assisted laser desorption/ionization and difficulties in preparing suitable sample solutions in the case of electrospray ionization make it impossible to use these methods in some cases. Matrix-assisted ionization was used to analyze products of chemical synthesis involving pyropheophorbide and fullerene. Mass spectra were acquired using a simple effective modification of the Exactive Orbitrap mass spectrometer electrospray interface. Reliable identification of pyropheophorbide-fullerene dyad ions and its derivatives was carried out. An experimental comparison of a matrix-assisted ionization and an electrospray ionization technique demonstrated the significant advantage in sensitivity to the ions under study (approximately 20 times higher) of the matrix-assisted ionization method in this particular study.

В статье описываются результаты исследования воздействия сверхзвуковой газовой струи, сформированной внутри цилиндрического канала и пропущенной через источник электронной ионизации, на выход дейтерозамещённых ионов из жидкости, подаваемой через капилляр внутрь радиочастотного квадруполя, сопряжённого с времяпролётным масс-спектрометром с ортогональным вводом ионов. При увеличении потока анализируемого раствора не наблюдалось явной зависимости изменения относительных вкладов дейтерированных ионов в жидкой фазе от скорости подачи образца. Полученные результаты подтверждают перспективность использования сверхзвуковой струи для создания высокоэффективного источника дейтерозамещённых ионов из растворов при остаточном давлении на уровне 10-4 Торр и в отсутствие сильных электрических полей. The article describes the results of a study of the effect of a supersonic gas jet on the formation and extraction of the deuterosubstituted ions from a liquid supplied through a capillary into a radio-frequency quadrupole coupled to a time-of-flight mass spectrometer with orthogonal ion injection the supersonic gas jet being formed inside a cylindrical channel and passed through the ion source with electron ionization. With an increase in the flow of the analyzed solution, there was no steady trend in the relative contributions of deuterated ions from liquid phase. The results confirm the prospects of using a supersonic jet to create a high-performance source of deuterosubstituted ions from a liquid supplied into a vacuum region under conditions of 10-4 Torr residiual pressure and absence of strong electric fields.

В статье описываются результаты исследования воздействия сверхзвуковой газовой струи, сформированной внутри цилиндрического канала и пропущенной через источник электронной ионизации, на образование и экстракцию анализируемых ионов из жидкости, подаваемой через капилляр внутрь радиочастотного квадруполя, который сопряжён с времяпролётным масс-спектрометром с ортогональным вводом ионов. Полученные результаты подтверждают перспективность использования сверхзвуковой струи для создания высокоэффективного источника ионов из жидкости, подаваемой в область вакуума 10-4 Торр.