Articles

The formation of radical species in solution can be triggered through thermal or photochemical activation of a suitable precursor. This EPR study aimed to establish if these two activation modes were as effective in mesoporous silicas as in solution. First, a calibration system was devised and validated to reliably quantify the radical formation. Alkoxyamines were selected to generate stable nitroxyl radicals upon heating or irradiation. Thanks to direct synthesis by the sol-gel process, these precursors were selectively located on the pore surface or in the framework of mesoporous silicas. The thermal or photo-chemical activation of the functionalized materials showed that nitroxides were formed in yields comparable to those observed in solution. No significant differences were observed with the implementation of these activation modes between the solution and the mesoporous silicas. Moreover, the thermal experiments enabled to measure the C-O bond dissociation constants of alkoxyamines covalently anchored to a nanostructured silica, their values were in the same order of magnitude than those determined in solution.

The electrostatic potential fitting method (ESPF) is a powerful way of defining atomic charges derived from quantum density matrices fitted to reproduce a quantum mechanical charge distribution in the presence of an external electrostatic potential. These can be used in the Hamiltonian to define a robust and efficient electrostatic embedding QM/MM method. The original formulation of ESPF QM/MM was based on two main approximations, namely, neglecting the grid derivatives and nonconserving of the total QM charge. Here, we present a new ESPF atomic charge operator, which overcomes these drawbacks at virtually no extra computational cost. The new charge operators employ atom-centered grids and conserve the total charge when traced with the density matrix. We present an efficient and easy-to-implement analytic form for the energy, gradient, and hessian that scales linearly with the MM subsystem size. We show that grid derivatives and charge conservation are fundamental to preserve the translational invariance properties of energies and their derivatives and exact conditions to be satisfied by the atomic charge derivatives. As proof of concept, we compute the transition state that leads to the formation of hydrogen peroxide during cryptochrome’s reoxidation reaction. Last, we show that the construction of the full QM/MM hessian scales linearly with the MM subsystem size.

In this work, the role of deoxycholic acid (DCA) as a coadsorbent was investigated in the sensitization of mesoporous TiO2 layers (host) with symmetrical carboxy heptamethine cyanine dyes (guest). Different approaches have been tested, aimed at reducing the H-aggregation and minimizing the competition between cyanine molecules and DCA for active sites of the host, thus improving solar cell efficiency. Heptamethine cyanines containing carboxylic anchoring groups were obtained with good yields. The cyanines present UV-Vis absorption in methanol and dimethylformamide solutions ascribed to fully allowed electronic transitions (1 pi pi*), as well as fluorescence emission in the NIR region, with any evidence of aggregations in both ground and excited states. TD-DFT calculations were also performed in order to study the geometry and charge distribution of these compounds in their ground and excited electronic states. Solid-state photophysics indicates that the cyanines showed excellent adsorption on TiO2, which can be justified by the presence of the -COOH moieties in the structure. Photophysical measurements have revealed the best concentrations of dye and DCA, which resulted in efficient inhibition of cyanine H-aggregates on the TiO2 surface in addition to allow large dye loading. HOMO and LUMO energy levels of the dyes were identified by cyclic voltammetry, showing oxidation and reduction potentials within acceptable limits for application as a photosensitizer in dye-sensitized solar cells (DSSCs) based on a TiO2 mesoporous photoanode. Assembled DSSCs have shown a large improvement of the electrical parameters and efficiency when a balance between dye aggregation and the competition to the host active sites was reached.

In this work, six new fluorescent dyes derived from the naphthalimide scaffold (Napht1-Napht6) were synthesized and used as high-performance photoinitiating systems (PISs) in two and three-component systems (combined with iodonium salt (Iod) and/or an electron donor amine (such as N-phenylglycine[NPG])) for the radical photopolymerization of acrylate and methacrylate monomers under visible light using a light-emitting diode at 405 nm. Markedly, these dyes were never synthesized before. In fact, these PISs showed high initiation efficiency with both demonstrating high final reactive function conversions and high polymerization rates. A further interest of our study is to determine the effect of the different substituents (chromophoric group) on the naphthalimide function, concerning the efficiency of initiation of the free radical polymerization. In order to improve the mechanical properties of the obtained polymers, these derivatives were also tested for the photopolymerization of a blend of acrylate/epoxy monomers (TA/EPOX); these latter properties were characterized by traction tests. To demonstrate the initiation efficiency of these dyes, several methods and characterization techniques were used, including steady state photolysis, real-time Fourier transform infrared spectroscopy, emission spectroscopy as well as cyclic voltammetry. In our study, these naphthalimides were used for the synthesis of photocomposites (one and multiple layers of glass fibres) using a UV@395 nm (4 W/cm(2)) conveyor, as well as in the preparation of 3D printed polymers. Markedly, one of the naphthalimide derivatives (Napht-4) can be used as a new high-performance water soluble photoinitiator for photopolymerization in water and hydrogel synthesis.

