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Three new tetraphenylethene (TPE) push-pull chromophores exhibiting strong intramolecular charge transfer (ICT) are described. They were obtained via [2+2] cycloaddition - retroelectrocyclization (CA-RE) click reactions on an electron-rich alkyne-tetrafunctionalized TPE (TPE-alkyne) using both 1,1,2,2-tetracyanoethene (TCNE), 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) as electron-deficient alkene. Only the starting TPE-alkyne displayed a significant AIE behavior, whereas for TPE-TCNE,a faint effect was observed and for TPE-TCNQ and TPE-F4-TCNQ, no fluorescence was observed in any conditions. The main ICT bands that dominate the UV-Visible absorption spectra underwent a pronounced red-shift beyond the near-infrared (NIR) region for TPE-F4-TCNQ. Based on TD-DFT calculations, it was shown that the ICT character shown by the compounds exclusively originated from the clicked moieties independently of the nature of the central molecular platform. Photothermal (PT) studies conducted on both TPE-TCNQ and TPE-F4-TCNQ in the solid state revealed excellent properties, especially for TPE-F4-TCNQ. These results indicated that CA-RE reaction of TCNQ or F4-TCNQ with donor-substituted are promising candidates for PT applications.

In this study, a new chiral α,ω-bifunctional polythiophene is synthesized and used as a nanoparticle linker molecule to synthesize the first layered conjugated polymer/nanoparticle (CP/NP) hybrid m...

In this report, the influence of heterogeneity on the chiral expression of star-shaped conjugated polymers is investigated. For this purpose, two heterogeneous star-shaped conjugated polymers, i.e....

Polymers produced with the most used controlled polymerization method with the simplest initiators, namely the Kumada catalyst transfer condensation polymerization (KCTCP) with Ni2+ salts, all have...

Magnetron sputter deposition of metal targets over liquids allows producing colloidal solutions of small metal nanoparticles (NPs) without any additional reducing or stabilizing reagents. Despite that this synthetic approach is known for almost 15 years, the detailed mechanism of NP formation is still unclear. Detailed investigations must be carried out to better understand the growth mechanism and, ultimately, control the properties of the NPs. Here, the combination of the gold (Au) target and castor oil, a highly available green solvent, was chosen as a model system to investigate how different experimental parameters affect the growth of NPs. The effect of deposition time, applied sputter power, working gas pressure, and type of sputter plasma (direct current magnetron sputtering (DC-MS) vs. high-power impulse magnetron sputtering (HiPIMS)) on properties of Au NPs has been studied by UV-vis spectroscopy and transmission electron microscopy (TEM), and further supported by quantum-chemistry calculations and mass-spectrometry analysis. The mechanism of the Au NP formation includes the production of primary NPs and their subsequent aggregative growth limited by diffusion in the viscous castor oil medium. Final Au NPs have a narrow size distribution and a medium diameter of 2.4–3.2 nm when produced in DC-MS mode. The NP size can be increased up to 5.2 ± 0.8 nm by depositing in HiPIMS mode which, therefore, mimics energy and time-consuming post synthesis annealing.

The attachment of conjugated polymers (CPs), characterized by their optical and electronic properties and excellent processability, to inorganic nanoparticles (NPs), known for their specialized ele...

International audience; We report a novel class of star-shaped multiazobenzene photoswitches comprising individual photochromes connected to a central trisubstituted 1,3,5-benzene core. The unique design of such C3-symmetric molecules, consisting of conformationally rigid and pseudoplanar scaffolds, made it possible to explore the role of electronic decoupling in the isomerization of the individual azobenzene units. The design of our tris-, bis-, and mono(azobenzene) compounds limits the π-conjugation between the switches belonging to the same molecule, thus enabling the efficient and independent isomerization of each photochrome. An in-depth experimental insight by making use of different complementary techniques such as UV–vis absorption spectroscopy, high performance liquid chromatography, and advanced mass spectrometry methods as ion mobility revealed an almost complete absence of electronic delocalization. Such evidence was further supported by both experimental (electrochemistry, kinetical analysis) and theoretical (DFT calculations) analyses. The electronic decoupling provided by this molecular design guarantees a remarkably efficient photoswitching of all azobenzenes, as evidenced by their photoisomerization quantum yields, as well as by the Z-rich UV photostationary states. Ion mobility mass spectrometry was exploited for the first time to study multiphotochromic compounds revealing the occurrence of a large molecular shape change in such rigid star-shaped azobenzene derivatives. In view of their high structural rigidity and efficient isomerization, our multiazobenzene photoswitches can be used as key components for the fabrication of complex stimuli-responsive porous materials.

