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International audience; In this work, we investigated a high-temperature reaction between ReS2, MoS2 and KCN resulting in the formation of the cluster-based K6[Re6-xMoxS8(CN)5] solid solution. The crystal structure is based on chains of [Re6-xMoxS8(CN)6] cluster units. It was found that both the sintering temperature of starting sulfides and the reaction temperature with KCN have an influence on the composition of the product allowing x to be varied within the range x = 2.75-3.63. The molar ration of ReS2:MoS2:KCN loaded composition is fixed to 3:3:14 in all experiments. Energy dispersive spectroscopy (EDS), powder X-ray diffraction (PXRD) and high-resolution electrospray (ESI) mass spectrometry were used to characterize the solid solution K6[Re6-xMoxS8(CN)5]. It was shown by mass spectrometry that the solid solution with fractional x contains anions based on the {Re4Mo2S8}, {Re3Mo3S8} and {Re2Mo4S8} cluster cores in different proportions depending on the above-mentioned factors. Particularly, the rise of the temperature of the synthesis or temperature of sintering of metal sulfides led to increase of the rhenium content in the solid solution.

Mechanism of direct UVC photolysis of dibenzazepine-type drug imipramine (IMI) was revealed by the combination of laser flash photolysis for the detection of short lived intermediates and steady-state photolysis coupled with LC-MS for identification of final products. Both quantum yield of IMI photoionization and molar absorption coefficient of IMI radical cation were determined for the first time.

Photodegradation of imipramine (IMI), a widely used tricyclic antidepressant, in the presence of Fe(III) oxalate and potassium persulfate (PS) was studied for the first time by combination of steady state and laser flash photolysis. It was demonstrated that Fe(III) oxalate system exhibits an effective photooxidation of IMI due to the formation of reactive oxygen species (ROS) with a very high quantum yield, φROS(308 nm) ∼0.3. The quantum yield of the most important ROS, hydroxyl radical, was also measured for the first time (φOH(308 nm) = 0.25 ± 0.02) as well as the rate constant of the reaction between •OH radical and IMI (kOH = (1.5 ± 0.1) ×1010 M−1s−1). Nature and spectral properties of short lived organic radicals formed in this reaction were also determined experimentally and proved by quantum-chemical calculations. At a IMI concentration of less than 10 µM it is possible to achieve full disappearance of the initial compound in Fe(III)-oxalate system. Main aromatic by-products of the IMI oxidation are connected with its consequent hydroxylation and elimination of aliphatic substituent. Complete degradation of both IMI and all aromatic byproducts needs joint application of Fe(III) oxalate and PS, as additional oxidizing agent. Combined Fe(III) oxalate – PS system demonstrates high photoactivity under UV irradiation and could be used for the effective degradation of IMI and its close analogues in aqueous media.

Cerium ammonium nitrate (NH4)2CeIV(NO3)6 (CAN) is widely used as a photolytic source of NO3 radicals in acetonitrile. In spite of that, the mechanistic aspects of CAN photochemistry were poorly discussed in the literature. In this work CAN photochemistry in CH3CN was studied using the combination of stationary methods and laser flash photolysis. In accordance with the literature, the inner-sphere electron transfer was found to be the primary photochemical process. The (NH4)2CeIII(NO3)5(CH3CN) complex was found to be the only reaction product formed with the rather high quantum yield (0.6 and 0.4 upon 308 and 355 nm excitation correspondingly). The NO3 radicals decay is mainly caused by the second-order reactions; their rate constants are determined. In addition to the direct release of the NO3 radicals, a part of the light-excited CAN molecules were found to form the radical complex [(NH4)2CeIII(NO3)5…NO3 ], which lifetime is ca. 2 μs.