We report the structure of a new high lithium content zincolithosilicate (MZS-1) obtained after hydrothermal treatment under high pressure from a glass precursor. After synthesis microcrystalline mixture of phases was obtained among which the main phase was unknown. Due to the sub micrometric size of the crystallites its structure was determined from precession-assisted 3D electron diffraction measured at 100 K and refined using the dynamical theory of diffraction. More accurate lattice parameters are obtained from Rietveld refinement of synchrotron powder data collected at the ambient temperature. The characteristic framework is described at the ambient temperature using an average unit cell a(0)=8.57999(5) angstrom, b(0)=14.12332(8) angstrom, c(0)=4.96827(3) angstrom in the space group Ccc2. The structure of the new zeolitic 10-membered ring zincosilicate with chemical formula per unit cell (SiO2)(2)Zn0.408LiO(OH)(2)(Li,H)(2.184) (Z=4) is composed of undulated silicate layers made of fused 6-membered rings connected via vertices of (Zn,Li)O-4 tetrahedra. A weak superstructure doubling the a(0) parameter is observed and is explained by a Zn/Li ordering within the (Zn,Li)O-4 layers.

Tamanu oil from Calophyllum inophyllum L. has long been used in traditional medicine. Ethanol extraction was found the best strategy for recovering bioactive compounds from the resin part of Tamanu oil, yielding two neutral and acidic resins fractions with high phenolics, flavonoids and pyranocoumarins concentrations. A further cascade of LPLC/HPLC separations of neutral and acidic resin fractions allowed identifying fifteen metabolites, and among them, calanolide D and 12-oxocalanolide A (both in neutral fraction) were first identified from a natural source. All these extracts, subfractions and isolated metabolites demonstrated increased free radical scavenging, antioxidant, anti-inflammatory, antimicrobial and antimycobacterial activity compared to Tamanu oil and its de-resinated lipid phase. Overall, these results could promote resinous ethanol-soluble Tamanu oil extracts as a useful multifaceted and renewable medicinal resource.

This perspective article highlights the challenges in the theoretical description of photoreceptor proteins using multiscale modeling, as discussed at the CECAM workshop in Tel Aviv, Israel. The participants have identified grand challenges and discussed the development of new tools to address them. Recent progress in understanding representative proteins such as green fluorescent protein, photoactive yellow protein, phytochrome, and rhodopsin is presented, along with methodological developments.

Mass spectrometry-based approaches have been successfully applied for identifying ancient proteins in bones and other tissues. On the contrary, there are relatively few examples of the successful recovery and identification of archeological protein residues from ceramic artifacts; this is because ceramics contain much lower levels of proteins which are extensively degraded by diagenetic effects. In this paper, we report the results of the characterization of proteins extracted from pottery of the Maltese site of Bahrija, the guide-site for the Bahrija period (half of 9th-second half of eighth century BCE), recently identified as the final part of the Bor in-Nadur culture. Proteomic data here reported confirm that one of the major issue of these kind of studies is represented by contamination of animal and human agents that may complicate endogenous protein identification and authentication. The samples tested included a small group of ceramic forms, namely three tableware and six coarse ware thought to have been used in food preparation and/or storage. In this context, the limited availability of paleobotanical and archeozoological analyses may be compensated by the outcomes of the first proteomics profiling which, even if obtained on a limited selection of vessels, revealed the centrality of wheat in the diet of the ancient community of Bahrija. The data have been deposited to the ProteomeXchange with identifier < PXD022848 > .