Peptoids constitute an emergent class of synthetic biocompatible macromolecules that are best described as polymers of N-substituted glycines. Peptides and peptoids are regioisomers with the side chains appended in peptoids to the nitrogen atoms rather than to the α-carbon atoms as in peptides. Peptide sequencing now takes great advantage of collision-induced dissociation experiments, based on the elucidation of the decomposition pathways of protonated peptides. In contrast, data on peptoid ion decompositions are to date scarcely present in the literature. Upon CID, protonated peptoids were recently shown to mostly dissociate by cleavages at the backbone amide bonds yielding B- and Y-fragment ions. In addition, the loss of the side-chain group and/or the formation of the side-chain fragment ion are common reactions for peptoids containing protonated N-α-aromatic side chain. In the present paper, we submitted protonated tailor-made peptoids to (energy-resolved) collision-induced dissociation experiments to investigate the side-chain loss reaction mechanisms. We also used orthogonal methods, such as quantum chemistry, ion mobility spectrometry and infrared photodissociation spectroscopy to establish the structures of the fragment ions. We ended up with different mechanistic scenarios consistent with the nature of the fragment ions and the kinetic energy dependence of decomposition reactions. Our mechanistic proposals associate the proton mobile model, proton bound dimer intermediacy and concerted rearrangement reactions.

Recent studies point to an additional stability of metal-complexed functionalized hydrocarbon chains. This additional stabilization is suggested to arise from a bidentate complexation of the metal cation with both the functional group and aliphatic chain, leading to more folded structures. In the present work, this issue is verified for silver complexed alkylamines by tandem mass spectrometry and ion mobility experiments combined with quantum-chemical calculations. Upon increasing the length of the hydrocarbon chains, the alkylamine/silver complexes undergo a structural transition to reach a folded structure in which the silver cation interacts with both the amine group and hydrogen atoms located at the chain end. This folding is further examined by monitoring the loss of AgH upon collision-induced dissociation experiments performed on alkylamines with different chain lengths. Ion mobility experiments performed on the fragment ions indicate that the removal of the silver cation induces the unfolding of the chain.

The research area of nonlinear topologies of conjugated polymers (CPs) became a topic of growing interest due to their unique optoelectronic properties compared to CPs with linear topologies. Nonetheless, the field of the third-order nonlinear optical response (TONO) is still largely unexplored, although, theoretically, nonlinear CPs should give a higher TONO response. Therefore, linear CPs and a trigonal nonlinear CP were synthesized via a combination of a controlled chain-growth polymerization, post-polymerization reactions and a click reaction. Afterward, the TONO response of the CPs was investigated with the highly sensitive third-harmonic scattering technique using solvatochromism experiments. In contrast to what was expected, trigonal nonlinear CPs do not possess a higher TONO response compared to their linear counterparts.

International audience; Pseudomonas aeruginosa is a human pathogen belonging to the top priorities for the discovery of new therapeutic solutions. Its propensity to generate biofilms strongly complicates the treatments required to cure P. aeruginosa infections. Herein we describe the synthesis of a series of novel rotaxanes comprised of a central galactosylated pillar [5]arene, a tetrafucosylated dendron and a tetra-guanidinium subunit. Strategically, we exploited a supramolecular assembly technology to generate complex rotaxanes from relatively simple subcomponents. The final glycorotaxanes displayed high affinity for the two P. aeruginosa lectins LecA and LecB as evaluated by Isothermal Titration Calorimetry. Potent inhibition levels of P. aeruginosa biofilm growth were evidenced showing that the three subunits of the glycorotaxanes work synergistically. Such antibiofilm potency had rarely been reached in the literature. Importantly, none of the final rotaxanes was bactericidal, showing that their antibiofilm activity is lectinmediated but does not depend on bacteria killing, which is a rare feature for antibiofilm agents.

International audience; Research toward bio-based polymers is an expanding field due to environmental concerns. A library of new aliphatic diol-diamide monomers with different chain lengths between the two amido groups was synthesized from sustainable levulinic acid and various linear aliphatic diamines (C 2-C 10). The monomers were prepared by diacylation of the diamines followed by reduction of the ketones to alcohols. These secondary diols were successfully recognized by an enzyme and polymerised in solution through a lipase-catalysed polycondensation. Poly(ester-co-amide)s with number-average molecular weights (M n) in the range of 1300-7200 g mol −1 were obtained, with dispersities between 1.5 and 1.8. An improvement of the M n value was observed upon increasing the monomer chain length. The variation of the aliphatic diol allows modulating the thermal properties of the final polymers. The glass transition temperatures were found to be between −23°C and 0°C. The polymers containing a long aliphatic segment (C 8-C 10) were able to crystallize (melting temperature of 90-97°C). TGA analyses showed that the ester linkages degrade at lower temperatures than the amide bonds. The stability of the latter was found to be higher when the number of methylene units increased from 2 (355°C) to 10 (378°C). This kind of biopolymer could be used as a drug delivery system or for tissue engineering applications. † Electronic supplementary information (ESI) available. See