This article reports the synthesis, crystal structure of new molybdenum hexaazide cluster complex ( n Bu 4 N) 2 [{Mo 6 I 8 }(N 3 ) 6 ] ( 3 ) and comparison of its photophysical and electrochemical properties to those of earlier reported analogues ( n Bu 4 N) 2 [{Mo 6 X 8 }(N 3 ) 6 ] (X = Cl, Br). Additionally, the dimerisation of 3 as a result of hydrolysis was revealed by mass spectrometry and single crystal X-Ray diffraction. Indeed, the structurally characterised compound ( n Bu 4 N) 4 [({Mo 6 I 8 }(N 3 ) 5 ) 2 O] represents the first example of oxo-bridged dimer of octahedral molybdenum clusters complexes.

The synthesis of the natural molecular UV filters − kynurenines (KN) − covalently bound to nitroxides has recently been proposed as an alternative for traditional combination of antioxidants and UV-filters in sunscreen formulations. Due to the spin-exchange interaction between KN and nitroxide moieties, the triplet lifetimes in such conjugates are much shorter than in KN molecule, but the triplet quantum yields are significantly higher. The reaction of intramolecular electron transfer between photoexcited KN and nitroxide moieties is the main factor determining the quantum yield of KN-RNO conjugates photodecomposition. Searching for a method to suppress this side process we synthesized analogues of previously prepared conjugates with the enlarged spacer between the nitroxide and kynurenine parts and with the sterically hindered access to the nitroxide group. The new spin-labeled kynurenines showed at least three-fold higher photostability compared to the previously synthesized compounds of this type.

Spatial distribution of 34 metabolites along the optical and equatorial axes of the human lens has been determined. For the majority of metabolites, the homogeneous distribution has been observed. That suggests that the rate of the metabolite transformation in the lens is low due to the general metabolic passivity of the lens fiber cells. However, the redox processes are active in the lens; as a result, some metabolites, including antioxidants, demonstrate the "nucleus-depleted" type of distribution, whereas secondary UV filters show the "nucleus-enriched" type. The metabolite concentrations at the lens poles and equator are similar for all metabolites under study. The concentric pattern of the "nucleus-depleted" and "nucleus-enriched" distributions testifies that the metabolite distribution inside the lens is mostly governed by a passive diffusion, relatively free along the fiber cells and retarded in the radial direction across the cells. No significant difference in the metabolite distribution between the normal and cataractous human lenses was found.

Photodegradation of thin films of organic semiconducting electron-donor materials P3HT, PCDTBT, DRCN5T and BTR upon illumination with visible light in air was studied. The changes of UV–vis absorption, photoluminescence and EPR spectra were monitored as functions of illumination time. Stable radicals were generated at concentrations that exceed the values of charge carrier density of organic solar cells in the operating conditions. Increase of the radical concentration was observed for P3HT, PCDTBT, DRCN5T. On the contrary, for BTR the radical concentration drops to zero after initial increase. This indicates different photodegradation processes in studied materials.

Octahedral rhenium cluster complexes with organic apical ligands have a high potential to be used in different fields due to their intrinsic luminescence and X-ray contrast properties. A series of new compounds based on cations [{Re6Q8}(3-Me-pzH)6]2+, where Q is S or Se and 3-Me-pzH is 3-methylpyrazole, were obtained and characterized in the solid state (FTIR, elemental and single crystal diffraction analysis) and in solution (1H NMR and ESI-MS). The compounds possess luminescence properties that mainly depend on inner Q ligands indicating the {Re6Q8}2+ core-centered nature of emission.

Reaction of (NH4)[NbO(C2O4)2(H2O)2]·3H2O with K12[H2P2W12O48]∙24H2O in aqueous solution at pH 1.7 leads to the formation of mixed Nb/W species based on [(P2M18O60)2(µ-O)2]n− (M is a Nb/W mixture, when Nb ratio ranges from 6 to 8 and charge differs from 14- to 16- correspondingly) archetype. Direct crystallization from the reaction media results in colorless crystals with the composition formulated as K9(NH4)5[cis-(P2W15Nb3O61)2]·48H2O (1). Crystallization in the presence of (NMe2H2)Cl yields two phases (2a and 2b), containing the same [trans-(P2W14.7Nb3.3O61)2]14.6− anions but different cation/H2O compositions. Both phases are present in a mixture with bulk composition corresponding to (NMe2H2)14.6[P2W14.7Nb3.3O61]2·28H2O (2). The solution behavior of 1 and 2 was studied with HR-ESI-MS and HPLC-ICP-AES. During XRPD study of 2 we found blue coloration of the thin film of the complex. This effect has only surface nature and was studied by diffuse reflectance spectra.