Five ketone derivatives (ketone-1 similar to ketone-5) never synthesized in the literature and containing the same peripheral 1,3-bis(allyloxy)benzene substituting group but different central cyclohexanone cores were designed and proposed as high-performance photoinitiators for the free radical polymerization of acrylates under mild conditions. In combination with an amine and an iodonium salt (Iod), these ketones could initiate the photopolymerization of di(trimethylolpropane) tetraacrylate (TA), a tetrafunctional acrylates monomer, upon visible LED irradiation at room temperature in both thick films (1.4 mm) and thin films (25 mu m) conditions. The distinct photopolymerization profiles of acrylates were studied by real time Fourier transform infrared spectroscopy, which indicated that the ketone-2/amine/Iod system could induce the highest final conversion of acrylates in thick films condition, while ketone-5/amine/Iod system could induce the highest final conversion of acrylates in thin films condition. Photoreactivity of ketone-2 and ketone-5 was systematically investigated by steady state photolysis and fluorescence quenching experiments in the presence of an amine and an iodonium salt, respectively. Moreover, eminent migration stability of ketones in photocured TA was observed. Finally, the ketone-2 and ketone-5-based three-component photoinitiating systems were applied for the laser writing experiments of TA, and macroscopically tridimensional patterns were fabricated with an excellent spatial resolution.

Molecular machines are ubiquitous in nature and function away from equilibrium by consuming fuels to produce appropriate work. Chemists have recently excelled at mimicking the fantastic job performed by natural molecular machines with synthetic systems soluble in organic solvents. In efforts toward analogous systems working in water, we show that guest molecules can be exchanged in the synthetic macrocycle cucurbit[7]uril by involving kinetic traps, and in such a way as modulating energy wells and kinetic barriers using pH, light, and redox stimuli. Ditolyl-viologen can also be exchanged using the best kinetic trap and interfaced with alginate, thus affording pH-responsive blue, fluorescent hydrogels. With tunable rate and binding constants toward relevant guests, cucurbiturils may become excellent ring molecules for the construction of advanced molecular machines working in water.

In this paper, nine organic compounds based on the coumarin scaffold and different substituents were synthesized and used as high-performance photoinitiators for free radical photopolymerization (FRP) of meth(acrylate) functions under visible light irradiation using LED at 405 nm. In fact, these compounds showed a very high initiation capacity and very good polymerization profiles (both high rate of polymerization (Rp) and final conversion (FC)) using two and three-component photoinitiating systems based on coum/iodonium salt (0.1%/1% w/w) and coum/iodonium salt/amine (0.1%/1%/1% w/w/w), respectively. To demonstrate the efficiency of the initiation of photopolymerization, several techniques were used to study the photophysical and photochemical properties of coumarins, such as: UV-visible absorption spectroscopy, steady-state photolysis, real-time FTIR, and cyclic voltammetry. On the other hand, these compounds were also tested in direct laser write experiments (3D printing). The synthesis of photocomposites based on glass fiber or carbon fiber using an LED conveyor at 385 nm (0.7 W/cm(2)) was also examined.

Rationale Among isomers of dihydroxybenzoic acid (DHB), 2,5-DHB is often the most efficient matrix in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for a great variety of compounds. Yet, when performing solvent-free MALDI, 2,6-DHB yields better results for poly(ethylene glycol [PEG]). This intriguing feature is explored here using solid-state nuclear magnetic resonance (NMR). Methods Ternary mixtures were prepared by grinding 2,X-DHB (X = 3-6), poly(ethylene glycol) (M-n = 2000 g mol(-1)) and lithium fluoride (LiF) in a matrix/analyte/salt molar ratio of 50/1/10 for 16 min under a controlled atmosphere. After mixing, a few grains were applied to the MALDI target for MS analysis, whereas the major part of the ground sample was transferred into rotors to perform C-13, Li-7, and F-19 NMR experiments. Results Lithiated PEG chains are mainly formed with 2,6-DHB in solvent-free MALDI, but their abundance increases with 2,3-DHB and 2,4-DHB when water uptake is favored by a humid atmosphere. Solid-state NMR shows that grinding 2,6-DHB-based samples in atmospheric conditions leads to a solid phase in which the matrix, PEG, and salt molecules exhibit a high mobility compared with systems involving other 2,X-DHB isomers. This mobile environment would favor (as a solvent) LiF dissociation and best promote PEG cationization. Conclusions Complementary data in C-13, Li-7, and F-19 NMR spectra are consistent with the formation of a solid phase of high mobility composed of 2,6-DHB, PEG, and the two salt components that ultimately favor the production of lithiated PEG chains.