The epimerization of polylactide is reported in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) at 105°C in toluene. The extent of the reaction depends on the amount of TBD introduced and the reaction time. Up to ca. 46% D units can be formed starting from poly(L-lactide) in the presence of 5 mol% TBD. The epimerization rate is slightly higher for D-stereoisomers vs. L-stereoisomers. From the decrease of the number-average molecular weight observed, a concomitant chain scission reaction is observed. A possible mechanism based on a nucleophilic attack of TBD is proposed based on NMR analyses, notably DOSY, MALDI ToF mass spectrometry and IR spectroscopy. The implications of the work in the field of polymer synthesis and chemical recycling of polylactide are discussed. 181;109188

The stereoisomerically pure synthesis of a novel heptanuclear Ru(II)–Os(II) antenna bearing multitopic terpyridine ligands is reported. An unambiguous structural characterization was obtained by 1H NMR spectroscopy and ion mobility spectrometry (IMS-MS). The heptanuclear complex exhibits large molar absorption coefficients (77900 M–1 cm–1 at 497 nm) and undergoes unitary, downhill, convergent energy transfer from the peripheral Ru(II) subunits to the central Os(II) that displays photoluminescence with a lifetime (τ = 161 ns) competent for diffusional excited-state electron transfer reactivity in solution.

Among the various catalysts that can be used for polycondensation reactions, enzymes have been gaining interest for three decades, offering a green and eco-friendly platform towards the sustainable design of renewable polyesters. However, limitations imposed by their delicate nature, render them less addressed. As a case study, we compare herein bulk and solution polycondensation of 1,6-hexanediol and diethyl adipate catalyzed by an immobilized lipase from Candida antarctica. The influence of various parameters including time, temperature, enzyme loading, and vacuum was assessed in the frame of a two-step polymerization with the help of response surface methodology, a statistical technique that investigates relations between input and output variables. Results in solution (diphenyl ether) and bulk conditions showed that a two-hour reaction time was enough to allow adequate oligomer growth for the first step conducted under atmospheric pressure at 100 &deg, C. The number-average molecular weight (Mn) achieved varied between 5000 and 12,000 g&middot, mol&minus, 1 after a 24 h reaction and up to 18,500 g∙mol&minus, 1 after 48 h. The statistical analysis showed that vacuum was the most influential factor affecting the Mn in diphenyl ether. In sharp contrast, enzyme loading was found to be the most influential parameter in bulk conditions. Recyclability in bulk conditions showed a constant Mn of the polyester over three cycles, while a 17% decrease was noticed in solution. The following work finally introduced a statistical approach that can adequately predict the Mn of poly(hexylene adipate) based on the choice of parameter levels, providing a handy tool in the synthesis of polyesters where the control of molecular weight is of importance.

Reactive extrusion and magnesium (II) N-heterocyclic carbene catalyst are successfully employed in continuous polylactide synthesis. The possibility of using six-membered N-heterocyclic carbene adducts to act as efficient catalysts towards the sustainable synthesis of poly(l-lactide) through ring-opening polymerization of l-lactide (LA) is first investigated in bulk batch reactions. Under optimized solvent-free conditions, polylactide (PLA) of moderate to high molecular weights and excellent optical activities are successfully achieved. These promising results are further applied in the continuous production of PLA in an extruder.

The present work deals with the building of novel, fully bio-based polyamide 11 (PA11)/polylactide (PLA) diblock copolymers (PA11 x PLA y ). The adopted two-step synthetic strategy involves first the preparation of an amino-terminated PA11 prepolymer ( i.e. , having the amino end-group available and the carboxylic one protected), to be employed subsequently as a macro-initiator in the ring-opening polymerization of d -lactide (or l -lactide). Upon tuning the lactide conversion, diblock copolymers with different PA11/PLA ratios are targeted and achieved, as demonstrated by 1 H NMR and TGA analysis. The thermal properties of these double-crystalline polymers are characterized by means of DSC. Finally, fast stereocomplexation is demonstrated upon mixing the enantiomeric PA11 x PLA y diblock pairs. Indeed, the idea behind these systems is to conjugate the properties of PLA with those of the high-performance PA11, in a cumulative rather than intermediate fashion, as for widely reported random poly(ester amide)s, but without phase separation occurring, which is the case for PLA/PA11 immiscible blends. In addition, the presence of the stereocomplex, well-known for its improved chemical/thermal resistance over PLA homopolymer, could impart even further quality to the final materials.

The development of sustainable synthetic approaches to biodegradable and biocompatible polymeric materials represents a key challenge in polymer chemistry. A novel solvent-free and organocatalyzed ring-opening (co)polymerization (ORO(c)P) method utilizing benzoic acid(BA) as simple thermostable carboxylic acid-type catalyst is proposed to not only produce structurally well-defined aliphatic homopolyesters derived from L-lactide (L-LA) and e-caprolactone (CL), but also and, unexpectedly, statistical copolyesters based on the two monomer units. RO(c)P reactions were conducted in bulk in a temperature range of 155–180 °C, in presence of alcohols as initiators. A triblock copolymer, namely, PLLA-b-PCL-b-PLLA, was also synthesized, attesting to the “controlled/living” character of this BA-OROP process. A bifunctional mechanism is proposed to operate, involving activation of both the monomer and the propagating hydroxyl by H-bonding. Very importantly, the BA organocatalyst could be readily recycled by simple sublimation and could be reused in further organocatalytic cycles.