Quantitative metabolomic profiles of normal and cataractous human lenses were obtained with the combined use of high-frequency nuclear magnetic resonance (NMR) and high-performance liquid chromatography with high-resolution mass-spectrometric detection (LC-MS) methods. The concentration of more than fifty metabolites in the lens cortex and nucleus has been determined. For the majority of metabolites, their concentrations in the lens cortex and nucleus are similar, which confirms low metabolic activity in the lens core. The difference between the metabolite levels in the cortex and nucleus of the normal lens is observed for antioxidants and UV filters, which demonstrates the activity of redox processes in the lens. A huge difference is found between the metabolomic compositions of normal and age-matched cataractous lenses: the concentrations of almost all metabolites in the normal lens are higher than in the cataractous one. The most pronounced difference is observed for compounds playing a key role in the lens cell protection and metabolic activity, including antioxidants, UV filters, and osmolytes. The results obtained imply that the development of the age-related cataracts might originate from the metabolic dysfunction of the lens epithelial cells.

The first example of dodecanuclear chalcohalide rhenium cluster complex, (Et4N)4(Me2NH2)2[Re12CS17Br6] (1), has been synthesized by reaction of polymeric cluster solid Re12CS17 with excess of Et4NBr in boiling DMF. The compound was characterized by a set of methods, including IR and UV–Vis spectroscopy, elemental analysis, EDS, mass-spectrometry, single-crystal X-ray diffraction analysis, and quantum-chemical calculations. The crystal structure presents an interesting case of 1D supramolecular architecture based on notably short Br⋯Br interactions of 3.432 A between the terminal bromide trans-ligands of adjacent [Re12CS17Br6]6− cluster anions. The DFT calculations performed for the [Re12CS17Br6]6− anion showed good agreement between calculated and experimental data.

Nanosecond laser flash photolysis and time-resolved fluorescence were used to study photochemistry of 4,4-Bis(4-hydroxyphenyl)valeric acid (diphenolic acid, DPA) and complex of DPA with β-cyclodextrin (DPA-βCD) in aqueous solutions. For both systems the primary photochemical process was found to be photoionization with the formation of a hydrated electron–phenoxyl radical pair. Inclusion of DPA in cyclodextrin cavity leads to the great increase of photoionization and fluorescence quantum yield (from 0.01 to 0.14) as well as fluorescence lifetime (from 0.17 to 2.9 ns) due to decreasing of the quenching rate of the singlet excited state of complexed DPA by solvent molecules.

The influence of irradiation wavelength and intensity on photochemistry of acetaminophen (APAP) in aqueous solution was investigated by combination of steady-state and laser flash photolysis as well as HPLC and LC–MS. Steady-state irradiation at 254 nm leads to APAP disappearance with the quantum yield 0.0014 and to formation of 1-(2-amino-5-hydroxyphenyl)ethanone ( P1 ) as a main primary photo-Fries product. In opposite the laser excitation at 266 nm leads predominantly to two-photon ionization of APAP with the quantum yield 0.013 ( I = 70 mJ/cm 2 ) and to the formation of one main product of phenoxyl radical reactions – N-(3,4-dihydroxyphenyl)acetamide ( P5 ). Steady-state excitation at 282 nm leads to both P1 and P5 products formation indicating competition of photo-Fries and photoionization processes. The wavelength-dependent mechanism of APAP photolysis is proposed and discussed.