The world is on the verge of a major antibiotic crisis as the emergence of resistant bacteria is increasing, and very few novel molecules have been discovered since the 1960s. In this context, scientists have been exploring alternatives to conventional antibiotics, such as ribosomally synthesized and post-translationally modified peptides (RiPPs). Interestingly, the highly potent in vitro antibacterial activity and safety of ruminococcin C1, a recently discovered RiPP belonging to the sactipeptide subclass, has been demonstrated. The present results show that ruminococcin C1 is efficient at curing infection and at protecting challenged mice from Clostridium perfringens with a lower dose than the conventional antibiotic vancomycin. Moreover, antimicrobial peptide (AMP) is also effective against this pathogen in the complex microbial community of the gut environment, with a selective impact on a few bacterial genera, while maintaining a global homeostasis of the microbiome. In addition, ruminococcin C1 exhibits other biological activities that could be beneficial for human health, as well as other fields of applications. Overall, this study, by using an in vivo infection approach, confirms the antimicrobial clinical potential and highlights the multiple functional properties of ruminococcin C1, thus extending its therapeutic interest.

A new procedure is described for the determination of Hg2+ ions in water samples. A Rhodamine based fluorescent sensor was synthesized and the experimental conditions were specifically optimized for application to environmental samples, which requires low detection limits and high selectivity in competitive experiments with realistic concentrations of other metal ions. Incorporation of a Rhodamine-6G fluorophore to a previously described sensor and optimization of the buffer system (detection with acetic acid at pH 5.25) enabled significant enhancement of the sensitivity (detection limit = 0.27 mu g L-1) and selectivity. The optimized procedure using high-throughput microplates has been applied to tap and river waters with good results.

Four series of bis-chalcone compounds based on benzylpiperidinone, tetrahydrothiopyranone, pyridine or biphenyl central parts are designed and synthesized, enabling the development of ten bis-chalcones varying both by the central cores and by the substitution patterns (ortho, meta, para-positions) and the choice of the different groups attached to the peripheral substituents (alkoxy or allyloxy-substituted aromatic rings, thiophene, or ferrocene). In this series of ten bis-chalcones, eight of them were never synthesized before (i.e. only bis-chalcones 8 and 10 were already reported albeit never used as photoinitiators). These different dyes are proposed as new near-UV/visible light sensitive photoinitiators, in combination with an amine and an iodonium salt, to initiate the free radical photopolymerization (FRP) of PEG-diacrylate and the cationic photopolymerization (CP) of EPOX under LED@405 nm and LED@375 nm irradiation conditions. For the photopolymerization of acrylates carried out between thin films in laminate, all the bis-chalcones proposed in this work show higher photoinitiation abilities upon irradiation with a LED at 375 nm than at 405 nm, which is mainly due to their excellent light absorption properties in the near-UV region. Markedly, in contrast with the other two series of bis-chalcone compounds, pyridine-based bis-chalcones prove to be the most efficient photoinitiators, especially the bis-chalcones 5 and 9. Furthermore, all of them can also promote the cationic polymerization of epoxides upon LED irradiation at 375 nm, in the presence of an iodonium salt and an amine. More interestingly, some 3D patterns fabricated through the free radical polymerization of PEG-diacrylate demonstrate reversible swelling properties and shape-memory for access to 4D printing.