Magnetron sputter deposition of metals onto low vapor pressure liquids is a clean and straightforward method of nanoparticle (NP) production. Herein, we discuss the production of silver nanoparticles (Ag NPs) via magnetron sputtering of a silver target onto castor oil, a biocompatible and highly available liquid. A state-of-the-Art (bipolar) high-power impulse magnetron sputtering (HiPIMS) was used for the first time for the sputtering onto liquid procedure. The effect of several parameters such as sputter time, applied power, working gas pressure, and type of sputtering plasma (direct current magnetron sputtering (DC-MS) vs. HiPIMS and bipolar HiPIMS) onto NP properties has been studied by UV–vis spectroscopy and transmission electron microscopy (TEM). The scenario of Ag NPs formation is inferred from these analyses, and further supported by mass-spectrometry and quantum-chemistry calculations. Initial Ag NPs formed in castor oil have a diameter ranging from 0.8 nm to 4 nm, its stability is discussed in terms of the plasma-liquid surface interaction and the quantum chemistry data.

© 2017 Elsevier Ltd Conjugated tootbrush copolymers are prepared by connecting end-capped poly(9,9’-dioctylfluorene) (PF) side-chains (PF) to a poly(3-alkylthiophene) (P3AT) backbone via the CuAAC reaction. The ratio of grafted/nongrafted segment is varied. The influence of the covalent attachment of sidechains to the backbone on the self-assembly is studied by UV–vis spectroscopy. By excitation of the PF side-chains energy transfer to the P3HT backbone is studied. ispartof: Polymer vol:112 pages:144-151 status: published

A poly(3-hexylthiophene)-block-perfluoropolyether-block-poly(3-hexylthiophene) (P3HT-b-PFPE-b-P3HT) triblock copolymer was synthesized by copper(I)-catalyzed alkyne–azide cycloaddition (CuAAC) in 95% yield. The copolymer was unequivocally characterized by size exclusion chromatography reaching 27 000 g mol−1 and nuclear magnetic resonance (NMR). As expected, diffusion-ordered spectroscopy NMR experiment revealed a lower diffusion coefficient (2.56 × 10-10 m2 s−1) for the P3HT-b-PFPE-b-P3HT triblock copolymer than the ethynyl end-functionalized P3HT (2.83 × 10-10 m2 s−1). Such a triblock copolymer exhibits i) a good thermal stability with no significant weight loss until 320 °C under air, ii) a glass transition of -50 °C due to the soft PFPE segment and iii) a melting peak arising from P3HT at 236 °C. The UV–vis absorption spectrum exhibits a similar absorption profile to that of pure P3HT with a vibronic structure. Analysis of terpolymer thin films by atomic force microscopy imaging and grazing incidence wide-angle X-ray scattering reveals the formation of P3HT crystallites and an “edge-on” orientation of the polymer chains towards the substrate. Preliminary photovoltaic studies on blends of this triblock copolymer combined with a fullerene derivative indicate that the devices using P3HT-b-PFPE-b-P3HT show an almost similar power conversion efficiency to commercial P3HT.

In this work, an atmospheric aerosol assisted pulsed plasma process is reported as an environmentally friendly technique for the preparation of tunable catechol-bearing thin films under solvent and catalyst free conditions. The approach relies on the direct injection of dopamine acrylamide dissolved in 2-hydroxyethylmethacrylate as comonomer into the plasma zone. By adjusting the pulsing of the electrical discharge, the reactive plasma process can be alternatively switch ON (tON) and OFF (tOFF) during different periods of time, thus allowing a facile and fine tuning of the catechol density, morphology and deposition rate of the coating. An optimal tON/tOFF ratio is established, that permits maximizing the catechol content in the deposited film. Finally, a diagram, based on the average energy input into the process, is proposed allowing for easy custom synthesis of layers with specific chemical and physical properties, thus highlighting the utility of the developed dry plasma route.

End-functionalized poly(3-hexylthiophene) (P3HT) and poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) were synthesized using controlled polymerization techniques and linked together to lead to a diblock copolymer structure via click cycloaddition. These diblock copolymers were further blended with carbon nanotubes (CNTs) to be used as cathodes in organic radical batteries. The performances of these batteries were studied during charge/discharge cycling at constant and variable current densities (C rate). In order to shed light on the importance of the diblock copolymer architecture, the results were compared to the capacities measured on electrodes made of blends of P3HT and PTMA homopolymers. Theoretical simulations were finally used to corroborate the good electrochemical properties of the synthesized diblock copolymers.

The desire for sustainability drives interest in the production of chemicals from carbon dioxide. The synthesis of poly(trimethylene carbonate), PTMC, by copolymerization of carbon dioxide and oxetane using organocatalysis affords a green route to this important polymer but has proven to be a very challenging process. Herein we report that the application of iodine, in combination with organic superbases provides a highly active system for the direct synthesis of PTMC from CO2 with very high levels of carbonate linkage (95% in selectivity). Mechanistic studies reveal the in situ formation of trimethylene carbonate which eventually polymerizes through an active chain-end process from an I2-oxetane adduct.

© 2018 American Chemical Society. The new conjugated poly(4,4-bis(2-ethylhexyl)cyclopentadithiophene-alt-p-phenylene) (PCPDTPP) has been synthesized in a controlled way via catalyst transfer condensative polymerization (CTCP) of the corresponding biaryl monomer. Therefore, a series of Ni catalysts as well as (new) Pd-PEPPSI catalysts were employed in different Kumada CTCPs (KCTCPs) and Negishi CTCPs (NCTCPs). A series of tests confirmed the absence of undesired transfer and termination reactions and, hence, the controlled character of the chain-growth polymerization with Ni(dppe)Cl2 as catalyst. This resulted in polymers with low dispersities (D = 1.2), Mn of 33 kDa, and relatively good end-group control. Furthermore, formation of PCPDTPP-b-poly(3-octylthiophene) (P3OT) block copolymers was possible. Via optical analysis and DSC measurements, we demonstrated that the conjugated alternating PCPDTPP copolymer is an amorphous, strongly fluorescent polymer with a fluorescence quantum yield (ψf) of 58% in chloroform. ispartof: MACROMOLECULES vol:51 issue:21 pages:9043-9051 status: published

The synthesis of symmetric cyclo poly(ε-caprolactone)–block–poly(l(d)-lactide) (c(PCL–b–PL(D)LA)) by combining ring-opening polymerization of ε-caprolactone and lactides and subsequent click chemistry reaction of the linear precursors containing antagonist functionalities is presented. The two blocks can sequentially crystallize and self-assemble into double crystalline spherulitic superstructures. The cyclic chain topology significantly affects both the nucleation and the crystallization of each constituent, as gathered from a comparison of the behavior of linear precursors and cyclic block copolymers. The stereochemistry of the PLA block does not have a significant effect on the nonisothermal crystallization of both linear and cyclo PCL-b-PDLA and PCL-b-PLLA copolymers., The authors acknowledge funding by the following projects: MAT2014-53437-C2-P and MAT2015-63704-P (Spanish MINECO); IT-654-13 (Basque Government), the Science Policy Office of the Belgian Federal Government (PAI 7/5), and the Belgian FRFC-FNRS (No. 2.4508.12). O.C. is Research Associate of the F.R.S.-FNRS. N.Z. acknowledges the fellowship from the UPV/EHU.

The influence of chitosaccharides on the symbiotic interaction between Bradyrhizobium and soybean was examined. The results show that chitosaccharides either positively or negatively affect soybean nodulation or plant growth depending on their molecular weight, concentration and the application methods. When directly added to the in vitro culture media, chitosan of high molecular weight inhibit Bradyrhizobium viability in a dose dependent manner while chitooligosaccharides reduce slightly the bacteria viability only at concentration equal or higher than 50 mg·L-1. Chitooligosaccharides significantly enhance nodule formation and dry mass in soybean roots at doses between 10 and 100 mg·L-1. Both types of chitosaccharides, at the highest doses (>500 mg·L-1), negatively affect plant height and root size, whereas medium doses (50 to 100 mg·L-1) increase slightly leave number. Under field conditions, foliar application of both chitosaccharides enhances growth and nodulation of soybean plants. Nevertheless, using this application method, chitosan remains more effective than chitooligosaccharides.

© 2015 American Chemical Society. Conjugated graft copolymers consisting of a chiral poly(phenyleneethynylene) (PPE) backbone and poly(3-hexylthiophene) side chains (P3HT) with different grafting degrees were synthesized. While PPE was prepared by classical Sonogashira couplings, the end-functionalized P3HT was prepared by a controlled Kumada catalyst transfer polycondensation (KCTP) allowing the installation of an acetylene end group. After some postpolymerization reactions on the PPE to introduce azide groups, the P3HT was clicked to the PPE through the CuAAC coupling reaction. Subsequently, the (chiral) self-assembly of these materials was studied by means of UV-vis and CD spectroscopy, AFM, and DSC. Finally, fluorescence spectroscopy is used to study the quenching of the PPE fluorescence by P3HT. ispartof: Macromolecules vol:48 issue:24 pages:8789-8796 status: published

© 2015 Wiley Periodicals, Inc. Conjugated graft copolymers consisting of a poly(3-hexylthiophene) (P3HT) backbone and poly(9,9'-dioctylfluorene) side chains (PF) with different grafting degrees were synthesized by the CuAAC reaction. The properties of these materials were studied by UV-Vis and fluorescence spectroscopy. The former technique provides insight in their self-assembly, while the latter is used to study the energy funneling from the PF side chains to the P3HT backbone. ispartof: Journal of Polymer Science A, Polymer Chemistry vol:54 issue:9 pages:1252-1258 status: published

In this article we investigate association of the Ni-catalyst during Kumada catalyst transfer condensative polymerization (KCTCP) and hypothesize that when adding a para-phenylene monomer to a living thiophene block to synthesize poly(thiophene)-b-poly(para-phenylene), an equilibrium exist between the incorporation of the para-phenylene monomer and the trapping of the Ni-catalyst by association with the thiophene block. We suggest that this equilibrium shifts toward the association with the thiophene block with increasing length of the thiophene block and that significant trapping only occurs when this block consist of several thiophene units.