In this paper, seven new photoinitiators based on the benzophenone scaffold are specifically designed for photopolymerization under mild conditions upon light-emitting diode (LED) irradiation, i.e. four benzophenone-triphenylamine photoinitiators (denoted as BT1-BT4) and three benzophenone-carbazole photoinitiators (denoted as BC1-BC3). Noticeably, these structures have never been reported in the literature except for BT4, so these molecules have been specifically designed for photopolymerization applications. Remarkably, various combinations of chemical groups were investigated in this work to determine the effects of the substitution patterns on their photoinitiation abilities. The formation of benzophenone-triphenylamine and benzophenone-carbazole hybrid structures not only contributes to red-shift of the absorption maxima but also strongly enhances their molar extinction coefficients. The different compounds showed high photoinitiation abilities upon irradiation with an LED@405 nm, and the free radical photopolymerization of acrylates and the cationic polymerization of epoxides could be promoted with high final function conversions (e.g. 77% for the BT3/iodonium salt/amine system in free radical photopolymerization). Remarkably, these new PIs are also able to sensitize sulfonium salts upon irradiation @405 nm. Markedly, because of the benzophenone moiety, a monocomponent Type II PI behavior could be observed, e.g. these compounds could initiate the polymerization alone. Remarkably, benzophenone-triphenylamine compounds BT2, BT3 and BT4 exhibited better hydrogen abstraction abilities as Type II photoinitiators than the benchmark and commercial photoinitiator 2-isopropylthioxanthone in the absence of amines as well as in the presence of amines. Furthermore, the interaction between the photoinitiators and the different additives was investigated by steady state photolysis and fluorescence quenching experiments. The free radical generation in the BT3/amine system was confirmed by the electron spin resonance-spin trapping technique, and the chemical mechanisms related to the polymerization efficiency are discussed. In addition, the migration stability of BT3 was investigated, which was excellent due to its high molecular weight and its trifunctional character. Finally, the three-component photoinitiating system based on BT3 was successfully applied in 3D printing and the 3D patterns showed a good spatial resolution.

Sequence-defined synthetic polymers have recently emerged as an attractive medium to store information at the molecular level, where comonomers of the chains are defined as letters of an alphabet. The main read-out methodology employed to retrieve such molecularly encoded information is tandem mass spectrometry (MS/MS), but a major current limitation remains the low storage capacity of readable chains. Ordering short oligomers at discrete locations onto surfaces to compose long messages is an attractive alternative to the difficult synthesis of long coded polymers. Yet, such surface storage requires a reliable sampling technique to be coupled on-line with MS/MS. Because it combines fast surface extraction with efficient analyte ionization in ambient conditions, desorption electrospray ionization (DESI) is shown here to be perfectly suited to envisage bidimensional data storage. The present study demonstrates performances of DESI-MS/MS at mapping oligomers used to write letters of a word, extracting digital labels from materials tagged for anticounterfeiting purposes, and imaging text written with coded polymeric inks.

Photoinitiators of polymerization with reversible electrochemical properties are actively researched as these molecules can advantageously be used in photocatalytic systems, enabling to reduce the photoinitiators content within the photocurable resins. In this field, ferrocene which is extensively used by electrochemists as a reference compound for cyclic voltammetry also exhibits a significant absorption in the visible range as well as a low oxidation potential so that this metallocene was used as a potential candidate for the design of photoinitiators of polymerization. Over the years, ferrocene has been examined in numerous polymerization processes going from anionic to cationic polymerizations, but also for the free-radical polymerization of acrylates or as a sacrificial electron donor in free radical polymerization processes. Parallel to this, the development of cheap, compact and energy-saving irradiation setups based on light-emitting diodes (LEDs) have clearly favored the development of visible light photoinitiators and this technology has nowadays the potential to replace the well-established UV photopolymerization. In this review, an overview of the recent development of the ferrocene-based photoinitiating systems is provided. To evidence the interest of the ferrocene derivatives recently developed, comparisons with benchmark photoinitiators will be provided.

Organic nitrates are secondary species in the atmosphere. Their fate is related to the chemical transport of pollutants from polluted areas to more distant zones. While their gas-phase chemistry has been studied, their reactivity in condensed phases is far from being understood. However, these compounds represent an important fraction of organic matter in condensed phases. In particular, their partition to the aqueous phase may be especially important for oxidized organic nitrates for which water solubility increases with functionalization. This work has studied for the first time the aqueous-phase center dot OH-oxidation kinetics of four alkyl nitrates (isopropyl nitrate, isobutyl nitrate, 1-pentyl nitrate, and isopentyl nitrate) and three functionalized organic nitrates (alpha-nitrooxyacetone, 1-nitrooxy-2-propanol, and isosorbide 5-mononitrate) by developing a novel and accurate competition kinetic method. Low reactivity was observed, with k(OH) ranging from 8 x 10(7) to 3.1 x 10(9) L mol(-1) s(-1) at 296 +/- 2 K. Using these results, a previously developed aqueous-phase structure-activity relationship (SAR) was extended, and the resulting parameters confirmed the extreme deactivating effect of the nitrate group, up to two adjacent carbon atoms. The achieved extended SAR was then used to determine the center dot OH-oxidation rate constants of 49 organic nitrates, including hydroxy nitrates, ketonitrates, aldehyde nitrates, nitrooxy carboxylic acids, and more functionalized organic nitrates such as isoprene and terpene nitrates. Their multiphase atmospheric lifetimes towards center dot OH oxidation were calculated using these rate constants, and they were compared to their gas-phase lifetimes. Large differences were observed, especially for polyfunctional organic nitrates: for 50% of the proposed organic nitrates for which the center dot OH reaction occurs mainly in the aqueous phase (more than 50% of the overall removal), their center dot OH-oxidation lifetimes increased by 20% to 155% under cloud/fog conditions (liquid water content LWC = 0.35 gm(-3)). In particular, for 83% of the proposed terpene nitrates, the reactivity towards center dot OH occurred mostly (> 98 %) in the aqueous phase, while for 60% of these terpene nitrates, their lifetimes increased by 25% to 140% compared to their gas-phase reactivity. We demonstrate that these effects are of importance under cloud/fog conditions but also under wet aerosol conditions, especially for the terpene nitrates. These results suggest that considering aqueous-phase center dot OH-oxidation reactivity of biogenic nitrates is necessary to improve the predictions of their atmospheric fate.

Extended quantum chemical calculations were performed for the tetracene dimer to provide benchmark results, analyze the excimer survival process, and explore the possibility of using long-range-corrected (LC) time-dependent second-order density functional tight-biding (DFTB2) for this system. Ground- and first-excited-state optimized geometries, vertical excitations at relevant minima, and intermonomer displacement potential energy curves (PECs) were calculated for these purposes. Ground-state geometries were optimized with the scaled-opposite-spin (SOS) second-order MOller-Plesset perturbation (MP2) theory and LC-DFT (density functional theory) and LC-DFTB2 levels. Excited-state geometries were optimized with SOS-ADC(2) (algebraic diagrammatic construction to second-order) and the time-dependent approaches for the latter two methods. Vertical excitations and PECs were compared to multireference configuration interaction DFT (DFT/MRCI). All methods predict the lowest-energy S-0 conformer to have monomers parallel and rotated relative to each other and the lowest S-1 conformer to be of a displaced-stacked type. LC-DFTB2, however, presents some relevant differences regarding other conformers for S-0. Despite some state-order inversions, overall good agreement between methods was observed in the spectral shape, state character, and PECs. Nevertheless, DFT/MRCI predicts that the S-1 state should acquire a doubly excited-state character relevant to the excimer survival process and, therefore, cannot be completely described by the single reference methods used in this work. PECs also revealed an interesting relation between dissociation energies and the intermonomer charge-transfer interactions for some states.

We have characterized the size, intensity, density, and distribution of charge-transfer (CT) excitons as a function of the acceptor-donor architecture of prototypical organic interfaces. This characterization was done by computational analysis of 17 models of varying numbers, positions, and orientations of the donor and acceptor molecules. The models’ building blocks were phenyl-C-61-butyric acid methyl ester (PCBM) fullerene acceptors and dual-band donor polymers composed of thiophene, benzothiadiazole, and benzotriazole subunits. The electronic structure of the donor-acceptor complexes was computed with the time-dependent long-range-corrected density-functional tight-binding method and analyzed with the fragment-based one-electron transition density matrix. In all models, the complexes with edge-on orientation have denser spectra of low-energy CT states lying below the absorption bands compared to the complexes with face-on orientation. This CT-state distribution in edge-on complexes provides a gate to efficiently populate cold CT excitons. Moreover, the cold CT excitons have a higher degree of charge separation in the edge-on than in the face-on complexes. The CT amount and the CT exciton size generally increase with the energy of the CT states, although the electron remains localized on a single molecule in cold CT states. Delocalization over two PCBM molecules was observed for high-energy CT states. The exciton size also depends on the orientation. Larger excitons are produced by the delocalization of the electrons perpendicularly to the interface. When the delocalization is parallel, the smaller electron-hole distances yield moderately sized CT excitons.