Biomolecular machines perform types of complex molecular-level tasks that artificial molecular machines can aspire to. The ribosome, for example, translates information from the polymer track it traverses (messenger RNA) to the new polymer it constructs (a polypeptide) 1 . The sequence and number of codons read determines the sequence and number of building blocks incorporated into the biomachine-synthesized polymer. However, neither control of sequence2,3 nor the transfer of length information from one polymer to another (which to date has only been accomplished in man-made systems through template synthesis) 4 is easily achieved in the synthesis of artificial macromolecules. Rotaxane-based molecular machines5–7 have been developed that successively add amino acids8–10 (including β-amino acids 10 ) to a growing peptide chain by the action of a macrocycle moving along a mono-dispersed oligomeric track derivatized with amino-acid phenol esters. The threaded macrocycle picks up groups that block its path and links them through successive native chemical ligation reactions 11 to form a peptide sequence corresponding to the order of the building blocks on the track. Here, we show that as an alternative to translating sequence information, a rotaxane molecular machine can transfer the narrow polydispersity of a leucine-ester-derivatized polystyrene chain synthesized by atom transfer radical polymerization 12 to a molecular-machine-made homo-leucine oligomer. The resulting narrow-molecular-weight oligomer folds to an α-helical secondary structure 13 that acts as an asymmetric catalyst for the Julia–Colonna epoxidation14,15 of chalcones. The ring of a rotaxane molecule traverses a polymer track picking up leucine amino acids and synthesizing a homo-leucine oligomer, which in turn folds into an alpha helix and catalyses a chemical reaction.

Saponins are natural compounds presenting a high structural diversity whose structural characterization remains extremely challenging. Ideally, saponin structures are best established using nuclear magnetic resonance experiments conducted on isolated molecules. However, saponins are also increasingly characterized using tandem mass spectrometry (MS/MS) coupled with liquid chromatography, even if collision-induced dissociation (CID) experiments are often quite limited in accurately determining the saponin structure.We consider here ion mobility mass spectrometry (IMMS) as an orthogonal tool for the structural characterization of saponin isomers by comparing the experimental collisional cross sections (CCSs) of saponin ions with theoretical CCSs for candidate ion structures. Indeed, state-of-the-art theoretical calculations perfectly complement the experimental results, allowing the ion structures to be deciphered at the molecular level.We demonstrate that ion mobility can contribute to the structural characterization of saponins because different saponin ions present significantly distinct CCSs. Depending on the nature of the cation (in the positive ion mode), the differences in CCSs can also be exacerbated, optimizing the gas-phase separation. When associated with molecular dynamics simulations, the CCS data can be used to describe the interactions between the cations, i.e. HOur work contributes to resolve the relationship between the primary and secondary structures of saponin ions. However, it is obvious that the structural diversity and complexity of the saponins cannot be definitively unraveled by measuring a single numerical value, here the CCS. Consequently, the structural characterization of unknown saponins will be difficult to achieve based on IMMS alone. Nevertheless, we demonstrated that monodesmosidic and bidesmosidic saponins can be distinguished via IMMS.

Ring closure click chemistry methods have been used to produce cyclic c-PLLA and c-PDLA of a number-average molecular weight close to 10 kg/mol. The effects of stereochemistry of the polymer chains and their topology on their structure, nucleation, and crystallization were studied in detail employing wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), polarized light optical microscopy (PLOM), and standard and advanced differential scanning calorimetry (DSC). The crystal structures of linear and cyclic PLAs are identical to each other, and no differences in superstructural morphology could be detected. Cyclic PLA chains are able to nucleate much faster and to produce a higher number of nuclei in comparison to linear analogues, either upon cooling from the melt or upon heating from the glassy state. In the samples prepared in this work, a small fraction of linear or higher molecular weight cycles were detected (according to SEC analyses). The presence of such “impurities” retards spherulitic growth rates of c-PLAs, making them nearly the same as those of l-PLAs. On the other hand, the overall crystallization rate determined by DSC was much larger for c-PLAs, as a consequence of the enhanced nucleation that occurs in cyclic chains. The equilibrium melting temperatures of cyclic chains were determined and found to be 5 °C higher in comparison with values for l-PLAs. This result is a consequence of the lower entropy of cyclic chains in the melt. Self-nucleation studies demonstrated that c-PLAs have a shorter crystalline memory than linear analogues, as a result of their lower entanglement density. Successive self-nucleation and annealing (SSA) experiments reveal the remarkable ability of cyclic molecules to thicken, even to the point of crystallization with extended collapsed ring conformations. In general terms, stereochemistry had less influence on the results obtained in comparison with the dominating effect of chain topology., The UPV/EHU team acknowledges funding from the following projects: “UPV/EHU Infrastructure: INF 14/38”; “Mineco/FEDER: SINF 130I001726XV1/Ref: UNPV13-4E-1726” and “Mineco MAT2014-53437−C2-P”, ’Ministerio de Economia y Competitividad (MINECO), code: MAT2015-63704-P (MINECO/FEDER, UE) and by the Eusko Jaurlaritza (Basque Government), code: IT-654-13. O.C. acknowledges financial support from the European Commission and Region Wallonne FEDER program (Materia Nova) and OPTI2 MAT program of excellence, by the Interuniversity Attraction Pole Program (P7/ 05) initiated by the Belgian Science Policy office and by the FNRS-FRFC. O.C. is a Research Associate of the F.R.S.-FNRS. The Organic Synthesis and Mass Spectrometry Laboratory thanks F.R.S.-FNRS for the financial support for the acquisition of the Waters QToF Premier and Synapt-G2Si mass spectrometers and for continuing support. Finally, all authors acknowledge Research and Innovation Staff Exchange (RISE) H2020-MSCA-RISE-2017-778092, project BIODEST, for promoting cooperation between the Mons team and the UPV/EHU team.

Photoactive ruthenium-based complexes are actively studied for their biological applications as potential theragnostic agents against cancer. One major issue of these inorganic complexes is to penetrate inside cells in order to fulfil their function, either sensing the internal cell environment or exert a photocytotoxic activity. The use of lipophilic ligands allows the corresponding ruthenium complexes to passively diffuse inside cells but limits their structural and photophysical properties. Moreover, this strategy does not provide any cell selectivity. This limitation is also faced by complexes anchored on cell-penetrating peptides. In order to provide a selective cell targeting, we developed a multivalent system composed of a photoreactive ruthenium(II) complex tethered to a calix[4]arene platform bearing multiple RGD-containing cyclopentapeptides. Extensive photophysical and photochemical characterizations of this Ru(II)-calixarene conjugate as well as the study of its photoreactivity in the presence of guanosine monophosphate have been achieved. The results show that the ruthenium complex should be able to perform efficiently its photoinduced cytotoxic activity, once incorporated into targeted cancer cells thanks to the multivalent platform., info:eu-repo/semantics/published

Linear polystyrenes carrying a mid-chain triazole, esters as well as terminal secondary bromines functionalities were synthesized via activators regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP) using a bifunctional triazole containing initiator (3.8 kDa ≤ Mn,SEC ≤ 125 kDa, 1.08 ≤ ≤ 1.19) with the aim of understanding their behavior under thermal and thermomechanical stress. As reference materials-isolating the influence of individual functional groups-three polystyrene homopolymers carrying an ω-bromine chain-end functionality, α,ω-ester-bromine functionalities as well as α,ω-dibromine/mid-chain ester functionalities (2 kDa ≤ Mn,SEC ≤ 39 kDa, 1.06 ≤ ≤ 1.08) were prepared via ARGET ATRP. Furthermore, a well-defined triazole mid-chain functionalized block homopolymer, i.e. polystyrene-b-polystyrene (PS-b-PS, Mn,SEC = 4.4 kDa,= 1.08), was synthesized via a combination of ARGET ATRP and copper(i)-catalyzed azide-alkyne cycloaddition (CuAAC) as a reference material. Reference polymers without bromine and with ester/triazole functionalities were additionally investigated. Thermomechanical stress was applied to the polymers via small scale extrusion as well as a rheological assessment (G′(t), G′′(t)) under processing conditions. The thermally challenged polymers were analyzed by size-exclusion chromatography (SEC), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF-MS), proton nuclear magnetic resonance (1H NMR) and X-ray photoelectron spectroscopy (XPS) to arrive at a detailed image of the degradation susceptibility of individual functional groups, especially esters, bromines and triazole functions. The findings indicate an enhanced degradation of ATRP polymers via an accelerated ester cleavage due to HBr release at high temperatures accompanied by a concomitant molecular weight increase due to the formation of triazolium salts via the reaction of triazole units with bromine terminal chain ends. This journal is © The Royal Society of Chemistry 2015.

Several families of polymers possessing various end-groups are characterized by ion mobility mass spectrometry (IMMS). A significant contribution of the end-groups to the ion collision cross section (CCS) is observed, although their role is neglected in current fitting models described in literature. Comparing polymers prepared from different synthetic procedures might thus, be misleading with the current theoretical treatments. We show that this issue is alleviated by comparing the CCS of various polymer ions (polyesters and polyethers) as a function of the number of atoms in the macroion instead of the usual representation involving the degree of polymerization. Finally, we extract the atom number density from the spectra which gives us the possibility to evaluate the compaction of polymer ions, and by extension to discern isomeric polymers.