Nowadays water scarcity represents a threat for human and living beings. Therefore, to satisfy the demands of people for clean and safe water, new technologies for wastewater treatment have been developed. Thus, photocatalysis has emerged as a green chemical approach for such treatment. In this context, new polyoxometalate (POM)/polymer composites with relevant photocatalytic properties have been developed via an easy and cheap photopolymerization process upon mild visible light irradiation at 405 nm. This fruitful association between POM and polymer allowed the obtention of shaped materials facile to collect and reuse at the end of the photocatalytic treatment avoiding then the usual time-consuming regeneration methods. The prepared photocomposites displayed excellent photocatalytic performance for the removal of bisphenol-A from water under different sources of irradiation. Hence, 100%, 88%, and 50% of this model compound were decomposed by the phosphomolybdic composite under just 90 min of UV lamp, solar and LED@375 nm irradiations, respectively. The effectiveness of these developed photocatalysts towards the degradation of other organic compounds, as well as the degradation mechanism based on the generation of highly reactive chemicals such as (OH)-O-center dot radicals promoting the degradation were already reported. Bisphenol-A degradation pathway and the identification of the photoproducts were discussed using mass spectroscopy technique. Therefore, this paper highlighted the photocatalytic efficiency of the new manufactured materials for the photodegradation of the bisphenol-A, thus expanding their application fields, under different sources of irradiation and under pure solar irradiation which make their applications more interesting and less energy consuming.

Uniform conjugates combining a DNA aptamer (either anti-MUC1 or ATP aptamer) and a synthetic polymer segment were synthesized by automated phosphoramidite chemistry. This multistep growth polymer chemistry enables the use of both natural (i.e., nucleoside phosphoramidites) and nonnatural monomers (e.g., alkyl- and oligo(ethylene glycol)phosphoramidites). Thus, in the present work, six different aptamer-polymer conjugates were synthesized and characterized by ion-exchange HPLC, circular dichroism spectroscopy, and electrospray mass spectrometry. All these methods evidenced the formation of uniform molecules with precisely controlled chainlength and monomer sequences. Furthermore, aptamer folding was not affected by polymer bioconjugation. The method described herein is straightforward and allows covalent attachment of homopolymers and copolymers to biofunctional DNA aptamers.

In pediatric wards, topiramate is prescribed as an antiepileptic at non-licensed dosages. Compounding is the best way to obtain topiramate drug adapted to pediatric patients, but this practice requires to control the quality of batches and to manage a stability study to establish a beyond-use-date. With this objective, 6 mg.mL(-1) topiramate oral suspension and 9 mg capsules were realized, and our laboratory was mandated for their quality control. Previously described dosing methods did not allow us to determine topiramate content in prescribed preparations. An original HPLC-UV derivatization dosing method of topiramate was validated and was proved to be stability indicating. This derivatization methodology, but also total aerobic microbial count (TAMC) and total combined yeasts and mold count (TYMC) allowed the quality control of topiramate capsules and topiramate suspension. Beyond-use-dates can be attributed with regards to United States Pharmacopoeia recommendations, and a stability study was performed on 6 mg.mL(-1) topiramate suspension to confirm empirical data. Topiramate pediatric suspension was found to be stable for two months at +21+8 degrees C, one month after opening and one day at ambient temperature.

Organic electron donors (OEDs) are increasingly used as efficient reducing agents in various radical reactions. However, their sensitivity to air restraints their practical use and the development of further industrial applications. To meet the community’s needs, this paper reports the preparation of air- and moisture-stable carboxylate precursors that can be conveniently activated into the corresponding organic reducer. The new strategy consists in the water-assisted decarboxylation of the adduct at room temperature, providing a straightforward protocol for the single-electron transfer reduction of aryl halides and sulfonamide. The resulting aryl radicals are engaged in the first examples of OED-promoted intermolecular addition reactions. A thorough mechanistic study supports the in situ formation of the organic reducer.

Silver nanoparticles (AgNPs) play a crucial role in biology and medical research as their extensive and efficient antibacterial activity and high electrical and thermal conductivity. However, the generation of them with a certain morphology under mild conditions (under air, solvent-free, room temperature, etc.,) is still a huge challenge. Herein, a simple one-step method is proposed to generate AgNPs in situ at room temperature under air by combining the photopolymerization process with the formation process of AgNPs within a few minutes. In detailed, 12 different dyes based on 2,5-diethylene-cyclopentan-1-one were first synthesized and used as high-performance type II photoinitiator. When using in conjunction of bis-(4-tert-butylphenyl) iodonium hexafluorophosphate (Iod) and ethyl 4-dimethylaminobenzoate (EDB), they can effectively boost the free radical photopolymerization (FRP) of polyethylene glycol diacrylate (PEG-DA) and the cationic photopolymerization (CP) of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (EPOX) upon irradiation with LED@405 nm. Furthermore, all the formulations containing/without AgNPs can be successfully used to perform the direct laser write experiment. However, even if all of the obtained 3D patterns exhibited reversible swelling performance and shape-memory effects caused by swelling and dehydration for the access to 4D printing, the presence of AgNPs will affect these properties.

Fourteen dyes based on 2,4,5,7-tetranitrofluorene (TNF) as the electron acceptor have been designed and prepared in a one-step synthesis. By modifying the electron donor, optical properties of the dyes could be efficiently tuned and an absorption ranging between 450 nm and 700 nm could be determined by UV?visible absorption spectroscopy. To get a deeper insight into the optical properties, solvatochromism of the fourteen dyes has also been examined. For all dyes, a positive solvatochromism was determined using different solvent polarity scales such as the Kamlet-Taft and the Catalan empirical scales. Finally, electrochemical properties were also examined, and a comparison of the electrochemical and optical bandgaps could be established. Theoretical calculations were also performed to characterize the different dyes.

A series of twelve dyes based on the 4-(9-ethyl-9H-carbazol-3-yl)-4-phenylbuta-1,3-dienyl donor were prepared with electron acceptors varying in their structures but also in their electron-withdrawing ability. For specificity, a butadienyl spacer was introduced between the donor and the acceptor to both lower the bandgap and furnish dyes with high molar extinction coefficients. The different dyes A-N were characterized using various techniques including UV-visible absorption and fluorescence spectroscopy, and cyclic voltammetry. All dyes showed an intense intramolecular charge transfer band located in the visible range. To further investigate the optical properties of the twelve dyes, their solvatochromism was investigated in twenty-three solvents of different natures, enabling linear correlations to be obtained on different polarity scales such as the Taft, Reichardt and Catalan scales. To support the experimental results, the optical properties were compared with those theoretically determined.

Establishing mechanistic understanding of crystallization processes at the molecular level is challenging, as it requires both the detection of transient solid phases and monitoring the evolution of both liquid and solid phases as a function of time. Here, we demonstrate the application of dynamic nuclear polarization (DNP) enhanced NMR spectroscopy to study crystallization under nanoscopic confinement, revealing a viable approach to interrogate different stages of crystallization processes. We focus on crystallization of glycine within the nanometric pores (7-8 nm) of a tailored mesoporous SBA-15 silica material with wall-embedded TEMPO radicals. The results show that the early stages of crystallization, characterized by the transition from the solution phase to the first crystalline phase, are straightforwardly observed using this experimental strategy. Importantly, the NMR sensitivity enhancement provided by DNP allows the detection of intermediate phases that would not be observable using standard solid-state NMR experiments. Our results also show that the metastable beta polymorph of glycine, which has only transient existence under bulk crystallization conditions, remains trapped within the pores of the mesoporous SBA-15 silica material for more than 200 days.

Cables, especially their insulation and jacket materials made of polymers, are vulnerable to ageing degradation during normal operation. However, they must remain functional for the entire life of a nuclear power plant, or even in the event of an accident for cables with a safety requirement. This study focuses on models of crosslinked polyethylene (XLPE)-based insulation of cables and deals with the structure modification and the behavior of XLPE for nuclear applications due to the effect of additives. Various additives are added to the polymer formulation to evaluate their impact on ageing. The samples are irradiated at room temperature by several gamma doses, up to 374 kGy, with two dose rates (40 Gy/h and 300 Gy/h) and compared with a non-irradiated sample used as reference. To understand the impact of gamma irradiation on the materials, the principal component analysis (PCA) method is applied on spectra recorded through attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The results highlight the effects of ageing depending on the dose rate and on the formulation of the materials, with the identification of different degradation products. A curve resolution study compares the effects of different additives on polymer oxidation and shows that the low dose rate leads to a higher degradation than the high dose rate.