The title ion (HBRC- 1 ) has recently been shown to be a stable hydrogen-bridged radical cation that is easily accessible by the decarbonylation of ionized methyl oxamate, NH 2 COCOOCH 3 . In this study, we report on the intriguing reactivity of HBRC- 1 and its deuterium isotopologue [NH 2 C O D OCD 2 ] •+ towards dioxygen in the ion-molecule reaction chamber of the Mons Autospec 6F mass spectrometer. Theory and experiment agree that the encounter complex [NH 2 C(O 2 ) O H OCH 2 ] •+ is the key starting configuration for the three product ions observed. These are: NH 2 C(OOH)OH + , the hydrogen-bridged ion [CH 2 O H N(H) C O] + and NH 2 C(O 2 )OH •+ , generated by loss of HCO • , O 2 H • and CH 2 O respectively. The peroxide-type ion NH 2 C(O 2 )OH •+ generated in this experiment is not observed in the reaction of solitary ions NH 2 C OH •+ with O 2 , which is ascribed to the stabilizing effect of the CH 2 O dipole in the terbody encounter complex.

Poly(3-hexylthiophene)s were synthesized with phosphonic ester, pyridine, thiol, and phenol end-groups using functionalized air-stable Ni initiators. The protected thiol- and phenol-functionalized P3HTs were converted into thiol and phenol P3HTs by quantitative postpolymerization reactions. 1H NMR and MALDI-ToF analysis showed very high degrees of functionalization and strong control over the polymerization except for the pyridine functionalized P3HT. These functional end-groups were used to prepare hybrid materials from a broad variety of nanoparticles, including metal oxides, quantum dots, and noble metals. © 2013 American Chemical Society. ispartof: Macromolecules vol:46 issue:21 pages:8500-8508 status: published

© 2016 Wiley Periodicals, Inc. This article deals with the Kumada Catalyst Transfer Polycondensation (KCTP) of 4,7-dioctylbenzo[2,1-b:3,4-b']dithiophene (BDP-Oct) using Ni(II) catalyst or In/cat combination. A combination of MALDI MS, GPC, and 31P NMR spectroscopy is used to reveal the failure of the KCTP of this particular monomer. Intermolecular transfer reactions to monomer appeared to prevent the formation of polymer. This result is remarkable, since isomeric benzo[1,2-b:4,5-b']dithiophene polymerizes in a controlled way. The presence of a "non-aromatic double bond" in annulated monomers is discussed. ispartof: Journal of Polymer Science A, Polymer Chemistry vol:54 issue:12 pages:1706-1712 status: published

Saponins are secondary metabolites that are abundant and diversified in echinoderms. Mass spectrometry is increasingly used not only to identify saponin congeners within animal extracts but also to decipher the structure/biological activity relationships of these molecules by determining their inter-organ and inter-individual variability. The usual method requires extensive purification procedures to prepare saponin extracts compatible with mass spectrometry analysis. Here, we selected the sea star Asterias rubens as a model animal to prove that direct analysis of saponins can be performed on tissue sections. We also demonstrated that carboxymethyl cellulose can be used as an embedding medium to facilitate the cryosectioning procedure. Matrix-assisted laser desorption/ionization (MALDI) imaging was also revealed to afford interesting data on the distribution of saponin molecules within the tissues. We indeed highlight that saponins are located not only inside the body wall of the animals but also within the mucus layer that probably protects the animal against external aggressions. Graphical Abstract Saponins are the most abundant secondary metabolites in sea stars. They should therefore participate in important biological activities. Here, MALDI imaging is presented as a powerful method to determine the spatial distribution of saponins within the animal tissues. The inhomogeneity of the intra-organ saponin distribution is highlighted, paving the way for future elegant structure/activity relationship investigations.

Tandem mass spectrometry is increasingly applied to polymer ions in the context of in-depth structural characterization. In particular, the well-known collision-induced dissociation (CID) methodology is nowadays advantageously used to characterize end-groups and to distinguish isomeric polymer ions. When applied to sodium-cationized polyesters, CID was demonstrated to mainly involve charge remote fragmentation processes and consecutive as well as competitive dissociation pathways. In the present report, an experimental and theoretical study of collision induced dissociation of isomeric sodium cationized polylactide was investigated. The investigated polymers were designed to obtain oligomers only differentiated on the basis of regioisomeric end-groups, using ortho-, meta-, and para-methylbenzyl alcohols as initiators. The CID spectra revealed the presence of competitive charge driven and charge remote fragmentations. In particular, the charge induced fragmentations allowed the minute distinction between the three isomeric end-groups. The intermediacy of an ion/neutral complex was proposed to account for the observed decomposition and some theoretical calculations were performed to support the proposal.